本文采用"Web of Science"数据库收录的1999-2013年期间发表的探讨时空关系相关文献,包括2263篇直接文献和这些文献引用的78139篇参考文献为基础数据,采用Histcite软件构建时空关系研究文献数据库,结合Citespace软件对该数据...本文采用"Web of Science"数据库收录的1999-2013年期间发表的探讨时空关系相关文献,包括2263篇直接文献和这些文献引用的78139篇参考文献为基础数据,采用Histcite软件构建时空关系研究文献数据库,结合Citespace软件对该数据库进行文献引用关系和知识图谱的可视化处理,并对热点文献进行解读与分析,从而分析时空关系研究的研究热点和发展趋势。研究发现:2000年前后,时空关系研究与GIS结合逐步突破了传统时间地理学研究的技术瓶颈和研究框架,迅速进入了一个文献爆炸的阶段,研究的内容逐步从时空行为的描述转向对时空关系的解释。随着时空GIS技术的不断成熟,本领域的研究更多地把时空行为作为一种变量,对各种时空现象和社会问题进行解释,而不仅仅是一个被描述和解释的对象,其学科应用价值将逐步突显。展开更多
Flowering is a major developmental transition in the life-history of plants. Flowering time is under complex genetic control. In this study, 172 doubled haploid(DH) lines derived from a cross between two Chinese cabba...Flowering is a major developmental transition in the life-history of plants. Flowering time is under complex genetic control. In this study, 172 doubled haploid(DH) lines derived from a cross between two Chinese cabbage(Brassica rapa ssp. pekinensis) DH lines, Y177 and Y195, were used for a high density linkage map construction and quantitative trait locus(QTL) mapping for flowering time in B. rapa. Parents and DH lines were resequenced at depth of 5× and 0.5× coverage, respectively. In total, 22 747 SNPs were called from the resequencing data and combined into 1 708 bins to construct the genetic linkage map. The map length was 958.6 c M, containing 887 bins and the average interval between binmarkers was 1.08 c M. A total of six QTLs controlling flowering time were detected under four different conditions. Potential candidate flowering homologues located near QTLs were identified with the aid of B. rapa genome annotation.展开更多
Retinoic acid can cause many types of cells,including mouse neuroblastoma Neuro-2 A cells,to differentiate into neurons.However,it is still unknown whether microRNAs(miRNAs)play a role in this neuronal differentiation...Retinoic acid can cause many types of cells,including mouse neuroblastoma Neuro-2 A cells,to differentiate into neurons.However,it is still unknown whether microRNAs(miRNAs)play a role in this neuronal differentiation.To address this issue,real-time polymerase chain reaction assays were used to detect the expression of several differentiation-related miRNAs during the differentiation of retinoic acid-treated Neuro-2 A cells.The results revealed that miR-124 and miR-9 were upregulated,while miR-125 b was downregulated in retinoic acid-treated Neuro-2 A cells.To identify the miRNA that may play a key role,miR-124 expression was regulated by transfection of miRNA mimics or inhibitors.Morphological analysis results showed that inhibition of miR-124 expression reversed the effects of retinoic acid on neurite outgrowth.Moreover,miR-124 overexpression alone caused Neuro-2 A cells to differentiate into neurons,and its inhibitor could block this effect.These results suggest that miR-124 plays an important role in retinoic acid-induced differentiation of Neuro-2 A cells.展开更多
Getting insight into the spatiotemporal distribution patterns of knowledge innovation is receiving increasing attention from policymakers and economic research organizations.Many studies use bibliometric data to analy...Getting insight into the spatiotemporal distribution patterns of knowledge innovation is receiving increasing attention from policymakers and economic research organizations.Many studies use bibliometric data to analyze the popularity of certain research topics,well-adopted methodologies,influential authors,and the interrelationships among research disciplines.However,the visual exploration of the patterns of research topics with an emphasis on their spatial and temporal distribution remains challenging.This study combined a Space-Time Cube(STC)and a 3D glyph to represent the complex multivariate bibliographic data.We further implemented a visual design by developing an interactive interface.The effectiveness,understandability,and engagement of ST-Map are evaluated by seven experts in geovisualization.The results suggest that it is promising to use three-dimensional visualization to show the overview and on-demand details on a single screen.展开更多
We study the existence of multiple positive solutions for a Neumann problem with singular φ-Laplacian{-(φ（u′）)′= λf（u）, x ∈（0, 1）,u′（0） = 0 = u′（1）,where λ is a positive parameter, φ（s） =s/（1-s;...We study the existence of multiple positive solutions for a Neumann problem with singular φ-Laplacian{-(φ（u′）)′= λf（u）, x ∈（0, 1）,u′（0） = 0 = u′（1）,where λ is a positive parameter, φ（s） =s/（1-s;）;, f ∈ C;（[0, ∞）, R), f′（u） > 0 for u > 0, and for some 0 < β < θ such that f（u） < 0 for u ∈ [0, β)（semipositone） and f（u） > 0 for u > β.Under some suitable assumptions, we obtain the existence of multiple positive solutions of the above problem by using the quadrature technique. Further, if f ∈ C;（[0, β） ∪（β, ∞）, R),f′′（u） ≥ 0 for u ∈ [0, β) and f′′（u） ≤ 0 for u ∈（β, ∞）, then there exist exactly 2 n + 1 positive solutions for some interval of λ, which is dependent on n and θ. Moreover, We also give some examples to apply our results.展开更多
文摘本文采用"Web of Science"数据库收录的1999-2013年期间发表的探讨时空关系相关文献,包括2263篇直接文献和这些文献引用的78139篇参考文献为基础数据,采用Histcite软件构建时空关系研究文献数据库,结合Citespace软件对该数据库进行文献引用关系和知识图谱的可视化处理,并对热点文献进行解读与分析,从而分析时空关系研究的研究热点和发展趋势。研究发现:2000年前后,时空关系研究与GIS结合逐步突破了传统时间地理学研究的技术瓶颈和研究框架,迅速进入了一个文献爆炸的阶段,研究的内容逐步从时空行为的描述转向对时空关系的解释。随着时空GIS技术的不断成熟,本领域的研究更多地把时空行为作为一种变量,对各种时空现象和社会问题进行解释,而不仅仅是一个被描述和解释的对象,其学科应用价值将逐步突显。
基金supported by NSFC funding(31272179)The Science and Technology Innovation Program of CAAS(CAAS-ASTIP-IVFCAAS)
文摘Flowering is a major developmental transition in the life-history of plants. Flowering time is under complex genetic control. In this study, 172 doubled haploid(DH) lines derived from a cross between two Chinese cabbage(Brassica rapa ssp. pekinensis) DH lines, Y177 and Y195, were used for a high density linkage map construction and quantitative trait locus(QTL) mapping for flowering time in B. rapa. Parents and DH lines were resequenced at depth of 5× and 0.5× coverage, respectively. In total, 22 747 SNPs were called from the resequencing data and combined into 1 708 bins to construct the genetic linkage map. The map length was 958.6 c M, containing 887 bins and the average interval between binmarkers was 1.08 c M. A total of six QTLs controlling flowering time were detected under four different conditions. Potential candidate flowering homologues located near QTLs were identified with the aid of B. rapa genome annotation.
基金supported by the Natural Science Foundation of Shanghai of China,No.16ZR1410500(to SZD)
文摘Retinoic acid can cause many types of cells,including mouse neuroblastoma Neuro-2 A cells,to differentiate into neurons.However,it is still unknown whether microRNAs(miRNAs)play a role in this neuronal differentiation.To address this issue,real-time polymerase chain reaction assays were used to detect the expression of several differentiation-related miRNAs during the differentiation of retinoic acid-treated Neuro-2 A cells.The results revealed that miR-124 and miR-9 were upregulated,while miR-125 b was downregulated in retinoic acid-treated Neuro-2 A cells.To identify the miRNA that may play a key role,miR-124 expression was regulated by transfection of miRNA mimics or inhibitors.Morphological analysis results showed that inhibition of miR-124 expression reversed the effects of retinoic acid on neurite outgrowth.Moreover,miR-124 overexpression alone caused Neuro-2 A cells to differentiate into neurons,and its inhibitor could block this effect.These results suggest that miR-124 plays an important role in retinoic acid-induced differentiation of Neuro-2 A cells.
文摘Getting insight into the spatiotemporal distribution patterns of knowledge innovation is receiving increasing attention from policymakers and economic research organizations.Many studies use bibliometric data to analyze the popularity of certain research topics,well-adopted methodologies,influential authors,and the interrelationships among research disciplines.However,the visual exploration of the patterns of research topics with an emphasis on their spatial and temporal distribution remains challenging.This study combined a Space-Time Cube(STC)and a 3D glyph to represent the complex multivariate bibliographic data.We further implemented a visual design by developing an interactive interface.The effectiveness,understandability,and engagement of ST-Map are evaluated by seven experts in geovisualization.The results suggest that it is promising to use three-dimensional visualization to show the overview and on-demand details on a single screen.
文摘We study the existence of multiple positive solutions for a Neumann problem with singular φ-Laplacian{-(φ（u′）)′= λf（u）, x ∈（0, 1）,u′（0） = 0 = u′（1）,where λ is a positive parameter, φ（s） =s/（1-s;）;, f ∈ C;（[0, ∞）, R), f′（u） > 0 for u > 0, and for some 0 < β < θ such that f（u） < 0 for u ∈ [0, β)（semipositone） and f（u） > 0 for u > β.Under some suitable assumptions, we obtain the existence of multiple positive solutions of the above problem by using the quadrature technique. Further, if f ∈ C;（[0, β） ∪（β, ∞）, R),f′′（u） ≥ 0 for u ∈ [0, β) and f′′（u） ≤ 0 for u ∈（β, ∞）, then there exist exactly 2 n + 1 positive solutions for some interval of λ, which is dependent on n and θ. Moreover, We also give some examples to apply our results.
