检索结果-南通市图书馆

Multi-locus population genetics analysis of Sonneratia alba in the Indo-West Pacific region

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Multi-locus population genetics analysis of Sonneratia alba ...

在后牛顿引力理论(PPN形式)中引力常数变化对地球自转产生的效应

后植物志时代的系统与进化植物学——2011年全国系统与进化植物学暨第十届青年学术研讨会

作者： Yuchen Yang,Renchao Zhou,Suhua Shi (Sun Yat-sen University,Guangzhou,510275,China)

Multi-locus population genetic analyses allow inference of population history and evolutionary *** are of special interest in this aspect because they inhabit intertidal zones where dramatic changes in population size happened in ice age due to sea level fluctuations and intense selective pressures. Sonneratia alba is one of the most salt tolerant mangrove species which occurs in low intertidal *** this study,we chose five populations of *** from western and eastern coasts of Thailand for population genetics *** each population,we pooled 50 individuals and sequenced 60 genes using Illumina GA *** with Qionghai and Sanya populations in China we examined before,populations in Thailand had higher level of diversity and the diversity in western populations was 5 folds as high as that in eastern *** were 12 moderate or high differentiate genes with Fst >0.1 between two populations from western coasts of *** eastern coast of Thailand,only 5 genes showed moderate or high differentiation between populations in Chi-ya and *** were 12 low-divergence sites between the two populations from western coast of Thailand,as 3-fold many as those between the two populations from eastern coast of *** from eastern coast of Thailand exhibited closer relationships to populations from Hainan than those from western coasts of *** study indicates that marginal populations of *** experience stronger bottleneck and possess less genetic diversity than those in central *** is high genetic differentiation between populations from western and eastern coasts of Thailand,suggesting Malay Peninsula functions as a strong land barrier for gene exchange.

关键词： Sonneratia alba population genetics demography process

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

天文研究与技术 2007年第2期4卷 135-140页

作者：李林森东北师范大学物理学院长春130024

介绍和论述了在后牛顿引力理论(PPN形式)中在优越参考系和非优越参考系中经过参数化后引力常数变化对地球自转产生的效应,其中特别重点介绍了年周期变化的效应。此外也将理论结果同观测结果相对比。

关键词： PPN参考系优越参考系引力常数变化地球自转效应

电网电压畸变下的级联H桥光伏并网逆变器谐波抑制控制策略

在线全文

学校读者我要写书评

暂无评论

电力自动化设备 2022年第3期42卷 68-75页

作者：袁义生吕森朱启航华东交通大学电气与自动化工程学院江西南昌330013

三次谐波补偿策略可有效解决单相级联H桥光伏并网逆变器的功率不平衡问题,但在电网电压畸变下易发生并网电流畸变。针对这一问题,提出一种电流谐波抑制环来消除电网电压畸变所带来的影响,并降低电网电流畸变率。分析了电网电压畸变导致... 详细信息

三次谐波补偿策略可有效解决单相级联H桥光伏并网逆变器的功率不平衡问题,但在电网电压畸变下易发生并网电流畸变。针对这一问题,提出一种电流谐波抑制环来消除电网电压畸变所带来的影响,并降低电网电流畸变率。分析了电网电压畸变导致电流畸变的机理原因,在此基础上,提出了将并网电流中的谐波成分作为控制对象,实时反馈至系统中,通过闭环控制实现对电流谐波成分的抑制。该电流谐波抑制环不改变原有的控制策略,只是作为额外的补充环节。仿真和实验结果表明,所提控制策略可大幅降低逆变器在电网电压畸变时的电流畸变率,证明了该控制策略的有效性和可行性。

关键词：级联H桥光伏逆变器谐波抑制功率平衡控制

LST变换和手部几何特征融合的模糊掌纹识别

在线全文

学校读者我要写书评

暂无评论

仪器仪表学报 2013年第2期34卷 415-422页

作者：林森苑玮琦荆澜涛魏明月沈阳工业大学视觉检测技术研究所沈阳110870 辽宁工程技术大学电子与信息工程学院葫芦岛125105

为了解决非接触采集时的离焦状况容易导致掌纹图像出现模糊现象,从而造成识别系统的性能降低的问题,在建立模糊模型并分析模糊现象机理的基础上,提出了一种新的解决方案。使用拉普拉斯平滑变换(laplacian smoothing transform,LST)提取... 详细信息

为了解决非接触采集时的离焦状况容易导致掌纹图像出现模糊现象,从而造成识别系统的性能降低的问题,在建立模糊模型并分析模糊现象机理的基础上,提出了一种新的解决方案。使用拉普拉斯平滑变换(laplacian smoothing transform,LST)提取模糊掌纹的低频系数作为稳定特征,提取手部几何特征即手指相对长度和宽度作为特征向量,将LST特征和几何特征进行融合,最后利用特征向量之间的欧式距离进行匹配和分类。在自建的SUT-D模糊掌纹图库上的测试结果表明该算法等误率可达7.01%,与融合之前及其他典型识别方法相比,等误率最高可降低13.11%,显示出该算法具备有效性,为解决模糊掌纹的识别问题提供了一条可行途径。

关键词：非接触离焦模糊掌纹识别拉普拉斯平滑变换几何特征

The grassland carbon cycle:Mechanisms,responses to global changes,and potential contribution to carbon neutrality

在线全文

学校读者我要写书评

暂无评论

Fundamental Research 2023年第2期3卷 209-218页

作者： Lingli Liu Emma J.Sayer Meifeng Deng Ping Li Weixing Liu Xin Wang sen Yang Junsheng Huang Jie Luo Yanjun Su JoséM.Grünzweig Lin Jiang Shuijin Hu Shilong Piao State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing 100093China University of Chinese Academy of Sciences Beijing 100049China Lancaster Environment Centre Lancaster UniversityLancaster LA14YQUnited Kingdom Department of Evolutionary Biology and Environmental Studies University of ZurichZurich 8057Switzerland Institute of Plant Sciences and Genetics in Agriculture The Robert H.Smith Faculty of AgricultureFood and EnvironmentThe Hebrew University of JerusalemRehovot 7610001Israel School of Biological Sciences Georgia Institute of Technology310 Ferst DriveAtlantaGA 30332United States Department of Plant Pathology North Carolina State UniversityRaleighNC 27607United States Sino-French Institute for Earth System Science College of Urban and Environmental SciencePeking UniversityBeijing 100871China National Hulunber Grassland Ecosystem Observation and Research Station Institute of Agricultural Resources and Regional PlanningChinese Academy of Agricultural SciencesBeijing 100081China

Grassland is one of the largest terrestrial biomes,providing critical ecosystem services such as food production,biodiversity conservation,and climate change *** climate change and land-use intensification have been causing grassland degradation and desertification *** one of the primary medium for ecosystem energy flow and biogeochemical cycling,grassland carbon(C)cycling is the most fundamental process for maintaining ecosystem *** this review,we first summarize recent advances in our understanding of the mechanisms underpinning spatial and temporal patterns of the grassland C cycle,discuss the importance of grasslands in regulating inter-and intra-annual variations in global C fluxes,and explore the previously unappreciated complexity in abiotic processes controlling the grassland C balance,including soil inorganic C accumulation,photochemical and thermal degradation,and wind *** also discuss how climate and land-use changes could alter the grassland C balance by modifying the water budget,nutrient cycling and additional plant and soil ***,we examine why and how increasing aridity and improper land use may induce significant losses in grassland C ***,we identify several priorities for future grassland C research,including improving understanding of abiotic processes in the grassland C cycle,strengthening monitoring of grassland C dynamics by integrating ground inventory,flux monitoring,and modern remote sensing techniques,and selecting appropriate plant species combinations with suitable traits and strong resistance to climate fluctuations,which would help design sustainable grassland restoration strategies in a changing climate.

关键词： Climate changes Land-use change Soil Biotic and abiotic interactions Grassland degradation Grassland restoration Carbon accounting Carbon storage and sequestration mechanisms

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

贫民窟中的水危机

人类居住 2001年第4期 19-20页

作者： Yima sen 张庆

拖拉机数字化设计数据库云存储服务数据安全研究

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

农机化研究 2018年第5期40卷 205-209页

作者：时磊余森河南工业职业技术学院河南南阳473000

目前,在拖拉机设计过程中,由于多数设计部门之间存在缺乏自动化信息交换的手段,设计效率低,难以满足当前设计制造信息化的实时性需求。为了解决这个问题,很多设计企业引入了云设计服务平台,但在信息交换共享的过程中,由于数据拥有者和... 详细信息

目前,在拖拉机设计过程中,由于多数设计部门之间存在缺乏自动化信息交换的手段,设计效率低,难以满足当前设计制造信息化的实时性需求。为了解决这个问题,很多设计企业引入了云设计服务平台,但在信息交换共享的过程中,由于数据拥有者和管理者的分离,会造成数据的安全和知识产权的侵犯问题。为了保护拖拉机数字化设计过程中的图纸和图像的隐私性,提出了一种基于图像退化和复原以及数据分离存储和共享的数据安全隐私保护方法。该方法除了会对拖拉机数字化设计过程中产生的作品图像进行重要信息退化之外,还采用了分离式的数据存储传输形式,将数据信息分离成多个部分,任意一个单一的单元都无法获取完整的信息,实现了数据的双重加密,使加密信息更加安全可靠。对云存储服务数据安全及隐私保护技术进行了验证,结果表明:随着数据规模的不断扩大,通信代价并没有出现过大的变化,并且数据的安全性较高,满足数据安全及隐私保护设计需求。

关键词：数字化设计数据安全隐私保护拖拉机产品云服务

The Eocene climate of China, the early elevation of the Tibetan Plateau and the onset of the Asian Monsoon

在线全文

学校读者我要写书评

暂无评论

The Eocene climate of China, the early elevation of the Tibe...

原发性开角型青光眼和高眼压患者及正常人群结膜印迹细胞学检查的比较（英文）

生态文明建设中的植物学：现在与未来——中国植物学会第十五届会员代表大会暨八十周年学术年会

作者： QING WANG ROBERT A.SPICER JIAN YANG YU-FEI WANG CHENG-sen LI State Key Laboratory of Systematic and Evolutionary Botany Institute of Botany Chinese Academy of Sciences Beijing Radiation Center College of Life Sciences Liaoning Normal University

Eocene palynological samples from 37 widely distributed sites across China were analysed using Co-existence Approach (CA) to determine trends in space and time for seven palaeoclimate variables: Mean Annual Temperature (MAT), Mean Annual Precipitation (MAP), Mean Temperature of the Warmest Month (WMMT), Mean Temperature of the Coldest Month (CMMT), Mean Annual Range of Temperature (MART), Mean Maximum monthly Precipitation (MMaP) and Mean Minimum monthly Precipitation (MMiP). Present day distributions and observed climates within China of the nearest living relatives of the fossil forms were used to find the range of a given variable in which a maximum number of taxa can coexist. Isotherm and isohyet maps for the early, middle and late Eocene were constructed. These illustrate regional changing patterns in thermal and precipitational gradients that may be interpreted as the beginnings of the modern Asian Monsoon system, and suggest that the uplift of parts of the Tibetan Plateau appear to have taken place by the middle to late Eocene.

关键词： China Eocene Quantitative palaeoclimate reconstruction Co-existence Approach Isogram map Tibetan Plateau Asian Monsoon.

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

国际眼科杂志 2015年第5期15卷 745-749页

作者： Ufuk Elgin Mehmet Citirik Hulya Haksever Emine sen Faruk Ozturk Huseyin Ustun 安卡拉Ulucanlar眼研究医院眼科土耳其安卡拉06240 安卡拉培训与研究医院病理科土耳其安卡拉06340

目的：比较原发性开角型青光眼和高眼压患者及拥有健康眼球表面的正常人群的泪膜功能和印象细胞学检查的数值。方法：此前瞻性研究中纳入了原发性开角型青光眼患者11例11眼（平均年龄：62.7±6.1岁）,高眼压患者12例12眼（平均年龄：6... 详细信息

目的：比较原发性开角型青光眼和高眼压患者及拥有健康眼球表面的正常人群的泪膜功能和印象细胞学检查的数值。方法：此前瞻性研究中纳入了原发性开角型青光眼患者11例11眼（平均年龄：62.7±6.1岁）,高眼压患者12例12眼（平均年龄：62.8±6.4岁）及健康人12例12眼（平均年龄：62.9±6.03岁）。这些患者均是最近被诊断出患有原发性开角型青光眼及高眼压,且之前未接受过抗青光眼方面的治疗。均行结膜印迹细胞学检查、泪膜破裂时间和基础泪液分泌试验。每组印迹细胞学检查的样本根据Nelson分级法分为0-3级。应用Kruskal-Wallis检验和Dunn多重比较检验进行统计分析。结果：原发性开角型青光眼患者,高眼压患者及正常人群平均基础泪液分泌值分别为10.4±1.3,10.9±1.2和11.1±1.1 mm/5min,其差距没有统计学意义（P=0.33）；三组的泪膜破裂时间分别为11.2±1.1,11.3±1.1和11.8±1.2s,其差距没有统计学意义（P=0.35）。原发性开角型青光眼患者中6眼（54.5%）为0级,5眼（45.5%）为1级。高眼压患者中6眼（50%）为0级,6眼（50%）为1级,健康人中6眼（50%）为0级,6只眼（50%）为1级（P=0.97）。结论：氧化应激可能会导致青光眼,眼表疾病,泪腺功能障碍及机体杯状细胞所分泌的黏液减少。原发性开角型青光眼患者,高眼压症患者及健康人群间的印象细胞学检查数值并无显著差异。

关键词：结膜印迹细胞学原发性开角型青光眼高眼压