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   1911篇
  免费   167篇
  国内免费   17篇
安全科学   506篇
废物处理   17篇
环保管理   581篇
综合类   463篇
基础理论   160篇
环境理论   19篇
污染及防治   39篇
评价与监测   39篇
社会与环境   159篇
灾害及防治   112篇
  2025年   7篇
  2024年   45篇
  2023年   59篇
  2022年   58篇
  2021年   61篇
  2020年   62篇
  2019年   85篇
  2018年   90篇
  2017年   123篇
  2016年   119篇
  2015年   113篇
  2014年   83篇
  2013年   122篇
  2012年   130篇
  2011年   116篇
  2010年   92篇
  2009年   87篇
  2008年   75篇
  2007年   96篇
  2006年   99篇
  2005年   82篇
  2004年   51篇
  2003年   37篇
  2002年   25篇
  2001年   22篇
  2000年   24篇
  1999年   21篇
  1998年   10篇
  1997年   10篇
  1996年   8篇
  1995年   10篇
  1994年   7篇
  1993年   7篇
  1992年   6篇
  1991年   2篇
  1989年   6篇
  1988年   3篇
  1986年   2篇
  1983年   3篇
  1982年   2篇
  1981年   2篇
  1980年   4篇
  1979年   6篇
  1978年   1篇
  1977年   2篇
  1975年   2篇
  1974年   1篇
  1973年   5篇
  1972年   3篇
  1971年   6篇
排序方式: 共有2095条查询结果,搜索用时 15 毫秒
71.
    
General backcasting as a decision support and planning method starts from desired future states and simulates developments backwards until reaching the present state. Development pathways that reveal steps to be taken to reach a certain future state, and milestones that serve as interim goals, are created during the process. Backcasting has hitherto only been applied in workshops or as a theoretical framework and no spatially explicit backcasting model has previously been established. This paper presents the development of a spatially explicit backcasting model. The proposed model first creates a future scenario utilizing an agent-based model and then simulates backwards. It is implemented using the programming language Python. The model has been applied to a case study for sustainable land-use planning in Salzburg, Austria. The results of the model run show a successful backcasting of land-use classes from a future state back to the present, in 10 year time steps.  相似文献   
72.
Beaches are a unique type of recreation setting, offering a variety of water- and land-based opportunities that can meet residents’ diverse and complex recreation needs. Providing and improving equitable access to recreation amenities such as beaches have been recognized as essential responsibilities of public leisure agencies. This study assessed the degree of equity inherent in the distribution of public beaches in the Detroit metropolitan area; to account for spatial effects, phenomena rarely considered in prior equity analyses, geographically weighted regression was employed. Considerable local variations in the relationships between level of access to public beaches and population density, proportion of elderly population and educational attainment were identified. Such findings can help parks and recreation agencies better understand local patterns of equity, an important first step in facilitating the formulation of more efficient and effective planning and policy approaches.  相似文献   
73.
    
Pesticide users, natural resource managers, regulators, government agencies and many others are concerned about the off-site impact of pesticides on the environment. Systematic methods of the assessment of potential risk of pesticides to environmental components can serve as valuable tools in decision making and policy formulation. Simple risk indicators have been developed which cover a range of scenarios such as toxicity to organisms, health of farm workers, consumer health, and residues in harvested produce. The authors have developed a software package named Pesticide Impact Rating Index (PIRI) that outputs an improved pesticide risk indicator for water quality. PIRI is a standalone, user-friendly, platform-independent program. It can be used to (i) rank pesticides in terms of their relative pollution potential to groundwater or surface water, and (ii) to compare different land uses in a catchment or at a regional scale in terms of their relative impact on water quality. It is based on pesticides use; the pathway through which the pesticides are released to the water resources (drift, runoff, erosion, leaching) and the value of the water resources threatened. Each component is quantified using pesticide characteristics (including toxicity to organisms at different trophic levels, i.e. fish, daphnia, algae, etc.), environmental and site conditions (e.g. organic carbon content of soil, water input, slope of land, soil loss, recharge rate, depth of water table, etc.). This paper describes two case studies of the application of PIRI in Australia. The comparison of the risk assessment by PIRI on these revealed that PIRI correctly estimated the pollution potential of pesticides in greater than 80% of cases. A GIS version of PIRI is described in a companion paper in this volume. An erratum to this article is available at .  相似文献   
74.
以TiO2为载体,选取过渡金属元素Mn为活性组分,稀土金属元素Ce为活性助剂,采用分步共混法制备了Mn-Ce/TiO2催化剂(活性组分负载量16%),系统研究了TiO2载体的晶型和晶粒尺寸对催化剂脱硝活性的影响。实验结果表明:分别以锐钛矿型和金红石型TiO2为载体制备的催化剂,其低温脱硝活性相差不大,活性组分均以无定型态高度分散于载体中,以金红石型TiO2为载体制备的催化剂中部分TiO2转变为锐钛矿型;以不同晶粒尺寸TiO2载体制备的催化剂的低温脱硝活性相差较大,比表面积较大、晶粒尺寸较小的TiO2载体制备的催化剂,其脱硝活性低于晶粒尺寸较大的TiO2载体制备的催化剂。  相似文献   
75.
尹先清  陈文娟  靖波  刘倩  杨航 《化工环保》2017,37(4):377-382
采用支持向量机(SVM)算法,将Box-Behnken设计法与支持向量回归算法(SVR)实验参数优化软件相结合,优化电化学去除油田污水COD的工艺参数。通过量子粒子群算法对SVM算法参数进行优化,从建立的回归模型中找到工艺参数的全局最佳点:电解时间60 min,电解电流3 A,三维电极填充料中石英砂质量695 g。模型得到的COD理论最优去除率为92.48%,验证实验得到的COD去除率为91.43%。  相似文献   
76.
建设项目竣工环境保护验收是我国环境保护管理的重要手段。阐述了建设项目竣工环境保护验收中公众参与的法律和制度基础,竣工环保验收中公众参与不仅能维护公众的环境权益,为竣工环保验收“三同时”制度的执行提供可靠依据,还可以推动环保行政主管部门决策的民主化、科学化。研究了竣工环保验收中公众意见调查的现状及存在的问题,提出加强和规范建设项目竣工环保验收公众参与的建议。  相似文献   
77.
党的十五大提出发展多种形式的公有制经济,在这种新形势下,环境管理如何转轨,本文进行了探讨和研究。  相似文献   
78.
ABSTRACT: Public information, an important contributer to citizen involvement in the governmental decision making process, has traditionally been given a low priority by government agencies. However, citizens are becoming increasingly concerned about governmental decisions that affect their lives and are demanding more information about governmental activities, including information about water resource issues, Because of this active citizen interest and involvement, the role of public information in increasing citizen awareness is becoming more important. Government officials and professionals should recognize that public information efforts also play an important role in achieving increased credibility and respect for their agencies. Once an agency recognizes the importance of public information and decides to initiate a public information program, careful planning is required to develop a program that addresses the needs of both the citizens and the agency. Two of the most flexible and cost effective ways to get information to the publié are through publications and public meetings. Both can be easily adapted to suit the needs of specific audiences and projects. A successful public information program can be carried out at a relatively low cost, but it requires a substantial amount of time and energy. The commitment of time and energy for this purpose is a good investment, however, because an effective public information program can play a significant role in improving the quality of governmental decisions through the increased involvement of the citizenry.  相似文献   
79.
    
ABSTRACT: Watershed stewardship activities throughout North America have evolved into a process that requires more involvement in planning and decision making by community stakeholders. Active involvement of all stakeholders in the process of watershed stewardship is dependent on effective exchange of information among participants, and active involvement of a wide range of stakeholders from “communities of place” as well as those from “communities of interest.” We developed a map‐based stream narrative tool as a means to: (a) assemble a wealth of incompletely documented, “traditional” ecological or natural history observations for rivers or streams; and (b) promote a higher level of active involvement by community stakeholders in contributing to information‐based, watershed management. Creation of stream narratives is intended for use as a tool to actively engage local stakeholders in the development of a more comprehensive information system to improve management for multiple stewardship objectives in watersheds. Completion of map‐based stream narrative atlases provides a valuable supplement to other independent efforts to assemble observations and knowledge about land‐based natural resources covering entire watersheds. We are confident that completion of stream narrative projects will make a valuable addition to the information and decision making tools that are currently available to the public and resource agencies interested in advancing the cause of community‐based approaches to watershed and ecosystem management.  相似文献   
80.
ABSTRACT. The water resources manager, concerned with providing for citizen needs for water in all its varied aspects, is obliged to consider the public interest in his decision making. But the public interest, although inferring the superiority of public over purely private interests, is more of a concept of political ethics than an operational objective. Recent attacks on water resources developments place in question just how responsive the water resources manager has been to the public at large during the planning process. The recent broadening of planning objectives beyond economic efficiency to include greater attention to social goals is an encouraging development. Efforts should be expanded toward greater citizen participation and more attention should be given to sampling surveys to determine citizen attitudes on water resources proposals. In the last analysis, the decision-making process must combine the expertise of the water resources manager and the participation of the people through the political process.  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