全文获取类型
收费全文 | 19676篇 |
免费 | 1557篇 |
国内免费 | 3632篇 |
专业分类
安全科学 | 1517篇 |
废物处理 | 341篇 |
环保管理 | 3429篇 |
综合类 | 11967篇 |
基础理论 | 2392篇 |
环境理论 | 11篇 |
污染及防治 | 1167篇 |
评价与监测 | 1967篇 |
社会与环境 | 1688篇 |
灾害及防治 | 386篇 |
出版年
2024年 | 96篇 |
2023年 | 353篇 |
2022年 | 558篇 |
2021年 | 672篇 |
2020年 | 695篇 |
2019年 | 600篇 |
2018年 | 535篇 |
2017年 | 720篇 |
2016年 | 855篇 |
2015年 | 959篇 |
2014年 | 954篇 |
2013年 | 1254篇 |
2012年 | 1306篇 |
2011年 | 1478篇 |
2010年 | 1120篇 |
2009年 | 1108篇 |
2008年 | 964篇 |
2007年 | 1323篇 |
2006年 | 1374篇 |
2005年 | 1085篇 |
2004年 | 957篇 |
2003年 | 973篇 |
2002年 | 804篇 |
2001年 | 729篇 |
2000年 | 652篇 |
1999年 | 502篇 |
1998年 | 341篇 |
1997年 | 323篇 |
1996年 | 297篇 |
1995年 | 220篇 |
1994年 | 190篇 |
1993年 | 157篇 |
1992年 | 133篇 |
1991年 | 114篇 |
1990年 | 83篇 |
1989年 | 41篇 |
1988年 | 47篇 |
1987年 | 39篇 |
1986年 | 26篇 |
1985年 | 20篇 |
1984年 | 20篇 |
1983年 | 10篇 |
1982年 | 23篇 |
1981年 | 24篇 |
1980年 | 21篇 |
1979年 | 20篇 |
1978年 | 24篇 |
1977年 | 11篇 |
1972年 | 11篇 |
1971年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
111.
Sustainable development of the aquatic environment depends upon routine and defensible cumulative effects assessment (CEA). CEA is the process of predicting the consequences of development relative to an assessment of existing environmental quality. Theoretically, it provides an on-going mechanism to evaluate if levels of development exceed the environment's assimilative capacity; i.e., its ability to sustain itself. In practice, the link between CEA and sustainable development has not been realized because CEA concepts and methods have developed along two dichotomous tracks. One track views CEA as an extension of the environmental assessment (EA) process for project developments. Under this track, stressor-based (S-B) methods have been developed where the emphasis is on local, project-related stressors, their link with aquatic indicators, and the potential for environmental effects through stressor-indicator interactions. S-B methods focus on the proposed development and prediction of project-related effects. They lack a mechanism to quantify existing aquatic quality especially at scales broader than an isolated development. This limitation results in the prediction of potential effects relative to a poorly defined baseline state. The other track views CEA as a broader, regional assessment tool where effects-based (E-B) methods specialize in quantification of existing aquatic effects over broad spatial scales. However, the predictive capabilities of E-B methods are limited because they are retrospective, i.e., the stressor causing the effect is identified after the effect has been measured. When used in isolation, S-B and E-B methods do not address CEA in the context necessary for sustainable development. However, if the strengths of these approaches were integrated into a holistic framework for CEA, an operational mechanism would exist to better monitor and assess sustainable development of our aquatic resources. This paper reviews the existing conceptual basis of CEA in Canada including existing methodologies, limitations and strengths. A conceptual framework for integrating project-based and regional-based CEA is presented. 相似文献
112.
Ulla Haverinen Mikko Vahteristo Juha Pekkanen Tuula Husman Aino Nevalainen Demetrios Moschandreas 《Environmental Modeling and Assessment》2003,8(4):303-309
An empirical moisture damage index was developed in order to reduce the subjectivity of the estimation of moisture damage in domestic residences, in relation to occupant health. The database was generated using information gathered from a sample of 164 houses that were examined by civil engineers, and questionnaire data collected from the occupants. The index was formulated to associate with the occupant reported respiratory symptoms by calculating weighted estimates of selected moisture damage attributes using 80% of the sample. The remaining 20% of the sample was used to verify the final index. The index associated strongly with the health symptoms of interest. This index is a tool that may be used as an indicator of moisture damage induced exposure in domestic residences. 相似文献
113.
长江流域等重污染行业经济和污染贡献率剖析 总被引:4,自引:0,他引:4
应用"污染贡献率"这一指标,分析了长江、黄河、珠江和松花江流域COD和氨氮排放的重污染行业以及地区分布,指出了各流域COD和氨氮排放的控制重点.同时分析了各流域重污染行业的经济贡献率,最后结合行业的污染贡献率和经济贡献率以及行业在地区所占的比例,提出了几点重要的结论. 相似文献
114.
115.
对室内装饰装修材料检测中甲醛分析方法的研究 总被引:2,自引:0,他引:2
目前室内装饰装修材料中甲醛含量的检测有六个类别,分析方法不统一,且没有一定的质量控制措施.文章对分析方法进行了改进,并且研究用水中的甲醛标样来对检测过程进行质量控制,结果较好. 相似文献
116.
117.
118.
119.
120.
The metal pollution in water and sediment of the River Hindon in western Uttar Pradesh (India) was assessed for Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn. The metal concentrations in water showed wide temporal variation compared with bed sediment because of variability in water discharge and variations in suspended solid loadings. Metal concentrations in bed sediments provided a better evaluation of the degree and the extent of contamination in the aquatic environment, Santagarh and Atali being the most polluted sites of the river. The ratio of heavy metals to conservative elements (Fe, Al, etc.) may reveal the geochemical imbalances due to the elevated metal concentrations normally attributed to anthropogenic sources. Metal/Al ratios for the bed sediments of the river Hindon were used to determine the relative mobility and general trend of relative mobility occurred Fe > Mn > Zn > Cr > Ni > Pb > Cu > Cd. 相似文献