全文获取类型
收费全文 | 792篇 |
免费 | 11篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 41篇 |
废物处理 | 40篇 |
环保管理 | 114篇 |
综合类 | 111篇 |
基础理论 | 169篇 |
污染及防治 | 220篇 |
评价与监测 | 71篇 |
社会与环境 | 35篇 |
灾害及防治 | 7篇 |
出版年
2023年 | 6篇 |
2022年 | 10篇 |
2021年 | 19篇 |
2020年 | 4篇 |
2019年 | 8篇 |
2018年 | 21篇 |
2017年 | 27篇 |
2016年 | 25篇 |
2015年 | 25篇 |
2014年 | 32篇 |
2013年 | 60篇 |
2012年 | 35篇 |
2011年 | 46篇 |
2010年 | 36篇 |
2009年 | 39篇 |
2008年 | 44篇 |
2007年 | 47篇 |
2006年 | 43篇 |
2005年 | 33篇 |
2004年 | 28篇 |
2003年 | 25篇 |
2002年 | 28篇 |
2001年 | 13篇 |
2000年 | 21篇 |
1999年 | 8篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 9篇 |
1993年 | 14篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 10篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1969年 | 2篇 |
1961年 | 2篇 |
1959年 | 2篇 |
1957年 | 2篇 |
1953年 | 1篇 |
1935年 | 1篇 |
排序方式: 共有808条查询结果,搜索用时 169 毫秒
141.
142.
We conducted case studies of three successful examples of collaborative, community-based natural resource conservation and development. Our purpose was to: (1) identify the functions served by interactions within the social networks of involved stakeholders; (2) describe key structural properties of these social networks; and (3) determine how these structural properties varied when the networks were serving different functions. The case studies relied on semi-structured, in-depth interviews of 8 to 11 key stakeholders at each site who had played a significant role in the collaborative projects. Interview questions focused on the roles played by key stakeholders and the functions of interactions between them. Interactions allowed the exchange of ideas, provided access to funding, and enabled some stakeholders to influence others. The exchange of ideas involved the largest number of stakeholders, the highest percentage of local stakeholders, and the highest density of interactions. Our findings demonstrated the value of tailoring strategies for involving stakeholders to meet different needs during a collaborative, community-based natural resource management project. Widespread involvement of local stakeholders may be most appropriate when ideas for a project are being developed. During efforts to exert influence to secure project approvals or funding, however, involving specific individuals with political connections or influence on possible sources of funds may be critical. Our findings are consistent with past work that has postulated that social networks may require specific characteristics to meet different needs in community-based environmental management. 相似文献
143.
Current demand analysis methods do not formally cover the case of chronic deficits in quantity or quality of water and sanitation
services. These services include drinking water supply (DWS), wastewater and sewage treatment (WST), and municipal solid waste
management (MSW). Formal analysis of this case would, at minimum, define the deficit state and evaluate appropriate options
for reducing it. This paper proposes for a formal analytical model for municipal sanitation systems (MSS) that operate with
deficits in at least one of the constituent services of DWS, WST, or MSW. The model introduces definitions and notation for
describing the deficit state for conducting demand analysis on municipal sanitation systems. This model of demand analysis
for systems with chronic deficits will hereinafter be referred to as deficit analysis. A case study for Bacoor, Philippines is presented as an example. 相似文献
144.
Accounting for Uncertainty in Risk Assessment: Case Study of Hector's Dolphin Mortality due to Gillnet Entanglement 总被引:1,自引:0,他引:1
Elisabeth Slooten David Fletcher † and Barbara L. Taylor‡ 《Conservation biology》2000,14(5):1264-1270
Abstract: Uncertainties about biological data and human effects often delay decisions on management of endangered species. Some decision makers argue that uncertainty about the risk posed to a species should lead to precautionary decisions, whereas others argue for delaying protective measures until there is strong evidence that a human activity is having a serious effect on the species. We have developed a method that incorporates uncertainty into the estimate of risk so that delays in action can be reduced or eliminated. We illustrate our method with an actual situation of a deadlock over how to manage Hector's dolphin ( Cephalorhychus hectori ). The management question is whether sufficient risk is posed to the dolphins by mortalities in gillnets to warrant regulating the fisheries. In our quantitative risk assessment, we use a population model that incorporates both demographic ( between-individual) and environmental ( between-year) stochasticity. We incorporate uncertainty in estimates of model parameters by repeatedly running the model for different combinations of survival and reproductive rates. Each value is selected at random from a probability distribution that represents the uncertainty in estimating that parameter. Before drawing conclusions, we perform sensitivity analyses to see whether model assumptions alter conclusions and to recommend priorities for future research. In this example, uncertainty did not alter the conclusion that there is a high risk of population decline if current levels of gillnet mortality continue. Sensitivity analyses revealed this to be a robust conclusion. Thus, our analysis removes uncertainty in the scientific data as an excuse for inaction. 相似文献
145.
146.
In multiphase systems capillary pressures play a significant role on fluid movement and retention. The facility to predict
the effect of different thermal remediation strategies requires the knowledge of the effect of temperature on capillary pressure-saturation
relationships in the soils.
The objective of recent study was (a) to develop a technique for routinely measuring the pressure-saturation curves of soil
samples saturated with a nonpolar liquid at different regulated temperatures (b) to build a database using the measured pressure-saturation
curves and the physical, chemical properties of the model soils (c) to establish the dependence of nonaqueous phase liquid
retention on the soil properties and the temperature.
The retention curves (extraction isotherms) with nonaqueous phase liquid were determined using a modified
pressure plate extractor. The wetting phase was a non-aromatic hydrocarbon distillation product. Pressure plates were designed and constructed in
the laboratory of our department. The temperature was held constant at 20, 40 and 60 ∘C.
Statistical analysis was performed involving selected soil parameters and the measured nonaqueous phase liquid retention data.
The results show that knowing some easily measurable soil parameters (bulk density, particle size distribution, humus and
lime content) we can estimate the nonaqueous phase liquid retention of the soils. The measured “extraction isotherms” provide
essential information about the temperature-dependency of pressure-saturation curves. 相似文献
147.
Ewelina Wawryk-Gawda Michał K. Zarobkiewicz Katarzyna Chłapek Patrycja Chylińska-Wrzos Barbara Jodłowska-Jędrych 《毒物与环境化学》2019,101(7-8):404-419
AbstractThe use of electronic cigarettes increases as a supposedly healthier form of nicotine consumption, but safety of vaping remains uncertain. In this study, we assessed whether the use of electronic cigarettes increases the risk of infertility in male rats. Malformations of sperm morphology were more frequent in nicotine-exposed groups than in the control group. Vacuolization of seminiferous epithelium, reduction of spermatogenesis, increased apoptosis of spermatogonia and spermatocytes, and acceleration of degeneration of testes were observed. The male reproductive organs are slightly less affected by vaping than by smoking. Nevertheless, in consequence both may lead to the reduction of fertility. 相似文献
148.
Steven L. H. Teo Andre Boustany Heidi Dewar Michael J. W. Stokesbury Kevin C. Weng Shana Beemer Andrew C. Seitz Charles J. Farwell Eric D. Prince Barbara A. Block 《Marine Biology》2007,151(1):1-18
Electronic tags were used to examine the biology of Atlantic bluefin tuna (Thunnus thynnus L.) on their breeding grounds in the Gulf of Mexico (GOM). The hypothesis that movement patterns, diving behavior, and thermal
biology change during different stages of the breeding migration was tested. Mature Atlantic bluefin tuna tagged in the western
Atlantic and the GOM, were on their breeding grounds from February to June for an average of 39 ± 11 days. The bluefin tuna
experienced significantly warmer mean sea surface temperatures (SSTs) within the GOM (26.4 ± 1.6°C) than outside the GOM (20.2 ± 1.9°C).
As the bluefin tuna entered and exited the GOM, the fish dove to daily maximum depths of 568 ± 50 and 580 ± 144 m, respectively,
and exhibited directed movement paths to and from the localized breeding areas. During the putative breeding phase, the bluefin
tuna had significantly shallower daily maximum depths (203 ± 76 m), and exhibited shallow oscillatory dives during the night.
The movement paths of the bluefin tuna during the breeding phase were significantly more residential and sinuous. The heat
transfer coefficients (K) were calculated for a bluefin tuna in the GOM using the recorded ambient and body temperatures. The K for this fish increased rapidly at the high ambient temperatures encountered in the GOM, and was significantly higher at
night in the breeding phase when the fish was exhibiting shallow oscillatory dives. This suggests that the fish were behaviorally
and physiologically thermoregulating in the Gulf of Mexico. This study demonstrates that the movement patterns, diving behavior,
and thermal biology of Atlantic bluefin tuna change significantly at different stages of the breeding migration and can be
used to define spawning location and timing.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
149.
Barbara Demmig-Adams 《Die Naturwissenschaften》1989,76(6):262-267
Mein Dank gilt Prof. O. Björkman für einen außerordentlich anregenden und lehrreichen Aufenthalt an der Carnegie Institution in Stanford (Californien) sowie Prof. O. L. Lange, Prof. K. Winter und Prof. F.-C. Czygan für die Möglichkeit, die anschließenden Untersuchungen in Würzburg durchzuführen. Für finanzielle Unterstützung danke ich der McKnight Foundation, der Carnegie Corporation und ganz besonders der Deutschen Forschungsgemeinschaft. 相似文献
150.