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提高我国女子七项全能运动水平的对策分析 被引量:10
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作者 董俊 《北京体育大学学报》 CSSCI 北大核心 2005年第7期998-1000,共3页
运用文献资料、调查访问、数理统计、比较分析等方法,对我国与世界女子七项全能运动成绩差距的主要原因进行了比较研究。认为:我国女子七项全能各单项成绩、技术等级发展不均衡,各单项成绩及整体水平方面均明显低于世界选手,投掷类项目... 运用文献资料、调查访问、数理统计、比较分析等方法,对我国与世界女子七项全能运动成绩差距的主要原因进行了比较研究。认为:我国女子七项全能各单项成绩、技术等级发展不均衡,各单项成绩及整体水平方面均明显低于世界选手,投掷类项目是影响我国女子七项全能发展的主要因素,为我国女子七项全能运动训练和比赛提供决策参考。 展开更多
关键词 女子七项全能 单项成绩 单项得分率 差距
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从亚洲软式网球对抗赛看中国与亚洲强队的差距 被引量:6
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作者 唐小林 《成都体育学院学报》 CSSCI 北大核心 2000年第4期72-75,共4页
对中国软式网球与亚洲强队的差距问题作了有关数据统计 ,对比分析结果及临场观察表明 ,中国软式网球与亚洲强队有比较明显的差距。为此 ,在今后的训练中应针对性地狠抓前卫基本技术训练 ,提高前卫技术运用能力 ;将发、接发及前 4拍的技... 对中国软式网球与亚洲强队的差距问题作了有关数据统计 ,对比分析结果及临场观察表明 ,中国软式网球与亚洲强队有比较明显的差距。为此 ,在今后的训练中应针对性地狠抓前卫基本技术训练 ,提高前卫技术运用能力 ;将发、接发及前 4拍的技术作为突破口 ,形成独特的得分手段 ;抓好后卫连续进攻以及节奏转换的能力训练 ;重视前、后卫战术配合意识及能力的培养 ;重视非技术因素影响 ,提高实战能力等等 ,从而逐步缩小中国与亚洲强队的差距。 展开更多
关键词 软式网球 对抗赛 中国 亚洲 战术 技术训练
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环形障碍物对瓦斯爆炸影响的实验研究 被引量:8
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作者 秦涧 谭迎新 《中北大学学报(自然科学版)》 CAS 北大核心 2011年第6期717-722,共6页
研究障碍物对瓦斯爆炸的影响,对预防和减小煤矿巷道内的瓦斯爆炸危害具有重要意义.利用长径比约为70的水平管道式爆炸实验装置,在常温常压下研究环形障碍物的数量、阻塞率和间距对瓦斯爆炸特性的影响.结果表明:障碍物的存在对瓦斯爆炸... 研究障碍物对瓦斯爆炸的影响,对预防和减小煤矿巷道内的瓦斯爆炸危害具有重要意义.利用长径比约为70的水平管道式爆炸实验装置,在常温常压下研究环形障碍物的数量、阻塞率和间距对瓦斯爆炸特性的影响.结果表明:障碍物的存在对瓦斯爆炸具有激励作用,其中障碍物的数量和阻塞率激励效果明显,而间距对其影响较小.研究结果对于预防和控制瓦斯爆炸事故有一定的参考意义. 展开更多
关键词 障碍物 瓦斯 间距 爆炸压力 火焰速度
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基于临界域法的桥梁钢丝腐蚀疲劳寿命 被引量:6
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作者 叶华文 黄云 +1 位作者 王义强 强士中 《西南交通大学学报》 EI CSCD 北大核心 2015年第2期294-299,共6页
为评估桥梁钢丝服役期间的腐蚀疲劳性能,采用临界域法,根据钢丝腐蚀坑局部应力梯度求解临界距离.采用精细有限元法,建立了钢丝腐蚀疲劳寿命预测模型;通过圆形、三角形和含切口的三角形3种形状腐蚀坑钢丝的疲劳试验,获得了它们的疲劳寿命... 为评估桥梁钢丝服役期间的腐蚀疲劳性能,采用临界域法,根据钢丝腐蚀坑局部应力梯度求解临界距离.采用精细有限元法,建立了钢丝腐蚀疲劳寿命预测模型;通过圆形、三角形和含切口的三角形3种形状腐蚀坑钢丝的疲劳试验,获得了它们的疲劳寿命,并与疲劳寿命的预测结果进行比较.研究结果表明:轴向应力分布决定钢丝的疲劳强度;临界距离随应力集中效应增强而减小;腐蚀钢丝的剩余寿命可根据应力集中系数评估,应力集中系数大于3的腐蚀钢丝应考虑更换. 展开更多
关键词 桥梁缆索 镀锌钢丝 腐蚀疲劳 临界域法 应力集中系数 TCD (theory of critical distances)
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High-resolution photogrammetry to measure physical aperture of two separated rock fracture surfaces
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作者 Masoud Torkan Mateusz Janiszewski +2 位作者 Lauri Uotinen Alireza Baghbanan Mikael Rinne 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第8期2922-2934,共13页
Photogrammetry,reconstructing three-dimensional(3D)models from overlapping two-dimensional(2D)photos,finds application in rock mechanics and rock engineering to extract geometrical details of reconstructed objects,for... Photogrammetry,reconstructing three-dimensional(3D)models from overlapping two-dimensional(2D)photos,finds application in rock mechanics and rock engineering to extract geometrical details of reconstructed objects,for example rock fractures.Fracture properties are important for determining the mechanical stability,permeability,strength,and shear behavior of the rock mass.Photogrammetry can be used to reconstruct detailed 3D models of two separated rock fracture surfaces to characterize fracture roughness and physical aperture,which controls the fluid flow,hydromechanical and shear behavior of the rock mass.This research aimed to determine the optimal number of scale bars required to produce high-precision 3D models of a fracture surface.A workflow has been developed to define the physical aperture of a fracture using photogrammetry.Three blocks of Kuru granite(25 cm×25 cm×10 cm)with an artificially induced fracture,were investigated.For scaling 3D models,321 markers were used as ground control points(GCPs)with predefined distances on each block.When the samples were wellmatched in their original positions,the entire block was photographed.Coordinate data of the GCPs were extracted from the 3D model of the blocks.Each half was surveyed separately and georeferenced by GCPs and merged into the same coordinate system.Two fracture surfaces were extracted from the 3D models and the vertical distance between the two surfaces was digitally calculated as physical aperture.Accuracy assessment of the photogrammetric reconstruction showed a 20-30 mm digital control distance accuracy when compared to known distances defined between markers.To attain this accuracy,the study found that at least 200 scale bars were required.Furthermore,photogrammetry was employed to measure changes in aperture under normal stresses.The results obtained from this approach were found to be in good agreement with those obtained using linear variable displacement transducers(LVDTs),with differences ranging from 1 mm to 8μm. 展开更多
关键词 PHOTOGRAMMETRY Physical aperture Rock fracture Predefined distances MARKERS
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Molecular evaluation of Conogethes punctiferalis(Guenée,1854):Species status and intraspecific divergence
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作者 Jin An Yalin Yao +2 位作者 Ping Gao Minghua Xiu Chengmin Shi 《Zoological Systematics》 CSCD 2024年第3期267-275,共9页
Species are not only the fundamental units of taxonomy but also the basic units of pest management.Insects of Conogethes are important agricultural and forestry pests.However,species boundaries within Conogethes often... Species are not only the fundamental units of taxonomy but also the basic units of pest management.Insects of Conogethes are important agricultural and forestry pests.However,species boundaries within Conogethes often appear obscure.In the present study,we reevaluated the species status of Conogethes by applying three species delimitation approaches based on the mitochondrial DNA sequences,with particular emphasis on the yellow peach moth C.punctiferalis(Guenée,1854).We first optimized species delimitation and inter-species genetic divergence threshold using a DNA barcoding dataset.The results revealed that several nominal species of Conogethes species harbored deeply diverged mitochondrial lineages which were recognized as independent species by the species delimitation methods.The p-distance between the delimited putative species ranged from 0.0159 to 0.1321 with a mean of 0.0841.Then we refined the species status of C.punctiferalis using the smallest interspecific distance threshold based on a geographically comprehensive population-scale dataset.This procedure narrowed the species concept of C.punctiferalis to a genetically coherent unit.Further investigation of its intraspecific divergence in the geographic context revealed that the refined C.punctiferalis was still widely distributed with the same or highly similar mitochondrial haplotypes occurring across South and East Asia. 展开更多
关键词 Species delimitation DNA barcoding genetic distances mitochondrial DNA
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A Time-Domain Numerical Simulation for Free Motion Responses of Two Ships Advancing in Head Waves
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作者 PAN Su-yong CHENG Yong 《China Ocean Engineering》 SCIE EI CSCD 2024年第3期519-530,共12页
The constant panel method within the framework of potential flow theory in the time domain is developed for solving the hydrodynamic interactions between two parallel ships with forward speed.When solving problems wit... The constant panel method within the framework of potential flow theory in the time domain is developed for solving the hydrodynamic interactions between two parallel ships with forward speed.When solving problems within a time domain framework,the free water surface needs to simultaneously satisfy both the kinematic and dynamic boundary conditions of the free water surface.This provides conditions for adding artificial damping layers.Using the Runge−Kutta method to solve equations related to time.An upwind differential scheme is used in the present method to deal with the convection terms on the free surface to prevent waves upstream.Through the comparison with the available experimental data and other numerical methods,the present method is proved to have good mesh convergence,and satisfactory results can be obtained.The constant panel method is applied to calculate the hydrodynamic interaction responses of two parallel ships advancing in head waves.Numerical simulations are conducted on the effects of forward speed,different longitudinal and lateral distances on the motion response of two modified Wigley ships in head waves.Then further investigations are conducted on the effects of different ship types on the motion response. 展开更多
关键词 ship motions time domain simulation forward speed different distances wave loads
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Relatedness dynamics and sex-biased dispersal in a seasonal cycle of corn mice from intensively managed agroecosystems
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作者 Lucia V.Sommaro Juan J.Martinez +3 位作者 Marina B.Chiappero Andrea R.Steinmann Cristina N.Gardenal JoséW.Priotto 《Current Zoology》 SCIE CAS CSCD 2024年第1期1-12,共12页
The sex-biased dispersal and kinship dynamics are important factors shaping the spatial distribution of individuals and are key parameters affecting a variety of ecological and evolutionary processes.Here,we studied t... The sex-biased dispersal and kinship dynamics are important factors shaping the spatial distribution of individuals and are key parameters affecting a variety of ecological and evolutionary processes.Here,we studied the spatial distribution of related individuals within a population of corn mice Calomys musculinus in a seasonal cycle to infer dispersal patterns.The sampling was carried out from spring 2005 to winter 2006 in field borders of intensively managed agroecosystems.Genotyping data from 346 individuals with 9 microsatellites showed spatial genetic structure was weak for males,but not for females.The results indicate a complex spatial kinship dynamic of related females across all seasons.Which,contrary to our expectations,dispersal distances decrease with the increase of the population abundance.Meanwhile,male dispersal distances were greater when population abundance increased and thus the availability of active females.Males disperse greater distances to mate and sire offspring with distant females as a possible inbreeding avoidance mechanism.This study shows that C.musculinus is capable of much greater scattering distances than previously reported and that dispersal occurs fluidly and without barriers across the agroecosystem.The indirect benefit of dispersal on individual fitness could be related to relaxing the competition in the natal area and increasing the mating rate.Our study highlights the value of combining genetic relatedness,fieldwork observations,and behavioral data to estimate dispersal at a fine geographical scale. 展开更多
关键词 dispersal distances kinship dynamics MICROSATELLITE small mammals spatial autocorrelation
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Essential proteins identification method based on four-order distances and subcellular localization information
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作者 卢鹏丽 钟雨 杨培实 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第1期765-772,共8页
Essential proteins are inseparable in cell growth and survival. The study of essential proteins is important for understanding cellular functions and biological mechanisms. Therefore, various computable methods have b... Essential proteins are inseparable in cell growth and survival. The study of essential proteins is important for understanding cellular functions and biological mechanisms. Therefore, various computable methods have been proposed to identify essential proteins. Unfortunately, most methods based on network topology only consider the interactions between a protein and its neighboring proteins, and not the interactions with its higher-order distance proteins. In this paper, we propose the DSEP algorithm in which we integrated network topology properties and subcellular localization information in protein–protein interaction(PPI) networks based on four-order distances, and then used random walks to identify the essential proteins. We also propose a method to calculate the finite-order distance of the network, which can greatly reduce the time complexity of our algorithm. We conducted a comprehensive comparison of the DSEP algorithm with 11 existing classical algorithms to identify essential proteins with multiple evaluation methods. The results show that DSEP is superior to these 11 methods. 展开更多
关键词 protein–protein interaction(PPI)network essential proteins four-order distances subcellular localization information
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Active Optics in LAMOST 被引量:3
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作者 Ding-QiangSu Xiang-QunCui 《Chinese Journal of Astronomy and Astrophysics》 CSCD 北大核心 2004年第1期1-9,共9页
Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) is one of the major national projects under construction in China. Active optics is one of the most important technologies for new large telescopes. I... Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) is one of the major national projects under construction in China. Active optics is one of the most important technologies for new large telescopes. It is used for correcting telescope errors generated by gravitational and thermal changes. Here, however, we use this technology to realize the configuration of LAMOST,—a task that cannot be done in the traditional way. A comprehensive and intensive research on the active optics used in LAMOST is also reported, including an open-loop control method and an auxiliary closed-loop control method. Another important development is in our pre-calibration method of open-loop control, which is with some new features: simultaneous calculation of the forces and displacements of force actuators and displacement actuators; the profile of mirror can be arbitrary; the mirror surface shape is not expressed by a fitting polynomial, but is derived from the mirror surface shape formula which is highly accurate; a proof is given that the solution of the pre-calibration method is the same as the least squares solution. 展开更多
关键词 galaxies: distances and redshifts techniques: active optics telescopes instrumentation: adaptive optics
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HⅠGalaxy Detections in the Zone of Avoidance with FAST
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作者 Chao Feng Bin Liu +1 位作者 Hong-Wei Xi Bo Peng 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第8期364-371,共8页
The Zone of Avoidance(ZoA)is a region of low galactic latitude that is heavily obscured by the Milky Way.Observations with radio telescopes are basically unaffected by dust extinction and can unveil the structure behi... The Zone of Avoidance(ZoA)is a region of low galactic latitude that is heavily obscured by the Milky Way.Observations with radio telescopes are basically unaffected by dust extinction and can unveil the structure behind it through the Milky Way.One of the scientific goals of the Five-hundred-meter Aperture Spherical radio Telescope(FAST)is to search for the neutral hydrogen and understand the large-scale physics to explore the origin and evolution of the universe.We take the 15,500 IRAS(the Infrared Astronomical Satellite)galaxies from PSCz(“Point Source Catalog”)survey to reconstruct the density field of the local universe,obtain the distribution of the relative density of galaxies in the ZoA region with a redshift z below 0.07,and the number of detectable galaxies with FAST is estimated by using the neutral hydrogen mass function of the ALFA(Arecibo L-band Feed Array)survey.We conclude that FAST can observe more than 2000 ZoA galaxies within a distance of 300 Mpc h_(70)^(-1),and present preliminary results of the partial GPPS(the FAST Galactic Plane Pulsar Snapshot survey)data,compared with ALFA ZoA(The Arecibo L-band Feed Array Zone of Avoidance),show that FAST has a higher detection sensitivity to search for HI galaxies in the ZoA area. 展开更多
关键词 GALAXIES distances and redshifts-(cosmology )large-scale structure of universe-surveys
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Surgical outcome comparisons of multifocal IOLs of Lentis Comfort LS-313 MF15 and Tecnis Eyhance DIB00V
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作者 Kyohei Sugawara Ryosuke Ito +4 位作者 Hiroshi Horiguchi Kei Mizobuchi Satoshi Katagiri Hisato Gunji Tadashi Nakano 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2023年第12期2004-2010,共7页
AIM:To compare the surgical outcomes of a multifocal intraocular lens(IOL;Lentis Comfort LS-313 MF15)with those of an enhanced monofocal IOL(Tecnis Eyhance DIB00V).METHODS:This retrospective study included patients wh... AIM:To compare the surgical outcomes of a multifocal intraocular lens(IOL;Lentis Comfort LS-313 MF15)with those of an enhanced monofocal IOL(Tecnis Eyhance DIB00V).METHODS:This retrospective study included patients who underwent cataract surgery with LS-313 MF15 or Eyhance IOL implantation.Data regarding patient demographics,surgical records,and ophthalmic examination before the cataract surgery and one and three months postoperatively were collected.Visual acuities,refractive values,defocus curves,contrast sensitivities and subjective symptoms were evaluated.RESULTS:Among the 71 eyes(47 patients)included in this study,32 eyes(20 patients)underwent LS-313 MF15 IOL implantation,and 39 eyes(27 patients)underwent Eyhance IOL implantation.No significant differences were observed in age,axial length,or refractive error between the two groups preoperatively.Furthermore,the distancecorrected and uncorrected distance visual acuities one month postoperatively did not differ between the groups,and both groups had sufficient visual acuities at the distances of 5,1 m,70,50,and 30 cm.Other ophthalmic data,including subjective symptoms based on the 14-item Visual Function Index Questionnaire,monocular defocus curves,contrast sensitivities,and halo and glare,did not differ between the groups three months postoperatively.Moreover,both groups had good outcomes.The spherical equivalent one month postoperatively was significantly myopic in the LS-313 MF15 group compared with that in the Eyhance group(P=0.033);however,this difference was not observed three months postoperatively(P=0.471).CONCLUSION:Comparison of the surgical outcomes of LS-313 MF15 with those of Eyhance with different optical properties reveal that both IOLs show good postoperative outcomes,with no significant differences being noted between the two IOLs. 展开更多
关键词 CATARACTS intermediate distances intraocular lens MULTIFOCAL surgical outcomes
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Rigid POSS Nanofiller Regulated the Interfacial Self-assembly of Particles into 2D Monolayer Superlattice with Fixed Interparticle Spacing
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作者 Yu Zhao Xiaoyuan Wang +3 位作者 Xiaoning Luo Liping Song Fengmei Su Youju Huang 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2023年第3期287-293,共7页
Plasmonic superlattices of nanoparticles(NPs)possess unique“surface lattice resonances”properties that facilitates their wide applications in plasmonic sensing,photocatalysis,and nanoscale light manipulation.However... Plasmonic superlattices of nanoparticles(NPs)possess unique“surface lattice resonances”properties that facilitates their wide applications in plasmonic sensing,photocatalysis,and nanoscale light manipulation.However,it is still challenging to manufacture superlattices with precisely controllable NPs distance and break the size limitation of NPs.Herein,we provided an effective strategy to construct NPs superlattices via shape-persistent polyhedral oligosilsesquioxane(POSS)molecular nanoparticles govern interfacial assembly.As a nanoscale molecule with diameter of 1.5 nm,the POSS-SH molecule provides sufficient rigid steric hindrance and hydrophobic effect for tailoring the uniformity and controllable distance between NPs in superlattices.Interestingly,synergistically with hydrophilic ligands of polyethylene glycol(PEG-SH)with optimized ratio,the rigid POSS ligands can effectively regulate the distance between NPs in a fixed range of 2.3—2.8 nm,which is independent of ligands molecular weight and particle size.Furthermore,the effective approach can be universal to anisotropic NPs for manufacturing monolayer films with high NPs density.We believe this nanoscale molecule tailored interfacial self-assembly strategy can effectively break the size of NPs and assembly obstacles for superlattice monolayer film.Additionally,the definite distance between NPs in superlattices can minimize optical energy attenuation and facilitates the applications such as surface-enhanced Raman spectroscopy and photocatalysis. 展开更多
关键词 Polyhedral oligosilsesquioxane Plasmonic superlattices Definite distances Monolayers Nanostructures 2D materials
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Smart Elevator Systems
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作者 Kheir Al-Kodmany 《Journal of Mechanical Materials and Mechanics Research》 2023年第1期41-53,共13页
Effective vertical mobility is a crucial element in the design and construction of tall buildings.This paper reviews recent“smart”developments in elevator technologies and analyzes how they affect the construction a... Effective vertical mobility is a crucial element in the design and construction of tall buildings.This paper reviews recent“smart”developments in elevator technologies and analyzes how they affect the construction and operation of tall buildings.In an approachable and non-technical discourse,it maps out,arranges,and compiles complicated and dispersed information on various elements of elevator design.It discusses hardware-based innovations,such as AC and gearless motors,machine-room-less(MRL)elevators,regenerative drives,elevator ropes,and LED lighting,as well as software-based solutions,such as destination dispatching systems,people flow solutions,standby mode,and predictive maintenance applications.Future vertical transportation models are also discussed,including multi-directional elevators and circulating multi-car elevators.Lastly,the paper suggests fruitful avenues for further studies on the subject,such as robotics,3D printing,and the impact of the COVID-19 pandemic on elevator design. 展开更多
关键词 Energy efficiency Energy conservation Long distances HARDWARE SOFTWARE APPLICATIONS
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Preliminary Study of Photometric Redshifts Based on the Wide Field Survey Telescope
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作者 Yu Liu Xiao-Zhi Lin +1 位作者 Yong-Quan Xue Huynh Anh N.Le 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第12期138-152,共15页
The Wide Field Survey Telescope(WFST)is a dedicated time-domain multi-band(u,g,r,i,and z)photometric survey facility under construction.In this paper,we present a preliminary study that assesses the quality of photome... The Wide Field Survey Telescope(WFST)is a dedicated time-domain multi-band(u,g,r,i,and z)photometric survey facility under construction.In this paper,we present a preliminary study that assesses the quality of photometric redshifts based on WFST by utilizing mock observations derived with the galaxy catalog in the COSMOS/UltraVISTA field.We apply the template fitting technique to estimate photometric redshifts by using the ZEBRA photometric-redshift code and adopting a modified set of adaptive templates.We evaluate the bias(median relative offset between the output photometric redshifts and input redshifts),normalized median absolute deviation(σ_(NMAD))and outlier fraction(f_(outlier))of photometric redshifts in two typical WFST observational cases,the single 30 s exposure observations(hereafter shallow mode)and co-added 50 minutes exposure observations(hereafter deep mode).We find bias≲0.006,σ_(NMAD)≲0.03,and f_(outlier)≲5%in the shallow mode and bias≈0.005,σ_(NMAD)≈0.06,and f_(outlier)≈17%–27%in the deep mode,respectively,under various lunar phases.Combining the WFST mock observational data with that from the upcoming CSST and Euclid surveys,we demonstrate that the zphot results can be significantly improved,with f_(outlier)≈1%andσ_(NMAD)≈0.02. 展开更多
关键词 GALAXIES distances and redshifts-galaxies high-redshift-galaxies PHOTOMETRY
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An Analytical Solution in the Complex Plane for the Luminosity Distance in Flat Cosmology 被引量:2
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作者 Lorenzo Zaninetti 《Journal of High Energy Physics, Gravitation and Cosmology》 2016年第4期581-586,共7页
We present an analytical solution for the luminosity distance in spatially flat cosmology with pressureless matter and the cosmological constant. The complex analytical solution is made of a real part and a negligible... We present an analytical solution for the luminosity distance in spatially flat cosmology with pressureless matter and the cosmological constant. The complex analytical solution is made of a real part and a negligible imaginary part. The real part of the luminosity distance allows finding the two parameters H<sub>0</sub> and Ω<sub>M</sub> . A simple expression for the distance modulus for SNs of type Ia is reported in the framework of the mini-max approximation. 展开更多
关键词 COSMOLOGY Observational Cosmology distances REDSHIFTS Radial Velocities Spatial Distribution of Galaxies
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19 low mass hypervelocity star candidates from the first data release of the LAMOST survey 被引量:2
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作者 Yin-Bi Li A-Li Luo +12 位作者 Gang Zhao You-Jun Lu Peng Wei Bing Du Xiang Li Yong-Heng Zhao Zhan-Wen Han Bo Wang Yue Wu Yong Zhang Yong-Hui Hou Yue-Fei Wang Ming Yang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2015年第8期1364-1377,共14页
Hypervelocity stars are believed to be ejected out from the Galactic center through dynamical interactions between(binary) stars and the central supermassive black hole(s). In this paper, we report 19 low mass F/G... Hypervelocity stars are believed to be ejected out from the Galactic center through dynamical interactions between(binary) stars and the central supermassive black hole(s). In this paper, we report 19 low mass F/G/K type hypervelocity star candidates from over one million stars found in the first data release of the LAMOST regular survey. We determine the unbound probability for each candidate using a MonteCarlo simulation by assuming a non-Gaussian proper-motion error distribution, and Gaussian heliocentric distance and radial velocity error distributions. The simulation results show that all the candidates have unbound possibilities over 50% as expected,and one of them may even exceed escape velocity with over 90% probability. In addition, we compare the metallicities of our candidates with the metallicity distribution functions of the Galactic bulge, disk, halo and globular clusters, and conclude that the Galactic bulge or disk is likely the birth place for our candidates. 展开更多
关键词 stars: low-mass—stars: kinematics and dynamics—Galaxy: abundances—stars: fundamental parameters—stars: distances
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Molecular Diversity of Fusarium oxysporum and Geotrichum candidum Isolated from Two Tomato Varieties Commonly Consumed in Some Southwestern Town in Nigeria 被引量:1
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作者 Ayodele Adegboyega Sobowale Olalekan Ajibolade Ogunoye 《American Journal of Plant Sciences》 2022年第5期668-685,共18页
Fusarium oxysporum and Geotrichum candidum, which are among important pathogens of Solanum lycopersicum L. (Tomato), are sometimes misidentified during morphological misidentification. The study was carried out to eva... Fusarium oxysporum and Geotrichum candidum, which are among important pathogens of Solanum lycopersicum L. (Tomato), are sometimes misidentified during morphological misidentification. The study was carried out to evaluate molecular diversity of F. oxysporum and G. candidum isolated from two tomato varieties obtained from Akure, Ilorin and Ibadan, Nigeria. The tomato samples were collected and brought back to the laboratory for fungal isolation. Isolation of the pathogens were done following standard procedures. DNA extraction from pure cultures of the pathogens was done at the Centre Laboratory of University of Ibadan. Genetic relationships among the organisms were also estimated by constructing a Dendrogram through UPGMA using the Mega6 Software and genetic distance was computed also using the Mega6 Software. Five strains of F. oxysporum and seven strains of G. candidum were identified. Percentage similarity of the pathogens with those in GenBank was 99.17% - 100.00% for F. oxysporum and 98.48% - 100.00% for G. candidum. The T-01 marker showed the lowest major allele frequency of 0.0833, while T-10 marker has the highest value for major allele frequency of 0.6667 and an average value of 0.3958. Evolutionary relationship showed that the two strains of G. candidum (MN650247 and MN650250) were similar. The three strains of F. oxysporum (MN650246 and MN650248, MN650245 and MN650253) were also similar. Genetic distances among pairs of the fungal strains ranged from 0.12 to 6.30 in pairwise fashion, with an average of 1.32. Evolutionary relationship or closeness among strains of a fungal species can thus be said not to depend on location. 展开更多
关键词 Fusarium oxysporum Geotricum candidum Genetic distances Evolutionary Relationship and Genes
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Integrative taxonomy of the Plain-backed Thrush(Zoothera mollissima)complex(Aves,Turdidae)reveals cryptic species,including a new species 被引量:3
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作者 Per Alstrom Pamela C.Rasmussen +8 位作者 Chao Zhao Jingzi Xu Shashank Dalvi Tianlong Cai Yuyan Guan Ruiying Zhang Mikhail V.Kalyakin Fumin Lei Urban Olsson 《Chinese Birds》 CSCD 2016年第1期2-39,1,共39页
Background: The Plain-backed Thrush Zoothera mollissima breeds in the Himalayas and mountains of central China. It was long considered conspecific with the Long-tailed Thrush Zoothera dixoni, until these were shown to... Background: The Plain-backed Thrush Zoothera mollissima breeds in the Himalayas and mountains of central China. It was long considered conspecific with the Long-tailed Thrush Zoothera dixoni, until these were shown to be broadly sympatric.Methods: We revise the Z. mollissima–Z. dixoni complex by integrating morphological, acoustic, genetic(two mitochondrial and two nuclear markers), ecological and distributional datasets.Results: In earlier field observations, we noted two very different song types of "Plain-backed" Thrush segregated by breeding habitat and elevation. Further integrative analyses congruently identify three groups: an alpine breeder in the Himalayas and Sichuan, China("Alpine Thrush"); a forest breeder in the eastern Himalayas and northwest Yunnan(at least), China("Himalayan Forest Thrush"); and a forest breeder in central Sichuan("Sichuan Forest Thrush"). Alpine and Himalayan Forest Thrushes are broadly sympatric, but segregated by habitat and altitude, and the same is probably true also for Alpine and Sichuan Forest Thrushes. These three groups differ markedly in morphology and songs. In addition, DNA sequence data from three non-breeding specimens from Yunnan indicate that yet another lineage exists("Yunnan Thrush"). However, we find no consistent morphological differences from Alpine Thrush, and its breeding range is unknown. Molecular phylogenetic analyses suggest that all four groups diverged at least a few million years ago, and identify Alpine Thrush and the putative "Yunnan Thrush" as sisters, and the two forest taxa as sisters. Cytochrome b divergences among the four Z. mollissima sensu lato(s.l.) clades are similar to those between any of them and Z. dixoni, and exceed that between the two congeneric outgroup species. We lectotypify the name Oreocincla rostrata Hodgson, 1845 with the Z. mollissima sensu stricto(s.s.) specimen long considered its type. No available name unambiguously pertains to the Himalayan Forest Thrush.Conclusions: The Plain-backed Thrush Z. mollissima s.l. compris 展开更多
关键词 Systematics Morphology BIOACOUSTICS Altitudinal distributions Genetic distances Undescribed taxa Zoothera dixoni Lectotypification HOLOTYPE
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A Check on the Cardassian Expansion Model with Type-la Supernovae Data 被引量:1
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作者 Li CaoNational Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 《Chinese Journal of Astronomy and Astrophysics》 CSCD 北大核心 2003年第4期341-346,共6页
We use the magnitude-redshift relation for the type Ia supernova datacompiled by Riess et al. to analyze the Cardassian expansion scenario. This scenario assumes theuniverse to be flat, matter dominated, and accelerat... We use the magnitude-redshift relation for the type Ia supernova datacompiled by Riess et al. to analyze the Cardassian expansion scenario. This scenario assumes theuniverse to be flat, matter dominated, and accelerating, but contains no vacuum contribution. Thebest fitting model parameters are H_0 = 65.3 km s^(-1) Mpc^(-1), n = 0.35 and Ω_m = 0.05. When thehighest redshift supernova, SN 1997ck, is excluded, H_0 remains the same, but n becomes 0.20 andΩ_m, 0.15, and the matter density remains unreasonably low. Our result shows that this particularscenario is strongly disfavoured by the SNeIa data. 展开更多
关键词 supernovae: general cosmology: theory distances and redshifts
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