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   389篇
  免费   24篇
管理学   32篇
民族学   4篇
人口学   36篇
丛书文集   2篇
理论方法论   22篇
综合类   27篇
社会学   202篇
统计学   88篇
  2023年   6篇
  2022年   8篇
  2021年   10篇
  2020年   13篇
  2019年   11篇
  2018年   25篇
  2017年   27篇
  2016年   23篇
  2015年   10篇
  2014年   9篇
  2013年   53篇
  2012年   102篇
  2011年   14篇
  2010年   11篇
  2009年   4篇
  2008年   5篇
  2007年   8篇
  2006年   6篇
  2005年   5篇
  2004年   6篇
  2003年   5篇
  2002年   14篇
  2001年   7篇
  2000年   7篇
  1999年   2篇
  1998年   1篇
  1997年   5篇
  1996年   2篇
  1992年   2篇
  1991年   5篇
  1990年   1篇
  1987年   2篇
  1983年   1篇
  1980年   1篇
  1975年   2篇
排序方式: 共有413条查询结果,搜索用时 78 毫秒
411.

The Neotropical region has been subjected to massive urbanization, which poses high risks for some global biodiversity hotspots and losses of ecosystem functions and services. In this study, we investigate how distance from large patches of native forests (source areas) and vegetation (green)/and infrastructure (gray) characteristics affect bird species richness and functional diversity in São Paulo megacity, southeastern Brazil. We analyzed the effects of source areas and green/gray characteristics on species richness and functional diversity (richness, evenness, and divergence) indices. We detected 231 bird species, and our data confirmed our predictions: (1) bird species richness in urbanized habitats was found to be (~?50–85%) lower than in source habitats; (2) species richness and trait composition significantly decreased as the distance from the source area increased, while functional richness was not affected by this metric; and (3) shrub and herbaceous covers and maximum height of trees were positively correlated with species richness and unique functional traits regarding habitat, diet, foraging and nesting strata and dispersal ability of birds in the forest-urban matrix. The number of buildings was negatively correlated with bird species richness and functional richness. Maximum height of buildings caused dramatic declines in functional evenness. Functional divergence was notably lower in sites with high shrub cover. Our study stresses the complexity of vegetation embedded in large Neotropical urban settlements and the need to maintain large protected areas surrounding megacities to mitigate the impacts of urbanization on birds.

  相似文献   
412.
A variable-centered and a person-centered approach were performed to examine the role of early memories of warmth and safeness (EMWS) and current experiences of warmth and safeness (CEWS) on depressive and anxious symptoms among adolescents from community and residential youth care (RYC) settings. Variable-centered results revealed EMWS were only indirectly (through CEWS) associated with depressive and anxious symptoms. Person-centered outcomes allowed to identify four different profiles based on EMWS and CEWS, which differed on depressive and anxious symptoms. EMWS and CEWS seem to play an important role in psychological distress during adolescence. CEWS seem to have a protective role on RYC adolescents' psychological distress, even when EMWS were poor.  相似文献   
413.
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