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   23056篇
  免费   311篇
  国内免费   979篇
安全科学   705篇
废物处理   1032篇
环保管理   2955篇
综合类   4626篇
基础理论   6243篇
环境理论   10篇
污染及防治   6172篇
评价与监测   1395篇
社会与环境   952篇
灾害及防治   256篇
  2022年   240篇
  2021年   226篇
  2020年   177篇
  2019年   213篇
  2018年   311篇
  2017年   356篇
  2016年   509篇
  2015年   450篇
  2014年   685篇
  2013年   1854篇
  2012年   765篇
  2011年   1023篇
  2010年   853篇
  2009年   826篇
  2008年   991篇
  2007年   989篇
  2006年   912篇
  2005年   763篇
  2004年   729篇
  2003年   704篇
  2002年   693篇
  2001年   867篇
  2000年   648篇
  1999年   394篇
  1998年   333篇
  1997年   329篇
  1996年   318篇
  1995年   367篇
  1994年   332篇
  1993年   305篇
  1992年   295篇
  1991年   285篇
  1990年   308篇
  1989年   280篇
  1988年   254篇
  1987年   244篇
  1986年   226篇
  1985年   202篇
  1984年   257篇
  1983年   212篇
  1982年   272篇
  1981年   219篇
  1980年   184篇
  1979年   201篇
  1978年   184篇
  1977年   153篇
  1974年   159篇
  1973年   162篇
  1972年   148篇
  1971年   146篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The incorporation of sustainability assessment into decision-making processes is a key task for water service providers in the UK and elsewhere. This paper describes the development and application of a set of sustainability criteria, which have been developed and tested with project partners in the UK and Romania. They will be used in a 'guidebook' that will set out a framework to facilitate the inclusion of sustainability in the decision-making process. This work is part of the Sustainable Water Industry Asset Resource Decisions project to develop a multi-criteria analysis decision support system to assist water service providers to assess the relative sustainability of water/wastewater system asset development decisions.  相似文献   
992.
Ten case studies of Superfund sites were done by the University of Tennessee's Waste Management Research and Education Institute. The case studies, which focused on stakeholder perspectives of site processes, revealed a number of problems with the Superfund process. They also revealed that some improvements had begun to take place. Recently, several modifications have been instituted in the Superfund program. Although it is too early to determine their efficacy, it appears that the Superfund program is beaded in the right direction.  相似文献   
993.
Packaging waste has become a focus for attention by policy‐makers in a number of countries. This article offers a simple policy measure — a packaging tax or levy — which serves the required aims of policy, namely: reducing waste at source; increasing the rate of recycling; and consistency with the polluter pays principle. The tax is illustrated in the context of beverage containers in the UK and Japan. The merits of the proposal are its simplicity and flexibility. The article suggests that the relevant environmental damages are captured by waste disposal costs and litter. Other life cycle impacts, such as emissions from energy use, could be included but only if there are not more efficient ways of regulating them.  相似文献   
994.
Today, U.S. corporations are discovering the merit of combining the principles of total quality environmental management (TQEM) into their measurement and communications programs. This approach has been particularly productive in the permitting process that is necessary for starting, expanding, or sustaining plant operations—a procedure that can easily be thwarted in the absence of a prominent and aggressive communications component. The need to benchmark and measure such a communication program'S progress is critical both for internal management and for environmental regulators concerned that an applicant demonstrate a high degree of public involvement.  相似文献   
995.
Corporate environmental practices have been evolving quite rapidly in recent years, as consumers express their preferences for environmentally friendly products and practices, as manufacturers look “upstream” and inquire into their suppliers' environmental practices due to liability and marketing concerns, and as company operating costs increase as a result of new environmental regulations. New corporate efforts are made to anticipate (rather than respond to) outside environmental pressures, to internalize costs, and to find strategic opportunities or competitive advantages based on company or product environmental performance. This article describes a survey and research project designed to explore one aspect of these evolving corporate practices—the use of analytical tools and associated programs, such as life-cycle assessment and design-for-environment—by companies to account for impacts throughout a product'S life-cycle.  相似文献   
996.
ABSTRACT: Confined production of poultry results in significant volumes of waste material which are typically disposed of by land application. Concerns over the potential environmental impacts of poultry waste disposal have resulted in ongoing efforts to develop management practices which maintain high quality of water downstream of disposal areas. The timing of application to minimize waste constituent losses is a management practice with the potential to ensure high quality of streams, rivers, and lakes downstream of receiving areas. This paper describes the development and application of a method to identify which time of year is best, from the standpoint of surface water quality, for land application of poultry waste. The procedure consists of using a mathematical simulation model to estimate average nitrogen and phosphorus losses resulting from different application timings, and then identifying the timings which minimize losses of these nutrients. The procedure was applied to three locations in Arkansas, and three different criteria for optimality of application timing were investigated. One criterion was oriented strictly to water quality, one was oriented only to crop production, and the last was a combination. The criteria resulted in different windows of time being identified as optimal. Optimal windows also varied with location of the receiving area. The results indicate that it is possible to land-apply poultry waste at times which both minimize nutrient losses and maximize crop yield.  相似文献   
997.
This paper provides an overview of the concepts of “risk” and “safety-integrity” in relation to safety-related electrical/electronic/programmable electronic systems. The paper is an abridged version of Annex A of the emerging International Electrotechnical Commission (IEC) Standard; “Functional safety of electrical/electronic/programmable electronic systems”. Although based on Annex A, the authors have deviated in a few instances, from the strict wording of Annex A in order to more properly represent their own views. Where this occurs, a note in the text has been added to alert the reader of the deviation. The concepts of risk (including tolerable risk; safety integrity; safety-related system; System and Software Integrity Levels) are discussed.  相似文献   
998.
The objective of this research was to analyze the retention of acid precipitation as a viable policy issue on the Congressional agenda during the 1980s. Issue maintenance (a term borrowed from Barbara Nelson's discussion of the four stages associated with agenda decision making) was examined in relation to a set of issue characteristics originally developed by Roger Cobb and Charles Elder, i.e., concreteness, social significance, temporal relevance, complexity, and categorical precedence. Each issue attribute was found to be somewhat useful in explaining the longevity of acid rain as an agenda item although the direction of influence for two factors, complexity and temporal relevance, was contrary to expectations. It was suggested that a conceptual merger of this sort could contribute to the comparative analysis of agenda policy decisions by providing a clearer and more restricted set of decision points to be explained.  相似文献   
999.
Companies that incorporate Total Quality Management into their operations are placing increased emphasis on identifying the root causes of deficiencies and problems. This is in keeping with the TQM principles identified by Deming in Out of the Crisis. Deming states that quality comes not from inspection or from management by objectives or results, but from improvements made in the process and products in order to meet customer needs. Deming's approach demands a shift in focus from addressing symptoms to addressing causes. In this article, environmental management audits are presented as the best means to assure that adequate management controls are in place to protect the company, its managers and its employees from penalties associated with civil and criminal enforcement actions.  相似文献   
1000.
ABSTRACT: An integrated remotely sensed database was used as the basis for a hydrologic and sediment transport modeling effort for an agricultural area of western Puerto Rico. Classified spectral images of airborne radiance data provided ground cover information and were used in conjunction with topographic and soils data to guide model construction and provide input to the water balance and sediment yield simulations. Runoff and sediment discharge from hydrologically homogeneous regions were routed through the drainage network and combined at the basin outlet. The model was used to simulate four years of observed sediment discharge from the basin. Relative contributions to the total sediment yield of forested and agricultural areas were determined and compared.  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