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   7043篇
  免费   62篇
  国内免费   35篇
安全科学   200篇
废物处理   304篇
环保管理   585篇
综合类   1172篇
基础理论   1763篇
环境理论   7篇
污染及防治   2151篇
评价与监测   558篇
社会与环境   369篇
灾害及防治   31篇
  2023年   67篇
  2022年   141篇
  2021年   162篇
  2020年   86篇
  2019年   97篇
  2018年   225篇
  2017年   250篇
  2016年   309篇
  2015年   232篇
  2014年   318篇
  2013年   562篇
  2012年   376篇
  2011年   452篇
  2010年   307篇
  2009年   267篇
  2008年   428篇
  2007年   391篇
  2006年   320篇
  2005年   245篇
  2004年   223篇
  2003年   210篇
  2002年   184篇
  2001年   115篇
  2000年   86篇
  1999年   65篇
  1998年   43篇
  1997年   35篇
  1996年   42篇
  1995年   54篇
  1994年   49篇
  1993年   30篇
  1992年   40篇
  1991年   41篇
  1990年   32篇
  1989年   31篇
  1988年   28篇
  1987年   24篇
  1986年   36篇
  1985年   29篇
  1984年   31篇
  1983年   19篇
  1982年   34篇
  1981年   26篇
  1980年   25篇
  1979年   28篇
  1978年   21篇
  1977年   24篇
  1976年   24篇
  1975年   20篇
  1966年   18篇
排序方式: 共有7140条查询结果,搜索用时 186 毫秒
101.
The aim of the study was to describe the opinion of pregnant women who had accepted or declined an alpha-fetoprotein (AFP) test, not only on AFP screening in general, but also on whether every pregnant woman should be offered amniocentesis (AC)/chorionic villus sampling (CVS) and an ultrasound scan for fetal malformations. An additional aim was to describe pregnant women's attitudes concerning continued research in the prenatal field. The study was performed as a questionnaire study in two regions over a 1-year period from 1 October 1988 to 30 September 1989. Results are based on answers from 3331 women who had taken an AFP test and 336 women who had declined the offer of a test. A total of 79 per cent of the women thought that an AFP test, 70 per cent that an ultrasound scan for fetal malformations, and 26 per cent that AC or CVS should be offered to all pregnant women. Fifty-nine per cent of the women were positive towards continued research in the prenatal field. Women who had had an AFP test were generally much more positive towards screening and research than women who had declined, who were generally against. Women who had left school without a high school degree were on average more positive towards the screening issues than women who had this degree. In conclusion, the results obtained in this study strongly suggest that women's attitudes are very dependent on how the prenatal screening programme is already organized in their local area.  相似文献   
102.
103.
104.
A de novo paracentric inversion of chromosome 11 identified through antenatal diagnosis is described along with long-term follow-up information on the child and discussion of reported experiences with de novo inversions.  相似文献   
105.
106.
We report relatively high citrulline concentration in amniotic fluid of a citrullinemic fetus suggesting that prenatal detection of this condition could be done on this basis in conjunction with a direct or an indirect determination of argininosuccinate synthetase activity in amniotic fluid cells.  相似文献   
107.
The “constituents” quarks and leptons of matter (with rest-mass) are compared with the historical development of “elements” in chemistry. If unsaturated quarks induce high (and at the moment unpredictable) rest-masses above l0GeV, we have a new view of nuclei comprising (2Z + N) u-quarks and (Z +2N) d-quarks in their low-energy states, without any reference to protons and neutrons as permanent building-blocks. Recent studies of quarks and possible rishons (sub-quarks) and technicolour hadrons are reviewed, and the rôle of identity and cardinality in quantum mechanics analyzed.  相似文献   
108.
The larvae and pupae of the ladybird Thalassa saginata develop inside colonies of the dolichoderine ant Dolichoderus bidens. This association is the first specific and obligatory relationship recorded between ants and ladybirds. The ants provide shelter and protection to the larvae but the diet of the latter remains unclear. The integration of T. saginata larvae into the ant colonies is achieved by mimicking the cuticular patterns of the ants brood. Moreover, the larvae secrete substances from their hairs and anal gland that are likely to enhance their attractiveness.  相似文献   
109.
110.
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