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   7667篇
  免费   141篇
  国内免费   96篇
安全科学   326篇
废物处理   304篇
环保管理   1528篇
综合类   905篇
基础理论   2400篇
环境理论   8篇
污染及防治   1540篇
评价与监测   497篇
社会与环境   341篇
灾害及防治   55篇
  2023年   57篇
  2022年   57篇
  2021年   62篇
  2020年   63篇
  2019年   71篇
  2018年   230篇
  2017年   245篇
  2016年   352篇
  2015年   169篇
  2014年   172篇
  2013年   426篇
  2012年   642篇
  2011年   509篇
  2010年   224篇
  2009年   264篇
  2008年   305篇
  2007年   317篇
  2006年   292篇
  2005年   572篇
  2004年   691篇
  2003年   541篇
  2002年   181篇
  2001年   125篇
  2000年   112篇
  1999年   98篇
  1998年   78篇
  1997年   69篇
  1996年   66篇
  1995年   88篇
  1994年   78篇
  1993年   68篇
  1992年   60篇
  1991年   46篇
  1990年   39篇
  1989年   40篇
  1988年   30篇
  1987年   39篇
  1986年   40篇
  1985年   39篇
  1984年   44篇
  1983年   44篇
  1982年   52篇
  1981年   43篇
  1980年   31篇
  1979年   15篇
  1978年   29篇
  1977年   16篇
  1976年   13篇
  1972年   9篇
  1971年   10篇
排序方式: 共有7904条查询结果,搜索用时 15 毫秒
101.
This paper demonstrates empirically the gain from adopting more general equilibrium approaches in projecting the effects on domestic output and international trade of environmental controls. The suggested models include a partial equilibrium case where all industries are treated independently, an intermediate case incorporating effects in supplying industries, and general equilibrium formulations based on alternative macroeconomic conditions. U. S. data is used to evaluate these models. Under both pollutor pays and subsidy financing schemes, moving from the simplest case to the intermediate model results in quite different industry projections. Including macroeconomic factors appears particularly important in the classical setting.  相似文献   
102.
103.
This article examines the role of economic development agencies in strengthening the environmental performance of industry within rapidly industrialising East Asian economies. Three case-study examples are considered, namely, the role of the Industrial Development Board in reducing industrial pollution in Taiwan, pollution control in the palm oil industry in Malaysia, and the role of the Economic Development Board in influencing environmental performance of industry in Singapore. The concept of embedded autonomy is developed to consider the ways in which agencies of economic development can work with firms and industries while simultaneously remaining autonomous from these firms with respect to setting and enforcing performance standards. The three cases suggest that a form of policy integration that more directly integrates economic and environmental goals within agencies of economic development may be feasible, but only where there exists a strong autonomous government bureaucracy and where there is strong societal commitment to improving the environmental performance of industry.  相似文献   
104.
105.
ABSTRACT: Accurate data about nutrient concentrations in wastewater treatment plant effluents are needed for river basin water-quality studies. As part of the U.S. Geological Survey's National Water-Quality Assessment Program in the South Platte River Basin, nutrient data were requested from 31 wastewater-treatment plants located in the basin. This article describes the types of nutrient data available from the plants, examines the variability of effluent nutrient concentrations, and discusses methods for estimation of nutrient concentrations where data are lacking. Ammonia was monitored at 88 percent of the plants, nitrite plus nitrate was monitored at 40 percent of the plants, and organic nitrogen and phosphorus were monitored at less than 25 percent of the plants. Median total nitrogen concentrations and median total phosphorus concentrations were small compared to typical literature estimates for wastewater-treatment plants with secondary treatment. Nutrient concentrations in effluent from wastewater-treatment plants varied widely between and within plants. For example, ammonia concentrations varied as much as 5 mg/L during a day, as much as 10 mg/L from day to day, and as much as 30 mg/L from summer to winter within a plant. In the South Platte River Basin, estimates of median annual ammonia and nitrite plus nitrate concentrations can be improved based on plant processes; and nitrite plus nitrate and organic nitrogen concentrations can be estimated based on ammonia concentrations. However, to avoid large estimation errors, more complete nutrient data from wastewater-treatment plants are needed for integration into river basin water quality studies. The paucity of data hinders attempts to evaluate the relative importance of point source and nonpoint source nutrient loadings to rivers.  相似文献   
106.
Conferences     
Second Caribbean Conference on Science, Hazards and Hazard Management; Kingston, Jamaica, 9-12 October 1996
Mitigating the Millennium: Seminar on Community Participation and Impact Measurement in Disaster Preparedness and Mitigation Programmes; Overseas Development Institute, London, 9 October 1996  相似文献   
107.
In-situ sparging has been accepted as a method to rapidly remediate groundwater at considerably lower costs compared to remedies based on groundwater recovery alone. The success of in-situ sparging depends on effective mass transfer between air and contaminated media in the subsurface. Factors affecting mass transfer include advective airflow, diffusive transport, interphase chemical partitioning, and chemical and biological reaction rates between sparged gases and subsurface contaminants, minerals, and naturally occurring organic compounds. Understanding these factors can increase the design efficiency of in-situ sparging and assist in developing sparging systems that use gases other than air (i.e., oxygen, ozone, and methane).  相似文献   
108.
Summary In order to consider appropriate sustainable development, it is first necessary to understand the problems of developments that are inappropriate for specific population groups. Variables, such as, the culture of the group, its historical experiences, demographic and economic resources, population density, and remoteness or urban proximity should be scrutinized. This is a case study of one population group with a history of resource dependency.Inchelium is a small Native American community on the Colville Indian Reservation in Washington, USA. The construction of a large dam ended fishing in Inchelium. Changes due to the dam have led to exploitation and degradation of the community's lifestyle. Several attempts at viable alternative economic development have led to disagreements about cultural and environmental issues. Lack of sustainable development has fostered a non-viable economy. In this economy half of the employable persons are unemployed, and 80 percent are dependent upon some form of government financial and service aid.These problems are related to the effects of colonization found on all North American Indian reservations. A dependency relationship with the federal government has resulted in qualitative changes in the use of natural resources, from subsistence to extraction.Dr Pamela Elkind is Department Chairperson and Professor of Environmental Sociology at Eastern Washington University. David Lundgren is based in the Department of Sociology at Stevenson College. This paper was first delivered at the Global Forum '94 Conference in Manchester, UK.  相似文献   
109.
There is some concern in the environmental quality management (EQM) community that small and mid-sized companies do not have the technical, economic, and personnel resources or expertise to carry out significant programs of pollution prevention or waste reduction in the way that large corporations do. Thus, a very significant proportion of the economy may not be contributing to or benefiting from EQM approaches. This article begins to clarify what small and mid-sized companies that are committed to EQM can actually do and how this compares with the efforts of larger plants or plants operated as part of large multiplant corporations.  相似文献   
110.
With the increased use of electric and electronic equipment in our offices, our daily exposure to electromagnetic fields has become increasingly complex due to the great variety of the frequency content of the fields. Today focus has shifted from monitors as the dominating sources of electromagnetic fields to other electronic equipment, cabling, nearby substations, power lines and stray currents in buildings. In the last 5 years wireless communication has become common in our offices. These devices use radio frequency waves to communicate and are therefore sources of radio frequency fields in our offices. To a certain degree, they all add to the complicated issue of the extensive field frequencies found in offices. The exposure of office workers is generally considered to be low and not in conflict with the existing guidelines, but if a precaution approach is applied there are a number of measures that can be taken to reduce the electromagnetic fields in offices in order to obtain a good electrical environment.  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