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   16281篇
  免费   232篇
  国内免费   1218篇
安全科学   530篇
废物处理   552篇
环保管理   2212篇
综合类   4976篇
基础理论   3627篇
环境理论   6篇
污染及防治   4485篇
评价与监测   680篇
社会与环境   463篇
灾害及防治   200篇
  2022年   214篇
  2021年   190篇
  2020年   129篇
  2019年   157篇
  2018年   238篇
  2017年   273篇
  2016年   334篇
  2015年   316篇
  2014年   498篇
  2013年   1280篇
  2012年   568篇
  2011年   727篇
  2010年   538篇
  2009年   622篇
  2008年   726篇
  2007年   674篇
  2006年   606篇
  2005年   447篇
  2004年   421篇
  2003年   477篇
  2002年   405篇
  2001年   546篇
  2000年   395篇
  1999年   287篇
  1998年   236篇
  1997年   214篇
  1996年   241篇
  1995年   232篇
  1994年   229篇
  1993年   216篇
  1992年   214篇
  1991年   197篇
  1990年   221篇
  1989年   208篇
  1988年   175篇
  1987年   174篇
  1986年   153篇
  1985年   167篇
  1984年   151篇
  1983年   162篇
  1982年   161篇
  1981年   166篇
  1980年   149篇
  1979年   145篇
  1978年   142篇
  1977年   129篇
  1976年   136篇
  1974年   142篇
  1973年   125篇
  1972年   125篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
131.
132.
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   
133.
134.
本文在建立D矿田找矿信息层次模型基础上,确定矿田统计单元划分和地质变量提取的赋值原则,将该矿田划分出466个统计单元,提取25个地质变量并进行二态赋值,而后应用数量化理论Ⅲ。特征分析法及勃尔法等方法,建立了矿田金矿资源定量评价模型,定位预测了45个勘探靶区。  相似文献   
135.
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   
136.
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   
137.
138.
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   
139.
Plasticity of honeybee castes   总被引:1,自引:0,他引:1  
  相似文献   
140.
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