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   5782篇
  免费   479篇
  国内免费   1697篇
安全科学   545篇
废物处理   262篇
环保管理   511篇
综合类   3675篇
基础理论   877篇
污染及防治   1040篇
评价与监测   402篇
社会与环境   356篇
灾害及防治   290篇
  2024年   25篇
  2023年   94篇
  2022年   301篇
  2021年   236篇
  2020年   264篇
  2019年   215篇
  2018年   259篇
  2017年   264篇
  2016年   218篇
  2015年   315篇
  2014年   412篇
  2013年   484篇
  2012年   428篇
  2011年   488篇
  2010年   428篇
  2009年   394篇
  2008年   381篇
  2007年   358篇
  2006年   337篇
  2005年   259篇
  2004年   252篇
  2003年   238篇
  2002年   259篇
  2001年   239篇
  2000年   198篇
  1999年   153篇
  1998年   104篇
  1997年   76篇
  1996年   66篇
  1995年   63篇
  1994年   37篇
  1993年   26篇
  1992年   23篇
  1991年   21篇
  1990年   15篇
  1989年   8篇
  1988年   4篇
  1987年   1篇
  1986年   4篇
  1985年   3篇
  1984年   1篇
  1983年   4篇
  1982年   1篇
  1972年   1篇
  1964年   1篇
排序方式: 共有7958条查询结果,搜索用时 709 毫秒
791.
水资源全流域管理模式研究   总被引:2,自引:0,他引:2  
水资源管理在社会经济发展中具有举足轻重的作用。本文通过分析国外流域管理的先进经验及发展趋势 ,结合我国实际 ,提出水资源全流域统一管理的模式 ,并指出这是我国水资源管理的必由之路  相似文献   
792.
Development of an ELISA for the detection of bromoxynil in water   总被引:4,自引:0,他引:4  
For development of an indirect competitive enzyme-linked immunosorbent assay (ELISA) for the nitrile herbicide bromoxynil, the polyclonal antibodies raised against 2,6-dibromo-4-cyano-phenoxyacetic acid (hapten) conjugated to bovine serum albumin (BSA) by the N-hydroxysuccinimide-activated ester method. Antiserum with a sufficiently high titer to provide the determinations of targeted compounds was obtained only 77 days after the primary immunization. Antiserum A2 was applied to the residual analysis of some water samples, under optimized ELISA condition, the quantitative working range was from 10 to 500 ppb with a limit of detection of 5 ppb. Cross-reactivity to structurally similar agrochemicals and related chemicals was determined. The antiserum showed little cross-reactivity with 2,6-dibromophenol and bromoxynil octanoate ester which have a dibromophenol group as common structure, but showed no cross-reactivity with other herbicides. Each water sample (river water, tap water, purified water, and bottled water) had a matrix effect and was investigated by adding Tween20 in the assay buffer. These four kinds of water samples were fortified with bromoxynil at several concentration levels and were directly analyzed with only dilution with an equal volume of antiserum solution, the mean recovery was 102.3%, and the mean coefficient of variation was 5.96%. The proposed ELISA turned out to be a powerful tool for monitoring of residual bromoxynil in water samples at trace level.  相似文献   
793.
原油管道储运行业地域辽阔、点多线长、易燃易爆,职业危害因素种类繁多,人员接触广泛,职业卫生工作难度较大.笔者结合工作实际,就原油管道储运企业职业健康监护谈谈工作体会.  相似文献   
794.
An experimental village-scale catchment was selected for investigation of nitrogen (N) sources and exports. The mean N application rate over the catchment was 350.2 kg N ha−1, but this rate varied spatially and temporally. The N leaching loss rate varied from 8.1 to 52.7 kg N ha−1 under different land use regimes. The average N leaching loss rate was 13.4 kg N ha−1 over the whole catchment, representing about 3.8% of the total N inputs. The N export rate through stormflows was 28.8 kg N ha−1, about 8.2% of the total N inputs. Seasonal patterns showed that 95% of N exports through stormflows occurred during July to September in 2002. Overall, the maximum riverine N exports were 12.1% of total N inputs and 15.5% of the inorganic fertilizer N applied. Understanding N sources and exports in a village-scale catchment can provide a knowledge base for amelioration of diffuse agricultural pollution.  相似文献   
795.
TiO2/SiO2催化剂光催化降解罗丹明B的表观动力学   总被引:2,自引:0,他引:2  
尤宏  姚杰  罗薇楠  陈平 《环境科学》2006,27(11):2154-2158
采用多孔硅胶为载体的TiO2/SiO2光催化剂,建立了三相内循环流化床光催化氧化体系,并以罗丹明B染料为典型污染物,研究其降解规律.通过对罗丹明B降解过程的表观动力学研究,发现在该体系中罗丹明B的降解并不符合Langmuir-Hinshelwood反应动力学模型.实验表明,其降解反应动力学符合双曲型模式,即降解率的倒数1/X和时间的倒数1/t成线性关系.反应速率常数与反应物初始浓度无关,与光源强度和相对体积能量吸收速率成正比.将不同实验条件下的罗丹明B的降解率实测值与模型计算值相比较,二者能很好吻合,平均相对偏差仅为3.25%.  相似文献   
796.
Hong SH  Yim UH  Shim WJ  Li DH  Oh JR 《Chemosphere》2006,64(9):1479-1488
To assess the organochlorine contamination in the Korean marine environment, a nationwide monitoring study was conducted. A total of 138 surface sediments, covering the whole Korean coast, were collected and analyzed. Organochlorine compounds (OCs) were widely distributed in the Korean coastal environment, with PCB and DDT contamination being particularly prevalent. The overall concentrations of PCBs, DDTs, HCHs, CHLs, and HCB in surface sediments were in the range of 0.088-199ngg(-1) (median value: 1.56ngg(-1)), 0.006-135ngg(-1) (0.68ngg(-1)), not detected (ND)-5.46ngg(-1) (0.32ngg(-1)), ND-3.26ngg(-1) (0.14ngg(-1)), and ND-2.59ngg(-1) (0.05ngg(-1)), respectively. The southeastern coast was found to be highly contaminated. Overall contamination status of Korean coastal sediments with regard to OCs is lower than that of USA. With the exception of highly industrialized sites, Korean coastal areas in general showed similar OC concentrations to those of other Asian countries. There was a significant correlation between distributions of most organochlorine contaminants with each other. OC contamination is closely related to shipping and industrial activities. Of the 7 sites categorized as highly polluted, 4 are in a harbor zone. Adverse effects to benthic communities are expected at the levels of OC contamination observed from harbor and industrial areas.  相似文献   
797.
王海燕  肖波  周军 《安全》2006,27(4):44-45
近两年来,频繁发生的"12·23重庆井喷"、"4·15重庆天原化工厂氯气泄漏"、"吉化11·13苯泄露事件"等等安全事故,让人触目惊心.从这些事故原因中,我们不难看到钻井作业卸掉"防喷阀"、危险化学品车辆押运员"逃逸"、化工厂职工现场"处置不当"等不安全状态(侥幸心理和麻痹大意思想)是导致这些事故发生的直接原因.我们安全管理人员在分析以上事故原因,吸取惨痛教训的同时,不能忽视事故发生的规律,并且应注重"安全管理三大定律"对基层安全管理和安全培训教育工作的启示.  相似文献   
798.
The development of local, accurate emission factors is very important for the estimation of reliable national emissions and air quality management. For that, this study is performed for pollutants released to the atmosphere with source-specific emission tests from the semiconductor manufacturing industry. The semiconductor manufacturing industry is one of the major sources of air toxics or hazardous air pollutants (HAPs); thus, understanding the emission characteristics of the emission source is a very important factor in the development of a control strategy. However, in Korea, there is a general lack of information available on air emissions from the semiconductor industry. The major emission sources of air toxics examined from the semiconductor manufacturing industry were wet chemical stations, coating applications, gaseous operations, photolithography, and miscellaneous devices in the wafer fabrication and semiconductor packaging processes. In this study, analyses of emission characteristics, and the estimations of emission data and factors for air toxics, such as acids, bases, heavy metals, and volatile organic compounds from the semiconductor manufacturing process have been performed. The concentration of hydrogen chloride from the packaging process was the highest among all of the processes. In addition, the emission factor of total volatile organic compounds (TVOCs) for the packaging process was higher than that of the wafer fabrication process. Emission factors estimated in this study were compared with those of Taiwan for evaluation, and they were found to be of similar level in the case of TVOCs and fluorine compounds.  相似文献   
799.
The behaviors of chlorine isotopes in relation to air-sea flux variables have been investigated through multivariate statistical analyses (MSA). The MSA technique provides an approach to reduce the data set and was applied to a set of 7 air-sea flux variables to supplement and describe the variation in chlorine isotopic compositions (delta37Cl) of ocean water. The variation in delta37Cl values of surface ocean water from 51 stations in 4 major world oceans--the Pacific, Atlantic, Indian and the Southern Ocean has been observed from -0.76 to +0.74 per thousand (av. 0.039+/-0.04 per thousand). The observed delta37Cl values show basic homogeneity and indicate that the air-sea fluxes act differently in different oceanic regions and help to maintain the balance between delta37Cl values of the world oceans. The study showed that it is possible to model the behavior of chlorine isotopes to the extent of 38-73% for different geographical regions. The models offered here are purely statistical in nature; however, the relationships uncovered by these models extend our understanding of the constancy in delta37Cl of ocean water in relation to air-sea flux variables.  相似文献   
800.
油层注水过程中水质不合要求的危害及保护措施   总被引:1,自引:0,他引:1  
分析了油田在二次采油注水过程中,对水质的要求,讨论了水质不合格带来的危害并提出了保护措施.  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