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   563篇
  免费   2篇
  国内免费   5篇
安全科学   4篇
废物处理   14篇
环保管理   27篇
综合类   270篇
基础理论   107篇
环境理论   1篇
污染及防治   102篇
评价与监测   20篇
社会与环境   23篇
灾害及防治   2篇
  2018年   7篇
  2016年   7篇
  2015年   4篇
  2013年   21篇
  2012年   12篇
  2011年   16篇
  2010年   12篇
  2009年   18篇
  2008年   18篇
  2007年   21篇
  2006年   22篇
  2005年   27篇
  2004年   18篇
  2003年   17篇
  2002年   34篇
  2001年   14篇
  2000年   8篇
  1999年   6篇
  1998年   10篇
  1996年   8篇
  1995年   12篇
  1994年   8篇
  1993年   7篇
  1990年   4篇
  1989年   5篇
  1988年   5篇
  1987年   6篇
  1985年   7篇
  1984年   5篇
  1983年   3篇
  1981年   4篇
  1979年   3篇
  1978年   3篇
  1977年   3篇
  1968年   3篇
  1967年   4篇
  1966年   8篇
  1965年   11篇
  1964年   11篇
  1963年   9篇
  1962年   11篇
  1961年   11篇
  1960年   18篇
  1959年   10篇
  1958年   10篇
  1957年   10篇
  1956年   10篇
  1955年   6篇
  1954年   5篇
  1951年   5篇
排序方式: 共有570条查询结果,搜索用时 7 毫秒
1.
2.
3.
4.
5.
6.
7.
8.
Recently, the Max Planck Society founded a new Project group for Psycholinguistics. This article reviews some of the kernel issues of the group's research program. The central concern is with the context dependency of the speaker's linguistic behavior. The process of linguistically formulating depends not only on what the speaker wants to express, but also on what has been said previously (linguistic context), and on the physical and social situation (nonlinguistic context). Special attention is paid to two context-dependent phenomena.  相似文献   
9.
The knowledge of the environmental fate of polycyclic aromatic hydrocarbons (PAHs) is restricted to few climatic regions of the world almost excluding the Taiga. Our objectives were to (i) separate anthropogenic from background contributions to PAH concentrations and (ii) determine temporal trends in PAH concentrations during the last century including the change in distribution of PAHs in interior and exterior portions of aggregates in soils of the Moscow region. Along a southeast-bound transect from Moscow (windward in winter) and at a background location northeast of Moscow (leeward in winter), seven topsoil samples were collected in 1910-1954 and 35 in 1998-2003. We fractionated the soils in interior and exterior portions of aggregates > 10 mm and remaining soil without aggregates. The sum of 21 PAHs (sigma21PAHs) concentrations in recent bulk soil ranged from 59 to 1350 ng g(-1). The concentrations of all PAHs were lower outside than in Moscow. The range of the concentrations of the sigma21PAHs in archived soil samples (159-1280 ng g(-1)) was similar as in recent soils. In most recent and archived samples, naphthalene and phenanthrene, were most abundant. The concentrations of low-molecular-weight PAHs decreased during the last century at most sites; those of high-molecular-weight compounds increased. The sigma21PAHs concentrations were accumulated in the exterior of aggregates (109%) and depleted in the interior (95%) relative to the concentration in bulk soil (defined as 100%), which was similar to that in the soil without aggregates (99%). The differences between aggregate interior and exterior did not change during the last century. The dominance of naphthalene and phenanthrene is typical of remote regions. The urban influence on PAH concentrations in the last century was small.  相似文献   
10.
One of the most interesting aspects of the mating system of pied flycatchers is the regular occurrence of polygyny. Here we present data on the reproductive success of polygynously paired pied flycatcher males compared to monogamous males based on paternity analyses through DNA fingerprinting. Males paired with two females suffered a higher loss in reproductive output per female compared to monogamous males due to (1) a greater proportion of unhatched eggs in their broods, (2) greater nestling mortality and (3) a greater probability of being cuckolded. Nevertheless, the number of fledglings was significantly greater for polygynous males. Based on the number of nestlings that returned for subsequent breeding seasons, however, the reproductive success of monogamous and polygynous males did not differ significantly. These data raise the question as to why males attempt polygyny. Received: 16 August 1999 / Received in revised form: 15 March 2000 / Accepted: 18 March 2000  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