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   23930篇
  免费   142篇
  国内免费   112篇
安全科学   360篇
废物处理   1183篇
环保管理   3235篇
综合类   4268篇
基础理论   6523篇
环境理论   6篇
污染及防治   5055篇
评价与监测   1638篇
社会与环境   1851篇
灾害及防治   65篇
  2018年   1703篇
  2017年   1610篇
  2016年   1434篇
  2015年   282篇
  2014年   214篇
  2013年   964篇
  2012年   797篇
  2011年   1858篇
  2010年   1134篇
  2009年   1079篇
  2008年   1444篇
  2007年   1892篇
  2006年   436篇
  2005年   421篇
  2004年   388篇
  2003年   519篇
  2002年   497篇
  2001年   485篇
  2000年   338篇
  1999年   224篇
  1998年   178篇
  1997年   146篇
  1996年   179篇
  1995年   177篇
  1994年   201篇
  1993年   180篇
  1992年   183篇
  1991年   181篇
  1990年   208篇
  1989年   194篇
  1988年   166篇
  1987年   163篇
  1986年   148篇
  1985年   165篇
  1984年   165篇
  1983年   168篇
  1982年   160篇
  1981年   163篇
  1980年   149篇
  1979年   145篇
  1978年   142篇
  1977年   129篇
  1976年   136篇
  1975年   114篇
  1974年   142篇
  1973年   125篇
  1972年   125篇
  1971年   105篇
  1970年   106篇
  1967年   116篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
In recent years, an increasing number of inherited diseases in man have been recognized in which there is an impairment in the peroxisomal β-oxidation of very-long-chain fatty acids. In general, these disorders are associated with severe neurological and physical abnormalities and death within the first years of life. In this paper we describe our experience with regard to the prenatal diagnosis of a number of different inborn errors of peroxisomal β-oxidation. Eleven pregnancies at risk were monitored by measuring very-long-chain fatty acid levels as well as very-long-chain fatty acid β-oxidation in cultured chorionic villous fibroblasts and/or amniotic fluid cells. Five affected fetuses were identified. It is concluded that prenatal diagnosis in this group of diseases can be done reliably using cultured chorionic villous fibroblasts or amniotic fluid cells.  相似文献   
142.
This paper reports results of an exploratory study of prenatal diagnosis patients who experienced voluntary terminations of pregnancy following the detection of an abnormality or spontaneous miscarriages. The 121 participants were part of the national collaborative Chorionic Villus Sampling and Amniocentesis Study. They completed semi-structured telephone interviews and mailed questionnaires at 1 month and 6 months after the pregnancy losses. Scores on the Profile of Mood States showed that mood levels improved significantly over time. However, there were some declines in loss-related support from partners and others. The persisting distress and difficulties of a minority highlight the variability in women's responses to pregnancy losses. Women who lost pregnancies later in gestation, showed the greatest mood disturbances at initial assessments, used professional mental health assistance after the loss, or reported less satisfactory loss-related support from significant others showed the greatest levels of mood disturbance at the six-month assessment. Follow-up contacts with patients who lose pregnancies should be used to inform women about the variation in possible grief reactions, to assess the extent of support the women are receiving from their partners and significant others, and to provide additional follow-up or referral of those experiencing the greatest distress.  相似文献   
143.
144.
The prenatal diagnosis of The Turner Syndrome is described at a menstrual age of 12 weeks. Detection of cystic hygroma was followed by vaginal chorionic villous sampling (CVS) which revealed a 45,X karyotype. Early documentation of fetal karyotype in the presence of a cystic hygroma is essential for accurate diagnosis and genetic counselling.  相似文献   
145.
Plasticity of honeybee castes   总被引:1,自引:0,他引:1  
  相似文献   
146.
147.
148.
149.
150.
The modern consumer is very much interested in healthy food. The reason is that a special group of consumers is focusing more and more attention on health and nutrition problems. Further, there is increased emphasis on education in food science at universities as well as polytechnics. For some years worldwide dietary goals are published with the intention to reduce nutrition-based sickness. For the first time in our nutrition report 1988, clear proposals for optimal nutrition were formulated.  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