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   1016篇
  免费   5篇
  国内免费   1篇
安全科学   36篇
废物处理   32篇
环保管理   90篇
综合类   219篇
基础理论   265篇
环境理论   3篇
污染及防治   243篇
评价与监测   77篇
社会与环境   51篇
灾害及防治   6篇
  2022年   4篇
  2021年   10篇
  2020年   9篇
  2019年   6篇
  2018年   21篇
  2017年   34篇
  2016年   27篇
  2015年   24篇
  2014年   24篇
  2013年   63篇
  2012年   38篇
  2011年   53篇
  2010年   39篇
  2009年   39篇
  2008年   60篇
  2007年   58篇
  2006年   49篇
  2005年   28篇
  2004年   27篇
  2003年   40篇
  2002年   33篇
  2001年   23篇
  2000年   30篇
  1999年   14篇
  1998年   8篇
  1997年   7篇
  1996年   9篇
  1995年   16篇
  1994年   9篇
  1993年   14篇
  1992年   9篇
  1991年   7篇
  1990年   5篇
  1989年   7篇
  1988年   9篇
  1987年   8篇
  1986年   5篇
  1985年   7篇
  1984年   14篇
  1983年   4篇
  1982年   9篇
  1981年   10篇
  1980年   9篇
  1979年   17篇
  1978年   10篇
  1977年   13篇
  1976年   13篇
  1975年   12篇
  1974年   4篇
  1962年   4篇
排序方式: 共有1022条查询结果,搜索用时 203 毫秒
21.
22.
23.
24.
A protocol for easy storage and later expansion of lymphocyte populations is given. Compared with methods using transformed cell lines, the method has a number of advantages for repeated production of cells for the isolation of DNA in amounts sufficient for use in diagnostic DNA technology.  相似文献   
25.
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   
26.
27.
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   
28.
29.
30.
Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is a potentially fatal inherited disease with a carrier frequency of approximately 1:100 in most Caucasian populations. The disease is implicated in sudden unexpected death in childhood. A prevalent disease-causing point mutation (A985G) in the MCAD gene has been characterized, thus rendering diagnosis easy in the majority of cases. Since the clinical spectrum of MCAD deficiency ranges from death in the first days of life to an asymptomatic life, there are probably other genetic factors—in addition to MCAD mutations—involved in the expression of the disease. Thus, families who have experienced the death of a child from MCAD deficiency might have an increased risk of a seriously affected subsequent child. In such a family we have therefore performed a prenatal diagnosis on a chorionic villus sample by a highly specific and sensitive polymerase chain reaction (PCR) assay for the G985 mutation. The analysis was positive and resulted in abortion. We verified the diagnosis by direct analysis on blood spots and other tissue material from the aborted fetus and from family members.  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