全文获取类型
收费全文 | 16233篇 |
免费 | 165篇 |
国内免费 | 125篇 |
专业分类
安全科学 | 421篇 |
废物处理 | 791篇 |
环保管理 | 1752篇 |
综合类 | 2161篇 |
基础理论 | 4216篇 |
环境理论 | 9篇 |
污染及防治 | 4843篇 |
评价与监测 | 1221篇 |
社会与环境 | 1039篇 |
灾害及防治 | 70篇 |
出版年
2023年 | 107篇 |
2022年 | 262篇 |
2021年 | 249篇 |
2020年 | 151篇 |
2019年 | 172篇 |
2018年 | 361篇 |
2017年 | 368篇 |
2016年 | 546篇 |
2015年 | 377篇 |
2014年 | 569篇 |
2013年 | 1261篇 |
2012年 | 650篇 |
2011年 | 893篇 |
2010年 | 663篇 |
2009年 | 652篇 |
2008年 | 852篇 |
2007年 | 830篇 |
2006年 | 724篇 |
2005年 | 599篇 |
2004年 | 523篇 |
2003年 | 560篇 |
2002年 | 477篇 |
2001年 | 613篇 |
2000年 | 390篇 |
1999年 | 248篇 |
1998年 | 169篇 |
1997年 | 163篇 |
1996年 | 157篇 |
1995年 | 204篇 |
1994年 | 164篇 |
1993年 | 116篇 |
1992年 | 153篇 |
1991年 | 143篇 |
1990年 | 154篇 |
1989年 | 148篇 |
1988年 | 110篇 |
1987年 | 99篇 |
1986年 | 91篇 |
1985年 | 101篇 |
1984年 | 102篇 |
1983年 | 102篇 |
1982年 | 103篇 |
1981年 | 82篇 |
1980年 | 74篇 |
1979年 | 76篇 |
1977年 | 60篇 |
1976年 | 57篇 |
1975年 | 60篇 |
1974年 | 53篇 |
1973年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
De-novo formation of dioxins and furans and the memory effect in waste incineration flue gases 总被引:1,自引:0,他引:1
The formation of dioxin (polychlorinated-rho-dibenzodioxins - PCDD) and furan (polychlorinated dibenzofurans - PCDF) in waste incineration flyash in relation to temperature has been investigated in a bench scale reactor. The PCDD/PCDF released into the exhaust gases of the reactor and trapped in a condensation and vapour phase adsorption system were also determined. The concentrations of PCDD/PCDF in the flyash were analysed in detail for all congeners and isomers including the mono-, di- and tri-PCDD/PCDF. De-novo synthesis of PCDD/PCDF was clearly seen in the flyash with large changes in concentrations of PCDD/PCDF with only small changes in temperature. Exhaust gas PCDD/PCDF were detected at all temperatures, with the maximum emission occurring at a flyash temperature of 350 degrees C, where the equivalent of over 42 times the total dioxin/furan concentration of the original flyash was lost to the vapour phase per unit mass of initial flyash. Although the desorbed species were mainly the lower mono- to tri-congener group of dioxins and furans, the desorbed dioxin/furans had a considerable toxic equivalent value. 相似文献
942.
K. Rajakumar V. Sarasvathy A. Thamarai Chelvan R. Chitra C. T. Vijayakumar 《Journal of Polymers and the Environment》2009,17(3):191-202
Polypropylene (PP) has achieved a dominating position and hence, their consumption increases thereby littering, which lead
to environmental pollution. Photodegradation seems to be a better choice because of naturally available sunlight as energy
source for degradation. The present work involves the study of the variation of degradation behavior of PP film during tropical
summer and winter seasons. The photodegradation is followed by Fourier transform infrared (FTIR) spectroscopic technique.
Various indices like hydroxyl, carbonyl, vinylidene, lactones, ester, carboxylic acid and crystallinity are calculated and
these values increased after a brief induction period. The variation in the mechanical properties like tensile strength and
elongation at break percentages are determined. The scanning electron microscopic (SEM) images of weathered PP showed surface
cracks when carbonyl index value increases sharply and the mechanical properties show a sudden decrease. Attempted life time
prediction using mathematical models showed that the carbonyl growth is more affected by ultraviolet (UV) and cumulative total
solar radiation for PP weathered during summer. The loss in tensile strength of PP weathered during summer is more dependent
on the average temperature and the UV portion of the total solar radiation whereas, intensity of UV radiation has profound
effect on the tensile strength of PP weathered during winter. 相似文献
943.
Jehangir T. Madhani Joseph Young Neil A. Kelson Richard J. Brown 《Water, Air, & Soil Pollution: Focus》2009,9(5-6):357-369
A novel method is developed to capture and analyze several experimental flow regimes through a gross pollutant trap (GPT) with fully and partially blocked screens. Typical flow conditions and screen blockages are based on findings from field investigations that show a high content of organic matter in urban areas. Fluid motion of neutral buoyant particles is tracked using a high-speed camera and particle image velocimetry (PIV) software. The recorded fluid motion is visualized through an image-based, line integral convolution (LIC) algorithm, generally suitable for large computational fluid dynamics (CFD) datasets. The LIC method, a dense representation of streamlines, is found to be superior to the point-based flow visualization (e.g., hedgehog or arrow plots) in highlighting main flow features that are important for understanding litter capture and retention in the GPT. Detailed comparisons are made between the flow regimes, and the results are compared with CFD data previously obtained for fully blocked screens. The LIC technique is a useful tool for identifying flow structures in the GPT and areas that are subjected to abnormalities difficult to detect by conventional methods. The novel method is found to be useful both in the laboratory and in the field, with little preparation and cost. The enhancements and pitfalls of the LIC technique along with the experimentally captured flow field are presented and discussed. 相似文献
944.
A value of statistical life (VSL) is used in cost-benefit analysis (CBA) as a monetary measure of the benefits to people from small risk reductions that arise from safety projects. Despite its widespread use in a number of countries, the concept of a VSL remains controversial, not least because it implies acceptance of the underlying ethical assumptions of CBA together with the idea that ‘social welfare’ can be measured and aggregated in some manner. In addition, to comply with theory, variable VSLs for different groups within society would be advocated. However, without fail, empirically, it is the case that those countries that employ a willingness to pay based approach to cost-benefit analysis of a safety project appraisal tend to use a single value for that accident context that is independent of the per capita income level, or indeed other personal characteristics, of the sub-group in society to which the safety improvement will actually apply. This article presents a straightforward, but theoretically justified adaptation to the calculation of a VSL which allows empirical practice by policymakers i.e. the application of a “common” VSL for any particular hazard within a given society, to be compatible with a CBA decision making approach. 相似文献
945.
Célestin Defo Bernard Palmer Kfuban Yerima Nestor Bemmo 《Environment, Development and Sustainability》2017,19(5):1649-1671
This study aimed at investigating the retention of Pb and Cd in soils and the geochemical factors influencing the adsorption of these pollutants. Soil samples were air-dried and ground to pass through a 2-mm sieve, and different soil extracts were prepared for chemical analysis (organic matter, cation exchange capacity and pH). Total Pb and Cd were extracted with diacid using digestion method and determined by atomic adsorption spectrophotometer (AAS) after filtration. Results revealed that the heavy metals retention ratio (RR) of the Rhodic ferralsol, Xanthic ferralsol and Mollic gleysol (2) were very high for Cd (>80 %) and was relatively low (generally < 60 %) for Pb. In contrast, RRs for the Plinthic gleysol and the Mollic gleysol (1) were relatively low (<60 %), regardless of the heavy metal concerned. Multiple regression equations indicated for Pb and Cd concentrations different linear relationships over simple linear regression, when pH, organic matter, clay percentage and cation exchange capacity (CEC) were used as independent variables. Results indicate that organic matter exerts major influences on the retention of Pb and Cd in soils, while CEC, clay content and pH have a minor influence in this process in the Ntem watershed. From these observations, the application of soil organic matter could be a solution in protecting shallow aquifers from heavy metal pollution and thus insuring that they are not a hazard to public health. 相似文献
946.
Hussein A. Kazem Ali H. A. Al-Waeli Miqdam T. Chaichan Asma S. Al-Mamari Atma H. Al-Kabi 《Environment, Development and Sustainability》2017,19(3):1041-1053
In the present paper, the optimum design of a PV system used to operate a water pumping system was determined for Oman. The system design focused on the environmental conditions of Sohar city. The implementation and measurement of the designed system are presented to prove the effectiveness of the proposed system. The results show that the system can provide the required power at peak hours, leading to a substantial reduction in the sizing of the PV system. Consequently, the investment capital costs 2400 USD, and the cost of energy is equal to 0.309 USD/kWh. Furthermore, the results indicate that the system annual yield factor is 2024.66 kWh/kWp and that the capacity factor is 23.05 %, which is encouraging since the latter is typically 21 %. The system capital cost and the cost of energy are worth comparing to a diesel generator. A comparison is made between the proposed system and several others in the literature. The comparison indicated that the system cost of energy is promising. 相似文献
947.
Amanda Jiménez Martha C. Monroe Natalia Zamora Javier Benayas 《Environment, Development and Sustainability》2017,19(1):221-238
Costa Rica is internationally recognized for its abundant biodiversity and being a leader in the promotion of education strategies for biodiversity conservation. We interviewed staff from 16 institutions developing key environmental communication, education, and participation projects for biodiversity conservation in the country. Through content analysis, hierarchical cluster analysis and Chi-square tests, we examined the characteristics of the projects carried out by these institutions and developed a typology of four categories derived from six variables: primary audience, content, project purpose, location, scale, and facility. Then, we designed a conceptual model describing the integration of conservation and economic development in the educational projects. We found two key approaches related to this integration: vision of nature protection which aims to inform audiences of ecological concepts and focuses on schoolchildren and vision of sustainability which engages adult audiences and is management-oriented. Education for community-based environmental management may serve as a good example of educational projects which integrate conservation and economic development, implementing a vision of sustainability. 相似文献
948.
E.?M.?NkoanaEmail author T.?Waas A.?Verbruggen C.?J.?Burman J.?Hugé 《Environment, Development and Sustainability》2017,19(5):1731-1760
The assumptions and empirical evidence linking climate change adaptation to development cooperation have led to the emergence of a range of climate change adaptation tools aiming at improving the quality of development cooperation initiatives in times of global change. In order to assess the quality of these tools, we develop an analytic framework to critically assess the social learning and sustainable development outcomes of climate change adaptation tools. The analytic framework defines project objectives, participation typology, participation tools, participation stages, scenarios development, modelling exercises, stakeholder analysis and risk communication strategies that support quality participation outcomes. 相似文献
949.
Suescún Diego Villegas Juan Camilo León Juan Diego Flórez Claudia P. García-Leoz Vanessa Correa-Londoño Guillermo A. 《Regional Environmental Change》2017,17(3):827-839
Regional Environmental Change - Mountain ecosystems provide key services to a large portion of the population in the tropics. However, they are particularly vulnerable to regional environmental... 相似文献
950.
Kharuk Viacheslav I. Im Sergei T. Petrov Ilya A. Dvinskaya Mariya L. Fedotova Elena V. Ranson Kenneth J. 《Regional Environmental Change》2017,17(3):803-812
Regional Environmental Change - Increased dieback and mortality of “dark needle conifer” (DNC) stands (composed of fir (Abies sibirica), Siberian pine (Pinus sibirica) and spruce (Picea... 相似文献