全文获取类型
收费全文 | 8353篇 |
免费 | 815篇 |
国内免费 | 985篇 |
专业分类
安全科学 | 757篇 |
废物处理 | 105篇 |
环保管理 | 1716篇 |
综合类 | 4615篇 |
基础理论 | 903篇 |
环境理论 | 11篇 |
污染及防治 | 278篇 |
评价与监测 | 510篇 |
社会与环境 | 952篇 |
灾害及防治 | 306篇 |
出版年
2024年 | 35篇 |
2023年 | 123篇 |
2022年 | 223篇 |
2021年 | 271篇 |
2020年 | 285篇 |
2019年 | 207篇 |
2018年 | 215篇 |
2017年 | 345篇 |
2016年 | 370篇 |
2015年 | 348篇 |
2014年 | 350篇 |
2013年 | 538篇 |
2012年 | 545篇 |
2011年 | 622篇 |
2010年 | 484篇 |
2009年 | 431篇 |
2008年 | 381篇 |
2007年 | 552篇 |
2006年 | 599篇 |
2005年 | 469篇 |
2004年 | 391篇 |
2003年 | 369篇 |
2002年 | 364篇 |
2001年 | 274篇 |
2000年 | 285篇 |
1999年 | 218篇 |
1998年 | 141篇 |
1997年 | 153篇 |
1996年 | 92篇 |
1995年 | 101篇 |
1994年 | 66篇 |
1993年 | 67篇 |
1992年 | 39篇 |
1991年 | 42篇 |
1990年 | 30篇 |
1989年 | 11篇 |
1988年 | 13篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 12篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1977年 | 7篇 |
1975年 | 6篇 |
1973年 | 7篇 |
1972年 | 3篇 |
1971年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Alexander Baklanov 《Environmental monitoring and assessment》2000,65(1-2):181-189
Different urban air pollution problems deal with complex structure of air flows and turbulence. For such problems the Computer Fluid Dynamics (CFD) methods become widely used. However, this approach despite a number of advantages has some problems. Experience of use of CFD tools for development of models and suggestions of their applications for a local scale air pollution over a complex terrain and stable stratification are discussed in this paper, including: Topography and complex geometry: choose of the co-ordinate system and computer grid; Turbulence closure for air pollution modelling: modified k- model for stable stratified ABL; Boundary conditions for vertical profiles of velocity for stable-stratified atmosphere; Effects of the radiation and thermal budget of inclined surfaces to dispersion of pollutants; Artificial sources of air dynamics and circulation.Some examples of CFD applications for air pollution modelling for a flat terrain, mountainous area, mining open cast and indoor ventilation are discussed. Modified k- model for stably-stratified ABL is suggested. Due to the isotropic character of the k- model a combination of it in vertical with the sub-grid turbulence closure in horizontal can be more suitable for ABL. An effective scheme of boundary conditions for velocity profiles, based on the developed similarity theory for stable-stratified ABL, is suggested. Alongside with the common studies of atmospheric dispersion, the CFD methods have also demonstrated a good potential for studying anthropogenic and artificial-ventilation sources of air dynamic and circulation in local-scale processes of air pollution. 相似文献
63.
Using environmental stressor information to predict the ecological status of Maryland non-tidal streams as measured by biological indicators 总被引:4,自引:0,他引:4
Vølstad JH Roth NE Mercurio G Southerland MT Strebel DE 《Environmental monitoring and assessment》2003,84(3):219-242
In Maryland, U.S., an interim framework has recentlybeen developed for using biologically based thresholds, or `biocriteria', to assess the health of nontidal streams statewide at watershed scales. The evaluation of impairment is based on indices of biological integrity from the Maryland Biological Stream Survey (MBSS). We applied logistic regression to quantify how the biotic integrity of streams at a local scale is affected by cumulative effects resulting from catchment land uses, point sources, and nearby transmission line rights-of-way. Indicators for land use were developed from the remote sensing National Land Cover Data and applied at different scales. We determined that the risk of local impairment in nontidal streams rapidly increases with increased urban land use in the catchment area. The average likelihood of failing biocriteria doubled with every 10% points increment in urban land, thus an increase in urban land use from 0 to 20% quadruples the risk of impairment. For the basins evaluated in this study, catchments with more than 40–50% urban land use had greater than 80% probability of failing biocriteria, on average. Inclusion of rights-of-way and point sources in the model did not significantly improve the fit for this data set, most likely because of their low numbers. The overall results indicate that our predictive modeling approach can help pinpoint stream ecosystems experiencing or vulnerable to degradation. 相似文献
64.
65.
66.
利用植物生态学常规方法进行了荒漠植被种群生物量和数量特证调查,以植物为监测对象,并就群落地上部分生物量,Shannon-Wiener多样性指数,群落均匀度,生态优势度等指标探讨了在荒漠生态环境监测和评价中的具体应用。 相似文献
67.
68.
本文系笔者对贵阳地区主要地质环境和工程地质特点进行的初步总结,内容为贵阳地区主要岩土构成情况、分布范围及与之相应的岩土工程地质特点和主要的岩土工程地质问题的描述,旨在给同行提供宏观性的了解和方向性的参考。 相似文献
69.
沿江施工产生悬浮物对环境影响分析 总被引:4,自引:0,他引:4
通过对太仓港围滩吹填工程施工过程泥浆水的采样分析,研究涉及工程施工过程泥浆扩散和演变规律;进而评价吹填工程施工引起悬浮物的增加对水质、水生生物和鱼类的影响。 相似文献
70.
根据自然地理、海洋动力、生物等特征!本文研究受大河作用的大丰潮滩地貌、沉积过程,讨论老黄河和长江对该潮滩发育的影响和潮滩生物群落空间分布及演变规律。本文评价了大丰潮滩开发利用现状,分析了它们的经济效益和环境效益,提出把目前受到强烈改造、过度利用的模式改变为顺应潮滩自然演变、有步骤合理开发利用潮滩的模式。 相似文献