全文获取类型
收费全文 | 53163篇 |
免费 | 513篇 |
国内免费 | 544篇 |
专业分类
安全科学 | 1356篇 |
废物处理 | 2705篇 |
环保管理 | 6795篇 |
综合类 | 8387篇 |
基础理论 | 14616篇 |
环境理论 | 28篇 |
污染及防治 | 13155篇 |
评价与监测 | 3789篇 |
社会与环境 | 3101篇 |
灾害及防治 | 288篇 |
出版年
2022年 | 413篇 |
2021年 | 418篇 |
2020年 | 306篇 |
2019年 | 379篇 |
2018年 | 1922篇 |
2017年 | 1880篇 |
2016年 | 2076篇 |
2015年 | 876篇 |
2014年 | 1189篇 |
2013年 | 3554篇 |
2012年 | 1828篇 |
2011年 | 3109篇 |
2010年 | 2213篇 |
2009年 | 2094篇 |
2008年 | 2704篇 |
2007年 | 3058篇 |
2006年 | 1799篇 |
2005年 | 1543篇 |
2004年 | 1458篇 |
2003年 | 1547篇 |
2002年 | 1431篇 |
2001年 | 1738篇 |
2000年 | 1221篇 |
1999年 | 744篇 |
1998年 | 545篇 |
1997年 | 557篇 |
1996年 | 560篇 |
1995年 | 658篇 |
1994年 | 646篇 |
1993年 | 553篇 |
1992年 | 571篇 |
1991年 | 545篇 |
1990年 | 593篇 |
1989年 | 549篇 |
1988年 | 473篇 |
1987年 | 450篇 |
1986年 | 398篇 |
1985年 | 406篇 |
1984年 | 481篇 |
1983年 | 420篇 |
1982年 | 446篇 |
1981年 | 387篇 |
1980年 | 321篇 |
1979年 | 343篇 |
1978年 | 318篇 |
1977年 | 250篇 |
1975年 | 259篇 |
1974年 | 250篇 |
1972年 | 248篇 |
1971年 | 248篇 |
排序方式: 共有10000条查询结果,搜索用时 102 毫秒
171.
Henry R. Balikov 《环境质量管理》1996,6(1):23-26
Conventional wisdom has advocated environmental auditing as a prudent part of an internal control program and one of the key tools in driving proactive efforts. As a part of risk management activities, it is often employed to protect an organization, its employees, and officers from liability. Conscientious use of such audits has undoubtedly protected human health and the environment. Ironically, those who make the most consistent efforts to audit compliance and management systems, according to advocates of audit protection, may be the most vulnerable to enforcement actions and lawsuits. This article places the escalating calls for audit protection in a proper context. 相似文献
172.
173.
William R. Krug 《Journal of the American Water Resources Association》1996,32(4):745-752
ABSTRACT: Streamflow for 67 years was simulated for Coon Creek at Coon Valley, Wisconsin, for three conditions in the drainage basin: (1) conditions in the 1930s; (2) conditions in the 1970s, excluding flood-detention reservoirs; and (3) conditions in the 1970s, including flood-detention reservoirs. These simulations showed that the changes in agricultural practices over 40 years (1940–80) reduced the 100-year flood by 53 percent (from 38,900 to 18,300 cubic feet per second). The flood-detention reservoirs reduced the 100-year flood by an additional 17 percent (to 15,100 cubic feet per second). The simulation was accomplished by calibrating a precipitation-runoff model to observed rainfall and runoff during two separate periods (1934–40 and 1978–81). Comparisons of model simulations showed that differences between the model calibrations for the two periods were statistically significant at the 95 percent confidence level. 相似文献
174.
Peggy A. Johnson Thomas M. Heil 《Journal of the American Water Resources Association》1996,32(6):1283-1291
ABSTRACT: Bankfull depth and discharge are basic input parameters to stream planform, stream restoration, and highway crossing designs, as well as to the development of hydraulic geometry relationships and the classification of streams. Unfortunately, there are a wide variety of definitions for bankfull that provide a range of values, and the actual selection of bankfull is subjective. In this paper, the relative uncertainty in determining the bankfull depth and discharge is quantified, first by examining the variability in the estimates of bankfull and second by using fuzzy numbers to describe bankfull depth. Fuzzy numbers are used to incorporate uncertainty due to vagueness in the definition of bankfull and subjectivity in the selection of bankfull. Examples are provided that demonstrate the use of a fuzzy bankfull depth in sediment trans. port and in stream classification. Using fuzzy numbers to describe bankfull depth rather than a deterministic value allows the engineer to base designs and decisions on a range of possible values and associated degrees of belief that the bankfull depths take on each value in that range. 相似文献
175.
L. Jeffrey Lefkoff Donald R. Kendall 《Journal of the American Water Resources Association》1996,32(3):451-463
ABSTRACT: A non-linear optimization model is applied to the California State Water Project (SWP) and portions of the Central Valley Project (CVP). The model accounts for the major hydrologic, regulatory, and operational features of both projects. The model maximizes long-term SWP yields over a 70-year period, using a quarterly time step. The potential for increased yield associated with a proposed facility improvement is evaluated with the model. The proposed facility is an extension of the Folsom-South Canal, which would allow water to be conveyed from the American River below Folsom Reservoir into New Melones Reservoir on the Stanislaus River or into the California Aqueduct. Model results indicate that extension of the Folsom-South Canal has the potential to increase SWP yields by 13 percent. 相似文献
176.
Groundwater was being remediated with pump and treat technology at a facility where the groundwater was contaminated with commonly used degreaser solvents. Hydraulic conductivity of the heterogeneous residuum was beneficiated by applying pneumatic fracturing technology. The remedial system was controlled and monitored by a sophisticated remote telemetry system. A case history follows. 相似文献
177.
M. R. Theobald U. Dragosits C. J. Place J. U. Smith M. Sozanska L. Brown D. Scholefield A. Del Prado J. Webb P. G. Whitehead A. Angus I. D. Hodge D. Fowler M. A. Sutton 《Water, Air, & Soil Pollution: Focus》2004,4(6):135-142
The distribution and impacts of different nitrogen pollutants are inextricably linked. To understand the problem fully, the interactions between the different pollutants need to be taken into account. This is particularly important when it comes to abatement techniques, since measures to reduce emissions of one nitrogen pollutant can often lead to an increase in another. This project represents a step towards greater understanding of these issues by linking together new and existing nitrogen flux models into a larger framework. The modelling framework has been constructed and some of the nitrogen flows between fields, farms and the atmosphere have been modelled for a UK study area for typical farm management scenarios. 相似文献
178.
The Ethical Contract as a Tool in Organic Animal Husbandry 总被引:1,自引:3,他引:1
Vonne Lund Raymond Anthony Helena Röcklinsberg 《Journal of Agricultural and Environmental Ethics》2004,17(1):23-49
This article explores what an ethicfor organic animal husbandry might look like,departing from the assumption that organicfarming is substantially based in ecocentricethics. We argue that farm animals arenecessary functional partners in sustainableagroecosystems. This opens up additional waysto argue for their moral standing. We suggestan ethical contract to be used as acomplementary to the ecocentric framework. Weexpound the content of the contract and end bysuggesting how to apply this contract inpractice. The contract enjoins us to share thewealth created in the agroecosystem (by ourjoint contributions) by enjoining us to carefor the welfare and needs of the individualanimal, and to protect them from exploitation(just as human co-workers should not beexploited). The contract makes promoting goodanimal welfare a necessary condition forbenefiting farm animals. Animals for their partare guaranteed coverage under the contract solong as they continue to contribute to thesystem with products and services. 相似文献
179.
Donna M. Cosgrove Gary S. Johnson 《Journal of the American Water Resources Association》2004,40(6):1469-1482
ABSTRACT: Increasing demands on western water are causing a mounting need for the conjunctive management of surface water and ground water resources. Under western water law, the senior water rights holder has priority over the junior water rights holder in times of water shortage. Water managers have been reluctant to conjunctively manage surface water and ground water resources because of the difficulty of quantification of the impacts to surface water resources from ground water stresses. Impacts from ground water use can take years to propagate through an aquifer system. Prediction of the degree of impact to surface water resources over time and the spatial distribution of impacts is very difficult. Response functions mathematically describe the relationship between a unit ground water stress applied at a specific location and stream depletion or aquifer water level change elsewhere in the system. Response functions can be used to help quantify the spatial and temporal impacts to surface water resources caused by ground water pumping. This paper describes the theory of response functions and presents an application of transient response functions in the Snake River Plain, Idaho. Transient response functions can be used to facilitate the conjunctive management of surface and ground water not only in the eastern Snake River Plain basin, but also in similar basins throughout the western United States. 相似文献
180.
S. M. Smart M. R. Ashmore M. Hornung W. A. Scott D. A. Fowler U. Dragosits D. C. Howard M. A. Sutton D. Famulari 《Water, Air, & Soil Pollution: Focus》2005,4(6):269-278
Model estimates of NOy and NHx deposition across Britain for 1996 (5 km square resolution) were applied as explanatory variables to account for national-scale, fine-grained changes in plant species composition between 1990 and 1998. Plant species data were recorded from up to 27 fixed plots located within a stratified random sample of 596 1 km2. The response variable was a cover-weighted Ellenberg fertility score for each plot. Analyses were carried out separately for woodlands, semi-natural grasslands and heaths/bogs. Most of the variation in the botanical response variable occurred between plots within squares and so could not be explained by the model deposition data. NHx deposition estimates accounted for significant, but small components of between 1 km2 variation in the change in Ellenberg score in grasslands (5.6%) and heath/bogs (9.8%) but not woodlands. NOy deposition estimates were not significantly associated with vegetation change. Linear models provided the best fit and the slope of the relationship was lower for heath/bogs than grasslands. Further signal attribution at sub-kilometre square scales requires the development of fine-grained models of N deposition that can be generalised across regional sampling domains. 相似文献