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   882篇
  免费   89篇
  国内免费   106篇
安全科学   194篇
废物处理   33篇
环保管理   220篇
综合类   301篇
基础理论   127篇
污染及防治   61篇
评价与监测   36篇
社会与环境   57篇
灾害及防治   48篇
  2024年   5篇
  2023年   12篇
  2022年   32篇
  2021年   44篇
  2020年   39篇
  2019年   39篇
  2018年   28篇
  2017年   46篇
  2016年   55篇
  2015年   49篇
  2014年   35篇
  2013年   81篇
  2012年   62篇
  2011年   55篇
  2010年   50篇
  2009年   49篇
  2008年   40篇
  2007年   60篇
  2006年   44篇
  2005年   31篇
  2004年   21篇
  2003年   32篇
  2002年   25篇
  2001年   17篇
  2000年   21篇
  1999年   18篇
  1998年   13篇
  1997年   9篇
  1996年   8篇
  1995年   5篇
  1994年   10篇
  1993年   4篇
  1992年   5篇
  1991年   3篇
  1989年   2篇
  1988年   2篇
  1986年   1篇
  1985年   2篇
  1984年   2篇
  1982年   1篇
  1981年   2篇
  1980年   1篇
  1979年   3篇
  1978年   5篇
  1977年   1篇
  1974年   1篇
  1973年   2篇
  1972年   1篇
  1971年   2篇
  1970年   1篇
排序方式: 共有1077条查询结果,搜索用时 171 毫秒
201.
缓冲液对微生物燃料电池产电性能影响研究   总被引:2,自引:0,他引:2  
强琳  袁林江  丁擎 《环境科学》2011,32(5):1524-1528
微生物燃料电池(microbial fuel cell,MFC)应用于废水处理是一项非常有潜力的除污产能的绿色技术.但MFC运行过程中采用磷酸盐缓冲液不符合除污产能要求,增加水体富营养化趋势且增加水处理成本.试验采用单极室微生物燃料电池处理模拟生活污水,以投加PBS(phosphate buffer solution)...  相似文献   
202.
垃圾渗沥液中氨氮的电化学氧化   总被引:21,自引:0,他引:21       下载免费PDF全文
针对目前国内外垃圾渗沥液处理中存在的问题,采用电化学氧化与上流式厌氧污泥床(UASB)相结合,研究建立了对香港垃圾渗沥液的二步法处理工艺.本文着重探讨了电化学间接氧化去除渗沥液中氨氮的反应机制及主要影响因素,并通过实验找出了最佳的操作条件:入水初始 pH值为9.0;流速为0.01-0.10cm/s;CI加入量2000mg/L;电流密度 32.3mA/cm2.在此条件下,经过 6h电解后,UASB反应器出水中NH-N和COD的去除率分别达到100%和87%.对该电化学氧化过程的运行成本进行了评估.  相似文献   
203.
Hydroxyl radical (.OH)-initiated photooxidation reaction of toluene was carried out in a self-made smog chamber. Four individual seed aerosols such as ammonium sulfate, ammonium nitrate, sodium silicate and calcium chloride, were introduced into the chamber to assess their influence on the growth of secondary organic aerosols (SOA). It was found that the low concentration of seed aerosols might lead to high concentration of SOA particles. Seed aerosols would promote rates of SOA formation at the start of the reaction and inhibit its formation rate with prolonging the reaction time. In the case of ca. 9000 pt/cm^3 seed aerosol load, the addition of sodium silicate induced a same effect on the SOA formation as ammonium nitrate. The influence of the four individual seed aerosols on the generation of SOA decreased in the order of calcium chloride〉sodium silicate and ammonium nitrate〉ammonium sulfate.  相似文献   
204.
For effective monitoring in social–ecological systems to meet needs for biodiversity, science, and humans, desired outcomes must be clearly defined and routes from direct to derived outcomes understood. The Arctic is undergoing rapid climatic, ecological, social, and economic changes and requires effective wildlife monitoring to meet diverse stakeholder needs. To identify stakeholder priorities concerning desired outcomes of arctic wildlife monitoring, we conducted in-depth interviews with 29 arctic scientists, policy and decision makers, and representatives of indigenous organizations and nongovernmental organizations. Using qualitative content analysis, we identified and defined desired outcomes and documented links between outcomes. Using network analysis, we investigated the structure of perceived links between desired outcomes. We identified 18 desired outcomes from monitoring and classified them as either driven by monitoring information, monitoring process, or a combination of both. Highly cited outcomes were make decisions, conserve, detect change, disseminate, and secure food. These reflect key foci of arctic monitoring. Infrequently cited outcomes (e.g., govern) were emerging themes. Three modules comprised our outcome network. The modularity highlighted the low strength of perceived links between outcomes that were primarily information driven or more derived (e.g., detect change, make decisions, conserve, or secure food) and outcomes that were primarily process driven or more derived (e.g., cooperate, learn, educate). The outcomes expand monitoring community and disseminate created connections between these modules. Key desired outcomes are widely applicable to social–ecological systems within and outside the Arctic, particularly those with wildlife subsistence economies. Attributes and motivations associated with outcomes can guide development of integrated monitoring goals for biodiversity conservation and human needs. Our results demonstrated the disconnect between information- and process-driven goals and how expansion of the monitoring community and improved integration of monitoring stakeholders will help connect information- and process-derived outcomes for effective ecosystem stewardship.  相似文献   
205.
The numerous formulated products which are introduced to the market consist of chemical ingredients that may cause various safety and health hazards to the consumers. Therefore, it is extremely important to practice a systematic methodology to formulate products with acceptable safety and health performances. This work presents an index-based methodology to assess the safety and health hazards of the ingredients during the early formulation stage of product design. Hence, new inherent safety and health sub-indexes are introduced to improve the current safety and health hazards that are needed in formulated product design. The inherent safety and health sub-indexes are assigned with scores based on the degree of potential hazards. A higher score indicates a higher safety risk or severe health effect, and vice versa. The proposed methodology will greatly assist the users to identify the adverse safety and health effects caused by the ingredients. Hence, it is pivotal to eliminate or reduce the safety and health impacts from product usage. A case study on common ingredients used in the formulation of paint is presented on this study to describe the proposed method.  相似文献   
206.
对安全科学理论中的安全、安全技术、安全系统、安全性与危险性、危险墒与危险度、安全管理与安全信息、安全本质与安全本质化等概念提出了新认识。  相似文献   
207.
Zimbabwean provincial plans were instituted to help in the achievement of the national goal of the creation of an egalitarian, socialist and integrated society. The national goal itself was adopted as an antithesis to the dualist society characterised by spatial, economic, social, politican and technological inequalities that Zimbabwe inherited from colonialism. This meant that provincial plans had to play both a functional (or growth allocating/distribution) and a territorial (or redistribution) role.

This paper reviews their role in achieving the national goal by examining their functions, content, structure and methodology. The paper concludes that because of their nature, provincial plans are not suitable tools for the achievement of the national goal.  相似文献   

208.
开展"千乡万村环保科普行动"对提高农民的环保意识,控制农村面源污染,改善农村生态环境,改变农民的生活方式将起到积极的促进作用。概述了这项活动在云南的开展情况,分析了整个活动的成功和不足之处,探讨了确保这项活动全面实施的具体思路、方法和措施。  相似文献   
209.
环境保护执法新探   总被引:2,自引:0,他引:2  
环境执法的方式、手段起到优化作用.随着环境立法的完备和社会公众对环境质量要求的提高.如何加强环境执法的力度、改变环境执法的方式和执法领域.只有严格的执法才能保证和刺激政府、企业对环境服务的需求.通过建立完备的环境执法体系,坚决做到有法可依、有法必依、执法必严.以法规的形式,进一步明确环境保护行政主管部门的执法主体地位,调整和强化环保行政主管部门的管理职责,加大统一监管力度.做到法定执法权限,公开执法程序,明晰执法责任,规范执法行为.文章通过分析现行环境执法的缺陷,提出中国环境执法的优化目标和方向.  相似文献   
210.
镜质组反射率是广泛使用的成熟度参数 ,长期以来人们普遍认为温度和时间是控制镜质组反射率的主要因素 ,而压力对反射率的影响人们知之甚少。本文综述了模拟实验和地质实例中压力对镜质组反射率和烃类生成影响的不同观点。介绍了过压造成镜质组反射率延尺的两个动力学模型  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