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   29542篇
  免费   334篇
  国内免费   253篇
安全科学   855篇
废物处理   1121篇
环保管理   4117篇
综合类   5157篇
基础理论   7767篇
环境理论   14篇
污染及防治   7438篇
评价与监测   1809篇
社会与环境   1642篇
灾害及防治   209篇
  2022年   217篇
  2021年   229篇
  2020年   201篇
  2019年   257篇
  2018年   394篇
  2017年   421篇
  2016年   618篇
  2015年   483篇
  2014年   674篇
  2013年   2388篇
  2012年   830篇
  2011年   1161篇
  2010年   954篇
  2009年   1009篇
  2008年   1195篇
  2007年   1247篇
  2006年   1158篇
  2005年   917篇
  2004年   976篇
  2003年   916篇
  2002年   847篇
  2001年   1127篇
  2000年   802篇
  1999年   477篇
  1998年   404篇
  1997年   368篇
  1996年   401篇
  1995年   426篇
  1994年   438篇
  1993年   389篇
  1992年   413篇
  1991年   387篇
  1990年   413篇
  1989年   380篇
  1988年   316篇
  1987年   278篇
  1986年   289篇
  1985年   299篇
  1984年   320篇
  1983年   313篇
  1982年   312篇
  1981年   314篇
  1980年   267篇
  1979年   268篇
  1978年   215篇
  1977年   210篇
  1975年   182篇
  1974年   210篇
  1973年   187篇
  1972年   221篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
571.
572.
This article reports the results of a retrospective study designed to examine the responses of couples to genetic amniocentesis and subsequent therapeutic abortions due to birth defects. Fourteen women and 12 men were interviewed by experienced interviewers using a structured format designed by the authors, and each interview was audiotaped for later rating. The 5 raters (all women) were instructed to independently rate each interview using forms designed by the authors to elicit information about many aspects of the participant's individual responses as well as perceptions of spouse's responses to the process of pregnancy, amniocentesis, therapeutic abortion, and sequelae. Ratings of all 5 raters were conjoined and an homogeneous narrative was constructed for each interview. Results indicate, in general, that the respondent couples coped well with this experience. In fact 70 per cent of the respondent couples described their marital relationships as becoming closer as a result of their experience. Only a few participants reported long-term deleterious effects. Most couples coped by relying on relatives, friends, and occasionally, professional counsellors. In addition, most participants in this study suggested ways to improve the medical and psychological aspects of this experience.  相似文献   
573.
574.
575.
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   
576.
577.
578.
579.
580.
HLA typing of amniotic fluid cells has been used for the prenatal diagnosis of the HLA linked diseases congenital adrenal hyperplasia (21-OH-deficiency (21-OH-def) type) and complement C4 deficiency and it has also been used for the prenatal de termination of paternity. There are, however, technical difficulties in this test associated with the weak expression of some B locus antigens on amniotic fluid cells, and theoretical difficulties related to associations between particular HLA antigens and the 21-OH-def allele. Since certain HLA-B locus antigens are found in significantly increased frequencies among patients with 21-OH-def, there is a relatively high incidence of HLA-B homozygosity among the patients and over 40 percent of the parents of these patients share one or more HLA-B locus antigens. Results of some prenatal HLA typing tests may thus be difficult to interpret, and supplementary tests should be used whenever possible. HLA typing of amniotic cells is, however, the only available procedure for prenatal diagnosis of C4 deficiency and it is the best available procedure for prenatal determination of paternity. A modification of our original procedure allows HLA typing to be performed with increased numbers of HLA typing sera, and sera with optimum reactivity for amniotic fluid cells have now been selected for the definition of most of the more commonly expressed HLA antigens. Although amniotic fluid cells do not express DR antigens, amniotic fluid cells can be typed for the HLA-linked marker glyoxalase I (GLO) and this may be the informative for prenatal diagnosis in some cases.  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