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   33966篇
  免费   9236篇
  国内免费   859篇
安全科学   3884篇
废物处理   484篇
环保管理   7526篇
综合类   18242篇
基础理论   4441篇
环境理论   17篇
污染及防治   2880篇
评价与监测   2168篇
社会与环境   2855篇
灾害及防治   1564篇
  2025年   95篇
  2024年   684篇
  2023年   874篇
  2022年   1041篇
  2021年   1108篇
  2020年   1191篇
  2019年   1085篇
  2018年   962篇
  2017年   1382篇
  2016年   1570篇
  2015年   1508篇
  2014年   1482篇
  2013年   2065篇
  2012年   2342篇
  2011年   2483篇
  2010年   1832篇
  2009年   1818篇
  2008年   1503篇
  2007年   2250篇
  2006年   2221篇
  2005年   1785篇
  2004年   1497篇
  2003年   1610篇
  2002年   1335篇
  2001年   1095篇
  2000年   1055篇
  1999年   989篇
  1998年   716篇
  1997年   612篇
  1996年   519篇
  1995年   485篇
  1994年   445篇
  1993年   391篇
  1992年   308篇
  1991年   236篇
  1990年   169篇
  1989年   133篇
  1988年   114篇
  1987年   90篇
  1986年   67篇
  1985年   64篇
  1984年   70篇
  1983年   76篇
  1982年   70篇
  1981年   81篇
  1980年   90篇
  1979年   81篇
  1978年   56篇
  1977年   55篇
  1971年   62篇
排序方式: 共有10000条查询结果,搜索用时 26 毫秒
1.
用StrandenE.推荐的测量方法对哈密地区环境空气中220Rn子体α潜能浓度测量结果表明,室内、外平均值分别为56.1和10.2(×10-7J·m-3)。室内外220Rn/222Rn子体α潜能浓度比值分别为0.84和032。220Rn子体所致居民有效剂量当量为228μSv·a-1(集体有效剂量当量为0.9×02man·Sv)。  相似文献   
2.
针对沈阳市地铁疏干水利用的现状,综合考虑沈阳市的实际情况,总结出地铁疏干水利用的几种方法,主要包括作为运河、湖泊的补换水源,用于修复、重建湿地,农业灌溉用水以及作为水源热泵的水源等。提出沈阳市地铁疏干水利用的指导思想和法律保障。  相似文献   
3.
    
ABSTRACT

Agriculture-to-urban water transfer is currently an important measure to meet the increasing water demand resulting from rapid industrialization and urbanization in China. Measuring benefits of agriculture-to-urban water transfer is critical to assess water transfer proposals, and it can also provide reliable basis for redistributing the benefits of agriculture-to-urban water transfer. This paper has developed a comprehensive framework in which production function approach is applied to quantify the value of water use in agricultural and industrial sectors, and contingent valuation method is employed to investigate the value of water use in municipal consumption and ecological environment. A case study from Zhuji City in China verified the feasibility and validity of the method proposed in the paper. Results indicate that the agriculture-to-urban water transfer increases the water value created by improving allocation efficiency of water use in different sectors. The benefits of agriculture-to-urban water transfer mainly originate from the fact that the economic value in industrial water use is higher than in the other sectors’ water use. Meanwhile, the urban residents have a stronger desire to improve the water eco-environment which leads to higher water value in urban area.  相似文献   
4.
As a byproduct of water treatment,drinking water treatment aluminum sludge(DWTAS)has challenges related to imperfect treatment and disposal,which has caused potential harm to human health and the environment.In this paper,heat treatment DWTAS as a supplement cementitious material was used to prepare a green cementing material.The results show that the 800℃ is considered as the optimum heat treatment temperature for DWTAS.DWTAS-800℃ is fully activated after thermal decomposition to form incompletely crystallized highly active γ-Al2O3 and active SiO2.The addition of DWTAS promoted the formation of ettringite and C-(A)-S-H gel,which could make up for the low early compres-sive strength of cementing materials to a certain extent.When cured for 90 days,the com-pressive strength of the mortar with 30% DWTAS-800℃ reached 44.86 MPa.The dynamic process was well simulated by Krstulovic-Dabic hydration kinetics model.This study pro-vided a methodology for the fabrication of environmentally friendly and cost-effective com-pound cementitious materials and proposed a\"waste-to-resource\"strategy for the sustain-able management of typical solid wastes.  相似文献   
5.
6.
Measurements of urban air quality at monitoring stations in developed countries have frequently involved the criteria gaseous pollutants, particulates, hazardous air pollutants, perceived air quality and relevant meteorological conditions. Large numbers of indicators have therefore been established to quantify emissions, concentrations and environmental and human health impacts of each of these groups of substances. To simplify the data for management, several indicators have been grouped together to form urban air quality indices but the weightings of individual variables is contentious. In industrialising and developing countries, data may be limited and traditional air pollutant indicators cannot often be constructed. The emphasis therefore has to be placed on the development of policy-relevant indicators, such as Response Indicators that reflect different policy principles for regulating air pollutant emissions. Indices that quantify the air quality management capabilities and capacities at the city level provide further useful decision-relevant tools. Four sets of indices, namely, 1. air quality measurement capacity, 2. data assessment and availability, 3. emissions estimates, and 4. management enabling capabilities, and a composite index to evaluate air quality management capability, were constructed and applied to 80 cities. The indices revealed that management capability varied widely between the cities. In some of the cities, existing national knowledge on urban air quality could have been more effectively used for management. It was concluded that for effective urban air quality management, a greater emphasis should be given, not just to monitoring and data capture programmes, but to the development of indicators and indices that empower decision-makers to initiate management response strategies. Over-reliance on restricted, predetermined sets of traditional air quality indicators should be avoided.  相似文献   
7.
焦炉装煤烟尘含有害物质,污染环境,危害人体健康。袋式除尘器的使用,消除了烟尘的污染,但因投资大、运行费用高、操作复杂,难以得到快速、广泛的推广。根据实验结果和已有应用情况,本文推荐了三相流化床除尘装置和颗粒层除尘器,它们可用于焦炉装煤烟尘治理,其投资和运行费用会大大降低。  相似文献   
8.
深床过滤机理及其在水处理中的应用研究与进展   总被引:2,自引:0,他引:2  
深床过滤既有过滤功能,又具生物处理作用,具有良好的应用前景;本文阐述了深床过滤的最新研究动向,深床过滤过程的数学模型的构建方法,国内外利用深床过滤技术处理微污染水源水、城市生活污水及污水深度处理的实验研究状况.  相似文献   
9.
Franke R  Franke C 《Chemosphere》1999,39(15):219-2659
A laboratory scale flow-through model reactor for the degradation of persistent chemicals using titanium dioxide (TiO2) as photocatalyst immobilized on glass beads is presented. In the test system with a volume of 18 L contaminated water is pumped to the upper part of the floating reactor and flows over the coated beads which are exposed to UV-radiation. The degradation of two dyes of different persistance was investigated. Primary degradation of methylene blue did not fit a first order kinetic due to coincident adsorption onto the photocatalyst and direct photolysis, resulting in a half-life of 6 h. A filtrate of a green algae suspension accelerated the colour removal. In contrast, reactive red 2 was degraded only by photocatalysis; neither adsorption nor direct photolysis led to a colour removal. The course of primary degradation followed a first order kinetic with a half-life of 18 h and a rate constant of 0.04 h−1. Analysis of the degradation products indicated mineralization by detection of NO2 and NO3, accompanied by a decrease of pH and an increase of conductivity. A successful adaptation of the model reactor (scale 1:10) to dimensions required for surface waters and waste water treatment plants would be a costefficient and environmentally sustainable application of photocatalysis for the treatment of industrially polluted water and could be of relevance for third world contries, particularly those favoured by high solar radiation.  相似文献   
10.
宁波市城市污水处理厂污泥处置方案探讨   总被引:2,自引:0,他引:2  
随着城市污水处理率提高导致的污水污泥产量的增长趋势也使得污水污泥的处理问题更为突出。在总结国内外城市污泥处置技术发展趋势的基础上,结合宁波市的实际情况,根据无害化、减量化和资源化的原则,提出城市污泥近远期处置方案,并对处置方案作出可行性分析。  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