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   916篇
  免费   79篇
  国内免费   61篇
安全科学   80篇
废物处理   22篇
环保管理   253篇
综合类   394篇
基础理论   133篇
环境理论   2篇
污染及防治   28篇
评价与监测   17篇
社会与环境   104篇
灾害及防治   23篇
  2024年   2篇
  2023年   5篇
  2022年   15篇
  2021年   21篇
  2020年   25篇
  2019年   26篇
  2018年   29篇
  2017年   46篇
  2016年   48篇
  2015年   32篇
  2014年   35篇
  2013年   61篇
  2012年   62篇
  2011年   59篇
  2010年   39篇
  2009年   42篇
  2008年   38篇
  2007年   53篇
  2006年   55篇
  2005年   36篇
  2004年   31篇
  2003年   43篇
  2002年   36篇
  2001年   23篇
  2000年   29篇
  1999年   25篇
  1998年   18篇
  1997年   17篇
  1996年   8篇
  1995年   9篇
  1994年   9篇
  1993年   9篇
  1992年   4篇
  1991年   4篇
  1990年   3篇
  1988年   2篇
  1987年   5篇
  1986年   2篇
  1983年   4篇
  1982年   1篇
  1981年   8篇
  1980年   6篇
  1979年   7篇
  1978年   3篇
  1977年   3篇
  1976年   5篇
  1975年   2篇
  1973年   2篇
  1972年   2篇
  1971年   6篇
排序方式: 共有1056条查询结果,搜索用时 15 毫秒
951.
自然资源代际转移机制及其可持续性度量   总被引:6,自引:1,他引:5  
自然资源是人类社会赖以生存和持续发展最直接的物质基础和能量源泉。本文在探讨自然资源代际转移动力机制的基础上,应用资源经济学和环境经济学原理,分析了对自然资源持续性全面度量的原理与方法。  相似文献   
952.
Soil erosion is a significant problem in the uplands of the Central Coast, Vietnam. It affects the livelihood of farmers and could hinder the long-term economic development efforts in the uplands. Yet, trapped in poverty, upland farmers, especially the ethnic minority, are still mining the soil using erosive land use systems to meet their urgent needs. This study demonstrates that the level of soil erosion varies across the typical land use systems. The fruit tree-based agroforestry (AF) system is least erosive and most financially profitable. The choice of land use system is influenced by farmers' attributes, land plot characteristics, and policy-related variables. The set of policy variables is important in explaining land use choice by upland farmers. Promoting the switch to AF system and the adoption of soil conservation is of great importance to reducing soil erosion and sustaining development in the uplands. However, it is a very challenging task.  相似文献   
953.
ABSTRACT: The Rural Clean Water Program has provided a unique opportunity to study the economics of agricultural nonpoint source pollution control. Several implications for improving the economic efficiency of future agricultural nonpoint source pollution control programs can be drawn from the results. First, individual projects should be targeted towards water bodies that have water quality problems causing economic damages. Considerable variation can exist among areas in the magnitude of economic damages, which may not be proportional to physical impacts. Second, the relative costs and effectiveness of the practices selected to reduce the delivery of pollutants can vary dramatically from one location to another. Early identification and emphasis on cost-effective BMPs can substantially reduce project costs and may make a project economically justifiable that would not otherwise be so. Finally, some projects that do not hive potential economic benefits from water quality improvements exceeding government cost may have on-farm benefits from reduced costs and increased long-term yields that are sufficient to make total benefits (water quality and on-farm) exceed costs.  相似文献   
954.
ABSTRACT: This paper is a computer simulation analysis of an agricultural nonpoint pollution problem. Computer modeling is a universally applicable tool that can be used for establishing the linkages between and the quality of agricultural runoff in both surface and subsurface flow. The tradeoffs between the costs of soil conservation practices and water quality are reported, and the economic implications of such tradeoffs are discussed. Soil and nutrient losses resulting from crop production practices are analyzed using a field-scale computer simulation model (CREAMS). No-till planting, reduced tillage, and sod waterway systems are more cost effective than other practices for controlling soil and nutrient runoff losses. Nitrate leaching losses are increased slightly by most soil conservation practices. Terrace systems and permanent vegetative cover impose the greatest societal cost for water quality protection. Public cost sharing and tax incentives encourage farmers to adopt expensive structural practices, and policies are needed to get cost-effective practices implemented on critical acreage. Extensive treatment of land is necessary for agricultural best management practices (BMPs) to significantly improve water quality in areas that are intensively farmed.  相似文献   
955.
The paper presents a quantitative engineering approach to analysis of total environment allowing for simultaneous consideration of a theoretically infinite number of quality indicators and physiological requirements. It discusses theory and fundamentals of a two-dimensional space and time function solution concerning a small estuarine-type environment. A three dimensional solution is indicated. Input data may range from reconnaissance-type to the outputs of mathematical transport models. Applications are discussed with respect to environmental quality problems, availability of suitable data, and some areas of research where results could find immediate application.  相似文献   
956.
ABSTRACT As availability of funds in the federal budget for water development has decreased recently, pressure has increased for state and local governments to pay a larger share of the costs. In this situation a difficult question immediately arises-what is the capability of state and local governments to pay a larger share? Of course, there is no easy answer. Expenditures of public funds are policy outcomes of a government's political process in which political, economic, legal and other factors are involved in complex relationships. The traditional sources of capital funds for state and local governments include bond proceeds, tax revenues, and federal financial aid (state aid is also a major source of local government funds). The issuing of bonds is hampered by a variety of legal debt limitations, but there are means for circumventing the limitations. State and local governments vary widely in amounts of taxable resources available and in the extent to which these resources have been tapped. More effective use of revenue resources could be made in some cases. New sources of capital funds for water development ought to be considered-a fee on the use of water per se, for example. Costs associated with water use currently are imposed to cover development costs, but a state might impose additional use fees earmarked for a state water development fund.  相似文献   
957.
This work addresses several policy questions arising from indirect power losses due to navigation of the Snake-Columbia Rivers. Losses incurred in 1978–79 are given, and these losses are then compared to current conservation efforts, new power projects, and present replacement costs associated with the system.  相似文献   
958.
ABSTRACT: In developing strategies for nonpoint pollution control in designated 208 areas, one of the issues facing planners is the relative emphasis which should be placed upon urban versus agricultural non-point control. Five criteria which should be considered in designing an appropriate BMP strategy mix are discussed: 1) BMP cost effectiveness; 2) information and administrative cost; 3) flexibility, which relates to the cost of reversibility given substantial uncertainties; 4) associated effects, both direct and indirect; and 5) acceptability to local jurisdictions and groups. Whatever an evaluation on the basis of the first four criteria may suggest, acceptance of agricultural BMPs will be difficult to achieve, thus favoring urban oriented strategies, unless local revenue sources are developed to offer payments to farmers for BMP adoption.  相似文献   
959.
ABSTRACT: Urban runoff as well as industrial and agricultural discharges have seriously affected the water quality of the Skudai River, Malaysia. A water quality model is developed for simulating BOD and oxygen relationship. The simulated values agree relatively well with survey data taken during low flow conditions. Survey and simulated values show that a pollution abatement program is needed to prevent further deterioration of the river from organic discharges. A systems approach, involving complete analysis of water quality models and environmental control procedures, considering various water use patterns, water quality criteria, and waste input, is essential for solution.  相似文献   
960.
事故经济损失估算方法   总被引:13,自引:4,他引:9  
说明了劳动安全卫生费用与事故费用的概念,事故费用中直接费用与间接费用的概念。重点讨论了事故给企业带来的经济损失的费用要素,以及这些要素的确定原则及其分类,同时说明了各费用要素的计算方法。  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