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   24957篇
  免费   178篇
  国内免费   135篇
安全科学   498篇
废物处理   1235篇
环保管理   3635篇
综合类   4459篇
基础理论   6658篇
环境理论   11篇
污染及防治   5624篇
评价与监测   1735篇
社会与环境   1328篇
灾害及防治   87篇
  2018年   1607篇
  2017年   1511篇
  2016年   1419篇
  2015年   326篇
  2014年   296篇
  2013年   1198篇
  2012年   874篇
  2011年   1848篇
  2010年   1082篇
  2009年   1060篇
  2008年   1394篇
  2007年   1803篇
  2006年   563篇
  2005年   434篇
  2004年   468篇
  2003年   548篇
  2002年   496篇
  2001年   542篇
  2000年   375篇
  1999年   265篇
  1998年   198篇
  1997年   187篇
  1996年   214篇
  1995年   216篇
  1994年   237篇
  1993年   212篇
  1992年   214篇
  1991年   204篇
  1990年   231篇
  1989年   210篇
  1988年   177篇
  1987年   177篇
  1986年   170篇
  1985年   181篇
  1984年   175篇
  1983年   192篇
  1982年   183篇
  1981年   187篇
  1980年   166篇
  1979年   158篇
  1978年   144篇
  1977年   139篇
  1976年   144篇
  1975年   123篇
  1974年   149篇
  1973年   126篇
  1972年   128篇
  1971年   116篇
  1970年   110篇
  1967年   119篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
141.
142.
The female silkmoth Bombyx mori L. emits a second pheromone component bombykal (E-10, Z-12-hexade-cadien-1-al) in addition to the well-known sexual attractant bombykol (E-10, Z-12-hexadecadien-1-ol). Bombykal stimulates its own specialized and highly sensitive olfactory cells of the male moth. Surprisingly, the aldehyde inhibits the release of the male's wing-fluttering response to bombykol.  相似文献   
143.
144.
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   
145.
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   
146.
147.
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   
148.
Plasticity of honeybee castes   总被引:1,自引:0,他引:1  
  相似文献   
149.
150.
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