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   16979篇
  免费   216篇
  国内免费   148篇
安全科学   471篇
废物处理   680篇
环保管理   2289篇
综合类   3193篇
基础理论   4194篇
环境理论   11篇
污染及防治   4258篇
评价与监测   1093篇
社会与环境   1022篇
灾害及防治   132篇
  2022年   201篇
  2021年   203篇
  2020年   143篇
  2019年   167篇
  2018年   265篇
  2017年   290篇
  2016年   395篇
  2015年   318篇
  2014年   441篇
  2013年   1426篇
  2012年   527篇
  2011年   699篇
  2010年   552篇
  2009年   610篇
  2008年   680篇
  2007年   705篇
  2006年   659篇
  2005年   530篇
  2004年   502篇
  2003年   517篇
  2002年   454篇
  2001年   559篇
  2000年   430篇
  1999年   245篇
  1998年   202篇
  1997年   194篇
  1996年   213篇
  1995年   217篇
  1994年   211篇
  1993年   206篇
  1992年   215篇
  1991年   203篇
  1990年   204篇
  1989年   176篇
  1988年   153篇
  1987年   132篇
  1986年   158篇
  1985年   160篇
  1984年   160篇
  1983年   162篇
  1982年   158篇
  1981年   163篇
  1980年   151篇
  1979年   146篇
  1978年   110篇
  1977年   121篇
  1974年   109篇
  1973年   92篇
  1972年   107篇
  1971年   88篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
221.
222.
 Chemical synapses are highly specialized cell–cell junctions designed for efficient signaling between nerve cells. Distinct cytoskeletal matrices are assembled at either side of the synaptic junction. The presynaptic cytomatrix at the active zone (CAZ) defines and organizes the site of neurotransmitter release from presynaptic nerve terminals. The postsynaptic density (PSD) tethers neurotransmitter receptors and the postsynaptic signal transduction machinery. Recent progress in the identification and characterization of novel CAZ and PSD components has revealed new insights into the molecular organization and assembly mechanisms of the synaptic neurotransmission apparatus. On the presynaptic side, Bassoon and Piccolo, two related giant proteins, are crucially involved in scaffolding the CAZ. On the postsynaptic side, two families of multi-domain adaptor proteins, the MAGuKs (membrane-associated guanylate kinase homologs) and the ProSAP (proline-rich synapse-associated protein, also termed Shank) family members are thought to be major organizing molecules of the PSD.  相似文献   
223.
224.
The restoration of surface mining landscapes requires the (re)creation of ecosystems. In Lusatia (eastern Germany), large-scale open-cast lignite mining operations generated spoil dumps widely consisting of acidified, phytotoxic substrates. Amelioration and rehabilitation measures have been developed and applied to these substrates since the 1950s. However, it is still not clear whether these approaches are sustainable. This paper reports on collaborative research work into the ecological potential of forest ecosystem development on typical minesites in the Lusatian lignite district. At first sight, pine stands on minesites along a chronosequence comprising about 35 years did not show differences when compared with stands on non-mined sites of the general region. Furthermore, with some modification, conceptual models for flora and fauna succession in forest stands on non-mined sites seem to be applicable, at least for the early stages of forest ecosystem development. For example, soil organism abundance and activity at minesites had already reached levels typical of non-mined sites after about 20-30 years. In contrast, mine soils are very different from non-mined soils of the test region. Chemically, mine soil development is dominated by processes originating from pyrite oxidation. Geogenic, i.e. lignitic, soil organic carbon was shown to substitute for some functions of pedogenic soil organic matter. Rooting was hampered but not completely impeded in strongly acidified soil compartments. Roots and mycorrhizae are apparently able to make use of the characteristic heterogeneity of young mine soils. Considering these recent results and the knowledge accumulated during more than 30 years of research on minesite rehabilitation internationally, it can be stated that minesite restoration might be used as an ideal case study for forest ecosystem development starting at "point zero" on "terra nova".  相似文献   
225.
226.
227.
228.
229.
230.
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