全文获取类型
收费全文 | 44212篇 |
免费 | 3530篇 |
国内免费 | 8781篇 |
专业分类
安全科学 | 5848篇 |
废物处理 | 798篇 |
环保管理 | 6878篇 |
综合类 | 26472篇 |
基础理论 | 5825篇 |
环境理论 | 24篇 |
污染及防治 | 3155篇 |
评价与监测 | 2773篇 |
社会与环境 | 2775篇 |
灾害及防治 | 1975篇 |
出版年
2024年 | 148篇 |
2023年 | 707篇 |
2022年 | 1192篇 |
2021年 | 1568篇 |
2020年 | 1570篇 |
2019年 | 1324篇 |
2018年 | 1148篇 |
2017年 | 1545篇 |
2016年 | 1797篇 |
2015年 | 1961篇 |
2014年 | 2142篇 |
2013年 | 2924篇 |
2012年 | 3099篇 |
2011年 | 3408篇 |
2010年 | 2547篇 |
2009年 | 2589篇 |
2008年 | 2035篇 |
2007年 | 3047篇 |
2006年 | 3078篇 |
2005年 | 2496篇 |
2004年 | 2145篇 |
2003年 | 2226篇 |
2002年 | 1852篇 |
2001年 | 1627篇 |
2000年 | 1466篇 |
1999年 | 1314篇 |
1998年 | 943篇 |
1997年 | 803篇 |
1996年 | 640篇 |
1995年 | 610篇 |
1994年 | 527篇 |
1993年 | 445篇 |
1992年 | 326篇 |
1991年 | 253篇 |
1990年 | 184篇 |
1989年 | 105篇 |
1988年 | 91篇 |
1987年 | 81篇 |
1986年 | 56篇 |
1985年 | 53篇 |
1984年 | 45篇 |
1983年 | 46篇 |
1982年 | 43篇 |
1981年 | 42篇 |
1980年 | 52篇 |
1979年 | 41篇 |
1978年 | 34篇 |
1977年 | 25篇 |
1973年 | 24篇 |
1971年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
111.
伞罩型除尘脱硫塔内除雾器性能研究 总被引:1,自引:0,他引:1
除雾器是湿法烟气脱硫(WFGD)系统内重要的设备之一,其性能对WFGD系统运行的可靠性有重要影响.利用Fluent6.2软件对新型伞罩型除尘脱硫塔内的三维两相流场进行数值模拟,气相采用RNG湍流模型,液相采用离散相模型,选择SIMPLE算法进行计算,分析塔内的折板除雾器和旋流板除雾器的速度场、压力场和液滴的分布情况.结果表明,烟气经过折板除雾器,产生了明显的压降,且在拐角区域湍流耗散强烈,是实现气液分离的关键区域;烟气经过旋流板除雾器,速度和压强分布具有良好的对称性,液滴被气流旋转抛向壁面实现气液分离.模拟结果对新型的WFGD除雾器的设计和运行具有一定的理论指导意义. 相似文献
112.
水安全危机是人类进入新世纪以来在生存及发展方面所面临的最严重挑战之一。研究科学合理的水安全战略成为区域可持续发展的重大课题。针对区域水战略问题涉及众多因素且各因素之间动态关联的特点,提出了基于水战略方案优选的兼容度极大化动态组合评价模型(CMM—DCEM),并将其成功地应用于我国广东省北江下游及其三角洲地区水安全战略方案优选评价。评价结果及模型基于不确定性的敏感性分析结果证明:CMM—DCEM实现了主、客观赋权方法以及单一评价模型的融合,使用实码加速遗传算法求解目标函数,克服了传统的组合评价方法计算繁琐的不足,评价过程更加科学合理。 相似文献
113.
N. O. Kin 《Russian Journal of Ecology》2008,39(4):254-260
Heavy metal accumulation by plant communities has been studied in different zones of impact of gas field development. The contents of heavy metals in different blocks of plant communities has proved to depend not only on the location of phytocenosis but also on its species composition. Communities dominated by species of the family Poaceae contain smaller amounts of heavy metals than those dominated by species of the family Asteraceae, especially of the genus Artemisia. The order of precedence in the accumulation of heavy metals in different blocks of plant communities has been revealed. 相似文献
114.
Although stewardship has been widely defined and used in environmental management and planning, there is a dearth of studies
that describe how the lay public perceives this concept. A national sample of residents in 14 states who live near DOE nuclear
facilities were interviewed to delineate public understanding and awareness of the stewardship program of the U.S. Department
of Energy (DOE). This study discusses the findings of the survey and discusses how institutional trust influences public participation
and resident’s choices of potential stewards. Almost 40% of the respondents could not define stewardship; those who did, believed
that ‘responsibility,’ ‘management,’ and ‘accountability’ are key elements of stewardship. In addition, about a third of the
respondents identified Federal groups and the DOE as potential stewards.
Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue 相似文献
115.
Matteo Carpentieri Paolo Giambini Andrea Corti 《Environmental Modeling and Assessment》2008,13(3):415-429
Several wind tunnel experiments of tracer dispersion from reduced-scale landfill models are presented in this paper. Different
experimental set-ups, hot-wire anemometry, particle image velocimetry and tracer concentration measurements were used for
the characterisation of flow and dispersion phenomena nearby the models. The main aim of these experiments is to build an
extensive experimental data set useful for model validation purposes. To demonstrate the potentiality of the experimental
data set, a validation exercise on several mathematical models was performed by means of a statistical technique. The experiments
highlighted an increase in pollutant ground level concentrations immediately downwind from the landfill because of induced
turbulence and mean flow deflection. This phenomenon turns out to be predominant for the dispersion process. Tests with a
different set-up showed an important dependence of the dispersion phenomena from the landfill height and highlighted how complex
orographic conditions downwind of the landfill do not affect significantly the dispersion behaviour. Validation exercises
were useful for model calibration, improving code reliability, as well as evaluating performances. The Van Ulden model proved
to give the most encouraging results. 相似文献
116.
环境质量评价的生物方法研究 总被引:1,自引:0,他引:1
环境质量的生物评价是以生物对环境污染的表现为基础的.环境质量评价的生物方法包括环境指示生物的选择,环境质量生物评价指标的确定和环境质量分类等3个步骤.论述了环境污染的生物表现,提出了选择环境指示生物的原则,给出了环境质量生物评价的3类指标,建立了环境质量4级分类体系. 相似文献
117.
118.
Kraigher H Al Sayegh Petkovsek S Grebenc T Simoncic P 《Environmental monitoring and assessment》2007,128(1-3):31-45
Mycorrhiza is the main spatial and temporal linkage between different constituents in a forest ecosystem. The functional compatibility
and stress tolerance of ectomycorrhizal types is species specific, and therefore the information on the ectomycorrhizal community
structure can add to the understanding of processes in forest ecosystems and can also be applied as tools for bioindication
of pollution stress in forest soils. We have studied the effects of pollution (N and S) on trees and forest soils by: (1)
quantification of ECM types diversity as in situ indicators in forest stands, (2) determination and quantification of pollution-sensitive or -insensitive ECM types as passive
monitors, (3) root growth and development of ECM on nonmycorrhizal spruce seedlings, planted at the studied sites (active
monitors), and (4) ECM infection (a bioassay based on mycorrhizal inoculum potential) of seedlings in an experimental set-up
as ex situ testers. ECM species richness for Norway spruce trees (Picea abies) showed higher values in unpolluted sites than in polluted ones, while the differences were not significant for European
beech trees (Fagus sylvatica). As pollution-sensitive or -insensitive ECM species in spruce forests, we suggest Hydnum rufescens (sensitive) and Paxillus involutus (unsensitive). Mycorrhizal potential in Norway spruce seedlings as a bioassay for soil N and S pollution was effective, and
is suggested as an additional, standardized and widely comparable system in bioindication of soil pollution. 相似文献
119.
120.
Pei Gu Ren Fang Shen Yi Ding Chen 《Environmental science and pollution research international》2008,15(3):273-277
BACKGROUND: The Yangtze Delta is one of the most developed regions in China and includes Shanghai, eight cities in Jiangsu province and eight cities in Zhejiang province. Meat consumption in this region has increased with economic growth, and most of the consumed meat is produced locally. The water quality of surface waters has deteriorated in recent years. An example was the huge blue-green algae bloom in Tai Lake in late May 2007, which affected millions of people's daily drinking water. However, animal husbandry is considered to be one of the main pollution sources. METHODS: Pollutants (NH3-N, total phosphorus (TP), and total nitrogen (TN)) excreted by livestock and poultry, and the resultant COD (chemical oxygen demand) and BOD (biochemical oxygen demand), were estimated using two different methods based on different data sets. RESULTS: The number of livestock and poultry has remained stable in the Yangtze Delta over the four years from 1999 to 2002, with the average number of pigs, cattle, sheep and poultry being 21.1 M, 0.4 M, 7.7 M and 597.6 M, respectively. Pollutants in livestock and poultry excreta estimated by Method I were: 0.12 Mt NH3-N, 0.11 Mt TP and 0.29 Mt TN, resulting in COD and BOD of 1.34 Mt and 1.30 Mt, respectively, while the estimations based on Method II were: 0.18 Mt NH3-N, 0.15 Mt TP and 0.40 Mt TN, resulting in COD and BOD of 1.95 Mt and 1.80 Mt, respectively. DISCUSSION: Pollutants excreted annually by livestock and poultry in the Yangtze Delta are estimated to be: 0.17 Mt NH3-N, 0.16 Mt TP and 0.42 Mt TN, giving rise to a COD of 1.86 Mt and a BOD of 1.72 Mt. Approximately 25% of this pollution was estimated to enter water bodies, which means that the annual pollutant load is 43,700 t NH3-N, 39,400 tTP, 104,600t TN with a COD of 465,000 tand a BOD of 430,100 t. Pollutants from animal husbandry were similar in magnitude to those from industrial wastewater. Pigs produced the most pollution, followed by poultry, cattle and sheep. The pollution load from animal husbandry in the Yangtze Delta is about twice the average level of the whole of China. CONCLUSIONS: Domestic wastewater was the main pollution source in the Yangtze Delta, followed by pollution from raising livestock and poultry and from industrial wastewater. The pollution load in Shanghai and Jiaxing were the greatest, followed by 7 cities of Jiangsu province (except Suzhou) and other cities of Zhejiang province and Suzhou. Pigs and poultry produced about 90% of the total pollutants from animal husbandry. RECOMMENDATIONS AND PERSPECTIVES: The local governments, especially in Shanghai and Jiaxing, should focus their attention on the pollution produced by livestock and poulrry. Controlling pollution from pigs and poultry will have the greatest impact in this region. Control of pollution will be facilitated by the development of large-scale livestock and poultry farming units and a shift away from small scale husbandry. 相似文献