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   8671篇
  免费   579篇
  国内免费   279篇
安全科学   1696篇
废物处理   148篇
环保管理   3246篇
综合类   2266篇
基础理论   861篇
环境理论   12篇
污染及防治   256篇
评价与监测   342篇
社会与环境   415篇
灾害及防治   287篇
  2023年   87篇
  2022年   125篇
  2021年   197篇
  2020年   254篇
  2019年   208篇
  2018年   181篇
  2017年   233篇
  2016年   319篇
  2015年   270篇
  2014年   344篇
  2013年   516篇
  2012年   476篇
  2011年   623篇
  2010年   410篇
  2009年   549篇
  2008年   401篇
  2007年   509篇
  2006年   500篇
  2005年   381篇
  2004年   409篇
  2003年   318篇
  2002年   287篇
  2001年   284篇
  2000年   283篇
  1999年   214篇
  1998年   134篇
  1997年   137篇
  1996年   109篇
  1995年   109篇
  1994年   54篇
  1993年   65篇
  1992年   57篇
  1991年   48篇
  1990年   36篇
  1989年   27篇
  1988年   35篇
  1987年   33篇
  1986年   28篇
  1985年   23篇
  1984年   27篇
  1983年   17篇
  1982年   22篇
  1981年   18篇
  1980年   24篇
  1979年   33篇
  1978年   21篇
  1975年   14篇
  1973年   14篇
  1972年   16篇
  1971年   14篇
排序方式: 共有9529条查询结果,搜索用时 397 毫秒
761.
阐述建立风险学的重要性,探讨了开展安全减灾风险评价与管理的关键问题。概要介绍国内外风险水平的表征、识别方法及指标体系,并提出风险管理的基本原则。引入风险地图、危机管理、风险数学、应急与预警等现代概念及方法,基本反映了在瑞典召开的“新区开发中的风险科学与管理”国际会议的内容。  相似文献   
762.
简述了我国重大工业事故发生的主要原因,提出了建立重大事故预防控制体系的建议,制定《重大事故预防和控制法》,实行重大危险源上报、登记、评价、分级监察管理,建立国家、省、市三级重大事故应急反应系统和重大危险源动态监控网络系统。  相似文献   
763.
为确保炼油厂设备安全而稳定地运行,各生产装置都要定期进行停工检修,在此期间排放的污染物对环境将产生一定的影响。停工检修中的环保工作包括实施环保措施;加强环境管理;并且将2000m~3隔油池由一间式变为两间式,提高污水处理率和达标率。  相似文献   
764.
The National Forest Management Act (1976) specifies that multiresource inventories be conducted to provide baseline data for development and, later, monitoring of national forest management plans. This mandate entails the most ambitious and complex resource planning effort ever attempted. In this paper we evaluate the structure and use of current inventory-monitoring programs and recommend a framework for gathering data to improve national forest planning. Current national guidelines are general and provide only basic directions to forest-level planners. Forest inventories have traditionally concentrated on timber. Although these inventories are often well designed, the questions we are now asking about forest resources have outgrown these methods. Forest management is impeded by general confusion over definitions of resources and the interactions among them. We outline a simple classification scheme that centers on identification of basic ecosystem elements that can be readily measured. Furthermore, spatial and temporal scales must be considered in the design of inventory-monitoring programs. The concept of ecological indicators is reviewed, and caution is advised in their use. Inventory-monitoring programs should be goal-directed and based on as rigorous a statistical design as possible. We also review fundamental issues of variable selection, validation, and sampling bias. We conclude by developing a flexible inventory-monitoring program that is designed to provide information on individual characteristics of the environment, rather than being based on fixed definitions of resources.  相似文献   
765.
United States-Mexican transboundary water resources management is presently experiencing significant reform resulting from long-term demographic processes in the border region and greater economic integration. The recently concluded North American Free Trade Agreement and supplementary environmental accord modify existing agreements and provide old institution with new mandates. Particularly affected is the International Boundary and Water Commission (IBWC), long the lead agency in binational water management. This essay reviews the development of the new water management regime against the two preceding phases of management reform and considers its implications for improved water management in the border region.  相似文献   
766.
Within the context of political democratization, this article explores environmental protection in Hong Kong since the government lauched a ten-year program to “save the environment” in 1989. Examining environmental management by law from a social-choice perspective, it argues that the government has yet to reach an integrative policy orocess. Hence the preconditions for an integrative set of environmental legislation are absent. Institutionally, without a comprehensive green policy, the current arrangements lack a vision as an integrative force to promote effective coordination among various sectoral environmental coordination among various sectoral environmental programs. The dominant approach of policy and law enforcement through consultation has rendered impossible strict enforcement of environmental rules and regulations as local economic growth enjoys a priority over environmental protection. At a time of environmental awakening, the people of Hong Kong are not yet prepared awakening, the people of Hong Kong are not yet prepared to participate in environmental management in a strict legal manner. The overall observation is that Hong Kong has yet to see more mature political, legal, administrative, and social conditions for managing its environment within a legal framework.  相似文献   
767.
Risk management practices under the current environmental regulations is a long, complex process that considers scientific, technologic, and management factors to develop various regulatory standards and pollution control measures. Using the mandatory enforcement approach, sometimes referred to as “command-and-control”, a set of preliminary environmental goals, such as better air and water qualities, were achieved. However, the information-intensive nature of the risk management process and the lack of flexibility in conventional regulatory methods to changing economic and technologic realities of the decade has created interest among risk managers to examine some innovative management approaches. Above all, environmental problems of a global scale require novel management methods while striving to achieve the desired environmental goals. As the principal analytical tool in risk management, quantitative risk assessment exerts considerable influence on the risk management process. Therefore, advances in risk management are closely associated with scientific developments that enhance the risk assessment process, particularly those efforts aimed at improving human exposure and toxicity assessments. Market incentives, information dissemination, creative enforcement practices, and interagency and intergovernmental interactions were identified as the key elements of innovative environmental risk management practices. This paper will present an overview of the emerging innovative risk management approaches.  相似文献   
768.
769.
ABSTRACT: Because of its importance and the perceived inability of private sector sources to meet water demands, many countries have depended on the public sector to provide water services for their populations. Yet this has resulted in many inefficient public water projects and in inadequate supplies of good quality and reliable water. Decentralization of water management, including the use of water markets, cannot solve all of these water problems, but it can improve the efficiency of water allocation. When given adequate responsibility and authority, water user associations have effectively taken over water management activities at a savings to tax payers. Moreover, water markets add the potential benefit of improving water efficiency within a sector as well as providing a mechanism for reallocating water among sectors. The key question involves developing innovative mechanisms for reducing the transaction costs of organizing water users and of making water trades. Water rights need to be established which are recorded, tradable, enforceable, and separate from land if markets are to operate effectively. Also, institutions are needed that effectively resolve conflicts over water rights, including third party impacts and water quality concerns.  相似文献   
770.
ABSTRACT: Both catchment experiments and a review of hydrologic processes suggest a varying effect of forest harvest on the magnitude of peak flows according to the cause of those peak flows. In northwestern Montana and Northeastern Idaho, annual maximum flows can result from spring snowmelt, rain, mid-winter rain-on-snow, or rain-on-spring-snowmelt. Meteorologic and physical data were used to determine the cause of annual maximum flows in six basins which had the necessary data and were smaller than 150 mi2. Rain-on-spring-snowmelt was the most frequent cause of annual maximum flows in all six basins, although there was a strong gradient in the magnitude and cause of peak flows from southwest to northeast. Less frequent mid-winter rain-on-snow events caused the largest flows on record in four basins. Mid-winter rain-on-snow should be distinguished from rain-on-spring-snowmelt because of differences in seasonal timing, the relative contributions of rain vs. snowmelt, and the projected effects of forest harvest. The effects of mixed flood populations on the flood-frequency curve varied from basin to basin. Annual maximum daily flows could not be reliably predicted from rainfall and snowmelt data.  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