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   1666篇
  免费   155篇
  国内免费   754篇
安全科学   170篇
废物处理   103篇
环保管理   164篇
综合类   1157篇
基础理论   252篇
污染及防治   530篇
评价与监测   80篇
社会与环境   62篇
灾害及防治   57篇
  2024年   8篇
  2023年   57篇
  2022年   119篇
  2021年   122篇
  2020年   107篇
  2019年   79篇
  2018年   84篇
  2017年   101篇
  2016年   89篇
  2015年   109篇
  2014年   150篇
  2013年   201篇
  2012年   137篇
  2011年   165篇
  2010年   127篇
  2009年   99篇
  2008年   103篇
  2007年   93篇
  2006年   88篇
  2005年   63篇
  2004年   43篇
  2003年   38篇
  2002年   45篇
  2001年   42篇
  2000年   47篇
  1999年   44篇
  1998年   38篇
  1997年   30篇
  1996年   34篇
  1995年   31篇
  1994年   18篇
  1993年   13篇
  1992年   17篇
  1991年   5篇
  1990年   7篇
  1989年   4篇
  1988年   2篇
  1987年   1篇
  1986年   3篇
  1985年   1篇
  1983年   1篇
  1982年   1篇
  1974年   1篇
  1973年   5篇
  1972年   1篇
  1971年   1篇
  1969年   1篇
排序方式: 共有2575条查询结果,搜索用时 265 毫秒
821.
澳洲能源公司在生产、经营的全过程中非常重视健康、安全及环境(HSE)工作,HSE管理体系得到了广泛的推广和应用。本文介绍了必和必拓、加德士等公司的可持续体系、HSE规划,论述了澳洲能源公司的减碳计划、碳排放公开、节能项目的落实及安全与风险管理等具体措施。分析了HSE管理体系的重要作用以及我国能源企业所面临的问题,包括安全事故多发、环境保护政策的落实不够充分、人员健康意识有待提高等。以中国国家电网公司、中国石油天然气集团公司及中国神华集团有限责任公司为例,分析其HSE体系,并从规范HSE建设、推动HSE可持续发展及责任落实等方面借鉴澳洲先进经验,提出明确我国HSE发展方向、战略,稳固HSE根基,完善我国能源企业HSE政策,保证体制全面、协调运转的具体建议。  相似文献   
822.
In this investigation we analyzed the spatiotemporal variation of ecosystem service values (ESVs) and its correlation with numerous environmental factors (EFs) for the karst region of Northwest Guangxi, China, from 1985 to 2005 using remote sensing, geographic information systems (GIS) and statistical techniques. The results indicate that historically ESVs for this karst region decreased from 1985 (109.652 billion Yuan) to 1990 (88.789 billion Yuan) and then increased at the turn of the twenty-first century. However, the ESVs in both 2000 (103.384 billion Yuan) and 2005 (106.257 billion Yuan) never achieved the level recorded in 1985. The total of nutrient cycling, organic production and gas regulation combined were 72.69, 64.57, 70.18 and 72.10% of ESVs in 1985, 1990, 2000 and 2005, respectively. In contrast, the ESVs of water conservation, soil reservation, recreation and culture were determined to be relatively low contributing only 17.44, 23.82, 19.26 and 24.76% of total ESVs, respectively, during these four years. With regards to the spatial distribution of ESVs, larger values were recorded in the west and smaller ones recorded in the east. The most significant factors that were deemed to influence ESVs are annual rainfall, per capita cropland, slope and vegetation coverage. Annual rainfall and slope exert a negative force, whereas per capita cropland and vegetation coverage exert a positive force on ESVs. The results of the study would suggest that ecosystem conditions of this important karst region have been improved as the result of the implementation of rocky desertification control policies.  相似文献   
823.
电子废弃物中的多溴二苯醚(PBDEs)因其环境持久性、可远距离传输、生物累积性及内分泌干扰等特性,已成为环境中一类广泛存在的有毒有害物质.综述了电子废弃物中PBDEs的分析技术及浓度分布最新研究,揭示了中国原始粗放型电子废弃物处理方式所导致的PBDEs环境污染,并对该领域未来研究的重点进行了展望.  相似文献   
824.
Fenton氧化4-氯酚降解机制研究   总被引:3,自引:3,他引:0  
封帆  高迎新  张昱  张强斌  杨敏 《环境化学》2011,30(11):1889-1893
为了深入探讨4-氯酚(4-CP)在Fenton氧化体系中的降解机制,利用高效液相色谱(HPLC)等多种手段系统分析了反应过程中Fe2+、Cl-、氧化中间产物对苯二酚、1,4-苯醌、4-氯邻苯二酚和4-氯间苯二酚的浓度以及氧化还原电位(ORP)的变化规律.研究结果表明,Fe2+浓度经历了短暂的下降之后迅速上升到接近初始的...  相似文献   
825.
氢化物发生原子荧光光谱法测定饮用水中的铅   总被引:1,自引:0,他引:1  
通过改变仪器条件及试剂配比进行优选实验,利用原子荧光光谱法测定饮用水中的铅可知:铅的检出限是0.020μg/L,能够满足GB 5749-2006《生活饮用水卫生标准》的要求;同时原子荧光光谱仪分析样品灵敏度高、重现性好、干扰少、操作简便、分析快捷,测定样品的准确度和精密度均能达到质量控制要求。  相似文献   
826.
基于协调度与熵权法的绩效评价新方法   总被引:2,自引:0,他引:2  
自人们意识到绩效评价的重要性以来,越来越多的研究集中于绩效评价的方法。以往的绩效评价侧重用数字表象进行评价,而忽略了政府、企业系统及其与社会经济发展之间的特性。基于此,根据既有的信息熵理论研究成果,提出了协调度与熵权法复合评价模型,并运用该模型对2009年度河北省区域创新绩效进行了实证分析,既科学、全面地衡量绩效情况,又便于政府、企业及其与社会经济发展之间的系统分析,是一种绩效评价方法的创新,具有一定的普适性和通用性。  相似文献   
827.
以处理20m^3/d城镇生活污水的深沟型气升推流立体循环倒置A^2O整体合建氧化沟中试装置为研究平台,通过对影响该工艺运行的有机物的去除效果、硝化反应与反硝化反应效果及除磷效果等因素进行探索及最佳工况的正交试验设计,实验结果表明该工艺对BOD,、COD、SS、NH4^-N、TN、TP的平均去除率分别为94.25%、90...  相似文献   
828.
秀丽线虫适应响应的形成与调控机理   总被引:1,自引:0,他引:1  
除了环境暴露评价,在环境毒理学研究中模式动物秀丽线虫也已经被应用于适应响应形成及其调控机理研究.在综述中,系统介绍了秀丽线虫中存在的几种形式毒物诱发的适应响应,即同一因素适应响应、交叉适应响应与特殊形式的适应响应;讨论了目前已经揭示出的6种影响适应响应形成因素;分析了适应响应形成可能机制,即抗氧化应激体系、热激蛋白、金...  相似文献   
829.
An intensive investigation was conducted to study the accumulation, speciation, and distribution of various heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in sediments from the Yangtze River catchment of Wuhan, China. The potential ecological risks posed by these heavy metals also were estimated. The median concentrations of most heavy metals (As, Cd, Cr, Cu, Ni, Pb, and Zn) were higher than the background values of soils in Wuhan and were beyond the threshold effect level (TEL), implying heavy metal contamination of the sediments. Carbonate-bound Cd and exchangeable Cd, both of which had high bioavailability, were 40.2% and 30.5% of the total for Cd, respectively, demonstrating that Cd poses a high ecological risk in the sediments. The coefficients of the relationship among Pb, Hg, and Cu were greater than 0.797 using correlation analysis, indicating the highly positive correlation among these three elements. Besides, total organic carbon content played an important role in determining the behaviors of heavy metals in sediments. Principal component analysis was used to study the distribution and potential origin of heavy metals. The result suggested three principal components controlling their variability in sediments, which accounted for 36.72% (factor 1: Hg, Cu, and Pb), 28.69% (factor 2: Cr, Zn, and Ni), and 19.45% (factor 3: As and Cd) of the total variance. Overall, 75% of the studied sediment samples afforded relatively low potential ecological risk despite the fact that generally higher concentrations of heavy metals relative to TEL were detected in the sediments.  相似文献   
830.
An application of dynamic Bayesian networks for quantitative risk assessment of human factors on offshore blowouts is presented. Human error is described using human factor barrier failure (HFBF), which consists of three categories of factors, including individual factor barrier failure (IFBF), organizational factor barrier failure (OFBF) and group factor barrier failure (GFBF). The structure of human factors is illustrated using pseudo-fault tree, which is defined by incorporating the intermediate options into fault tree in order to eliminate the binary restriction. A methodology of translating pseudo-fault tree into Bayesian networks and dynamic Bayesian networks taking repair into consideration is proposed and the propagation is performed. The results show that the human factor barrier failure probability only increases within the first two weeks and rapidly reaches a stable level when the repair is considered, whereas it increases continuously when the repair action is not considered. The results of mutual information show that the important degree sequences for the three categories of human factors on HFBF are: GFBF, OFBF and IFBF. In addition, each individual human factor contributes different to the HFBF, those which contribute much should given more attention in order to improve the human reliability and prevent the potential accident occurring.  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