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   2879篇
  免费   19篇
  国内免费   35篇
安全科学   85篇
废物处理   144篇
环保管理   275篇
综合类   541篇
基础理论   584篇
环境理论   2篇
污染及防治   837篇
评价与监测   252篇
社会与环境   193篇
灾害及防治   20篇
  2023年   29篇
  2022年   86篇
  2021年   108篇
  2020年   55篇
  2019年   45篇
  2018年   106篇
  2017年   107篇
  2016年   127篇
  2015年   72篇
  2014年   121篇
  2013年   182篇
  2012年   135篇
  2011年   174篇
  2010年   118篇
  2009年   117篇
  2008年   129篇
  2007年   118篇
  2006年   78篇
  2005年   119篇
  2004年   158篇
  2003年   157篇
  2002年   98篇
  2001年   76篇
  2000年   33篇
  1999年   36篇
  1998年   14篇
  1997年   28篇
  1996年   19篇
  1995年   24篇
  1994年   21篇
  1993年   13篇
  1992年   12篇
  1991年   19篇
  1990年   11篇
  1989年   12篇
  1988年   7篇
  1987年   10篇
  1986年   10篇
  1985年   11篇
  1984年   10篇
  1983年   13篇
  1982年   5篇
  1981年   7篇
  1979年   8篇
  1968年   7篇
  1964年   6篇
  1962年   5篇
  1958年   4篇
  1933年   4篇
  1931年   4篇
排序方式: 共有2933条查询结果,搜索用时 15 毫秒
21.
引言 莫日-瓜苏河位于纳斯吉拉斯州,海拔高1450m.流淌470km后,该河流注入圣保罗州的帕尔杜河.其流域总面积为1400km2,其中有86%位于圣保罗州,包括一个工业化地区[1].  相似文献   
22.
23.
This paper examines how legal standards of liability may apply to geologic carbon storage. The liability regime governing geologic carbon storage will shape the technology's cost-effectiveness and overall attractiveness. We classify potential sources of liability into operational, in situ, and climate liability. As a first step, we explore in situ liability in the United States. After summarizing legal standards of liability including negligence, breach of implied warranty, strict liability, and product liability, we discuss how liability may be addressed at the level of the federal government, state government, industry, and the firm. Finally, we address the implications of judicial treatment of liability for carbon storage, including the apportionment of liability and the adequacy of current regulations.  相似文献   
24.
The Science of Nature - Because of the sudden rise in primary-energy costs and the rapid inflation of plants which are used for the conversion of primary to secondary energy, the storage of energy,...  相似文献   
25.
26.
Two types of fermented organic waste (trade and industry waste and fruit and vegetable waste) were successfully used as a sole carbon source to produce poly-3-hydroxybutyrate-co-valerate (PHBV) by Ralstonia eutrophus (formerly Alcaligenes eutrophus) via oxygen limitation.The production of PHBV could be optimized by optimizing the oxygen transfer through the fermentor. Thereby, a peak concentration of 1.1 g PHBV per liter cell suspension, 40 w% of cell dry weight, was obtained at an aeration rate of 0.24 mol O2/h·kg biomass. The yield of PHBV on the fatty acid concentration in the organic waste was 0.16 g polymer/g volatile organic matter. The process obtained, compares well with the commercial production process of PHBV based on glucose.  相似文献   
27.
In a case of hydrops fetalis, serological examination showed a recent maternal human parvovirus B19 infection. Amniocentesis revealed a unique unbalanced translocation between chromosomes 3 and 11 of the fetus. The mother proved to have a balanced reciprocal translocation between chromosomes 3 and 11. A grossly macerated hydropic male fetus was delivered with a flat nose and low implanted deformed ears. Histopathological examination revealed nuclear inclusion bodies in fetal erythroid cells, confirming human parvovirus B19 infection. Parvovirus B19 DNA was demonstrated by in situ hybridization in the nuclei of heart muscle cells. Our finding of two different disorders in one case illustrates the importance of a complete evaluation of every case of hydrops fetalis, especially concerning counselling on the outcome of future pregnancies. The human parvovirus B19 infection will not recur due to the acquired immunity of the mother, whereas the balanced reciprocal translocation will endanger future pregnancies.  相似文献   
28.
We describe a patient with a significantly elevated serum alphafetoprotein (AFP) concentration at 17 weeks of gestation, who showed only a marginally increased amniotic fluid AFP and lacked the second rapidly migrating band of acetylcholinesterase electrophoresis. Ultrasound examination revealed an encephalocele and ventriculomegaly. Autopsy showed that the encephalocele was not covered by skin.  相似文献   
29.
30.
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