检索结果-南通市图书馆

Life forms affect beta-diversity patterns of larch forests in China

Plant Diversity 2024年第1期46卷 49-58页

作者： wenjing fang Qiong Cai Chengjun Ji Jiangling Zhu Zhiyao Tang Jingyun fang School of Ecology and Environmental Science Yunnan UniversityKunming 650091China Department of Ecology College of Urban and Environmental Sciencesand Key Laboratory for Earth Surface Processes of the Ministry of EducationPeking UniversityBeijing 100871China

Beta-diversity reflects the spatial changes in community species composition which helps to understand how communities are assembled and biodiversity is formed and maintained. Larch(Larix) forests, which are coniferous forests widely distributed in the mountainous and plateau areas in North and Southwest China, are critical for maintaining the environmental conditions and species diversity. Few studies of larch forests have examined the beta-diversity and its constituent components(species turnover and nestedness-resultant components). Here, we used 483 larch forest plots to determine the total betadiversity and its components in different life forms(i.e., tree, shrub, and herb) of larch forests in China and to evaluate the main drivers that underlie this beta-diversity. We found that total betadiversity of larch forests was mainly dependent on the species turnover component. In all life forms,total beta-diversity and the species turnover component increased with increasing geographic, elevational, current climatic, and paleoclimatic distances. In contrast, the nestedness-resultant component decreased across these same distances. Geographic and environmental factors explained 20%-25% of total beta-diversity, 18%-27% of species turnover component, and 4%-16% of nestedness-resultant component. Larch forest types significantly affected total beta-diversity and species turnover component. Taken together, our results indicate that life forms affect beta-diversity patterns of larch forests in China, and that beta-diversity is driven by both niche differentiation and dispersal limitation. Our findings help to greatly understand the mechanisms of community assemblies of larch forests in China.

关键词： Beta-diversity Species turnover Nestedness-resultant Geographic distance Climatic distance Larch forest

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A high-performance multi-wavelength optical switch based on multiple Fano resonances in an all-dielectric metastructure

引用

Optoelectronics Letters 2024年第4期20卷 193-199页

作者： CAO Shuangshuang FAN Xinye fang wenjing CHEN Huawei BAI Chenglin TONG Cunzhu School of Physics Science and Information Engineering Liaocheng UniversityLiaocheng 252000China Shandong Provincial Key Laboratory of Optical Communication Science and Technology Liaocheng 252000China Liaocheng Key Laboratory of Industrial-Internet Research and Application Liaocheng 252000China Institute of Semiconductors Chinese Academy of SciencesBeijing 100083China State Key Laboratory of Luminescence and Applications Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China

The multi-wavelength optical switch based on an all-dielectric metastructure consisting of four asymmetric semi-circular rings was designed and analyzed in this *** Fano resonance modes,which can be explained by bound states in the continuum(BIC)theory,are excited in our structure with a maximum Q-factor of about 2450 and a modulation depth close to 100%.By changing the polarization direction of the incident light,the transmission amplitude of Fano resonances can get effectively *** on this tuning property,the metastructure can achieve a multi-wavelength optical switch in the near-infrared region(900—980 nm)and the maximum extinction ratio can reach 38.3 d *** addition,the results indicate that the Fano resonances are sensitive to the changes in the refractive *** sensitivity(S)and the figure of merit(FOM)are 197 nm/RIU and 492 *** proposed metastructure has promising potential in applications such as optical switches,sensors,modulators and lasers.

关键词： dielectric structure resonance

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

声触诊弹性成像评估生物反馈电刺激治疗初产妇腹直肌分离效果

引用

中国医学影像技术 2024年第4期40卷 570-574页

作者：方文静马桂凤朱雯王欣徐灵菲齐永涛林秀梅潍坊医学院附属医院超声科山东潍坊261031 山东第二医科大学医学影像学院山东潍坊261053

目的观察声触诊弹性成像(STE)评估生物反馈电刺激治疗初产妇腹直肌分离(DRA)效果的价值。方法前瞻性纳入98例DRA初产妇,根据是否接受生物反馈电刺激治疗将其分为治疗组(n=48)及未治疗组(n=50);以50名健康未孕育龄期女性为对照组。比... 详细信息

目的观察声触诊弹性成像(STE)评估生物反馈电刺激治疗初产妇腹直肌分离(DRA)效果的价值。方法前瞻性纳入98例DRA初产妇,根据是否接受生物反馈电刺激治疗将其分为治疗组(n=48)及未治疗组(n=50);以50名健康未孕育龄期女性为对照组。比较治疗组与未治疗组产后42天与产后10周(即治疗1个疗程后)腹直肌间距离(IRD_(1)/IRD_(2))、6个位点杨氏模量(E_(1)/E_(2))及其均值(E_(mean-1)/E_(mean-2));以Pearson相关分析评估治疗组E_(mean-3)(E_(mean-2)与E_(mean-1)差值)与IRD_(3)(IRD_(2)与IRD_(1)差值)的相关性。结果治疗组IRD_(2)显著低于IRD_(1)(P0.05)。治疗组IRD_(3)、E_(mean-2)、E_(mean-3)及6个位点E_(2)均高于未治疗组(P均0.05)且均低于对照组(P均<0.05)。治疗组E_(mean-3)与IRD_(3)呈高度正相关(r=0.823,P<0.01)。结论 STE可有效评估生物反馈电刺激治疗早期初产妇DRA效果。

关键词：产次腹直肌超声检查电刺激前瞻性研究

来源：

维普期刊数据库博看期刊

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The structural characteristics and climatic and human impacts of deciduous oak forests in China

引用

Journal of Plant Ecology 2022年第2期15卷 265-276页

作者： Guoping Chen Qiong Cai wenjing fang Yuhao Feng Jiangling Zhu Chengjun Ji Zhiyao Tang Jingyun fang Institute of Ecology College of Urban and Environmental Sciencesand Key Laboratory for Earth Surface Processes of the Ministry of EducationPeking UniversityBeijing 100871China

Deciduous oak forest is one of the typical vegetation types in temperate and subtropical mountain zones in ***,the patterns and determinants of the structural characteristics of these forests remain poorly *** investigated 682 oak forest plots across China to characterize the community structures of the oak forests and analyze the underlying factors controlling their spatial *** all plots,the overall mean values were 13.7 cm,10.0 m,1468 stems/ha and 24.3 m^(2)/ha for the diameter at breast height(DBH),height,stem density and total basal area(TBA)of trees,*** average species richness was 6 species/600 m^(2),10 species/100 m^(2) and 4 species/1 m^(2) for the tree,shrub and herb layers,*** latitude increased,the mean tree height,stem density,TBA,tree species richness and shrub species richness decreased,and the mean DBH did not show a significant trend,while species richness of herbs increased *** and anthropogenic variables could explain more variations in mean DBH,mean tree height,TBA,tree species richness,shrub species richness than those in stem density and herb species *** analysis showed that precipitation-related climatic factors were major factors shaping the spatial patterns of community *** findings provide a basis for recognizing the biogeographic patterns of oak forest structures and their responses to global change in China.

关键词： Quercus deciduous oak forests structural characteristics climate human disturbance China

来源：

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

The relationships among structure variables of larch forests in China

引用

Forest Ecosystems 2020年第4期7卷 807-818页

作者： wenjing fang Qing Zhao Qiong Cai Anwar Eziz Guoping Chen Yuhao Feng Heng Zhang Jiangling Zhu Chengjun Ji Zhiyao Tang Jingyun fang Department of Ecology College of Urban and Environmental Scienceand Key Laboratory for Earth Surface Processes of the Ministry of EducationPeking UniversityBeijing 100871China

Background:Larch(Larix Mill.)forests are widely distributed in the upper parts of mountainous areas in China,playing vital roles in constructing mountain landscapes and maintaining mountain *** their importance,our knowledges on the large-scale patterns of structure characteristics and the relationships between different structure variables are *** this paper,we investigated 155 plots from 11 natural larch forest types across the country to explore the biogeographic patterns of the structure characteristics and the allometric relationships between different structure variables for Chinese larch ***:The structure characteristics were significantly different among larch forest *** different larch forest types,the power function fits the relationships between tree height and diameter at breast height(DBH),average DBH and stem density,and taper and stem density well,but with different exponents among larch forest *** power exponents of the allometric relationships between tree height and DBH for different larch forest types varied from 0.61 to 0.93(mean=0.86)by standard major axis regression(SMA),and from 0.51 to 0.78(mean=0.56)by ordinary least square regression(OLS).The 50%,75%and 95%quantile regression(QR)and OLS indicated that the average DBH and taper of the *** forests,*** ***-rupprechtii forests,and *** forests were significantly correlated with stem ***:The relationship between tree height and DBH showed a power function relationship for all larch forest types in China,but with different ***,stem density was negatively correlated with average DBH and *** *** forests exhibited stand density *** findings provide an important basis for recognizing the biogeographic patterns of structure factors and for the management of larch forests in China.

关键词： Larch forests Stand factor Allometric relationship Power function Density effect and self-thinning

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

胃肠充盈超声造影预测早期胃癌患者淋巴结转移的价值

引用

医学影像学杂志 2024年第6期34卷 61-63,67页

作者：付海龙卢成伟韩霖王博能方文静山东省昌邑市柳疃镇中心卫生院山东潍坊261302 山东第二医科大学附属医院山东潍坊261035

目的探讨胃肠充盈超声造影预测早期胃癌(EGC)淋巴结转移的价值。方法选取接受胃肠充盈超声造影检查并经胃镜诊断术后病理证实EGC患者63例,对病灶及周围正常胃壁勾画感兴趣区(ROI),获取病灶峰值强度(PKI)、上升时间(RT),根据术后病理结... 详细信息

目的探讨胃肠充盈超声造影预测早期胃癌(EGC)淋巴结转移的价值。方法选取接受胃肠充盈超声造影检查并经胃镜诊断术后病理证实EGC患者63例,对病灶及周围正常胃壁勾画感兴趣区(ROI),获取病灶峰值强度(PKI)、上升时间(RT),根据术后病理结果分为淋巴结转移组N1(31例)和非淋巴结转移组N0(32例),比较两组胃癌充盈超声造影参数差异及与淋巴结转移的关系。结果与N0组EGC患者相比,N1组EGC患者在一般资料与病灶浸润深度方面差异无统计学意义(P>0.05)。N1组EGC患者病灶PKI值高于N0组,而RT值短于N0组,其差异均具有统计学意义(P<0.05)。PKI、RT值预测EGC患者淋巴结转移ROC曲线下面积分别为0.930、0.762。结论胃肠充盈超声造影对术前无创定量评估EGC患者淋巴结转移有一定的诊断价值。

关键词：超声造影早期胃癌淋巴结转移

来源：

维普期刊数据库

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Changes in carbon storages of Fagus forest ecosystems along an elevational gradient on Mt. Fanjingshan in Southwest China

引用

Journal of Plant Ecology 2020年第2期13卷 139-149页

作者： Qiong Cai Chengjun Ji Xuli Zhou Helge Bruelheide wenjing fang Tianli Zheng Jiangling Zhu Lei Shi Haibo Li Jianxiao Zhu Jingyun fang Department of Ecology College of Urban and Environmental Sciencesand Key Laboratory for Earth Surface Processes of the Ministry of EducationPeking University100871 BeijingChina Institute of Biology/Geobotany and Botanical Garden Martin Luther University Halle-WittenbergAm Kirchtor 106108 HalleGermany German Centre for Integrative Biodiversity Research(iDiv)Halle-Jena-Leipzig Deutscher Platz 5e04103 LeipzigGermany Administration Bureau of Guizhou Fanjingshan National Nature Reserve 554400 JiangkouChina

Aims There are different components of carbon(C)pools in a natural forest ecosystem:biomass,soil,litter and woody *** asked how these pools changed with elevation in one of China’s ecologically important forest ecosystem,***(Fagus L.,Fagaceae)forests,and what were the underlying driving factors of such *** The four C pools in nine beech forests were investigated along an elevational gradient(1095–1930 m)on *** in Guizhou Province,Southwest *** partitioning was used to explore the relative effects of stand age,climate and other factors on C *** addition,we compared the four C pools to other beech forests in Guizhou Province and *** Findings The total C pools of beech forest ecosystems ranged from 190.5 to 504.3 Mg C ha^(–1),mainly attributed to biomass C(accounting for 33.7–73.9%)and soil C(accounting for 23.9–65.5%).No more than 4%of ecosystem C pools were stored in woody debris(0.05–3.1%)and litter(0.2–0.7%).Ecosystem C storage increased significantly with elevation,where both the biomass and woody debris C pools increased with elevation,while those of litter and soil exhibited no such *** the Guizhou beech forests,climate and stand age were found to be key drivers of the elevational patterns of ecosystem and biomass C storage,while for beech forests globally,stand age was the most important *** to beech forests worldwide,beech forests in Guizhou Province displayed a relatively higher biomass C accumulation rate,which may be explained by a much higher precipitation in this *** present study provides basic data for understanding the C budgets of Chinese beech forests and their possible roles in regional C cycling and emphasizes the general importance of stand age and climate on C accumulation.

关键词： carbon components climate ecosystem carbon storage elevational gradient Fagus forests stand age

来源：

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‑Crack Interaction and Influence on the Spherical Pressure Hull for a Deep‑Sea Manned Submersible

引用

Journal of Marine Science and Application 2021年第3期20卷 491-503页

作者： Rujun Li Yongmei Zhu wenjing fang Baoji Yin School of Mechanical Engineering Jiangsu University of Science and TechnologyZhenjiangZhenjiang 212003China

This study investigates the interaction and influence of surface cracks on the spherical pressure hull of a deep-sea manned *** finite element model of the spherical hull is established,and a semi-elliptical surface crack is inserted in the welding toe of the spherical hull as the main *** the combined effect of external uniform pressure and welding residual stress at the weld toe,the stress intensity factor(SIF)is obtained based on the M-integral *** disturbing cracks at different positions on the spherical hull surface,the interaction and influence between multi-cracks are revealed by numerical *** results show that the existence of the disturbing crack has a great influence on the stress intensity factor of the main crack,and the influence is different with the different location of disturbing *** study of the interaction of multiple cracks under different interference factors and the influence of disturbing cracks on the main crack can provide some reference for future engineering applications.

关键词： Spherical pressure hull Surface cracks Multi-crack interaction Stress intensity factor Welding residual stress Manned submersible Finite element model

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

聚甘油脂肪酸酯的乳化性能研究进展

引用

沈阳药科大学学报 2024年第7期41卷 855-866页

作者：黄梦雨鲁丹丹方文静陶怡陈稞垒骆翔绍兴文理学院化学化工学院浙江绍兴312000

聚甘油脂肪酸酯,简称聚甘油酯,是一种乳化性能优良的非离子型表面活性剂,被广泛应用于食品、化妆品等领域。作为一种新型乳化剂,聚甘油脂肪酸酯既可作为油包水型乳化剂,也可作为水包油型乳化剂,还可形成重乳状液,适于各种特殊用途,满足... 详细信息

聚甘油脂肪酸酯,简称聚甘油酯,是一种乳化性能优良的非离子型表面活性剂,被广泛应用于食品、化妆品等领域。作为一种新型乳化剂,聚甘油脂肪酸酯既可作为油包水型乳化剂,也可作为水包油型乳化剂,还可形成重乳状液,适于各种特殊用途,满足市场需求。通过对国内外报道的70余篇聚甘油脂肪酸相关文献的整理,本文着重针对聚甘油脂肪酸酯乳化性的机理、测定方法、影响因素、乳液的种类和应用领域进行分析与讨论。聚甘油脂肪酸酯的乳化性与其亲水亲油平衡值相关,通过改变聚甘油的聚合度、脂肪酸碳链长度以及酯化度即可得到性质各异的聚甘油脂肪酸酯乳化剂,以符合多种应用需求。本文借助对聚甘油脂肪酸酯乳化性能的深入探讨,将为聚甘油脂肪酸酯乳化性能研究的进一步发展提供更完善的理论依据和实际应用价值。

关键词：聚甘油脂肪酸酯乳化性能亲水亲油平衡值应用领域

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

铁路混凝土梁配件多层防腐厚度测量方法探讨

引用

金属制品 2024年第2期50卷 40-43页

作者：王军尹亚豪房文静王禾佳苏建锋国家金属制品质量检验检测中心河南郑州450001

针对高速铁路混凝土梁配件的多层防腐涂层厚度检测技术问题,探讨磁性法、显微镜法、扫描电镜法等方法对金属制件多元合金共渗+锌铬涂层+封闭层处理的三级防腐涂层厚度的检测分析能力。结果表明:磁性法检测金属制件多元合金共渗渗层具有... 详细信息

针对高速铁路混凝土梁配件的多层防腐涂层厚度检测技术问题,探讨磁性法、显微镜法、扫描电镜法等方法对金属制件多元合金共渗+锌铬涂层+封闭层处理的三级防腐涂层厚度的检测分析能力。结果表明:磁性法检测金属制件多元合金共渗渗层具有操作简单快捷的优点,但局限性较大,在考虑检测精度的情况下建议采用其他检测方法;显微镜法检测多元合金共渗渗层厚度时制样困难且检测效率较低,不适合作为多元合金共渗渗层厚度检测方法;扫描电镜法检测多元合金共渗渗层厚度时精度高、重复性好,通过能谱仪的元素面扫描可识别不同类型的防腐层,因此是一种作为金属制件防腐涂层型式检验和仲裁检验的适宜方法。

关键词：高速铁路防腐涂层混凝土梁多元合金共渗磁性法

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：