全文获取类型
收费全文 | 9294篇 |
免费 | 541篇 |
国内免费 | 1994篇 |
专业分类
安全科学 | 443篇 |
废物处理 | 778篇 |
环保管理 | 1682篇 |
综合类 | 5764篇 |
基础理论 | 975篇 |
环境理论 | 3篇 |
污染及防治 | 1115篇 |
评价与监测 | 221篇 |
社会与环境 | 767篇 |
灾害及防治 | 81篇 |
出版年
2024年 | 29篇 |
2023年 | 79篇 |
2022年 | 160篇 |
2021年 | 203篇 |
2020年 | 244篇 |
2019年 | 208篇 |
2018年 | 210篇 |
2017年 | 273篇 |
2016年 | 311篇 |
2015年 | 325篇 |
2014年 | 428篇 |
2013年 | 582篇 |
2012年 | 640篇 |
2011年 | 665篇 |
2010年 | 552篇 |
2009年 | 542篇 |
2008年 | 480篇 |
2007年 | 762篇 |
2006年 | 840篇 |
2005年 | 628篇 |
2004年 | 553篇 |
2003年 | 543篇 |
2002年 | 432篇 |
2001年 | 377篇 |
2000年 | 333篇 |
1999年 | 333篇 |
1998年 | 223篇 |
1997年 | 170篇 |
1996年 | 153篇 |
1995年 | 114篇 |
1994年 | 105篇 |
1993年 | 83篇 |
1992年 | 50篇 |
1991年 | 45篇 |
1990年 | 26篇 |
1989年 | 11篇 |
1988年 | 13篇 |
1986年 | 11篇 |
1985年 | 5篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 12篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1975年 | 11篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 4篇 |
1971年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
42.
Land use change is an important topic in the field of global environmental change and sustainable development. Land use change
modeling has attracted substantial attention because it helps researchers understand the mechanisms of land use change and
assists regulatory bodies in formulating relevant policies. Maotiao River Basin is located in the province of Guizhou, China,
which has a developed agricultural industry in the karst mountain areas. This paper selected biophysical and social–economic
factors as independent variables, and constructed a multiple logistic regression of farmland spatial distribution probability
by random sampling. Then, by using GIS technology and integrating the 2000 data, this study predicted the farmland spatial
pattern. When the predicted map was compared with the actual farmland map for 2000, we noted that 71% of the simulation is
in accordance with the 2000 farmland pattern. The result satisfactorily proves the reasonability and applicability of our
model. 相似文献
43.
上海部分城市污水处理厂现状调查 总被引:5,自引:0,他引:5
钱瑾 《环境监测管理与技术》1997,9(3):22-24
对上海市部分城市水污水处理厂的工艺特点,处理能力,污染物去除率,废水排放达标率进行了调查与分析,指出,必须加强对城市污水处理厂的监督监测,并就污水处理厂的建设,改造提出了一些建议。 相似文献
44.
介绍了多级活性生化处理 (MSABP)这项新的废水处理技术的原理、技术特点及两个实例运用。这是此项技术在国内的首次运用 ,其最大的优点是无剩余污泥产生 ,不需要沉淀池 相似文献
45.
Assessing land use impacts on flood processes in complex terrain by using GIS and modeling approach 总被引:1,自引:0,他引:1
Y. B. Liu F. De Smedt L. Hoffmann L. Pfister 《Environmental Modeling and Assessment》2005,9(4):227-235
A distributed hydrologic modeling and GIS approach is applied for the assessment of land use impact in the Steinsel sub-basin, Alzette, Grand-Duchy of Luxembourg. The assessment focuses on the runoff contributions from different land use classes and the potential impact of land use changes on runoff generation. The results show that the direct runoff from urban areas is dominant for a flood event compared with runoff from other land use areas in this catchment, and tends to increase for small floods and for the dry season floods, whereas the interflow from forested, pasture and agricultural field areas contributes to the recession flow. Significant variations in flood volume, peak discharge, time to the peak, etc., are found from the model simulation based on the three hypothetical land use change scenarios. 相似文献
46.
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
47.
Combating desertification in natural rangelands has recently become a priority in large parts of southern Africa. Rangeland
managers, farmers, scientists, conservationists and land users have been applying a variety of restoration technologies to
address this problem. Bush encroachment, as part of the desertification process, involves the natural replacement of the herbaceous
plant cover by undesirable problem woody species. The active and passive restoration technologies that are applied, are mainly
based on indigenous knowledge and include the chemical, mechanical or manual reclamation of unproductive rangelands, as well
as the combating of woody and alien species encroachment. Indigenous practices and knowledge play a major role in the effectiveness
and success rate of these technologies. This project faces the challenge of bringing together both local and scientific knowledge
in a single user-friendly, computerised Decision Support System (DSS) which is directly accessible by land users to support
them in the process of decision making, concerning the combating of desertification. Case studies from central and northern
Namibia were used to combine qualitative and quantitative data to develop this Decision Support System. The DSS currently
consists of two databases and an expert system, which evaluates the results of land users’ management practices, and provides
easily accessible information and advice for participants in the system, based on the incorporated data. The DSS is also linked
to national and international web sites and databases to offer a wider range of information on technologies concerning agricultural
and conservation practices. 相似文献
48.
49.
密切值法在污染源治理方案优选中的应用 总被引:5,自引:0,他引:5
本文采用密切值法进行污染源多个治理方案的优化决策研究,并通过实例分析获得了与实际状况相符合的优化结果。 相似文献
50.