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   746篇
  免费   41篇
  国内免费   200篇
安全科学   131篇
废物处理   41篇
环保管理   60篇
综合类   362篇
基础理论   101篇
污染及防治   193篇
评价与监测   27篇
社会与环境   29篇
灾害及防治   43篇
  2024年   5篇
  2023年   12篇
  2022年   32篇
  2021年   28篇
  2020年   35篇
  2019年   28篇
  2018年   24篇
  2017年   43篇
  2016年   38篇
  2015年   31篇
  2014年   39篇
  2013年   50篇
  2012年   47篇
  2011年   57篇
  2010年   57篇
  2009年   59篇
  2008年   56篇
  2007年   52篇
  2006年   43篇
  2005年   23篇
  2004年   22篇
  2003年   23篇
  2002年   29篇
  2001年   24篇
  2000年   29篇
  1999年   17篇
  1998年   14篇
  1997年   15篇
  1996年   12篇
  1995年   7篇
  1994年   12篇
  1993年   8篇
  1992年   4篇
  1991年   3篇
  1990年   3篇
  1989年   2篇
  1988年   1篇
  1987年   2篇
  1983年   1篇
排序方式: 共有987条查询结果,搜索用时 0 毫秒
21.
Based on the China high resolution emission gridded data (1 km spatial resolution), this article is aimed to create a Chinese city carbon dioxide (CO2) emission data set using consolidated data sources as well as normalized and standardized data processing methods. Standard methods were used to calculate city CO2 emissions, including scope 1 and scope 2. Cities with higher CO2 emissions are mostly in north, northeast, and eastern coastal areas. Cities with lower CO2 emissions are in the western region. Cites with higher CO2 emissions are clustered in the Jing-Jin-Ji Region (such as Beijing, Tianjin, and Tangshan), and the Yangtze River Delta region (such as Shanghai and Suzhou). The city per capita CO2 emission is larger in the north than the south. There are obvious aggregations of cities with high per capita CO2 emission in the north. Four cities among the top 10 per capita emissions (Erdos, Wuhai, Shizuishan, and Yinchuan) cluster in the main coal production areas of northern China. This indicates the significant impact of coal resources endowment on city industry and CO2 emissions. The majority (77%) of cities have annual CO2 emissions below 50 million tons. The mean annual emission, among all cities, is 37 million tons. Emissions from service-based cities, which include the smallest number of cities, are the highest. Industrial cities are the largest category and the emission distribution from these cities is close to the normal distribution. Emissions and degree of dispersion, in the other cities (excluding industrial cities and service-based cities), are in the lowest level. Per capita CO2 emissions in these cities are generally below 20 t/person (89%) with a mean value of 11 t/person. The distribution interval of per capita CO2 emission within industrial cities is the largest among the three city categories. This indicates greater differences among per capita CO2 emissions of industrial cities. The distribution interval of per capita CO2 emission of other cities is the lowest, indicating smaller differences of per capita CO2 emissions among this city category. Three policy suggestions are proposed: first, city CO2 emission inventory data in China should be increased, especially for prefecture level cities. Second, city responsibility for emission reduction, and partitioning the national goal should be established, using a bottom-up approach based on specific CO2 emission levels and potential for emission reductions in each city. Third, comparative and benchmarking research on city CO2 emissions should be conducted, and a Top Runner system of city CO2 emission reduction should be established.  相似文献   
22.
It is well known that model-building of chlorine decay in real water distribution systems is difficult because chlorine decay is influenced by many factors (e.g., bulk water demand, pipe-wall demand, piping material, flow velocity, and residence time). In this paper, experiments were run to investigate the kinetic model of chlorine decay and the formation model of trihalomethanes (THMs) in pilot-scale water distribution systems. Experimental results show that the rate constants of chlorine decay, including wall decay and bulk decay, increasing with temperature. Moreover, the kinetic model of chlorine decay and the formation model of THMs describe experiment data of pilot-scale water distribution systems. The effect of different piping material on chlorine decay and THMs formation were also investigated. The rate constants of chlorine decay are ranked in order: stainless steel pipe, ductile iron pipe, and last, polyethelene pipe because wall decay is the largest in stainless steel pipe than that in other piping material. Correspondingly, the rate of THMs formation follows the order of stainless steel pipe, ductile iron pipe, and last, polyethelene pipe because of less chlorine in bulk water reacting with the trihalomethane formation potential (THMFP).  相似文献   
23.
Afforestation of agricultural lands has been one of the major land use changes in China in recent decades. To better understand the effect of such land use change on soil quality, we investigated selected soil physical, chemical and microbial properties (0–15 cm depth) in marginal agricultural land and a chronosequence of poplar (Populus euramericana cv. ‘N3016’) plantations (5-, 10-, 15- and 20-years old) in a semi-arid area of Northeast China. Soil bulk density significantly declined after conversion of agricultural lands to poplar plantations. Soil total organic carbon (TOC) and nitrogen (TN) concentrations, microbial biomass C (MBC) and potential N mineralization rate (PNM) decreased initially following afforestation of agricultural lands, and then increased with stand development. However, soil metabolic quotient (qCO2) exhibited a reverse trend. In addition, soil particulate organic matter C (POM-C) and N (POM-N) concentrations showed no significant changes in the first 10 years following afforestation, and then increased with stand age. These findings demonstrated that soil quality declined initially following afforestation of agricultural lands in semi-arid regions, and then recovered with stand development. Following 15 years of afforestation, many soil quality parameters recovered to the values found in agricultural land. We propose that change in soil quality with stand age should be considered in determining optimum rotation length of plantations and best management practices for afforestation programs.  相似文献   
24.
位于长江北翼、黄海之滨的江苏省如东县海域内拥有一条纯天然深水航道(古长江人海口),一般水深均在-17米以上,港口水深-20- -30米左右,且直通外海、航道、港池和人工岛,是江苏唯一可建10万-20万吨级国际深水大港的理想港址,是长江三角洲地区乃至全国极其珍贵的建港资源。经过十多年的前期基础工作努力,为适应江苏省经济发展迫切需要大港的愿望,  相似文献   
25.
Environmental Science and Pollution Research - In this study, the immature mice were taken to assess the potential neurological toxicity of lead (Pb) and di (n-butyl) phthalates (DBP) combination...  相似文献   
26.
Environmental Science and Pollution Research - The effect of air staging strategies on NOx control was investigated on a 210-kW small-scale biomass boiler (SBB) and a 1.4-MW medium-scale biomass...  相似文献   
27.
Environmental Science and Pollution Research - The distributions of 31 pharmaceuticals grouped into nine therapeutic classes, including six anticancer drugs, were investigated in the waters and...  相似文献   
28.
污染土壤的微波辐照技术研究进展   总被引:2,自引:1,他引:2  
简要介绍了土壤污染的状况,总结了国外学者对重金属和有机物两大类污染土壤所进行的微波修复工作,探讨了修复机理及影响因素,最后展望了微波修复污染土壤的研究重点.  相似文献   
29.
微生物絮凝剂PF-2的成分分析及絮凝机制研究   总被引:5,自引:0,他引:5  
筛选得到的荧光假单胞菌(Pseudomonas fluorescens)产生的絮凝剂——PF-2在处理高岭土悬浊液时,具有用量少、絮凝效果好等优点,对高岭土悬浊液的絮凝率可达96.5%.呈色反应和紫外扫描的测定结果表明,PF-2大部分为胞外分泌的多糖,含有少量的核酸,提取后每升发酵液可制得絮凝剂粗品2.3 g;ζ电位测定及氢键和离子键检验结果表明,PF-2与高岭土颗粒之间的作用力为离子键;红外光谱扫描分析PF-2中含有O-H、C-H、C=C和C-O-C等多糖的特征吸收峰;利用扫描电镜观察絮体形态表明,絮体结构密实,其絮凝机制为PF-2和高岭土以离子键的形式结合,之后通过架桥作用絮凝沉淀.  相似文献   
30.
介绍了由道路交通事故引发的地表水污染事故风险定量分析方法,重点分析了突发水污染事故源发生概率和危害后果表征方法.以评价水域内道路危险品运输泄漏事故发生概率为水污染事故源发生概率.污染事故后果危害水平的表征:1)敏感区(点)最高浓度; 2)敏感区(点)超标总历时;3)水质超标的范围(如超标河流长度).评估方法为陆源造成的突发水污染事故的预防管理与应急计划的制订实施提供了科学依据.  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