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   8952篇
  免费   69篇
  国内免费   66篇
安全科学   208篇
废物处理   460篇
环保管理   745篇
综合类   1430篇
基础理论   2125篇
环境理论   8篇
污染及防治   2793篇
评价与监测   739篇
社会与环境   537篇
灾害及防治   42篇
  2023年   90篇
  2022年   239篇
  2021年   247篇
  2020年   129篇
  2019年   133篇
  2018年   291篇
  2017年   315篇
  2016年   425篇
  2015年   278篇
  2014年   444篇
  2013年   682篇
  2012年   477篇
  2011年   603篇
  2010年   405篇
  2009年   362篇
  2008年   501篇
  2007年   464篇
  2006年   365篇
  2005年   344篇
  2004年   355篇
  2003年   333篇
  2002年   249篇
  2001年   185篇
  2000年   99篇
  1999年   91篇
  1998年   48篇
  1997年   55篇
  1996年   40篇
  1995年   65篇
  1994年   57篇
  1993年   22篇
  1992年   41篇
  1991年   43篇
  1990年   34篇
  1989年   31篇
  1988年   22篇
  1987年   22篇
  1986年   34篇
  1985年   23篇
  1984年   23篇
  1983年   25篇
  1982年   26篇
  1981年   17篇
  1980年   14篇
  1979年   17篇
  1966年   20篇
  1965年   15篇
  1964年   14篇
  1958年   14篇
  1956年   14篇
排序方式: 共有9087条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
75.
76.
Hybridization between Aegilops geniculata, A. biuncialis and bread wheat Triticum aestivum has been evaluated during two seasons under simulated field conditions to estimate the field hybridization rate under Central Spain conditions. The mean frequencies of hybridization between A. biuncialis and A. geniculata with wheat were 0.34% and 0.31%, respectively. Data from 10 hybrid plants for each combination showed that hybrids can be partially fertile by backcrossing with wheat parent, with percent averages of 3.17 grains/spikelets for A. biuncialis × wheat hybrids and 2.87 grains/spikelets for A. geniculata × wheat hybrids. Self-pollination, although at very low rates, was also possible in hybrids. The potential risks associated with natural hybridization in the context of transgenic wheat cultivation are discussed.  相似文献   
77.
This paper examines how legal standards of liability may apply to geologic carbon storage. The liability regime governing geologic carbon storage will shape the technology's cost-effectiveness and overall attractiveness. We classify potential sources of liability into operational, in situ, and climate liability. As a first step, we explore in situ liability in the United States. After summarizing legal standards of liability including negligence, breach of implied warranty, strict liability, and product liability, we discuss how liability may be addressed at the level of the federal government, state government, industry, and the firm. Finally, we address the implications of judicial treatment of liability for carbon storage, including the apportionment of liability and the adequacy of current regulations.  相似文献   
78.
The Science of Nature - Because of the sudden rise in primary-energy costs and the rapid inflation of plants which are used for the conversion of primary to secondary energy, the storage of energy,...  相似文献   
79.
80.
The observation that thyroid disease is frequent in mothers of children with Down syndrome (DS) has suggested that maternal thyroid antibodies could be a factor predisposing to trisomy 21 in their offspring. In this study, the incidences of thyroglobulin (Tg) and thyroid peroxidase (TPO) antibodies were analysed with a sensitive solid-phase immunosorbent radioassay in sera from 29 mothers giving birth to children with trisomy 21 and 87 control mothers. The serum samples were collected at delivery. There was no statistical difference regarding the proportion of thyroid antibodies (against Tg and/or TPO) in the two groups. Thyroid antibodies were detected in 6/29 (20.7 per cent) of the DS mothers and in 23/87 (26.4 per cent) of the control mothers. Among the women with thyroid antibodies, 4/6 (66.7 per cent) of the DS mothers and 12/23 (52 per cent) of the control mothers had antibodies against both Tg and TPO. There was no increase in the relative risk of having a child with DS if the titre of either Tg or TPO antibodies or both were positive, i.e. ≥ 1/5. The results indicate that the presence of thyroid antibodies in the serum of a pregnant woman has no prognostic value for the birth of an infant with DS.  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