For inhomogeneous lattices we generalize the classical Gaussian model, i.e. it is proposed that the Gaussian type distribution constant and the external magnetic field of site i in this model depend on the coordinatio...For inhomogeneous lattices we generalize the classical Gaussian model, i.e. it is proposed that the Gaussian type distribution constant and the external magnetic field of site i in this model depend on the coordination number qi of site i, and that the relation $b_{q_i}/b_{q_j} = q{_i}/q{_j}$ holds among bq's, where bq is the Gaussian type distribution constant of site j. Using the decimation real-space renormalization group following the spin-rescaling method, the critical points and critical exponents of the Gaussian model are calculated on some Koch type curves and a family of the diamond-type hierarchical (or DH) lattices. At the critical points, it is found that the nearest-neighbor interaction and the magnetic field of site j can be expressed in the form $K^* = b{_q }_{_i } /q{_i } and h_{q_j }^* = 0$ respectively. It is also found that most critical exponents depend on the fractal dimensionality of a fractal system. For the family of the DH lattices, the results are identical with the exact results on translation symmetric lattices, and if the fractal dimensionalityd f=4, the Gaussian model and the mean field theories give the same results.展开更多
With the deepening of neural network research,object detection has been developed rapidly in recent years,and video object detection methods have gradually attracted the attention of scholars,especially frameworks inc...With the deepening of neural network research,object detection has been developed rapidly in recent years,and video object detection methods have gradually attracted the attention of scholars,especially frameworks including multiple object tracking and detection.Most current works prefer to build the paradigm for multiple object tracking and detection by multi-task learning.Different with others,a multi-level temporal feature fusion structure is proposed in this paper to improve the performance of framework by utilizing the constraint of video temporal consistency.For training the temporal network end-to-end,a feature exchange training strategy is put forward for training the temporal feature fusion structure efficiently.The proposed method is tested on several acknowledged benchmarks,and encouraging results are obtained compared with the famous joint detection and tracking framework.The ablation experiment answers the problem of a good position for temporal feature fusion.展开更多
With the advent of the information age, it will be more troublesome to search for a lot of relevant knowledge to find the information you need. Text reasoning is a very basic and important part of multi-hop question a...With the advent of the information age, it will be more troublesome to search for a lot of relevant knowledge to find the information you need. Text reasoning is a very basic and important part of multi-hop question and answer tasks. This paper aims to study the integrity, uniformity, and speed of computational intelligence inference data capabilities. That is why multi-hop reasoning came into being, but it is still in its infancy, that is, it is far from enough to conduct multi-hop question and answer questions, such as search breadth, process complexity, response speed, comprehensiveness of information, etc. This paper makes a text comparison between traditional information retrieval and computational intelligence through corpus relevancy and other computing methods. The study finds that in the face of multi-hop question and answer reasoning, the reasoning data that traditional retrieval methods lagged behind in intelligence are about 35% worse. It shows that computational intelligence would be more complete, unified, and faster than traditional retrieval methods. This paper also introduces the relevant points of text reasoning and describes the process of the multi-hop question answering system, as well as the subsequent discussions and expectations.展开更多
In this paper, we obtain some necessary and sufficient conditions for the oscillation of all positive solutions of a delay Logistic equation with continuous and piecewise constant arguments about the positive equilibr...In this paper, we obtain some necessary and sufficient conditions for the oscillation of all positive solutions of a delay Logistic equation with continuous and piecewise constant arguments about the positive equilibrium.展开更多
In this paper, both low order and high order extensions of the Iyengar type inequality are obtained. Such extensions are the best possible in the same sense as that of the Iyengar inequality. hzrthermore, the Chebyshe...In this paper, both low order and high order extensions of the Iyengar type inequality are obtained. Such extensions are the best possible in the same sense as that of the Iyengar inequality. hzrthermore, the Chebyshev central algorithms of integrals for some function classes and some related problems are also considered and investigated.展开更多
The kinetic behaviors of aggregation-fragmentation-annihilation processes of three n-species systems arestudied in this paper. Aggregation reaction occurs only between the same species but irreversible annihilation re...The kinetic behaviors of aggregation-fragmentation-annihilation processes of three n-species systems arestudied in this paper. Aggregation reaction occurs only between the same species but irreversible annihilation reactionoccurs between two different species, and meanwhile the fragmentation reaction coexists. Based on the mean-field theory,we investigate the rate equations of the processes and obtain the asymptotic descriptions of the cluster-mass distributionsfor the symmetrical cases. We find that the fragmentation reaction may lead to the complete breakdown of the standardscaling description for the cluster-mass distribution of each species contrast to the scaling behavior of aggregation-annihilation processes without fragmentation.In our joint annihilation model, we also observe that the kinetic behaviorsof distinct species are quite complicated for the case with different initial concentrations. The cluster-mass distributionof heavy species with the largest initial concentration possesses peculiar scaling properties, while that of light species hasnot scaling behavior.展开更多
Tetrahydrofuran ring can be opened with acyl chlorides or anhydrides catalyzed by gallium triiodides to afford iodo esters under mild conditions in good yields.
In any classical value-based reinforcement learning method,an agent,despite of its continuous interactions with the environment,is yet unable to quickly generate a complete and independent description of the entire en...In any classical value-based reinforcement learning method,an agent,despite of its continuous interactions with the environment,is yet unable to quickly generate a complete and independent description of the entire environment,leaving the learning method to struggle with a difficult dilemma of choosing between the two tasks,namely exploration and exploitation.This problem becomes more pronounced when the agent has to deal with a dynamic environment,of which the configuration and/or parameters are constantly changing.In this paper,this problem is approached by first mapping a reinforcement learning scheme to a directed graph,and the set that contains all the states already explored shall continue to be exploited in the context of such a graph.We have proved that the two tasks of exploration and exploitation eventually converge in the decision-making process,and thus,there is no need to face the exploration vs.exploitation tradeoff as all the existing reinforcement learning methods do.Rather this observation indicates that a reinforcement learning scheme is essentially the same as searching for the shortest path in a dynamic environment,which is readily tackled by a modified Floyd-Warshall algorithm as proposed in the paper.The experimental results have confirmed that the proposed graph-based reinforcement learning algorithm has significantly higher performance than both standard Q-learning algorithm and improved Q-learning algorithm in solving mazes,rendering it an algorithm of choice in applications involving dynamic environments.展开更多
In recent years,nonlinear chemical reactions,mechanisms and complex phenomena inunhalogen aqueous reaction systems have attracted much attention.Jesen oscillator andsulfide-sulfite-oxygen-methylene blue oscillator aro...In recent years,nonlinear chemical reactions,mechanisms and complex phenomena inunhalogen aqueous reaction systems have attracted much attention.Jesen oscillator andsulfide-sulfite-oxygen-methylene blue oscillator aroused great interest in nonlinear reactionsystems without halogen.Later,hydrogen peroxide-thiocyanate-copper sulfate reaction wasdesigned to display bistability and oscillation.According to the experimental results at展开更多
The title compound, bis( μ 2 aqua)(aqua)(3 carboxy acrylate) monosodium(Ⅰ), was synthesized in an ethanol water solution and its crystal structure was determined by means of X ray diffraction. The crystal is triclin...The title compound, bis( μ 2 aqua)(aqua)(3 carboxy acrylate) monosodium(Ⅰ), was synthesized in an ethanol water solution and its crystal structure was determined by means of X ray diffraction. The crystal is triclinic , space group P 1 with the cell parameters a =0 592 4(2) nm, b =0 635 7(3) nm, c =1 117 7(6) nm, α =104 18°, β =91 53°, γ =100 19°, V =0 400 6(3) nm 3, Z =2, the final R value is 0 033 5. The supramolecule is made up of coordination chains, which are further extended into a three dimensional network via the hydrogen bonding interactions.展开更多
The decolorization of Direct Black 22 by Aspergillus ficuum has been studied. It was found that Aspergillus ficuum could effectively decolorize Direct Black 22 especially when grown as pelleted mycelia. Results showed...The decolorization of Direct Black 22 by Aspergillus ficuum has been studied. It was found that Aspergillus ficuum could effectively decolorize Direct Black 22 especially when grown as pelleted mycelia. Results showed that the media containing Direct Black 22 at 50 mg/L could be decolorized by 98.05% of the initial color in 24 h. The optimum pH and temperature of decolorization are 4.0 and 33 °C respectively. Aeration was quite beneficial to decolorization. Medium composition and the concentration of Direct Black 22 could affect the rate of decolorization. The dye degraded products assayed by UV-visible spectrophotometer and macroscopic observation showed that the decolorization of Direct Black 22 by mycelial pellets includes two important processes: bioadsorption and biodegradation. The degradation experiment agree with the Michaelis-Menten kinetics equation.展开更多
Catalyzed by zinc bromide, tetrahydrofuran ring can be opened with acyloxyphos- phonium bromide generated in situ to afford 4-bromobutyl esters under mild conditions in good to excellent yields.
The Gaussian model on Sierpinski carpets with two types of nearest neighbour interactions K and Kw and two corresponding types of the Gaussian.distribution constants b and bw is constructed by generalizing that on tra...The Gaussian model on Sierpinski carpets with two types of nearest neighbour interactions K and Kw and two corresponding types of the Gaussian.distribution constants b and bw is constructed by generalizing that on translationally invariant square lattice.The critical behaviours are studied by the renormalization-group approach and spin rescaling method.They are found to be quite different from that on translationally invariant square lattice.There are two critical points at(K^(*)=b,K^(*)_(w)=0)and(K^(*)=0,K^(*)_(w)=bw),and the correlation length critical exponents are calculated.展开更多
Applying randomly amplified polymorphic DNA (RAPD), the genetic variation of Cabomba caro- liniana Gray (cabomba or fanwort), a new alien plant in China, was analyzed in this paper. Total 143 bands, in- cluding 47 pol...Applying randomly amplified polymorphic DNA (RAPD), the genetic variation of Cabomba caro- liniana Gray (cabomba or fanwort), a new alien plant in China, was analyzed in this paper. Total 143 bands, in- cluding 47 polymorphic bands, were amplified from 23 primers in 20 samples. The sampling distance was large, but its genetic diversity was low. The main results were that: (1) Cabomba, which grew and dispersed mainly in fragment, was an abundant and dominant species in freshwater, and its main dispersal mechanism was vegetative reproduction. (2) Cabomba was originally introduced into China as an aquarium submerged plant. Somehow, those discarded cabomba became invasive species in the areas of Hangzhou, Shanghai, and Meicheng, and other places. (3) Although the level of genetic diversity in cabomba was low, their rapid dispersion and propagation could seriously harm to local aquatic community. Therefore, specific measure should be used to control cabomba from uncontrolled spreading and damage to local vegetation communities.展开更多
This paper studies the long time behavior of the following Cauchy problem δu/δt＋σδ^4u/δx^4＋ru＋uδu/δx=f,x∈R,t〉0,The authors prove the existence of global attractor by showing the corresponding operator semi...This paper studies the long time behavior of the following Cauchy problem δu/δt＋σδ^4u/δx^4＋ru＋uδu/δx=f,x∈R,t〉0,The authors prove the existence of global attractor by showing the corresponding operator semigroup is asymptotically compact.展开更多
The analysis of residue-residue contacts in protein structures can shed some light on our understanding of the folding and stability of proteins. In this paper, we study the statistical properties of long-range and sh...The analysis of residue-residue contacts in protein structures can shed some light on our understanding of the folding and stability of proteins. In this paper, we study the statistical properties of long-range and short-range residue- residue contacts of 91 globular proteins using CSU software and analyze the importance of long-range contacts in globular protein structure. There are many short-range and long-range contacts in globular proteins, and it is found that the average number of long-range contacts per residue is 5.63 and the percentage of residue-residue contacts which are involved in long- range ones is 59.4%. In more detail, the distribution of long-range contacts in different residue intervals is investigated and it is found that the residues occurring in the interval range of 4-10 residues apart in the sequence contribute more long-range contacts to the stability of globular protein. The number of long-range contacts per residue, which is a measure of ability to form residue-residue contacts, is also calculated for 20 different amino acid residues. It is shown that hydrophobic residues (including Leu, Val, He, Met, Phe, Tyr, Cys and Trp) having a large number of long-range contacts easily form long-range contacts, while the hydrophilic amino acids (including Ala, Gly, Thr, His, Glu, Gln, Asp, Asn, Lys, Ser, Arg, and Pro) form long-range contacts with more difficulty. The relationship between the Fauchere-Pliska hydrophobicity scale (FPH) and the number of short-range and long-range contacts per residue for 20 amino acid residues is also studied. An approximately linear relationship between the Fauchere-Pliska hydrophobicity scale (FPH) and the number of long-range contacts per residue CL, is found and can be expressed as CL = a + b × FPH where a = 5.04 and b = 1.23. These results can help us to understand the role of residue-residue contacts in globular protein structure.展开更多
It is important to know the rate of intra-molecular contact formation in proteins in order to understand how proteins fold clearly. Here we investigate the rate of intra-molecular contact formation in short two-dimens...It is important to know the rate of intra-molecular contact formation in proteins in order to understand how proteins fold clearly. Here we investigate the rate of intra-molecular contact formation in short two-dimensional compact polymer chains by calculating the probability distribution p（r） of end-to-end distance r using the enumeration calculation method and HP model on two-dimensional square lattice. The probability distribution of end-to-end distance p（r） of short two-dimensional compact polymers chains may consist of two parts, i.e. p（r） = p1（r） ＋ p2（r）, where p1（r） and p2（r） are different for small r. The rate of contact formation decreases monotonically with the number of bonds N, and the rate approximately conforms to the scaling relation of k（N）∝ N^-α. Here the value of α increases with the contact radius a and it also depends on the percentage of H （hydrophobic） residues in the sequences of compact chains and the energy parameters of ^εНН、 ^εНН and ^εpp. Some comparisons of theoretical predictions with experimental results are also made. This investigation may help us to understand the protein folding.展开更多
A new dimeric lanthanum (Ⅲ) complex [La_2(phen)_2(C_7H_3N_2O_6)_6] (phen=1, 10-phenanthroline) was synthesized by the hydrothermal method and determined by single crystal X-ray diffraction analysis. The La(Ⅲ) ion is...A new dimeric lanthanum (Ⅲ) complex [La_2(phen)_2(C_7H_3N_2O_6)_6] (phen=1, 10-phenanthroline) was synthesized by the hydrothermal method and determined by single crystal X-ray diffraction analysis. The La(Ⅲ) ion is coordinated to seven oxygen atoms from five carboxylate groups and two nitrogen atoms from a phen ligand, forming a monocapped square antiprismatic geometry. Six carboxylate groups coordinate to two La(Ⅲ) ions in three modes which are chelating bidentate, bridging bidentate and bridging tridentate. The crystal is triclinic with space group P-1, a=1.2030(4) nm, b=1.2962(5) nm, c=1.3330(5) nm, α=104.410(5)°, β=114.048(4)°, γ=100.054 (4)°, V=1.7467 (10) nm^3, M_r=952.46, Z=2, D_c=1.811 g·cm^(-3), F(000)=944, S=1.017, μ=1.320 mm^(-1), with R1=0.0298 and wR2=0.0625.展开更多
Azido-3,5-dichloropyridine and 2-azido-5-chloro-3-fluoropyridine were given by reaction of sodium azide with 2,3,5-trichloropyridine, 3,5-dichloro-2-fluoropyridine or 5-chloro-2,3-difluoropyridine in ionic liquids. 1,...Azido-3,5-dichloropyridine and 2-azido-5-chloro-3-fluoropyridine were given by reaction of sodium azide with 2,3,5-trichloropyridine, 3,5-dichloro-2-fluoropyridine or 5-chloro-2,3-difluoropyridine in ionic liquids. 1,3-Dipolar cycloaddition of 2-azido-3,5-dichloropyridine or 2-azido-5-chloro-3-fluoropyridine to alkynes in ionic liquids afforded the corresponding 1,4,5-trisubstituted [1,2,3]-triazoles in good yields and regioselectivities.展开更多
文摘For inhomogeneous lattices we generalize the classical Gaussian model, i.e. it is proposed that the Gaussian type distribution constant and the external magnetic field of site i in this model depend on the coordination number qi of site i, and that the relation $b_{q_i}/b_{q_j} = q{_i}/q{_j}$ holds among bq's, where bq is the Gaussian type distribution constant of site j. Using the decimation real-space renormalization group following the spin-rescaling method, the critical points and critical exponents of the Gaussian model are calculated on some Koch type curves and a family of the diamond-type hierarchical (or DH) lattices. At the critical points, it is found that the nearest-neighbor interaction and the magnetic field of site j can be expressed in the form $K^* = b{_q }_{_i } /q{_i } and h_{q_j }^* = 0$ respectively. It is also found that most critical exponents depend on the fractal dimensionality of a fractal system. For the family of the DH lattices, the results are identical with the exact results on translation symmetric lattices, and if the fractal dimensionalityd f=4, the Gaussian model and the mean field theories give the same results.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(No.LQ24F020016)the General Scientific Research Fund of Zhejiang Provincial Education Department(No.Y202248776)+1 种基金the Wenzhou Science and Technology Plan Project(No.G20220035)the Wenzhou Key Laboratory Construction Project(No.2022HZSY0048)。
文摘With the deepening of neural network research,object detection has been developed rapidly in recent years,and video object detection methods have gradually attracted the attention of scholars,especially frameworks including multiple object tracking and detection.Most current works prefer to build the paradigm for multiple object tracking and detection by multi-task learning.Different with others,a multi-level temporal feature fusion structure is proposed in this paper to improve the performance of framework by utilizing the constraint of video temporal consistency.For training the temporal network end-to-end,a feature exchange training strategy is put forward for training the temporal feature fusion structure efficiently.The proposed method is tested on several acknowledged benchmarks,and encouraging results are obtained compared with the famous joint detection and tracking framework.The ablation experiment answers the problem of a good position for temporal feature fusion.
文摘With the advent of the information age, it will be more troublesome to search for a lot of relevant knowledge to find the information you need. Text reasoning is a very basic and important part of multi-hop question and answer tasks. This paper aims to study the integrity, uniformity, and speed of computational intelligence inference data capabilities. That is why multi-hop reasoning came into being, but it is still in its infancy, that is, it is far from enough to conduct multi-hop question and answer questions, such as search breadth, process complexity, response speed, comprehensiveness of information, etc. This paper makes a text comparison between traditional information retrieval and computational intelligence through corpus relevancy and other computing methods. The study finds that in the face of multi-hop question and answer reasoning, the reasoning data that traditional retrieval methods lagged behind in intelligence are about 35% worse. It shows that computational intelligence would be more complete, unified, and faster than traditional retrieval methods. This paper also introduces the relevant points of text reasoning and describes the process of the multi-hop question answering system, as well as the subsequent discussions and expectations.
基金This work was partially supported by the National Natural Science Foundation of China (10071045)Foundation of Zhejiang for Middle-young-aged Leader of Branch of Learning.
文摘In this paper, we obtain some necessary and sufficient conditions for the oscillation of all positive solutions of a delay Logistic equation with continuous and piecewise constant arguments about the positive equilibrium.
基金the Special Funds for Major State Basic Research Projects (Grant No.G19990328) National Science Foundation of China (Grant No.10471128)
文摘In this paper, both low order and high order extensions of the Iyengar type inequality are obtained. Such extensions are the best possible in the same sense as that of the Iyengar inequality. hzrthermore, the Chebyshev central algorithms of integrals for some function classes and some related problems are also considered and investigated.
文摘The kinetic behaviors of aggregation-fragmentation-annihilation processes of three n-species systems arestudied in this paper. Aggregation reaction occurs only between the same species but irreversible annihilation reactionoccurs between two different species, and meanwhile the fragmentation reaction coexists. Based on the mean-field theory,we investigate the rate equations of the processes and obtain the asymptotic descriptions of the cluster-mass distributionsfor the symmetrical cases. We find that the fragmentation reaction may lead to the complete breakdown of the standardscaling description for the cluster-mass distribution of each species contrast to the scaling behavior of aggregation-annihilation processes without fragmentation.In our joint annihilation model, we also observe that the kinetic behaviorsof distinct species are quite complicated for the case with different initial concentrations. The cluster-mass distributionof heavy species with the largest initial concentration possesses peculiar scaling properties, while that of light species hasnot scaling behavior.
基金the National Natural Science Foundation of China !298720I0the NSF of she-hang Provincethe Laboratory of Organometallic Ch
文摘Tetrahydrofuran ring can be opened with acyl chlorides or anhydrides catalyzed by gallium triiodides to afford iodo esters under mild conditions in good yields.
基金This research work is supported by Fujian Province Nature Science Foundation under Grant No.2018J01553.
文摘In any classical value-based reinforcement learning method,an agent,despite of its continuous interactions with the environment,is yet unable to quickly generate a complete and independent description of the entire environment,leaving the learning method to struggle with a difficult dilemma of choosing between the two tasks,namely exploration and exploitation.This problem becomes more pronounced when the agent has to deal with a dynamic environment,of which the configuration and/or parameters are constantly changing.In this paper,this problem is approached by first mapping a reinforcement learning scheme to a directed graph,and the set that contains all the states already explored shall continue to be exploited in the context of such a graph.We have proved that the two tasks of exploration and exploitation eventually converge in the decision-making process,and thus,there is no need to face the exploration vs.exploitation tradeoff as all the existing reinforcement learning methods do.Rather this observation indicates that a reinforcement learning scheme is essentially the same as searching for the shortest path in a dynamic environment,which is readily tackled by a modified Floyd-Warshall algorithm as proposed in the paper.The experimental results have confirmed that the proposed graph-based reinforcement learning algorithm has significantly higher performance than both standard Q-learning algorithm and improved Q-learning algorithm in solving mazes,rendering it an algorithm of choice in applications involving dynamic environments.
基金supported by the National Natural Science Foundation of China.
文摘In recent years,nonlinear chemical reactions,mechanisms and complex phenomena inunhalogen aqueous reaction systems have attracted much attention.Jesen oscillator andsulfide-sulfite-oxygen-methylene blue oscillator aroused great interest in nonlinear reactionsystems without halogen.Later,hydrogen peroxide-thiocyanate-copper sulfate reaction wasdesigned to display bistability and oscillation.According to the experimental results at
基金Supported by the Education Comm ission of Zhejiang Province(No. 2 0 0 10 12 9) and " 5 5 1" Distinguished PersonFoundation of Wenzhou.
文摘The title compound, bis( μ 2 aqua)(aqua)(3 carboxy acrylate) monosodium(Ⅰ), was synthesized in an ethanol water solution and its crystal structure was determined by means of X ray diffraction. The crystal is triclinic , space group P 1 with the cell parameters a =0 592 4(2) nm, b =0 635 7(3) nm, c =1 117 7(6) nm, α =104 18°, β =91 53°, γ =100 19°, V =0 400 6(3) nm 3, Z =2, the final R value is 0 033 5. The supramolecule is made up of coordination chains, which are further extended into a three dimensional network via the hydrogen bonding interactions.
文摘The decolorization of Direct Black 22 by Aspergillus ficuum has been studied. It was found that Aspergillus ficuum could effectively decolorize Direct Black 22 especially when grown as pelleted mycelia. Results showed that the media containing Direct Black 22 at 50 mg/L could be decolorized by 98.05% of the initial color in 24 h. The optimum pH and temperature of decolorization are 4.0 and 33 °C respectively. Aeration was quite beneficial to decolorization. Medium composition and the concentration of Direct Black 22 could affect the rate of decolorization. The dye degraded products assayed by UV-visible spectrophotometer and macroscopic observation showed that the decolorization of Direct Black 22 by mycelial pellets includes two important processes: bioadsorption and biodegradation. The degradation experiment agree with the Michaelis-Menten kinetics equation.
文摘Catalyzed by zinc bromide, tetrahydrofuran ring can be opened with acyloxyphos- phonium bromide generated in situ to afford 4-bromobutyl esters under mild conditions in good to excellent yields.
基金Supported by the Foundation of“151 Talent Engineering”of Zhejiang Province,and the Foundation of“551 Talent Engineering”of Wenzhou City of China.
文摘The Gaussian model on Sierpinski carpets with two types of nearest neighbour interactions K and Kw and two corresponding types of the Gaussian.distribution constants b and bw is constructed by generalizing that on translationally invariant square lattice.The critical behaviours are studied by the renormalization-group approach and spin rescaling method.They are found to be quite different from that on translationally invariant square lattice.There are two critical points at(K^(*)=b,K^(*)_(w)=0)and(K^(*)=0,K^(*)_(w)=bw),and the correlation length critical exponents are calculated.
基金Supported by National Natural Science Foundation of China (No.39970145) and Major State Basic Research Development Program ofChina (No. G2000046803)
文摘Applying randomly amplified polymorphic DNA (RAPD), the genetic variation of Cabomba caro- liniana Gray (cabomba or fanwort), a new alien plant in China, was analyzed in this paper. Total 143 bands, in- cluding 47 polymorphic bands, were amplified from 23 primers in 20 samples. The sampling distance was large, but its genetic diversity was low. The main results were that: (1) Cabomba, which grew and dispersed mainly in fragment, was an abundant and dominant species in freshwater, and its main dispersal mechanism was vegetative reproduction. (2) Cabomba was originally introduced into China as an aquarium submerged plant. Somehow, those discarded cabomba became invasive species in the areas of Hangzhou, Shanghai, and Meicheng, and other places. (3) Although the level of genetic diversity in cabomba was low, their rapid dispersion and propagation could seriously harm to local aquatic community. Therefore, specific measure should be used to control cabomba from uncontrolled spreading and damage to local vegetation communities.
基金Supported by the Natural Science Foundation of China(10001013)Supported by the NSF Zhejiang Province(M103043)Supported by NSF of Wenzhou Normal College NSF(2003Y16)
文摘This paper studies the long time behavior of the following Cauchy problem δu/δt＋σδ^4u/δx^4＋ru＋uδu/δx=f,x∈R,t〉0,The authors prove the existence of global attractor by showing the corresponding operator semigroup is asymptotically compact.
基金This work was supported by the National Natural Science Foundation of China (Nos. 29874012, 20174036, and20274040), and the Natural Science Foundation of Zhejiang Province (10102) and Science Technology Development Plan of Wenzhou City (S2002A014).
文摘The analysis of residue-residue contacts in protein structures can shed some light on our understanding of the folding and stability of proteins. In this paper, we study the statistical properties of long-range and short-range residue- residue contacts of 91 globular proteins using CSU software and analyze the importance of long-range contacts in globular protein structure. There are many short-range and long-range contacts in globular proteins, and it is found that the average number of long-range contacts per residue is 5.63 and the percentage of residue-residue contacts which are involved in long- range ones is 59.4%. In more detail, the distribution of long-range contacts in different residue intervals is investigated and it is found that the residues occurring in the interval range of 4-10 residues apart in the sequence contribute more long-range contacts to the stability of globular protein. The number of long-range contacts per residue, which is a measure of ability to form residue-residue contacts, is also calculated for 20 different amino acid residues. It is shown that hydrophobic residues (including Leu, Val, He, Met, Phe, Tyr, Cys and Trp) having a large number of long-range contacts easily form long-range contacts, while the hydrophilic amino acids (including Ala, Gly, Thr, His, Glu, Gln, Asp, Asn, Lys, Ser, Arg, and Pro) form long-range contacts with more difficulty. The relationship between the Fauchere-Pliska hydrophobicity scale (FPH) and the number of short-range and long-range contacts per residue for 20 amino acid residues is also studied. An approximately linear relationship between the Fauchere-Pliska hydrophobicity scale (FPH) and the number of long-range contacts per residue CL, is found and can be expressed as CL = a + b × FPH where a = 5.04 and b = 1.23. These results can help us to understand the role of residue-residue contacts in globular protein structure.
基金This research was financially supported by the National Natural Science Foundation of China(Nos.20174036,20274074,20574052)the Natural Science Foundation of Zhejiang Province(No.R404047).
文摘It is important to know the rate of intra-molecular contact formation in proteins in order to understand how proteins fold clearly. Here we investigate the rate of intra-molecular contact formation in short two-dimensional compact polymer chains by calculating the probability distribution p（r） of end-to-end distance r using the enumeration calculation method and HP model on two-dimensional square lattice. The probability distribution of end-to-end distance p（r） of short two-dimensional compact polymers chains may consist of two parts, i.e. p（r） = p1（r） ＋ p2（r）, where p1（r） and p2（r） are different for small r. The rate of contact formation decreases monotonically with the number of bonds N, and the rate approximately conforms to the scaling relation of k（N）∝ N^-α. Here the value of α increases with the contact radius a and it also depends on the percentage of H （hydrophobic） residues in the sequences of compact chains and the energy parameters of ^εНН、 ^εНН and ^εpp. Some comparisons of theoretical predictions with experimental results are also made. This investigation may help us to understand the protein folding.
文摘A new dimeric lanthanum (Ⅲ) complex [La_2(phen)_2(C_7H_3N_2O_6)_6] (phen=1, 10-phenanthroline) was synthesized by the hydrothermal method and determined by single crystal X-ray diffraction analysis. The La(Ⅲ) ion is coordinated to seven oxygen atoms from five carboxylate groups and two nitrogen atoms from a phen ligand, forming a monocapped square antiprismatic geometry. Six carboxylate groups coordinate to two La(Ⅲ) ions in three modes which are chelating bidentate, bridging bidentate and bridging tridentate. The crystal is triclinic with space group P-1, a=1.2030(4) nm, b=1.2962(5) nm, c=1.3330(5) nm, α=104.410(5)°, β=114.048(4)°, γ=100.054 (4)°, V=1.7467 (10) nm^3, M_r=952.46, Z=2, D_c=1.811 g·cm^(-3), F(000)=944, S=1.017, μ=1.320 mm^(-1), with R1=0.0298 and wR2=0.0625.
基金Project supported by the National Natural Science Foundation of China (No. 20272075) and the National Natural Science Foundation of Zhejiang Province (No. M203001).
文摘Azido-3,5-dichloropyridine and 2-azido-5-chloro-3-fluoropyridine were given by reaction of sodium azide with 2,3,5-trichloropyridine, 3,5-dichloro-2-fluoropyridine or 5-chloro-2,3-difluoropyridine in ionic liquids. 1,3-Dipolar cycloaddition of 2-azido-3,5-dichloropyridine or 2-azido-5-chloro-3-fluoropyridine to alkynes in ionic liquids afforded the corresponding 1,4,5-trisubstituted [1,2,3]-triazoles in good yields and regioselectivities.
