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   7437篇
  免费   3457篇
  国内免费   235篇
安全科学   476篇
废物处理   25篇
环保管理   1393篇
综合类   5472篇
基础理论   1001篇
环境理论   4篇
污染及防治   373篇
评价与监测   627篇
社会与环境   1392篇
灾害及防治   366篇
  2025年   52篇
  2024年   224篇
  2023年   255篇
  2022年   368篇
  2021年   358篇
  2020年   351篇
  2019年   325篇
  2018年   295篇
  2017年   405篇
  2016年   457篇
  2015年   490篇
  2014年   377篇
  2013年   492篇
  2012年   637篇
  2011年   650篇
  2010年   442篇
  2009年   424篇
  2008年   408篇
  2007年   563篇
  2006年   561篇
  2005年   482篇
  2004年   365篇
  2003年   346篇
  2002年   292篇
  2001年   224篇
  2000年   227篇
  1999年   188篇
  1998年   122篇
  1997年   115篇
  1996年   107篇
  1995年   92篇
  1994年   87篇
  1993年   66篇
  1992年   49篇
  1991年   44篇
  1990年   36篇
  1989年   12篇
  1988年   19篇
  1987年   9篇
  1986年   9篇
  1985年   9篇
  1984年   6篇
  1983年   7篇
  1982年   12篇
  1981年   9篇
  1980年   13篇
  1979年   14篇
  1978年   8篇
  1973年   5篇
  1971年   6篇
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
1.
中国环境保护产业协会王心芳会长在2006年7月18-19日在北京召开的全国环境保护产业协会工作会议上,就我国环保产业的现状及存在的主要问题、环保产业“十一五”期间面临的形势及“十一五”期间中国环境保护产业协会主要的工作思路做了讲话(本文为讲话摘录)。  相似文献   
2.
城市河流水质常规评价技术研究   总被引:11,自引:0,他引:11  
运用综合水质标识指数法,对我国河流水质评价面临的关键技术问题,包括水质评价方法、水质评价项目,水质级别评价,水环境功能区达标评价、水质定性评价、河流及水系整体水质比较、水质随时间和空间变化等作了明确界定,并介绍了在上海河流水质评价中的应用。  相似文献   
3.
改善深圳河水质的补水方案及生态影响初步分析   总被引:3,自引:0,他引:3  
深圳河旱季天然径流量小而污染负荷高,为了改善河流水质,在削减入河污染物的同时有必要采取补水措施。利用水质模型,计算了不同污水处理率下,分别以污水资源化再生水、珠江口海水和大鹏湾海水为补水水源时,深圳河达到基本不黑臭所需的补水量。讨论了补水方案对河流水质、盐度、水动力条件的改变及其对生态系统的影响。研究表明,引海水对河流生态系统的冲击不容忽视。而污水资源化是较优的补水方案。  相似文献   
4.
Chang BV  Liao CS  Yuan SY 《Chemosphere》2005,58(11):1000-1607
We investigated anaerobic degradation rates for three phthalate esters (PAEs), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), and di-(2-ethylhexyl) phthalate (DEHP), from river sediment in Taiwan. The respective anaerobic degradation rate constants for DEP, DBP, and DEHP were observed as 0.045, 0.074, and 0.027 1/day, with respective half-lives of 15.4, 9.4, and 25.7 days under optimal conditions of 30 °C and pH 7.0. Anaerobic degradation rates were enhanced by the addition of the surfactants brij 35 and triton N101 at a concentration of 1 critical micelle concentration (CMC), and by the addition of yeast extract. Degradation rates were inhibited by the addition of acetate, pyruvate, lactate, FeCl3, MnO2, NaCl, heavy metals, and nonylphenol. Our results indicate that methanogen, sulfate-reducing bacteria, and eubacteria are involved in the degradation of PAEs.  相似文献   
5.
Background The management of its available water resources has become a key issue for Iran. During the last few decades, the water quality of Siahroud River in the coastal plain of the Caspian Sea in Gilan Province in Northern Iran has significantly degraded. The scarcity of water has been compounded by rapid population growth and increasing pollution from fertilizers, pesticides, and municipal and industrial wastes. One of the sources of this degradation is the movement of heavy metals from the river's watershed into the various water systems supported by the river, including the water system for Rasht City. Methods To study the magnitude of heavy metal pollution in the Siahroud River, seven heavy metals including Zn, Cu, Pb, Cd, Mn, Fe, and Ni were measured in duplicate from replicated water samples collected over five consecutive seasons and analyzed by Atomic Absorption Spectrometry. In situ measurements of pH were taken with the samples and total organic carbon (TOC) was analyzed by IR gas measurement. Results The results demonstrated that four of the seven heavy metals including Pb, Fe, Cd, and Mn exceeded permissible safe levels as established by the United States Environmental Protection Agency. Multivariate factor analysis suggested that industrial land-use was the main contributing factor for the high levels of Fe and Mn in the Siahroud River, whereas, Cd was principly from agricultural activities in the watershed. The data also suggested that pH and TOC had an important role in the behaviour of Pb and Mn, and that the elevated levels of these two heavy metals in Siahroud River was the consequence of other anthropogenic sources. Only negligible levels of Zn, Cu and Ni were detected. Finally, all the sampling stations were subjected to cluster analysis. The results indicated that three different zones could be distinguished according to the levels of pollution. In addition, it was shown that the urban areas did not have a significant impact on the heavy metal pollution in the river. This observation stems from the fact that the data from the sampling stations before and after Rasht City were not significantly different. Recommendation . Preventive measures need to be undertaken in the land-use systems and watersheds of the Siahroud River to reduce the pollution levels of Pb, Cd, Mn and Fe.  相似文献   
6.
The toxicity of seawater dispersions of a chemical dispersant to two marine crustaceans was investigated in the presence and absence of various quantities of a non-toxic mineral oil. From the results and a physical-chemical partitioning analysis, a limiting value of the oil-water partition coefficient of the toxic compounds is deduced suggesting that essentially all of the toxic compounds in the dispersant will partition into solution in water following dispersant application to an oil spill. This conclusion simplifies interpretation and prediction of the toxic effects of a dispersed oil spill.The combined bioassay-partitioning procedure may have applications to the study of the toxicity of other complex mixtures such as industrial effluents.  相似文献   
7.
An optimized code for the near real-time retrieval of line of sight, temperature and volume-mixing ratio profiles of five key species (O3, H2O, HNO3, CH4 and N2O) from infrared limb spectra recorded by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) experiment on board the ENVISAT-1 satellite was developed as part of an ESA-supported study. In this code line of sight and temperature are retrieved simultaneously among themselves, but sequentially with respect to the volume-mixing ratio of the five key species. The sequential retrieval leaves unaccounted the mapping of line of sight and temperature errors in the retrieved volume-mixing ratio of the constituents. This paper illustrates an algorithm that provides the a-posteriori evaluation of temperature and line-of-sight-induced error on the retrieved volume-mixing ratio of the MIPAS key species. It is shown that in most cases temperature and line-of-sight-induced error provides a significant contribution to the total volume-mixing ratio error. The variability of this error as a function of latitude, season and atmospheric model is also analyzed.  相似文献   
8.
Increasing anthropogenic pressure on the largest remaining tracts of old-growth boreal forest in Europe necessitates additional conservation of ecosystems and biodiversity in northeastern European Russia. In a regional network comprising 8 % of the Nenets Autonomous District and 13.5 % of the Komi Republic, 248 areas have varying protected statuses as state nature reserves (zapovedniks), national parks, reserves/sanctuaries (zakazniks), or natural monuments. Due to increased natural resource extraction in this relatively pristine area, designation of additional protected areas is critical for the protection of key ecological sites. The history of ecological preservation in these regions is herein described, and recent recommendations for incorporating additional ecologically representative areas into the regional network are presented. If the protected area network can be expanded, the overall environmental stability in these globally significant ecosystems may remain intact, and can help Russia meet the 2020 Aichi conservation targets, as set forth by the Convention of Biological Diversity.  相似文献   
9.
区域规划环境影响跟踪评价的理论研究   总被引:4,自引:0,他引:4  
随着环境影响评价制度的深入实施,其实施领域已由项目环评向区域环评和规划环评转变,评价内容也由广泛实施的预测评价向后评价和跟踪评价转变。然而,对于区域规划环评的评价层次、评价程序和评价内容,目前还没有明晰的认识;同时,对于促进规划环评有效实施的跟踪评价,其相关的理论和实践研究几乎没有。文中就此问题作了深入探讨。  相似文献   
10.
For over two decades, a manufacturer of electrical capacitors disposed of its waste within the karstic hinterland of the Krupa River (Slovenia) resulting in the surroundings becomming heavily polluted with PCB. Albeit the extent of the contamination has been known since 1983 and the Krupa River has become one of the most PCB polluted river in Europe, the effects on the cave fauna of the region remain unknown. The most famous cave dweller of the Krupa hinterland is the endemic cave salamander Proteus anguinus anguinus. In this study we determine the levels of PCB in the tissues of the Proteus and in river sediments. The total concentration of PCB in individual tissue samples from specimens of the Krupa spring was between 165.59 μg g−1 and 1560.20 μg g−1 dry wt, which is at least 28-times higher than those from an unpolluted site. The kidneys contained the lowest concentration, while the highest concentration was in subcutaneous fat and tissues with high lipid contents like visceral fat and liver. Total PCB concentrations in sediment samples from the Krupa River were between 5.47 and 59.20 μg g−1 dry wt showing that a high burden of PCB still remains in the region. The most abundant PCB congeners in all analyzed samples were di-ortho substituted (PCB #101, #118, #138 and #158), but higher proportion of mono-ortho PCB was present in sediments. The ability of Proteus to survive a high PCB loading in its environment and especially in its tissues is remarkable. Its partial elimination of low chlorinated and mono-ortho substituted congeners is also reported.  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