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   420篇
  免费   2篇
  国内免费   2篇
安全科学   6篇
废物处理   11篇
环保管理   20篇
综合类   73篇
基础理论   139篇
污染及防治   143篇
评价与监测   14篇
社会与环境   16篇
灾害及防治   2篇
  2022年   3篇
  2021年   5篇
  2018年   4篇
  2017年   3篇
  2016年   3篇
  2015年   4篇
  2014年   6篇
  2013年   13篇
  2012年   11篇
  2011年   19篇
  2010年   11篇
  2009年   26篇
  2008年   15篇
  2007年   25篇
  2006年   22篇
  2005年   14篇
  2004年   11篇
  2003年   20篇
  2002年   12篇
  2001年   5篇
  2000年   18篇
  1999年   25篇
  1998年   16篇
  1997年   17篇
  1996年   18篇
  1995年   14篇
  1994年   8篇
  1993年   11篇
  1992年   6篇
  1991年   4篇
  1990年   7篇
  1989年   2篇
  1988年   2篇
  1987年   2篇
  1986年   2篇
  1983年   2篇
  1981年   2篇
  1979年   2篇
  1978年   4篇
  1969年   2篇
  1968年   2篇
  1967年   3篇
  1965年   3篇
  1959年   2篇
  1957年   1篇
  1955年   1篇
  1937年   1篇
  1934年   1篇
  1932年   1篇
  1931年   1篇
排序方式: 共有424条查询结果,搜索用时 31 毫秒
81.
82.
83.
The study of the fetal platelet count and size can, according to the literature, be used for the prenatal diagnosis of the Wiskott-Aldrich syndrome (WAS). So far, no affected fetuses have been identified by this method. All pregnancies in which this method had been applied to resulted, as correctly predicted, in the birth of normal children. Here we report on a familial case of WAS where the haematological parameters failed to reveal the affected second child. Hence we assume that the platelet count and size of platelets remain normal in fetuses with WAS to the gestational age of 22 weeks and cannot be used for prenatal diagnosis.  相似文献   
84.
A case of aortic atresia with insufficiency of mitral valve diagnosed prenatally at 33 weeks of gestation is presented. An accurate diagnosis of this fetal cardiovascular malformation was possible by application of Doppler colour flow mapping, which demonstrated (a) the absence of forward flow in the hypoplastic ascending aorta, (b) reverse flow of blood from the ductus arteriosus into the severely hypoplastic ascending aorta in the late systole, (c) pansystolic mitral valve regurgitation, and (d) absent flow across the foramen ovale as a result of premature closure of the foramen ovale.  相似文献   
85.
This report of an international conference about the problems around lakeshores, their evaluation and the possibilities to improve the situation for lake shores, continues the series ‘Lake shores, a forgotten ecotone’ as article 4. Five main topics were discussed: (1) applied ecology of lakeshores, (2) human impact, (3) ecological assessment, (4) protection and restoration, (5) sustainable development and use of lake shores.  相似文献   
86.
Nematodentest     
For the assessment of contaminated and remediated soils and substrates, and the estimation of chronic toxicity of soil contaminations, an ecotoxicological test was developed using the terrestrial nematodePanagrellus redivivus. The population dynamics expressed by the reproduction factor (VF) allows an estimation of soil quality within seven days. Due to the rapid generation time ofPanagrellus (< 5 d), the short test duration is considered to be sufficient. The suitability of this test duration is considered to be sufficient. The suitability of this test was evaluated by investigating soils which had been contaminated using applications of specific pollutants (lindane and PCB 52).  相似文献   
87.
The concentrations of Ag, Al, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, La, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, Sr, Ti, V and Zn were determined by AES/ICP inMolinia caerulea andEriophorum vaginatum grown in the Leegmoor, which is in reinstatement. In the soil substrate analytical detection limits were obtained for Ag, Co, Li, Mo and Rb and additionally for Al, Be, Cd, Cr, La, Li, Ni, Pb, Ti and V in plants. Compared with mineral soils, the concentration of elements in peat is low. The elements K and P were enriched byMolinia caerulea andEriophorum vaginatum, and in addition Mn and Zn byEriophorum vaginatum. Altogether the ability of accumulation essential elements seem to be more efficient byEriophorum vaginatumthan byMolinia caerulea, which can be an ecophysiological advantage on peats, whereMolinia caerulea is normally not distributed.  相似文献   
88.
Diphenylarsenic chloride (CLARK I) and diphenylarsenic cyanide (CLARK II) react quickly and quantitatively with dimercaptanes at room temperature to yield diphenylarsine thiolthioether. The thiolthioethers could be identified using mass spectrometry. This reaction can be used for the gas-chromatographic detection of diphenylarsenic compounds.  相似文献   
89.
90.
The responsiveness of adult beech and spruce trees to chronic O(3) stress was studied at a free-air O(3) exposure experiment in Freising/Germany. Over three growing seasons, gas exchange characteristics, biochemical parameters, macroscopic O(3) injury and the phenology of leaf organs were investigated, along with assessments of branch and stem growth as indications of tree performance. To assess response pattern to chronic O(3) stress in adult forest trees, we introduce a new evaluation approach, which provides a comprehensive, readily accomplishable overview across several tree-internal scaling levels, different canopy regions and growing seasons. This new approach, based on a three-grade colour coding, combines statistical analysis and the proficient ability of the "human eye" in pattern recognition.  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