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   875篇
  免费   10篇
  国内免费   15篇
安全科学   51篇
废物处理   20篇
环保管理   125篇
综合类   140篇
基础理论   220篇
环境理论   1篇
污染及防治   222篇
评价与监测   79篇
社会与环境   34篇
灾害及防治   8篇
  2023年   7篇
  2022年   4篇
  2021年   7篇
  2020年   6篇
  2019年   11篇
  2018年   17篇
  2017年   14篇
  2016年   18篇
  2015年   24篇
  2014年   15篇
  2013年   99篇
  2012年   35篇
  2011年   59篇
  2010年   41篇
  2009年   44篇
  2008年   54篇
  2007年   44篇
  2006年   34篇
  2005年   30篇
  2004年   27篇
  2003年   26篇
  2002年   33篇
  2001年   16篇
  2000年   17篇
  1999年   6篇
  1998年   13篇
  1997年   8篇
  1996年   13篇
  1995年   8篇
  1994年   11篇
  1993年   7篇
  1992年   11篇
  1991年   13篇
  1990年   7篇
  1989年   8篇
  1988年   4篇
  1987年   5篇
  1986年   6篇
  1985年   9篇
  1984年   5篇
  1982年   7篇
  1981年   6篇
  1978年   5篇
  1977年   4篇
  1976年   3篇
  1975年   3篇
  1971年   4篇
  1969年   4篇
  1960年   4篇
  1956年   3篇
排序方式: 共有900条查询结果,搜索用时 15 毫秒
161.
162.
In this study, an environmental test chamber with controlled temperature, relative humidity, and airflow rate was developed to evaluate emissions of total volatile organic compounds (TVOCs) from three different kinds of furniture polish. The time dependence of TVOC concentrations produced from the emissions of furniture polish products in the chamber was tested. TVOC emissions from each furniture polish were compared. The main volatile organic compounds emitted from each polish were identified by gas chromatography/mass spectrometry. A double-exponential equation was developed to evaluate the characteristics of emissions of TVOCs from these furniture polish products. With this double-exponential model, the physical processes of TVOC emissions can be explained. A variety of emission parameters can be calculated. These emission parameters could be used to estimate real indoor TVOC concentrations.  相似文献   
163.
种植密度和降水对冬小麦田N2O排放的影响   总被引:6,自引:2,他引:4  
为研究种植密度对农田N2O排放的影响和探讨N2O排放季节性波动的原因,于1999~2000年小麦生长季在南京市郊江宁县进行了不同播种量(0、90、180和270kg/hm2)的大田试验.观测分析结果表明:在相同的气象条件和田间管理下,播种~越冬阶段的N2O排放不受播种量的影响,返青~成熟阶段的N2O排放通量与播种量成正比.裸地条件下的N2O排放与播量为90kg/hm2下的排放无明显差异.造成该生长季内N2O排放季节性波动的主要原因是降水,返青~成熟阶段的N2O排放通量随观测日前6d的加权平均降水量呈指数增加.  相似文献   
164.

Background

Methane as a gas influencing our climate is of high importance according to the Kyoto-Protocol. The more precisely we can determine anthropogenic and biogenic sources, the more effective measures we can take to reduce the gas. Direct emission of methane from plants apparently contributes significantly to the total emission but has not been accounted for in emission balances until now.

Methods

A model was created to calculate methane emission for a short time period in regional resolution for Lower Austria and to relate the results to known literature.

Results and Discussion

First model results suggest that the amount of methane released from plants in relation to emissions from other known sources are of importance.

Perspectives

The uncertainties associated with both measurements and quantification require reduction by further research.  相似文献   
165.
166.
167.
Refuse trucks play an important role in the waste collection process. Due to their typical driving cycle, these vehicles are characterized by large fuel consumption, which strongly affects the overall waste disposal costs. Hybrid hydraulic refuse vehicles offer an interesting alternative to conventional diesel trucks, because they are able to recuperate, store and reuse braking energy. However, the expected fuel savings can vary strongly depending on the driving cycle and the operational mode. Therefore, in order to assess the possible fuel savings, a typical driving cycle was measured in a conventional vehicle run by the waste authority of the City of Stuttgart, and a dynamical model of the considered vehicle was built up. Based on the measured driving cycle and the vehicle model including the hybrid powertrain components, simulations for both the conventional and the hybrid vehicle were performed. Fuel consumption results that indicate savings of about 20% are presented and analyzed in order to evaluate the benefit of hybrid hydraulic vehicles used for refuse collection.  相似文献   
168.
169.
ABSTRACT: As part of a major project to provide the Rhine delta protection from North Sea floods, the Dutch installed sluices at Haringvliet in the late 1960s and converted the Haringvliet-Hollandsch Diep-Biesbosch (HHB) estuary into a tidally-damped, fresh-water system. Two decades later, the Dutch Rijkswaterstaat commissioned a study of alternative policies for managing the sluices and removing contaminated bottom sediments, including policies which would at least partially restore estuarine conditions to the HHB. This paper describes the public policy analysis comprising that study, focusing on the role played by formal mullicriteria evaluation (MCE), including the Analytic Hierarchy Process. Through the tasks of value-tree structuring, impact measurement, and criterion prioritization, the MCE influenced the entire structure of the analysis, became an integral part of it, and, despite initial skepticism among the participants about the utility of multicriteria analysis, was subsequently accepted and viewed favorably by the majority of them.  相似文献   
170.
Summary The US federal government has deliberately shifted a great deal of responsibility for protecting public health and the environment to the 50 US States. Some States are able and willing to assume control, but many others cannot or will not. It is argued that the American federal government should be prepared to intervene in those States that do not place health and environment on their agenda.Dr. Michael Greenberg is Professor of the School of Urban and Regional Policy at Rutgers as well as being an Advisory Board member to this journal. Prof. Frank Popper chairs the Department of Urban Studies and Community Health at Rutgers University. He has written extensively about land use issues and the American Great Plains. Bernadette West is a doctoral candidate in the Department of Urban Planning and Policy Development, Rutgers University. Her thesis concerns scientific and political issues in developing cancer research centers.  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