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   344篇
  免费   11篇
  国内免费   9篇
安全科学   105篇
废物处理   3篇
环保管理   52篇
综合类   95篇
基础理论   32篇
污染及防治   17篇
评价与监测   49篇
社会与环境   6篇
灾害及防治   5篇
  2023年   8篇
  2022年   3篇
  2021年   12篇
  2020年   14篇
  2019年   6篇
  2018年   8篇
  2017年   9篇
  2016年   12篇
  2015年   16篇
  2014年   24篇
  2013年   32篇
  2012年   11篇
  2011年   27篇
  2010年   11篇
  2009年   22篇
  2008年   20篇
  2007年   12篇
  2006年   19篇
  2005年   12篇
  2004年   7篇
  2003年   8篇
  2002年   8篇
  2001年   9篇
  2000年   7篇
  1999年   8篇
  1998年   5篇
  1997年   8篇
  1996年   6篇
  1994年   1篇
  1993年   2篇
  1992年   2篇
  1991年   1篇
  1989年   2篇
  1987年   3篇
  1986年   3篇
  1984年   1篇
  1983年   1篇
  1981年   1篇
  1979年   2篇
  1968年   1篇
排序方式: 共有364条查询结果,搜索用时 31 毫秒
171.
In the hard rock areas of India, overdraft of groundwater has led to negative externalities. It increased costs of groundwater irrigation and caused welfare losses. At the same time informal groundwater markets are slowly emerging and are believed to improve water distribution and to increase water use efficiency in the irrigation sector. These claims are evaluated in this study. For this purpose data was collected from a sample containing three different groups of water users: water sellers, water buyers and a control group of non-traders. First the socio-economic characteristics of these groups are compared. Then the efficiency of water use of the three groups is studied using Data Envelopment Analysis. The results indicate that groundwater markets provide resource poor farmers access to irrigation water, giving them the opportunity to raise their productivity. Water buyers are furthermore shown to be most efficient in their water use, while water sellers are also shown to be more efficient than the control group. The differences in efficiency between the groups are statistically significant. The demonstrated potential of groundwater markets to improve the efficiency of water use and to increase equity in resource access should be taken into account by the Indian government when deciding on their attitude towards the emerging groundwater markets.  相似文献   
172.
污染源自动监测数据有效性影响因素分析   总被引:1,自引:0,他引:1       下载免费PDF全文
结合我国污染源自动监测现状,分别从技术、产品、建设、管理与环境等各不同角度,分析了各因素对监测数据有效性的影响,并提出了一些相应的建议与对策。  相似文献   
173.
随着烟气排放连续监测系统(CEMS)的广泛安装和验收,CEMS数据的应用将成为污染源管理最直接最有效的手段.在国家规定的数据有效性审核基础上,结合实际工作遇到的问题和长期实践经验,提出每日审核对于数据有效性的重要作用,并通过上海市特有的CEMS数据审核机制,介绍该审核机制的建立背景、内容、流程及取得的成果.  相似文献   
174.
In the context of a study by the International Geomechanical Commission (IGC) and the International Atomic Energy Agency (IAEA) on the effects of nuclear tests at the atolls of Mururoa and Fangataufa, release to the biosphere is estimated for 35 radionuclides originating from 147 nuclear underground tests. Based on a qualitatively characterised hydrogeological situation of atolls and relatively scarce site-specific data, a model chain was developed to conservatively estimate the radionuclide fluxes via groundwater, from their sources, the explosion cavities, towards the biosphere, the ocean or lagoon.Finite element hydro-thermal modelling was used to describe water flow. Parameters were calibrated by a very few measured pre-test temperature profiles in bore holes. The impact of the tests on groundwater flow and mechanical impact on rock was considered. Estimates were made to quantify spatial extensions and temporal evolution of impact by using measurements on refilling rate of the cavities. Tests were categorised according to their specific yield and location although detailed data were missing. A base case parameter set was defined for the hydraulic conditions and for the initial radionuclide inventory of individual tests. Models were used to describe the concentration of radionuclides in the cavities as a function of time. Radionuclide transport from the cavities to the biosphere was represented by two different approaches: a double porosity model for the fractured volcanic rock and a single porosity model for the overlaying, highly porous carbonates. Results consist of conservative estimates on radionuclide release into the environment, or concentration in the lagoon or ocean water. Their sensitivity was investigated using different models and parameters. A few measured data (concentrations in a few cavities, in the deep carbonates and in the lagoons for selected radionuclides, such as 3H, 14C, 36Cl, 90Sr, 129I, 137Cs239, 240Pu and 241Am) were available for a comparison with the calculations. In view of the lack and uncertainty of site-specific data, the agreement is of acceptable quality.  相似文献   
175.
176.
海南省环境质量与经济发展DEA有效性评价   总被引:2,自引:0,他引:2  
以海南省环境质量作为研究对象,结合海南经济发展的现状构建评价指标体系,运用DEA模型对海南省环境质量与经济发展有效性进行评价。结果表明,DEA的有效性与地区经济的发展水平紧密相关,DEA有效性与经济发展好坏基本一致;部分区域的环境污染物排放集中与转移,实现了经济与环境发展协调的DEA有效。在此基础上,对DEA无效的背后因素做了进一步分析,提出提升资源利用效率和优化经济结构才是实现环境质量与经济协调发展的根本途径。  相似文献   
177.
本文通过谷物装卸设备存在危险的实例,强调了储粮仓内农工存在淹埋及窒息风险,重点介绍了美国职业安全和健康署(OSHA)提出的标准和相关法规,以及粮仓农工的安全风险识别与防护经验,以对我国粮仓农工的安全与防护提供帮助。  相似文献   
178.
The issue of municipal solid waste (MSW) arisings has received great attention recently since it is not only a by-product of economic activity but also serves as an input to the economy through material or energy recovery. The main focus of this study is cultural formation and especially the current picture of waste culture and public perception across European Union (EU) member states. Thus, this study will first evaluate environmental efficiency with data envelopment analysis (DEA) based on five parameters: waste, gross domestic product (GDP), labour, capital, and population density for 22 EU Member States and for the years 2005, 2010 and 2015 in order to evaluate which Member States are more efficient. Then the efficiency results are contrasted to Hofstede’s and Schwartz’s cultural dimensions on STATA with the use of regression modelling. Results show that for year 2005 no significant relationship is noticed for both cultural models, whereas for years 2010 and 2015 there appears to be a significant connection. The above-mentioned findings can be associated with the financial crisis that has hit Europe after 2008 making people more sceptical, while EU legislations have laid out some important directives in the field of waste management. Finally, along with the factors above, EU has faced severe environmental challenges due to waste arisings, as well as accidents and injuries for people working in this sector, which in turn have widely modified EU’s waste culture as supported by this study’s results.  相似文献   
179.
/ An exhaustive search of the literature for foot and vehicle traffic impacts on vegetation has yielded more than 400 citations, two thirds of which held sufficient detail to be usefully distilled into a personal-computer data base. A total of 1444 individual observations involving 737 species that were trampled are included. Compromises were made in the depth of entry detail and to allow comparability among data. Inconsistent, generally short-term, experimental practices disallowed formal statistical analyses. Within those constraints, graminoids emerged with the highest mean resistance and resilience among life-forms. Climbers and cactoids ranked lowest in these categories. The herbaceous, typically broader-leaved (forb) life-form appeared most likely to suffer immediate losses. Shrubs and trees had the longest-lasting decreases in diversity following traffic impact. All life-forms had sensitive species. The greatest general species and individual plant losses take place in the first few passes by feet, wheels, or tracks. Plant and soil damage increases with the amount of weight and power applied. Greater soil moisture and/or deeper overstory shading magnify those impacts. Additional precepts may become apparent to data-base users through increased ease in making comparisons.KEY WORDS: Vegetation; Trampling; Vehicles; Traffic; Resistance; Resilience; Data base  相似文献   
180.
The paper outlines the emerging effects of the Information Technological revolution and examines the likely consequences for planning in Britain. A number of possible scenarios are described as a basis for thinking about the design of a new planning system for the future.  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