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   6256篇
  免费   56篇
  国内免费   32篇
安全科学   144篇
废物处理   285篇
环保管理   462篇
综合类   1005篇
基础理论   1540篇
环境理论   6篇
污染及防治   2025篇
评价与监测   485篇
社会与环境   373篇
灾害及防治   19篇
  2023年   63篇
  2022年   150篇
  2021年   173篇
  2020年   81篇
  2019年   103篇
  2018年   255篇
  2017年   266篇
  2016年   337篇
  2015年   223篇
  2014年   329篇
  2013年   486篇
  2012年   352篇
  2011年   413篇
  2010年   273篇
  2009年   250篇
  2008年   372篇
  2007年   336篇
  2006年   281篇
  2005年   220篇
  2004年   213篇
  2003年   163篇
  2002年   141篇
  2001年   94篇
  2000年   55篇
  1999年   52篇
  1998年   31篇
  1997年   26篇
  1996年   27篇
  1995年   37篇
  1994年   34篇
  1993年   20篇
  1992年   23篇
  1991年   24篇
  1990年   22篇
  1989年   20篇
  1988年   18篇
  1987年   12篇
  1986年   26篇
  1985年   15篇
  1984年   14篇
  1983年   13篇
  1982年   22篇
  1980年   13篇
  1976年   12篇
  1966年   19篇
  1965年   12篇
  1964年   11篇
  1959年   10篇
  1956年   11篇
  1954年   11篇
排序方式: 共有6344条查询结果,搜索用时 15 毫秒
41.
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   
42.
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   
43.
44.
45.
46.
47.
48.
49.
50.
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