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   10414篇
  免费   79篇
  国内免费   44篇
安全科学   215篇
废物处理   523篇
环保管理   826篇
综合类   1422篇
基础理论   2170篇
环境理论   8篇
污染及防治   2995篇
评价与监测   932篇
社会与环境   1408篇
灾害及防治   38篇
  2023年   67篇
  2022年   182篇
  2021年   237篇
  2020年   95篇
  2019年   125篇
  2018年   269篇
  2017年   287篇
  2016年   382篇
  2015年   212篇
  2014年   453篇
  2013年   911篇
  2012年   504篇
  2011年   563篇
  2010年   450篇
  2009年   411篇
  2008年   513篇
  2007年   578篇
  2006年   443篇
  2005年   403篇
  2004年   350篇
  2003年   311篇
  2002年   283篇
  2001年   292篇
  2000年   234篇
  1999年   113篇
  1998年   77篇
  1997年   84篇
  1996年   70篇
  1995年   100篇
  1994年   76篇
  1993年   64篇
  1992年   62篇
  1991年   65篇
  1990年   79篇
  1989年   55篇
  1988年   48篇
  1987年   42篇
  1986年   49篇
  1985年   50篇
  1984年   52篇
  1983年   37篇
  1982年   50篇
  1981年   37篇
  1980年   48篇
  1979年   44篇
  1973年   34篇
  1972年   40篇
  1970年   35篇
  1969年   35篇
  1958年   47篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Anticardiolipin antibodies were measured in 60 pregnant women with acute parvovirus B19 infection. Test results for eight (13.3 per cent) women were positive for anticardiolipin antibody. Six of these eight women became negative later, yielding a prevalence of anticardiolipin antibodies of 3.3 per cent (2/60) 6 months after acute parvovirus B19 infection. Anticardiolipin antibody positivity was not associated with an increased risk of abortion, fetal death, or maternal complications. This study suggests that there is an elevated frequency of anticardiolipin antibodies in pregnant women with acute parvovirus B19, probably representing an epiphenomenon. However, this is not associated with an adverse maternal or perinatal outcome.  相似文献   
142.
Microorganisms (bacteria, fungi) are common residents of the roots, stems and leaves of higher plants. In order to explore the dependency of plant development on the presence of epiphytic microorganisms, the achenes (seeds) of sunflower (Helianthus annuus L.) were sterilized and germinated under aseptic conditions. The sterility of the seedlings was determined with the agar impression method. In seedlings from non-sterile seeds (control) that were likewise raised in a germ-free environment, all plant organs investigated (stem, cotyledons and primary leaves) were contaminated with bacteria. Hypocotyl elongation was not affected by epiphytic microorganisms. However, the growth rates of the cotyledons and primary leaves were higher in sterile seedlings compared with the control. The implications of this differential inhibition of organ development by epiphytic bacteria that are transmitted via the outer surface of the seed coat are discussed. We conclude that epiphytes in the above-ground phytosphere are not necessary for the development of the sunflower seedling.  相似文献   
143.
144.
145.
An analysis of the impacts on Mexican energy demand and associated carbon dioxide (CO2) emissions in the year 2005 due to efficient lighting in the commercial and residential sectors and cogeneration in the industrial sector is presented. Estimation of CO2 abatement costs and an incremental cost curve for CO2 mitigation options are considered. These technologies are cost effective opportunities, and together are projected to reduce CO2 emissions in 2005 by nearly 13 percent. Implementation of efficient lighting is already part of the demand side management (DSM) programs of the Mexican state-owned utility. However, there are important barriers that may hinder the implementation of large scale cogeneration plants.  相似文献   
146.
147.
148.
149.
Ninety-two families with spinal muscular atrophy (SMA) applied for genetic counselling and further prenatal diagnosis. To minimize expenses, only one tightly linked informative marker was determined in the course of preliminary examination, and non-radioactive allele detection was preferably used. Four prenatal diagnoses of SMA type I, four of SMA type II, and one of SMA type III were made. This trial programme shows the considerable requirements, importance, and potential effectiveness of prenatal prediction of SMA in Russia.  相似文献   
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