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   28693篇
  免费   245篇
  国内免费   182篇
安全科学   569篇
废物处理   1617篇
环保管理   4053篇
综合类   3755篇
基础理论   8109篇
环境理论   9篇
污染及防治   6620篇
评价与监测   2297篇
社会与环境   1955篇
灾害及防治   136篇
  2022年   145篇
  2021年   145篇
  2020年   128篇
  2019年   159篇
  2018年   1659篇
  2017年   1606篇
  2016年   1533篇
  2015年   470篇
  2014年   551篇
  2013年   1701篇
  2012年   1060篇
  2011年   2129篇
  2010年   1406篇
  2009年   1288篇
  2008年   1695篇
  2007年   2077篇
  2006年   794篇
  2005年   678篇
  2004年   716篇
  2003年   738篇
  2002年   722篇
  2001年   731篇
  2000年   571篇
  1999年   345篇
  1998年   248篇
  1997年   266篇
  1996年   272篇
  1995年   304篇
  1994年   290篇
  1993年   243篇
  1992年   264篇
  1991年   225篇
  1990年   249篇
  1989年   224篇
  1988年   180篇
  1987年   195篇
  1986年   193篇
  1985年   194篇
  1984年   201篇
  1983年   194篇
  1982年   161篇
  1981年   171篇
  1980年   157篇
  1979年   143篇
  1978年   119篇
  1977年   130篇
  1975年   100篇
  1974年   93篇
  1973年   105篇
  1972年   91篇
排序方式: 共有10000条查询结果,搜索用时 427 毫秒
251.
In 1964, Walter Rothenbuhler proposed a two-gene model to explain phenotypic variance in the remarkable behavior in which honey bee workers remove dead brood from their colonies. Rothenbuhler's model proposed that one locus controls the uncapping of brood cells containing dead pupae, while a second controls the removal of the cell contents. We show here, through molecular techniques and quantitative trait loci (QTL) linkage mapping, that the genetic basis of hygienic behavior is more complex, and that many genes are likely to contribute to the behavior. In our cross, we detected seven suggestive QTLs associated with hygienic behavior. Each detected QTL controlled only 9-15% of the observed phenotypic variance in the character.  相似文献   
252.
A United Nations Framework Convention on Climate Change (UNFCCC) Joint Implementation (JI) host country has to make sure that JI projects are additional to avoid extra costs to generate the reductions necessary to cover the deduction of Emission Reduction Units (ERUs) from the country’s Kyoto Protocol emissions budget. A tender of ERUs by the government allows to generate additional reductions beyond the ERUs issued if it thoroughly checks project additionality. The government of New Zealand is running a tender for JI projects under the title “Projects to Reduce Emissions” since 2003. In two rounds, 10 million ERUs have been awarded and several projects have already entered into contracts with European buyers. The ratio of ERUs awarded to reductions achieved was 0.8 in the second tender. However it remains to be seen whether the additionality test of this tender is sufficient to exclude clearly non-additional projects.  相似文献   
253.
The possible effects of landscape structure on starling roost distribution were investigated in western France using GIS analysis at different radii (2, 4, 8 and 10 km). Composition (11 land use classes) and configuration (patch size, diversity index) of the landscapes surrounding 97 roost sites used by starlings from 1981 to 2002 and surrounding 50 random points not used as roost sites were compared. Significant results suggested that starling roosts were established preferentially in the centre of an agricultural landscape where large units of pastures and arable land predominated and where natural areas were lacking both in large patches (forests or wetland classes) and in small patches such as woods in the mixed land class. A varied farmland landscape with natural areas and small patches should be promoted to limit the starling damage in wintering regions and also to favour their reproduction in regions where it has declined.  相似文献   
254.
255.
256.
257.
Haase-Wessel  W.  Ohmasa  M.  Süsse  P. 《Die Naturwissenschaften》1977,64(8):435-435
The Science of Nature -  相似文献   
258.
Hurler's disease was excluded in a fetus at 23 weeks' gestation by demonstrating normal iduronidase activity in fetal leucocytes following failure of amniotic cell culture after amnic-centesis at 16 and 19 weeks' gestation. The diagnosis was confirmed in the neonate.  相似文献   
259.
260.
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