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   90069篇
  免费   1296篇
  国内免费   1448篇
安全科学   3791篇
废物处理   3290篇
环保管理   13759篇
综合类   21785篇
基础理论   26289篇
环境理论   72篇
污染及防治   14316篇
评价与监测   5375篇
社会与环境   3585篇
灾害及防治   551篇
  2022年   875篇
  2021年   873篇
  2020年   697篇
  2019年   893篇
  2018年   1162篇
  2017年   1205篇
  2016年   2192篇
  2015年   1893篇
  2014年   2678篇
  2013年   9368篇
  2012年   2227篇
  2011年   2411篇
  2010年   3320篇
  2009年   3401篇
  2008年   1902篇
  2007年   1693篇
  2006年   2201篇
  2005年   2202篇
  2004年   2499篇
  2003年   2352篇
  2002年   1894篇
  2001年   2235篇
  2000年   1958篇
  1999年   1542篇
  1998年   1390篇
  1997年   1378篇
  1996年   1488篇
  1995年   1579篇
  1994年   1485篇
  1993年   1325篇
  1992年   1318篇
  1991年   1283篇
  1990年   1235篇
  1989年   1198篇
  1988年   1047篇
  1987年   968篇
  1986年   995篇
  1985年   1064篇
  1984年   1153篇
  1983年   1163篇
  1982年   1171篇
  1981年   1088篇
  1980年   941篇
  1979年   918篇
  1978年   816篇
  1977年   707篇
  1976年   636篇
  1975年   599篇
  1973年   625篇
  1972年   621篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
281.
The situation and the latest findings of forest damage research in Germany are discussed. A newly developed concept for this research is described. This concept allows to identify the drawbacks of the recent damage research concept but also the integration of results compiled up to now. The importance for including natural occurring stress factors such as climate, soil conditions or local situation of individual species is outlined.  相似文献   
282.
283.
284.
Abstract:  Broadly conceived and considered in its many usages, sustainability has grave defects as a planning goal, particularly when used by conservationists: it confuses means and ends; it is vague about what is being sustained and who or what is doing the sustaining; it is uninspiring; it is little more than Pinchot-era conservation (and thus ignores the many lessons learned since then); it need not be linked to land, to the land's functioning, or to any ecological science; it need not include a moral component; it is consistent with the view of humans as all-powerful manipulators of the planet; and, in general, it is such a malleable term that its popularity provides only a facade of consensus. When sustainability is defined broadly to include the full range of economic and social aspirations, it poses the particular risk that ecological and biodiversity concerns will be cast aside in favor of more pressing human wants. Given these many defects, the conservation movement should discard the term in favor of a more alluring goal, attentive to nature and its ecological functioning. A sound goal would incorporate and distill the considerable ecological and moral wisdom accumulated since Pinchot's day while giving conservationists the rhetorical tools needed to defend the land against competing pressures. In our view, conservation would be well served by an updated variant of "land health," Aldo Leopold's ecologically grounded goal from the 1940s. Land health as an independent understanding should set the essential terms of how we live and enjoy the earth, providing the framework within which we pursue our many social and economic aims.  相似文献   
285.
We report the prenatal diagnosis at 16 weeks' gestation of bilateral split-hand/split-foot malformation (SHSFM) with severe lobster claw deformity of hands and feet in a male fetus without associated malformations. A minor manifestation of SHSFM was present in the father with only mild bilateral foot involvement (syndactyly I–II; cleft II–III; left cutaneous syndactyly III–IV). Mutation analysis of the p63 gene on chromosome 3q27 showed a missense mutation 577A→G (predicting amino acid substitution K193E) in the father. This mutation has not been reported so far in SHSFM but resembles the previously reported 580A→G (predicting amino acid substitution K194E) in a family with SHSFM. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
286.
287.
5p deletion syndrome commonly known as cri du chat is well described in affected neonates with catlike cry and hypotonia. Karyotyping will usually show a deletion of the short arm of one chromosome 5 with variable breakpoints. Only a few cases have been reported prenatally, and the fetal form of the syndrome has not been clearly individualised. We report a new case of 5p deletion syndrome diagnosed prenatally in association with Dandy–Walker syndrome and agenesis of the corpus callosum. Other brain anomalies have been reported previously, but this unusual association suggests the use of a specific probe in the investigation of these malformations. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
288.
The interdependences between climate and humanity are becoming increasingly apparent, which makes climatology an upto-date and strongly discussed subject. Its task is to identify and examine relatively long-term, regional and global, natural and anthropogenic developments. A global, long-term view reveals a striking increase of surfacenear air temperature since the beginning of the industrial age. On a regional scale, trends differ considerably, but also Germany shows an apparent trend of increasing temperature and precipitation. The development of extreme events is more difficult to judge; the heat summer of 2003 in Europe, however, is among the phenomena that are likely to occur more frequently in the future. The influence of different natural and anthropogenic factors on the climate is expressed, amongst others, through their radiative forcings. Greenhouse gases emitted from anthropogenic activities are of particular significance since their concentration in the atmosphere keeps increasing. Mathematical modeling has made it possible to reconstruct the climate development of the past with increasing precision. The currently observed warming can only be comprehended by assuming anthropogenic influences. For the future development different scenarios have been calculated in order to deduce strategies for necessary action.  相似文献   
289.
Stormwater runoff is now a major contributor to the pollution of coastal waters in the United States. Public agencies are responding by requiring stormwater monitoring to satisfy the National Pollutant Discharge Elimination System stormwater permit. However, studies to understand the utility of the current programs or to improve their usefulness have not yet been performed. In this paper, we evaluate the land-use-based program, the industrial stormwater permit program, and beach water-quality monitoring in the County of Los Angeles, California, to determine if the results will be helpful to planners and regulators in abating stormwater pollution. The utility of the program has been assessed based on the programs' ability to accurately estimate the emissions for different classes of land use. The land-use program appears successful, while the industrial monitoring program does not. Beach water-quality monitoring suffers from a lack of real-time monitoring techniques. We also provide suggested improvements, such as sampling method and time, and parameter selection.  相似文献   
290.
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