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   4668篇
  免费   310篇
  国内免费   1139篇
安全科学   333篇
废物处理   606篇
环保管理   906篇
综合类   2801篇
基础理论   323篇
环境理论   2篇
污染及防治   799篇
评价与监测   239篇
社会与环境   99篇
灾害及防治   9篇
  2024年   11篇
  2023年   85篇
  2022年   117篇
  2021年   152篇
  2020年   165篇
  2019年   111篇
  2018年   124篇
  2017年   171篇
  2016年   233篇
  2015年   199篇
  2014年   394篇
  2013年   356篇
  2012年   374篇
  2011年   358篇
  2010年   255篇
  2009年   286篇
  2008年   238篇
  2007年   293篇
  2006年   336篇
  2005年   250篇
  2004年   212篇
  2003年   238篇
  2002年   197篇
  2001年   154篇
  2000年   166篇
  1999年   128篇
  1998年   100篇
  1997年   74篇
  1996年   71篇
  1995年   64篇
  1994年   52篇
  1993年   43篇
  1992年   30篇
  1991年   13篇
  1990年   11篇
  1989年   4篇
  1988年   3篇
  1987年   6篇
  1986年   3篇
  1984年   3篇
  1983年   3篇
  1982年   3篇
  1981年   4篇
  1980年   6篇
  1979年   5篇
  1977年   3篇
  1976年   2篇
  1973年   3篇
  1971年   3篇
  1970年   1篇
排序方式: 共有6117条查询结果,搜索用时 15 毫秒
991.
PW—W膜分离式活性污泥法处理中小规模高浓度有机废水   总被引:3,自引:0,他引:3  
阐述PW-W膜分离式活性污泥法处理高浓度有机废水的原理、工艺流程及特点。处理系统集生化处理功能和固液分离于一体,对高浓度有机废水的处理取得了良好的效果,且剩余污泥量少,处理水质稳定,维护管理方便,运行费用低。  相似文献   
992.
IntroductionSincethefirstenvironmentalinputoutputmodel(EIOM)(Cumberland,1966)wasestablishedbyincorporatingenvironmentalfactorsint?..  相似文献   
993.
Environmental quality for environmental health has been examined visually by describing general conditions and drinking water supply, sanitation and solid waste treatment conditions and practices in six South-East Asian villages with a dense population. The environmental review was supplemented by discussions with local people and political and administrative decision makers. Some drinking water analyses were done in order to show the water quality to the local people. The quality of the general conditions and the conditions and practices of drinking water supply, excreta disposal and solid waste treatment practices have been graded with the grading system presented below. The grading could be done in 1 or 2 days in each area by two persons, of which one was an environmental scientist and the other a social scientist, who also knew the local culture and worked as a translator.  相似文献   
994.
995.
It has traditionally been argued that recycling municipal solid waste (MSW) is usually not economically viable and that only when externalities, long-term dynamic considerations, and/or the entire product life cycle are taken into account, recycling becomes worthwhile from a social point of view. This article explores the results of a wide study conducted in Israel in the years 2000–2004. Our results reveal that recycling is optimal more often than usually claimed, even when externality considerations are ignored. The study is unique in the tools it uses to explore the efficiency of recycling: a computer-based simulation applied to an extensive database. We developed a simulation for assessing the costs of handling and treating MSW under different waste-management systems and used this simulation to explore possible cost reductions obtained by designating some of the waste (otherwise sent to landfill) to recycling. We ran the simulation on data from 79 municipalities in Israel that produce over 60% of MSW in Israel. For each municipality, we were able to arrive at an optimal method of waste management and compare the costs associated with 100% landfilling to the costs born by the municipality when some of the waste is recycled. Our results indicate that for 51% of the municipalities, it would be efficient to adopt recycling, even without accounting for externality costs. We found that by adopting recycling, municipalities would be able to reduce direct costs by an average of 11%. Through interviews conducted with representatives of municipalities, we were also able to identify obstacles to the utilization of recycling, answering in part the question of why actual recycling levels in Israel are lower than our model predicts they should be.  相似文献   
996.
Recent targets for reduced amounts of waste to landfills in Sweden will result in a large increase in waste incineration with recovery of energy, used primarily for district heating. The aim of this study is to investigate what changes in the usage of other fuels and technologies for district heat production would be caused by this increase. A questionnaire was sent out to the largest district heating companies, and simulations in an energy systems model were carried out. The analysis shows that increased waste incineration reduces the demand for other fuels, especially biomass, for district heat production. The effects include reductions in operating hours as well as the avoidance or postponement of investments in new plants for district heat production. Increased waste incineration will also lead to a greater use of district heating in Sweden.  相似文献   
997.
● MSWNet was proposed to classify municipal solid waste. ● Transfer learning could promote the performance of MSWNet. ● Cyclical learning rate was adopted to quickly tune hyperparameters. An intelligent and efficient methodology is needed owning to the continuous increase of global municipal solid waste (MSW). This is because the common methods of manual and semi-mechanical screenings not only consume large amount of manpower and material resources but also accelerate virus community transmission. As the categories of MSW are diverse considering their compositions, chemical reactions, and processing procedures, etc., resulting in low efficiencies in MSW sorting using the traditional methods. Deep machine learning can help MSW sorting becoming into a smarter and more efficient mode. This study for the first time applied MSWNet in MSW sorting, a ResNet-50 with transfer learning. The method of cyclical learning rate was taken to avoid blind finding, and tests were repeated until accidentally encountering a good value. Measures of visualization were also considered to make the MSWNet model more transparent and accountable. Results showed transfer learning enhanced the efficiency of training time (from 741 s to 598.5 s), and improved the accuracy of recognition performance (from 88.50% to 93.50%); MSWNet showed a better performance in MSW classsification in terms of sensitivity (93.50%), precision (93.40%), F1-score (93.40%), accuracy (93.50%) and AUC (92.00%). The findings of this study can be taken as a reference for building the model MSW classification by deep learning, quantifying a suitable learning rate, and changing the data from high dimensions to two dimensions.  相似文献   
998.
含重金属水处理污泥的固化和浸出毒性研究   总被引:2,自引:0,他引:2  
工业危险固体废物在进行安全填埋前需要进行固化稳定处理。针对电镀厂和皮革厂含重金属的水处理污泥 ,用不同比例的水泥、粉煤灰进行固化稳定处理。考虑酸雨环境 ,浸出实验采用TCLP标准。电镀厂污泥单独固化时 ,其浸出液中铜离子浓度由 78 0mg/L下降到 1 5mg/L ;镍离子浓度由 2 2 4 5mg/L下降到 2 2 2mg/L ,高于危险废物允许进入填埋区 15mg/L的控制限值。电镀厂污泥与皮革厂污泥混合后固化 ,浸出液毒性明显降低。铜离子的浸出浓度降低到1 98mg/L ,镍离子降低到 4 10mg/L ,总铬降低到 0 4 0mg/L ,各项指标均低于国家危险废物允许进入填埋区的控制限值 ,可安全填埋。  相似文献   
999.
针对城市生活垃圾焚烧(MSWI)过程中二(口恶)英类的生成机制以及焚烧飞灰的组成,研究了MSWI飞灰中常见的钙化合物(CaO,Ca(OH)2,CaCl2,CaSO4及Ca(NO3)2)对前生体五氯酚(PCP)及六氯苯(HCB)生成二(口恶)英类的阻滞作用.结果表明,280℃下加热2 h,Ca(NO3)2,Ca(OH)2和CaO对PCP生成二(口恶)英类的总阻滞效率分别为93.7%,80.4%和98.9%,而CaCl2和CaSO4几乎没有效果.CaO对PCP和HCB混合物生成二(口恶)英类物质同样具有良好的阻滞效果.另外,探讨了上述钙化合物对PCP及HCB生成二(口恶)英类的阻滞作用机理.  相似文献   
1000.
针对油田酸化过程中返排出的残酸处理困难,造成较大污染、浪费等问题,分析了残酸作为调剖剂的价值,研究了利用“残酸”进行调剖的工艺技术,并进行了现场试验,投入产出比为1:28,取得了较好的经济效益和社会效益,为”残酸”的再利用和环境保护找到了一条有效途径。  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