首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   10784篇
  免费   849篇
  国内免费   6篇
  2023年   67篇
  2022年   109篇
  2021年   280篇
  2020年   155篇
  2019年   282篇
  2018年   310篇
  2017年   276篇
  2016年   399篇
  2015年   623篇
  2014年   633篇
  2013年   822篇
  2012年   954篇
  2011年   899篇
  2010年   556篇
  2009年   537篇
  2008年   649篇
  2007年   662篇
  2006年   558篇
  2005年   501篇
  2004年   444篇
  2003年   400篇
  2002年   369篇
  2001年   94篇
  2000年   60篇
  1999年   82篇
  1998年   93篇
  1997年   67篇
  1996年   61篇
  1995年   67篇
  1994年   62篇
  1993年   42篇
  1992年   55篇
  1991年   41篇
  1990年   28篇
  1989年   42篇
  1988年   24篇
  1987年   27篇
  1986年   27篇
  1985年   31篇
  1984年   19篇
  1983年   27篇
  1982年   14篇
  1981年   12篇
  1980年   18篇
  1979年   23篇
  1978年   15篇
  1977年   15篇
  1974年   15篇
  1972年   11篇
  1968年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
Current approaches that compare spatial genetic structure of a given species and the dispersal of its mobile phase can detect a mismatch between both patterns mainly due to processes acting at different temporal scales. Genetic structure result from gene flow and other evolutionary and demographic processes over many generations, while dispersal predicted from the mobile phase often represents solely one generation on a single time-step. In this study, we present a spatial graph approach to landscape genetics that extends connectivity networks with a stepping-stone model to represent dispersal between suitable habitat patches over multiple generations. We illustrate the approach with the case of the striped red mullet Mullus surmuletus in the Mediterranean Sea. The genetic connectivity of M. surmuletus was not correlate with the estimated dispersal probability over one generation, but with the stepping-stone estimate of larval dispersal, revealing the temporal scale of connectivity across the Mediterranean Sea. Our results highlight the importance of considering multiple generations and different time scales when relating demographic and genetic connectivity. The spatial graph of genetic distances further untangles intra-population genetic structure revealing the Siculo-Tunisian Strait as an important corridor rather than a barrier for gene flow between the Western- and Eastern Mediterranean basins, and identifying Mediterranean islands as important stepping-stones for gene flow between continental populations. Our approach can be easily extended to other systems and environments.  相似文献   
162.
The International Journal of Life Cycle Assessment - Weighting in life cycle assessment (LCA) incorporates stakeholder preferences in the decision-making process of comparative LCAs. Research...  相似文献   
163.
164.
Retention forestry, which retains a portion of the original stand at the time of harvesting to maintain continuity of structural and compositional diversity, has been originally developed to mitigate the impacts of clear‐cutting. Retention of habitat trees and deadwood has since become common practice also in continuous‐cover forests of Central Europe. While the use of retention in these forests is plausible, the evidence base for its application is lacking, trade‐offs have not been quantified, it is not clear what support it receives from forest owners and other stakeholders and how it is best integrated into forest management practices. The Research Training Group ConFoBi (Conservation of Forest Biodiversity in Multiple‐use Landscapes of Central Europe) focusses on the effectiveness of retention forestry, combining ecological studies on forest biodiversity with social and economic studies of biodiversity conservation across multiple spatial scales. The aim of ConFoBi is to assess whether and how structural retention measures are appropriate for the conservation of forest biodiversity in uneven‐aged and selectively harvested continuous‐cover forests of temperate Europe. The study design is based on a pool of 135 plots (1 ha) distributed along gradients of forest connectivity and structure. The main objectives are (a) to investigate the effects of structural elements and landscape context on multiple taxa, including different trophic and functional groups, to evaluate the effectiveness of retention practices for biodiversity conservation; (b) to analyze how forest biodiversity conservation is perceived and practiced, and what costs and benefits it creates; and (c) to identify how biodiversity conservation can be effectively integrated in multi‐functional forest management. ConFoBi will quantify retention levels required across the landscape, as well as the socio‐economic prerequisites for their implementation by forest owners and managers. ConFoBi's research results will provide an evidence base for integrating biodiversity conservation into forest management in temperate forests.  相似文献   
165.
166.
167.
168.
169.
170.
Coral Reefs - A correction to this paper has been published: https://doi.org/10.1007/s00338-021-02120-y  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号