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   96152篇
  免费   1293篇
  国内免费   1331篇
安全科学   3945篇
废物处理   3615篇
环保管理   14576篇
综合类   21762篇
基础理论   27005篇
环境理论   76篇
污染及防治   17045篇
评价与监测   5833篇
社会与环境   4293篇
灾害及防治   626篇
  2022年   888篇
  2021年   914篇
  2020年   742篇
  2019年   895篇
  2018年   1283篇
  2017年   1303篇
  2016年   2289篇
  2015年   1878篇
  2014年   2669篇
  2013年   9405篇
  2012年   2498篇
  2011年   3031篇
  2010年   3480篇
  2009年   3613篇
  2008年   2533篇
  2007年   2401篇
  2006年   2645篇
  2005年   2545篇
  2004年   2788篇
  2003年   2699篇
  2002年   2211篇
  2001年   2587篇
  2000年   2175篇
  1999年   1590篇
  1998年   1390篇
  1997年   1394篇
  1996年   1508篇
  1995年   1612篇
  1994年   1488篇
  1993年   1342篇
  1992年   1345篇
  1991年   1305篇
  1990年   1270篇
  1989年   1229篇
  1988年   1071篇
  1987年   1000篇
  1986年   993篇
  1985年   1077篇
  1984年   1172篇
  1983年   1174篇
  1982年   1180篇
  1981年   1100篇
  1980年   950篇
  1979年   939篇
  1978年   823篇
  1977年   725篇
  1976年   645篇
  1974年   625篇
  1973年   647篇
  1972年   657篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
111.
This paper presents the technical aspects of a new methodology for assessing the susceptibility of society to drought. The methodology consists of a combination of inference modelling and fuzzy logic applications. Four steps are followed: (1) model input variables are selected—these variables reflect the main factors influencing susceptibility in a social group, population or region, (2) fuzzification—the uncertainties of the input variables are made explicit by representing them as ‘fuzzy membership functions’, (3) inference modelling—the input variables are used to construct a model made up of linguistic rules, and (4) defuzzification—results from the model in linguistic form are translated into numerical form, also through the use of fuzzy membership functions. The disadvantages and advantages of this methodology became apparent when it was applied to the assessment of susceptibility from three disciplinary perspectives: Disadvantages include the difficulty in validating results and the subjectivity involved with specifying fuzzy membership functions and the rules of the inference model. Advantages of the methodology are its transparency, because all model assumptions have to be made explicit in the form of inference rules; its flexibility, in that informal and expert knowledge can be incorporated through ‘fuzzy membership functions’ and through the rules in the inference model; and its versatility, since numerical data can be converted to linguistic statements and vice versa through the procedures of ‘fuzzification’ and ‘defuzzification’.  相似文献   
112.
113.
114.
115.
Male Baladi rabbits were acutely and sub-chronically intoxicated with cyanofenphos and profenophos. The levels of cholesterol, triglycerides, B-lipoproteins and total proteins were determined in the serum, brain, spinal cord and sciatic nerve of rabbits. Moreover, the activities of alkaline phosphatase, acid phosphatase and glutamic-pyruvic transaminase were determined in the liver of the animals. The whole studies revealed that the biochemical constituents were highly affected by the tested insecticides. Also, the liver function suffered from adverse effects of the tested insecticides.  相似文献   
116.
工业革命以来,全球环境发生了前所未有的变化,将可能给地球系统带来灾难性后果,究其原因主要是由于人类活动造成的。人的行为深受意识的影响和制约,环境意识对于环境问题的产生和解决至关重要。本文选取上海、香港两个地区来分析公民对环境的关注度、公民的环保意识、环保行为以及公民对政府环境工作的看法和评价,研究公民对全球环境变化反应的区域差异,为政府制定相关环境保护政策提供理论依据。调查结果显示,上海、香港两地公民在很多环境闷题上具有共识。但是。在对手环境状况好转的期待值、参与环境保护活动的积极性、对人为因素主导力量的认识、环境保护与日常生活的切实关系、为环境保护的支付意愿、对于环境教育内容的认可度等方面存在着一定的差异。  相似文献   
117.
118.
A statistical analysis of interannual variation in a set of vegetative and generative characters over 13 years has been performed to characterize the growth and seed production dynamics of the Siberian stone pine (Pinus sibirica Du Tour) in the southeast of the forest zone in western Siberia. The results have shown that the range of fluctuations in most of vegetative characters is ordinary and their distribution is close to normal. The range of fluctuations in many generative characters is enormous (from 0 to +∞), and the distribution of their values is usually skewed, with low values being recorded several times more frequently than high values. Most variable are the proportion of abortive cones and other characters that are determined mainly in the spring of the pollination year. These characters account for a very high level of variation in the total seed production.  相似文献   
119.
In areas of war and armed conflict it is difficult to get trustworthy and coherent information. Civil society and human rights groups often face problems of dealing with fragmented witness reports, disinformation of war propaganda, and difficult direct access to these areas. Turkish Kurdistan was used as a case study of armed conflict to evaluate the potential use of satellite images for verification of witness reports collected by human rights groups. The Turkish army was reported to be burning forests, fields and villages as a strategy in the conflict against guerrilla uprising. This paper concludes that satellite images are useful to validate witness reports of forest fires. Even though the use of this technology for human rights groups will depend on some feasibility factors such as prices, access and expertise, the images proved to be key for analysis of spatial aspects of conflict and valuable for reconstructing a more trustworthy picture.  相似文献   
120.
This paper presents preliminary data on polybrominated diphenyl ethers (PBDEs) in the Scottish aquatic environment. Sediment and biota (fish liver, fish muscle and mussels) from a number of locations around Scotland were analysed for PBDEs with samples being from both remote and from potentially contaminated areas such as the former sewage sludge dump site at Garroch Head in the Clyde. PBDEs were measured in both cultivated, rope grown mussels and wild mussels collected from 5 sites around Scotland in 2006. Total PBDE concentrations (sum of tri- to hepta-BDEs) ranged from 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