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   405篇
  免费   20篇
  2023年   1篇
  2022年   2篇
  2021年   10篇
  2020年   9篇
  2019年   3篇
  2018年   13篇
  2017年   5篇
  2016年   15篇
  2015年   18篇
  2014年   21篇
  2013年   34篇
  2012年   42篇
  2011年   33篇
  2010年   16篇
  2009年   21篇
  2008年   23篇
  2007年   32篇
  2006年   22篇
  2005年   30篇
  2004年   20篇
  2003年   13篇
  2002年   13篇
  2001年   2篇
  1999年   2篇
  1998年   3篇
  1997年   1篇
  1996年   1篇
  1995年   3篇
  1994年   3篇
  1993年   5篇
  1992年   1篇
  1986年   1篇
  1985年   1篇
  1983年   1篇
  1981年   1篇
  1977年   1篇
  1974年   1篇
  1963年   2篇
排序方式: 共有425条查询结果,搜索用时 0 毫秒
421.
422.
EcoHealth - As the Ebola outbreak in West Africa wanes, it is time for the international scientific community to reflect on how to improve the detection of and coordinated response to future...  相似文献   
423.
Compositional dissimilarity patterns of biotic communities can vary among different types of insular systems and among taxa with different dispersal abilities. In this work we examined compositional dissimilarity patterns of four avian groups, namely birds of prey, waterbirds, seabirds and landbirds, in various insular systems around the world. Compositional dissimilarity of avian communities was calculated for 25 presence-absence matrices compiled from the literature. We used generalized linear mixed-effects models to check for differences in between-island compositional dissimilarity among the aforementioned avian groups that differ in their dispersal abilities, as well as between two different types of insular systems, oceanic and continental shelf. In agreement with our original hypothesis, landbirds which have relatively poorer dispersal abilities than birds of prey and waterbirds, exhibit higher between-island compositional dissimilarity compared to these two avian groups. On the contrary, seabirds present a deviation from the expected pattern, since they show higher between-island compositional dissimilarity compared to landbirds, even though they also have better dispersal abilities than landbirds, which can be explained by the relatively irregular occurrence of proper breeding habitats among islands for this avian group. Island type (oceanic or continental shelf) does not appear to affect between-island compositional dissimilarity of avian communities. Distance, area and elevation differences among islands are positively related to compositional dissimilarity. In conclusion, compositional dissimilarity of avian communities differs between avian groups but cannot always be associated with differences in the dispersal ability among these groups.  相似文献   
424.
The present study investigated the mite fauna and the relative abundance of mites present in foliage and litter of two adjacent and similar alfalfa fields, differing only in the number of cuttings, in Kopais Valley (Central Greece) through 2008–2010. We also examined the relationship between assemblage patterns of Mesostigmata, Oribatida and Prostigmata by comparing their population fluctuation, population density, species richness and diversity. Spatial distribution of common dominant and influent mite species was also estimated. Our results showed that both fields supported a very rich and similar mite fauna with eight new species records for alfalfa of Greece, although these species have been previously reported from other habitats in Greece. The pattern of population fluctuation in foliage was similar in both fields, unlike the fluctuation in litter. Population density significantly differed between fields, being higher in the less harvested field, except Prostigmata. Species richness in litter was higher in the less harvested field, whereas it was higher in the foliage of the more harvested field, apart from that of prostigmatic mites in litter, which was higher in the more harvested field, and that of oribatid mites in foliage, which was higher in the less harvested field. The diversity of mites was higher in the more harvested field, with the exception of prostigmatic mites. The spatial distribution of mites in foliage and litter was aggregated in both fields. Our results indicate that despite the considerable similarity of the study fields, the different harvesting frequency might have disturbed differently the mite communities hosted in foliage and litter.  相似文献   
425.
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