检索结果-南通市图书馆

Plant Diversity 2020年第3期42卷 174-180页

作者： Jinhu Ma Xinxin Feng xiaohuan yang Yongheng Cao Weifeng Zhao Liangliang Sun College of Enginemng Shanxi Agricultural UniversityTaigu030807China College of Horticulture Shanxi Agricultural UniversityTaigu030801China College of Agriculture Shanxi Agricultural UniversityTaigu030801China Faculty of Tropical Crops Yunnan Agricultural UniversityPuer665000China

The extract of crofton weed(Eupatorium adenophorum) inhibits seed germination and weed growth;however,the physiological mechanisms underlying the effect of crofton weed extract on the modulation of seedling growth and root system development remain largely unclear.In this study,we investigated the effects of the leaf extract of crofton weed(LECW) on primary root(PR) growth in maize seedlings.Treatment with LECW markedly inhibited seed germination and seedling growth in a dose-dependent manner.Physiological analysis indicated that the LECW induced reactive oxygen species(ROS) accumulation in root tips,thereby leading to cell swelling and deformation both in the root cap and elongation zone of root tips,finally leading to cell death in root border cells(RBCs) and PR growth inhibition.The LECW also inhibited pectin methyl esterase(PME) activity,thereby decreasing the RBC number.Taken together,our results indicated that the LECW inhibited PR growth by inducing ROS accumulation and subsequent cell death in RBCs.The present study provides a better understanding of how the LECW modifies root system development and provides insight for evaluating the toxicity of crofton weed extracts in plants.

关键词： Leaf extract of crofton weed Maize Cell death Pectin methyl esterase Root border cell

创业生态系统健康性与新创企业创业绩效:基于泽国镇电商企业的实证研究

在线全文

学校读者我要写书评

暂无评论

科学学与科学技术管理 2024年第3期45卷 41-56页

作者：蔡小锦刘庆全杨小欢施扬宁波财经学院新经济研究院浙江宁波315175 复旦大学管理学院上海200433 上海商学院工商管理学院上海200235 上海商学院商务经济学院上海200235

数字经济的蓬勃发展正在有力地推动着乡村的全面振兴,淘宝村、淘宝镇的涌现正是其重要体现,农村电商创业生态系统与新创企业之间的影响机制也因此成为一个关键问题。尽管现有文献已经探讨了创业生态系统的组成要素和关键参与者,但是在... 详细信息

数字经济的蓬勃发展正在有力地推动着乡村的全面振兴,淘宝村、淘宝镇的涌现正是其重要体现,农村电商创业生态系统与新创企业之间的影响机制也因此成为一个关键问题。尽管现有文献已经探讨了创业生态系统的组成要素和关键参与者,但是在解释创业生态系统的竞争力和系统中新创企业绩效方面仍显不足。许多研究都强调了生态系统的健康性在创业生态系统持续发展过程中发挥的关键作用,它会影响所有生态系统参与者的命运。创业生态系统内资源相对稀缺,通过创业拼凑的方式是新创企业取得发展的有效途径之一。从微观的企业视角出发,在分析理解创业生态系统理论和创业拼凑理论的基础上,依据“环境感知—行为—结果”的研究逻辑,构建“创业生态系统健康性—创业拼凑—新创企业创业绩效”的理论模型,采用问卷调查方法,以泽国镇农村电商创业生态系统中的电商企业为研究对象,采用统计分析软件SPSS 22.0和AMOS 24.0对收集的605家电商企业的样本数据进行信效度检验,并构建结构方程模型,对假设进行检验,实证结果显示:(1)创业生态系统中生态稳定性和生态多样性对新创企业创业绩效具有正向影响;(2)创业拼凑对新创企业创业绩效具有正向影响;(3)创业生态系统中生态活力和生态多样性对创业拼凑具有正向影响;(4)创业拼凑在生态活力与新创企业创业绩效间发挥中介作用,在生态多样性与新创企业创业绩效间发挥中介作用,但是在生态稳定性与新创企业创业绩效间的中介作用不显著。研究结论对于新创企业在创业过程中如何从创业生态系统健康性的角度出发,运用创业拼凑策略,克服新创企业面临的“新生弱性”,从而获得生存与发展,具有一定的启示作用。新创企业应在创业生态系统中关注生态多样性、生态活力等因素,以充分利用现有资源,提高自身竞争力。

关键词：农村电商创业生态系统生态系统健康性创业拼凑创业绩效

硝普钠浸种对复合盐碱胁迫下红芸豆种子萌发和内源激素含量的影响

在线全文

学校读者我要写书评

暂无评论

核农学报 2024年第7期38卷 1398-1407页

作者：王成龙王子然杨婧怡宋亚萍马金虎杨小环山西农业大学农学院山西太谷030801 山西农业大学创新创业学院山西太谷030801

为探究硝普钠(SNP,NO供体)浸种对复合盐碱胁迫下红芸豆种子萌发和内源激素含量的影响,以芸选2号红芸豆种子为材料,采用响应面(RSA)和主成分分析法(PCA)优选硝普钠浸种提高复合盐碱胁迫下红芸豆种子萌发的条件;以最佳硝普钠浸种条件对种... 详细信息

为探究硝普钠(SNP,NO供体)浸种对复合盐碱胁迫下红芸豆种子萌发和内源激素含量的影响,以芸选2号红芸豆种子为材料,采用响应面(RSA)和主成分分析法(PCA)优选硝普钠浸种提高复合盐碱胁迫下红芸豆种子萌发的条件;以最佳硝普钠浸种条件对种子进行浸种处理,研究复合盐碱胁迫下,外源NO对种胚保护酶系统以及种胚内源激素含量变化的影响。结果表明,50 mmol·L^(-1)复合盐碱溶液胁迫下,以发芽率、发芽势、发芽指数、活力指数、根长和种胚干重为目标,经RSA和PCA得到SNP浸种促进盐碱胁迫种子萌发生长的最佳浓度为0.3 mmol·L^(-1),浸种时间为12 h。50 mmol·L^(-1)盐碱胁迫下,用0.3 mmol·L^(-1) SNP对种子浸种处理后,种子的发芽率和发芽势分别较去离子水浸种处理提高38.17和10.83个百分点,发芽指数和活力指数分别较去离子水浸种处理提高19.56%和23.74%。与去离子水浸种处理相比,0.3 mmol·L^(-1) SNP浸种处理种胚萌发72 h的超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性分别提高9.26%、59.79%和36.14%;过氧化氢(H_(2)O_(2))、超氧阴离子(O_(2)^(-))和丙二醛(MDA)含量分别降低45.45%、37.71%和25.51%。盐碱胁迫下,0.3 mmol·L^(-1) SNP浸种处理相较于去离子水浸种处理,种胚脱落酸(ABA)含量降低,赤霉素(GA_(3))含量和GA_(3)/ABA值提高。其中种子萌发48和96 h时,SNP浸种处理种胚ABA含量分别较去离子水浸种处理降低12.89%和29.99%,GA_(3)含量分别较去离子水浸种处理升高12.52%和85.79%,GA_(3)/ABA值分别较去离子水浸种处理高3.45和2.06。综上,外源NO可通过提高盐碱胁迫下红芸豆种胚抗氧化酶活性,降低ABA含量来提高GA_(3)含量,进而减轻盐碱氧化胁迫伤害,促进种子萌发。本研究结果为红芸豆抗盐碱高产栽培提供了理论依据。

关键词：红芸豆一氧化氮复合盐碱胁迫种子萌发内源激素

维普期刊数据库博看期刊

The existence of harmonic maps from Finsler manifolds of Riemannian manifolds

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2005年第1期48卷 115-130页

作者： MO xiaohuan yang Yunyan LMAM School of Mathematical SciencesPeking UniversityBeijing 100871China Department of MathematicsRenmin University of ChinaBeijing 100872China

In this paper,we consider the existence of harmonic maps from a Finsler manifold and study the characterisation of harmonic maps,in the spirit of Ishihara.Using heat quation method we show that any map from a compact Finsler manifold M to a compact Riemannian manifold with non-positive sectional curvature can be deformed into a harmonic map which has minimum energy in its homotopy class.

关键词： harmonic map,Finsler manifold,existence.

A new quantity in Finsler geometry

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2024年第4期67卷 883-890页

作者： xiaohuan Mo Xiaoyang Wang Key Laboratory of Pure and Applied Mathematics School of Mathematical SciencesPeking UniversityBeijing 100871China School of Mathematics and Statistics Beijing Institute of TechnologyBeijing 100081China

In this paper,we study a new Finslerian quantity■defined by the T-curvature and the angular metric tensor.We show that the■-curvature not only gives a measure of the failure of a Finsler metric to be of scalar flag curvature but also has a vanishing trace.We find that the■-curvature is closely related to the Riemann curvature,the Matsumoto torsion and theΘ-curvature.We solve Z.Shen’s open problem in terms of the■-curvature.Finally,we give a global rigidity result for Finsler metrics of negative Ricci curvature on a compact manifold via the■-curvature,generalizing a theorem previously only known in the case of negatively curved Finsler metrics of scalar flag curvature.

关键词： Finsler metric Finslerian quantity T-curvature -curvature Randers metric

Effect of Cropland Occupation and Supplement on Light-temperature Potential Productivity in China from 2000 to 2008

在线全文

学校读者我要写书评

暂无评论

中国地理科学：英文版 2010年第6期20卷 536-544页

作者： yang xiaohuan CHENG Chuanzhou LI Yuejiao State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences And Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Graduate University of the Chinese Academy of Sciences Beijing 100049China

There are more people but less land in China,so food safety has always been a most important issue government concerned.With continuous population increase,economic development and environment protection,cropland occupation and supplement are unavoidable.It not only leads to the variation of cropland area,but also makes the light-temperature potential productivity per unit area different due to regional climate differentiation,therefore impacts the total potential productivity and food output eventually.So,it is necessary to analyze the climate differentiation between occupation and supplement cropland areas and to study its impact on total potential productivity,which is significant to reasonably develop natural resources and instruct agricultural arrangement.This study firstly discussed the variation and distribution of occupation and supplement croplands in China from 2000 to 2008,then analyzed the climate differentiation between occupation and supplement cropland areas and its effect on light-temperature potential productivity.The results demonstrate:1) From 2000 to 2008,the cropland variation presented occupation in the south and supplement in the north,but overall decreased.Supplement cropland was mainly from ecological reclamation(77.78%) and was mainly distributed in Northeast China and Northwest China with poor climatic and natural conditions.Occupation cropland was mainly used for construction(52.88%) and ecological restoration(44.78%) purposes,and was mainly distributed in the Huang-Huai-Hai Plain,and the middle and lower reaches of the Changjiang(yangtze) River with better climatic and natural conditions.2) The climate conditions were quite different in supplement and occupation cropland areas.The annual precipitation,annual accumulated temperature and average annual temperature were lower in the supplement cropland area,and its average po-tential productivity per unit was only 62% of occupation cropland area,which was the main reason for the decrease of total potential productivity.3) Cropland occupa

关键词：光温生产潜力耕地面积占用中国农业自然资源潜在生产力自然生态环境气候差异

Food nutrition and toxicology targeting on specific organs in the era of single-cell sequencing

在线全文

学校读者我要写书评

暂无评论

Food Science and Human Wellness 2024年第1期13卷 75-89页

作者： Xiaofei Wang Xiaowen Cheng Huiling Liu xiaohuan Mu Hao Zheng National Engineering Technology Research Center for Fruit and Vegetable Processing Key Open Laboratory of Fruit and Vegetable ProcessingMinistry of Agriculture and Rural AffairsBeijing Key Laboratory of Food Non-Thermal ProcessingCollege of Food Science and Nutritional EngineeringChina Agricultural UniversityBeijing 100083China

Due to the complex natures of dietary food components,it is difficult to elucidate how the compounds affect host health.Dietary food often selectively presents its mechanism of action on different cell types,and participates in the modulation of targeted cells and their microenvironments within organs.However,the limitations of traditional in vitro assays or in vivo animal experiments cannot comprehensively examine cellular heterogeneity and the tissue-biased influences.Single-cell RNA sequencing(sc RNA-seq)has emerged as an indispensable methodology to decompose tissues into different cell types for the demonstration of transcriptional profiles of individual cells.Sc RNA-seq applications has been summarized on three typical organs(brain,liver,kidney),and two representative immune-and tumor related health problems.The everincreasing role of sc RNA-seq in dietary food research with further improvement can provide sub-cellular information and the coupling between other cellular modalities.In this review,we propose utilizing sc RNAseq to more effectively capture the subtle and complex effects of food chemicals,and how they may lead to health problems at single-cell resolution.This novel technique will be valuable to elucidate the underlying mechanism of both the health benefits of food nutrients and the detrimental consequences food toxicants at the cellular level.

关键词： Dietary food Cellular heterogeneity Single-cell RNA sequencing Food nutrients Food toxicants

基于密绕小直径线圈的磁感应透地无线起爆系统性能分析

在线全文

学校读者我要写书评

暂无评论

电波科学学报 2024年第3期39卷 534-543页

作者：李晓奂杨维北京交通大学电子信息工程学院北京100044

为了在矿区开采时实现安全便携的透地无线起爆,提出了地上发射端采用密绕小直径线圈的磁感应透地无线起爆方案,并建立了地面发射线圈与地下接收线圈等效耦合电路分析模型,推导了地下接收端负载的电压表达式,用地面发射线圈与地下接收线... 详细信息

为了在矿区开采时实现安全便携的透地无线起爆,提出了地上发射端采用密绕小直径线圈的磁感应透地无线起爆方案,并建立了地面发射线圈与地下接收线圈等效耦合电路分析模型,推导了地下接收端负载的电压表达式,用地面发射线圈与地下接收线圈间的互感系数表征了收发线圈间耦合强度的大小。由于地面发射线圈与地下接收线圈间的相对位置关系不是平行共轴,传统基于平行且共轴线圈的互感公式不再适用,本文从磁矢位出发推导出了考虑涡流效应的具有一般位置关系的单匝圆线圈间互感系数的通用表达式。由于地面发射线圈采用横放模式存在爆破盲区,地面发射线圈应采用竖放模式。基于负载电压公式分析了发射线圈半径与匝数、发射信号频率和垂直透地深度对透地起爆系统地下接收端负载电压和水平覆盖距离的影响。仿真结果表明:发射线圈采用竖放模式的透地无线起爆系统的水平覆盖距离可达到200~300m;随着透地深度的增加,系统的水平覆盖距离逐渐降低,但可以通过适当增加发射线圈半径和匝数、降低发射信号频率的方式提高透地无线起爆系统的水平覆盖距离,以满足在不同规模矿区开采应用场景下的透地无线起爆需求。

关键词：透地通信磁感应无线起爆涡流损耗互感

维普期刊数据库博看期刊

在线全文

学校读者我要写书评

暂无评论

中国森林遥感Rao′s Q指数时空演变

生态学报 2023年第8期43卷 3045-3056页

作者：蒋啸蔡红艳杨小唤李果中国科学院地理科学与资源研究所北京100101 中国科学院大学北京100049 中国环境科学研究院生态所北京100012

明确宏观森林植物多样性时空分布格局,对于评估森林生态工程效果以及有效开展区域生物多样性保护工作具有重要意义。遥感生物多样性研究能够弥补原位观测在时空连续性方面的不足,研究旨在为区域尺度生物多样性研究引入一种新方法——遥... 详细信息

明确宏观森林植物多样性时空分布格局,对于评估森林生态工程效果以及有效开展区域生物多样性保护工作具有重要意义。遥感生物多样性研究能够弥补原位观测在时空连续性方面的不足,研究旨在为区域尺度生物多样性研究引入一种新方法——遥感Rao′s Q指数。结果表明:基于归一化植被指数(NDVI)计算的Rao′s Q指数与收集的物种丰富度在空间分布上基本一致,且两者的数值拟合通过极显著检验(R^(2)=0.66,P<0.001),Rao′s Q指数随物种丰富度增加而增加,适用于表征宏观尺度跨气候带地区的森林植物多样性。2000—2017年间,中国森林的Rao′s Q指数时空分布基本一致,整体呈南高北低的态势;不同时段中均以降低为主,降低面积占总面积的44.23%—54.08%,武夷山-南岭一带增高特征凸显,而2010—2017年也表现出降低特征,该区域森林植物多样性本底丰富,应加强管控力度,阻止降低热点区扩散。引入遥感Rao′s Q指数有效表征区域森林植物多样性分布特征,可为区域生态质量评估提供一种新的监测指标,进而为森林植物多样性保护及区域生态质量改善相关政策制定提供支撑。

关键词：森林植物多样性遥感Rao′s Q指数演变遥感

Microglial glutaminase 1 mediates chronic restraint stress-induced depression-like behaviors and synaptic damages

在线全文

学校读者我要写书评

暂无评论

Signal Transduction and Targeted Therapy 2024年第1期9卷 40-43页

作者： Huili Chen Shengyang Fu Xiangyu Li Meng Shi Jiazhen Qian Shu Zhao Ping Yuan Lu Ding xiaohuan Xia Jialin C.Zheng Center for Translational Neurodegeneration and Regenerative Therapy Tongji Hospital affiliated to Tongji University School of Medicine200065 ShanghaiChina Department of Cardio-Pulmonary Circulation Shanghai Pulmonary HospitalSchool of MedicineTongji UniversityShanghaiChina Translational Research Institute of Brain and Brain-Like Intelligence Shanghai Fourth People’s Hospital affiliated to Tongji University School of Medicine200434 ShanghaiChina

Dear Editor,Major depressive disorder(MDD)is one of the most common psychiatric illnesses that significantly increase the risk of suicide.1 Stress-triggered dysfunctions of microglia have been identified as a commonly occurred pathological feature of MDD.1–3 Microglial dysfunction contributes to the pathogenesis of MDD via immunoresponses/neuroinflammation-mediated neural damage and pathological synapse loss-mediated neural circuit disruption.1 Although the involvement of microglia in MDD has been widely investigated,the molecular mechanisms underlying microglial dysfunction remain largely unknown.Recently,we identified glutaminase 1(Gls1)as one key protein that participates in microglial dysfunction.4–6 Gls1 catalyzes the hydrolysis of glutamine to produce glutamate in the brain.4 Besides its well-known role in excitatory neurotoxicity,we found Gls1 up-regulation in microglia in animal models of Alzheimer’s disease and ischemic stroke.4,7 Gls1 activates microglia to overproduce cytokines and release inflammatory extracellular vesicles,therefore leading to neuroinflammation in animal models of Alzheimer’s disease and ischemic stroke.4–6 More importantly,Gls1 has been found to be up-regulated in the brains of MDD patients,and microglial Gls1 deficiency mitigated LPS-induced depression-like behaviors.8 However,LPS exposure is not an appropriate model to mimic MDD phenotypes,leaving the involvement of Gls1 in MDD an undetermined question.

关键词： involvement inflammation media