全文获取类型
收费全文 | 826篇 |
免费 | 17篇 |
国内免费 | 7篇 |
专业分类
安全科学 | 46篇 |
废物处理 | 56篇 |
环保管理 | 231篇 |
综合类 | 70篇 |
基础理论 | 167篇 |
环境理论 | 1篇 |
污染及防治 | 188篇 |
评价与监测 | 54篇 |
社会与环境 | 29篇 |
灾害及防治 | 8篇 |
出版年
2023年 | 9篇 |
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 16篇 |
2019年 | 16篇 |
2018年 | 29篇 |
2017年 | 23篇 |
2016年 | 27篇 |
2015年 | 27篇 |
2014年 | 28篇 |
2013年 | 64篇 |
2012年 | 33篇 |
2011年 | 48篇 |
2010年 | 50篇 |
2009年 | 27篇 |
2008年 | 43篇 |
2007年 | 53篇 |
2006年 | 40篇 |
2005年 | 24篇 |
2004年 | 26篇 |
2003年 | 27篇 |
2002年 | 37篇 |
2001年 | 13篇 |
2000年 | 15篇 |
1999年 | 15篇 |
1998年 | 8篇 |
1997年 | 10篇 |
1996年 | 12篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 12篇 |
1992年 | 3篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1983年 | 9篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1972年 | 1篇 |
1971年 | 6篇 |
排序方式: 共有850条查询结果,搜索用时 218 毫秒
71.
Meghan Ellis Thomas Gunton Murray Rutherford 《Journal of environmental management》2010,91(6):1268-1277
Sustainable environmental management is contingent on having an effective environmental planning system. A new methodology for designing and evaluating environmental planning systems is described and applied to a case study evaluation of the Canadian environmental planning process. The methodology is based on eight international best practice principles for environmental planning and 45 indicators. The research illustrates the benefits of the evaluation methodology in identifying how to improve environmental planning systems to achieve desired results. The methodology is applicable to a wide variety of jurisdictions. 相似文献
72.
Giuliano Cecchi William Wint Alexandra Shaw Andrea Marletta Raffaele Mattioli Timothy Robinson 《Agriculture, ecosystems & environment》2010,135(1-2):98-110
The central role played by livestock in the livelihoods of rural households in the developing world is seldom fully appreciated by policy makers, development agencies and donors. Knowledge gaps in the geographic distribution and environmental determinants of farming systems, especially if viewed through the livestock lens, compound this problem. We have produced a map of pastoral, agro-pastoral and mixed farming systems across Eastern Africa, by analysing datasets collected in the framework of livelihood analysis. Input data were gathered between 2000 and 2007 by various emergency and development agencies for Djibouti, Eritrea, Kenya, Somalia, Uganda and parts of Ethiopia and Sudan. A quantitative definition of the production systems is adopted, based on the ratio of livestock- to crop-derived income. The resulting livelihood-based map of livestock production systems was compared through correspondence analysis to an alternative livestock production systems map, produced independently from environmental data. Convergence between the two mapping approaches was evident. The geographic distribution of the livestock production systems was also modelled using multivariate analysis of remotely sensed and other geospatial datasets. Models show high statistical accuracy, and were thus used to fill the gaps in the observed distribution of livestock production systems. Finally, selected environmental factors underpinning the systems (agro-climatology, human and livestock populations and land cover) were analysed in detail, enabling the livestock production systems to be characterized in terms of them. The regional scope of the map, as well as its direct link with a vast amount of livelihood information, render it a valuable tool for a range of development and research applications, including those related to global change. 相似文献
73.
Timothy Fitzgerald 《Environmental management》2013,52(6):1503-1517
One way coalbed methane production differs from traditional oil and gas extraction is in the large quantities of produced water. This water must be disposed of for production to occur. Surface discharge has proven to be a low-cost alternative; regulations are in place to protect surface water quality. This paper investigates the effects of alternative ownership regimes on regulatory compliance. A unique dataset linking coalbed methane wells in Wyoming to water disposal permit violations is used to explore differences in environmental performance across severed and unified minerals. Empirical analysis of these data suggest that ownership does impact environmental compliance behavior. Most violations occur on split estate. Federal split estate wells have more severe violations, though not necessarily more of them. Federal unified wells performed best, with fewer and less serious violations. Wells on private land have more, though not necessarily more severe, violations. These results suggest some room for policy proposals accounting for alternative ownership regimes. 相似文献
74.
Saud A. Amer Timothy O. Keefer Mark A. Weltz David C. Goodrich Leslie B. Bach 《Journal of the American Water Resources Association》1994,30(1):69-83
ABSTRACT: Certain physical and chemical properties of soil vary with soil water content. The relationship between these properties and water content is complex and involves both the pore structure and constituents of the soil solution. One of the most economical techniques to quantify soil water content involves the measurement of electrical resistance of a dielectric medium that is in equilibrium with the soil water content. The objective of this research was to test the reliability and accuracy of fiberglass soil-moisture electrical resistance sensors (ERS) as compared to gravimetric sampling and Time Domain Reflectometry (TDR). The response of the ERS was compared to gravimetric measurements at eight locations on the USDA-ABS Walnut Gulch Experimental Watershed. The comparisons with TDR sensors were made at three additional locations on the same watershed. The high soil rock content (≥45 percent) at seven locations resulted in consistent overestimation of soil water content by the ERS method. Where rock content was less than 10 percent, estimation of soil water was within 5 percent of the gravimetric soil water content. New methodology to calibrate the ERS sensors for rocky soils will need to be developed before soil water content values can be determined with these sensors. 相似文献
75.
Jy S. Wu Ellis L. King Michael Wang 《Journal of the American Water Resources Association》1985,21(3):417-421
Traditionally, identification of the Muskingum routing coefficients has been based on observations of the linearity of a loop formed by graphically plotting a forward and a reverse path. This graphical procedure is time-consuming and may not minimize the error of estimation. A procedure was developed to improve the drawbacks of the graphical method. This procedure calls for (a) the use of least square regression on the forward and reverse paths to determine their respective slopes, and (b) the use of statistical t-test to evaluate the hypothesis that these two slopes are equal. The computational procedure is repeated, using incremental values of the flow weighting coefficient, x. A graph of the computed t-value versus x can be constructed. The optimal value of x, as read from the graph, occurs at the minimum computed t-value. The procedure has been demonstrated superior to the graphical method for three illustrative examples, resulting in a reduction of the error squares by factors ranging from 5 to 6. 相似文献
76.
A core goal of both US and European pollution control policies has been to establish rules and regulations pertaining to the movement of reactive-nitrogen (Nr) through the environment. This is manifest in US federal legislation such as the Clean Air Act Amendments and the Clean Water Act Amendments and in various protocols of the United Nations Economic Commission for Europe (UNECE) and its Convention on Long-Range Transboundary Air Pollution (CLRTAP). In this paper, we begin by reviewing the two US laws and their effectiveness and make some comparisons with the approaches used mainly in Europe by the UNECE and CLRTAP. Next we use the Mississippi drainage/Gulf of Mexico hypoxia case study to highlight the importance of applying a "systems approach" to address the reactive nitrogen problem at the regional scale. After briefly posing a number of unanswered questions related to nitrogen control policies, we conclude by sketching a blueprint for future actions related to the development of improved policies to regulate reactive nitrogen. 相似文献
77.
Timothy L. Carter Todd C. Rasmussen 《Journal of the American Water Resources Association》2006,42(5):1261-1274
ABSTRACT: Control of stormwater runoff from impervious surfaces is an important national goal because of disruptions to downstream ecosystems, water users, and property owners caused by increased flows and degraded quality. One method for reducing stormwater is the use of vegetated (green) roofs, which efficiently detain and retain stormwater when compared to conventional (black) roofs. A paired green roof‐black roof test plot was constructed at the University of Georgia and monitored between November 2003 and November 2004 for the green roof's effectiveness in reducing stormwater flows. Stormwater mitigation performance was monitored for 31 precipitation events, which ranged in depth from 0.28 to 8.43 cm. Green roof precipitation retention decreased with precipitation depth; ranging from just under 90 percent for small storms (< 2.54 cm) to slightly less than 50 percent for larger storms (> 7.62 cm). Runoff from the green roof was delayed; average runoff lag times increased from 17.0 minutes for the black roof to 34.9 minutes for the green roof, an average increase of 17.9 minutes. Precipitation and runoff data were used to estimate the green roof curve number, CN = 86. This information can be used in hydrologic models for developing stormwater mitigation programs. 相似文献
78.
Timothy Beatley 《Environmental management》1992,16(1):7-19
Habitat conservation plans (HCPs) permitted under Section 10(A) of the federal Endangered Species Act, have been increasingly
used to overcome conflicts between urban development and species conservation. This article profiles one such HCP, the Coachella
Valley (CA) Fringe-Toed Lizard Habitat Conservation Plan. The second HCP officially approved by the US Fish and Wildlife Service,
the Coachella Valley case is frequently cited as a model for resolving conservation and development conflicts. The article
begins with a discussion of the use of HCPs, and then provides a detailed discussion of Coachella Valley experience, its history,
specific provisions, and success to date. A final section examines whether Coachella Valley does in fact represent a positive
model. It is argued that the HCP has been less than fully successful and leaves unresolved a series of fundamental ethical
and policy questions concerning the protection of endangered species.
Funding for this report was provided by the National Fish and Wildlife Foundation. Any opinions, findings, conclusions, or
recommendations are those of the author and do not necessarily represent the views of the Foundation. 相似文献
79.
Thomas L. Huntzinger Michael J. Ellis 《Journal of the American Water Resources Association》1993,29(4):533-574
ABSTRACT: The Central Nebraska Basins (NAWQA) study unit includes the Platte River and two major tributaries, the Loup and Elkhorn Rivers. Platte River flows are variable in the western part of the study unit because of diversions, but the Loup and Elkhorn Rivers originate in an area of dune sand covered by grassland that generates consistent base flows. More frequent runoff in the eastern part of the study unit also sustains stream flow. Ground water in the study unit has no regional confining units and the system is a water table aquifer throughout. Macroinvertebrate and fish taxa at biological sampling sites in the state were related to stream flow. One of the four wetland complexes identified in the study unit includes habitat for threatened and endangered bird species. The study unit is an agricultural area that includes row crops, both irrigated and nonirrigated in the eastern and southern parts, and rangeland in the Sand Hills of the western part. A water quality assessment will be based on the differences in environmental setting in each of four subunits within the study unit.] 相似文献
80.
Dan M. Wells Ellis W. Huddleston Robert G. Rekers 《Journal of the American Water Resources Association》1971,7(1):124-132
ABSTRACT. .Eighteen rural lakes in Lubbock County were sampled on a routine basis following runoff-producing rainfall for a period of approximately eighteen months to determine whether or not runoff from intensively farmed agricultural areas contained significant concentrations of nitrates, phosphates, herbicides, or insecticides. An additional fifteen lakes lying within a triangle bounded by the cities of Plainview, Canyon, and Hereford, Texas, were sampled one time during the summer of 1969 to provide additional data regarding the nature and extent of the potential problem in an area with a different soil type and a slightly different cropping pattern. Based on results of detailed analyses of approximately two hundred samples of water collected from the lakes and an equal number of sediment samples collected from the same lakes at the same time, it appears that the concentrations of all chemical pollutants in runoff from agricultural lands in the High Plains are well below the allowable concentrations for drinking water. 相似文献