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   5605篇
  免费   46篇
  国内免费   23篇
安全科学   148篇
废物处理   278篇
环保管理   400篇
综合类   878篇
基础理论   1373篇
环境理论   5篇
污染及防治   1840篇
评价与监测   433篇
社会与环境   302篇
灾害及防治   17篇
  2023年   57篇
  2022年   131篇
  2021年   149篇
  2020年   75篇
  2019年   88篇
  2018年   200篇
  2017年   213篇
  2016年   277篇
  2015年   193篇
  2014年   292篇
  2013年   438篇
  2012年   323篇
  2011年   374篇
  2010年   245篇
  2009年   207篇
  2008年   343篇
  2007年   305篇
  2006年   270篇
  2005年   209篇
  2004年   183篇
  2003年   165篇
  2002年   128篇
  2001年   84篇
  2000年   42篇
  1999年   53篇
  1998年   26篇
  1997年   23篇
  1996年   24篇
  1995年   36篇
  1994年   32篇
  1993年   14篇
  1992年   22篇
  1991年   23篇
  1990年   25篇
  1989年   18篇
  1988年   17篇
  1987年   14篇
  1986年   27篇
  1985年   16篇
  1984年   13篇
  1983年   13篇
  1982年   21篇
  1981年   12篇
  1980年   14篇
  1978年   10篇
  1966年   16篇
  1965年   10篇
  1957年   10篇
  1956年   11篇
  1954年   10篇
排序方式: 共有5674条查询结果,搜索用时 312 毫秒
51.
The objective of this study was to explore women's attitudes towards prenatal diagnosis of trisomy 21 and to examine some of the factors possibly responsible for these attitudes before implementing in real practice serological screening of pregnant women at risk for trisomy 21. We carried out a telephone survey on a representative sample of women who had recently had a normal livebirth delivery in the Marseille district in 1990. The participation rate was 80 per cent and the average age of the mothers was 28-9 years. Among the 514 women interviewed, 78 per cent stated that they would ask for an amniocentesis for a 1 per cent risk of trisomy 21 at their next pregnancy. When adjusting for confounding factors, the decision to have or not to have an amniocentesis was found to depend not only on the women's attitude towards induced abortion, but also on their understanding of the risk involved and on the social context (knowing a handicapped child, discussion with the father). It also depended on the women's age and on what they knew about amniocentesis from the medical point of view. The risk of miscarriage can influence a woman's choice but this objection was not found to affect the women's decisions significantly in our survey. The data showed the existence of a high potential demand for fetal karyotyping.  相似文献   
52.
During a 7-year period, 117 fetal karyotypes were available from 131 genetic amniocenteses. These procedures were performed between 14 and 37 weeks' gestation for the following abnormal ultrasound findings: (1) intrauterine growth retardation (IUGR)—61 cases; (2) fetal malformation—71 cases; and (3) amniotic fluid volume (AFV) abnormality—60 cases. Chromosomal abnormalities were identified in 19 cases (16.2 per cent). Aneuploidy was 2.5 times as frequent in the presence of malformations than in their absence. No correlation was demonstrated between specific fetal malformations and specific chromosomal abnormalities. Aneuploidy was also twice as frequent in the presence of symmetrical IUGR than in its absence. No chromosomal abnormalities were found among eight cases of asymmetrical IUGR. Four cases of aneuploidy presented with isolated IUGR, three of these involving the X chromosome. The frequency of aneuploidy was the same with or without abnormalities of AFV (14.3 versus 16.4 per cent). No chromosomal abnormality was found associated with isolated AFV abnormalities.  相似文献   
53.
54.
55.
56.
57.
58.
59.
60.
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