全文获取类型
收费全文 | 20566篇 |
免费 | 326篇 |
国内免费 | 412篇 |
专业分类
安全科学 | 797篇 |
废物处理 | 837篇 |
环保管理 | 3429篇 |
综合类 | 3256篇 |
基础理论 | 5207篇 |
环境理论 | 14篇 |
污染及防治 | 5295篇 |
评价与监测 | 1184篇 |
社会与环境 | 1133篇 |
灾害及防治 | 152篇 |
出版年
2023年 | 110篇 |
2022年 | 193篇 |
2021年 | 193篇 |
2020年 | 212篇 |
2019年 | 183篇 |
2018年 | 323篇 |
2017年 | 324篇 |
2016年 | 485篇 |
2015年 | 386篇 |
2014年 | 513篇 |
2013年 | 1786篇 |
2012年 | 738篇 |
2011年 | 1040篇 |
2010年 | 775篇 |
2009年 | 872篇 |
2008年 | 968篇 |
2007年 | 1024篇 |
2006年 | 841篇 |
2005年 | 709篇 |
2004年 | 734篇 |
2003年 | 672篇 |
2002年 | 630篇 |
2001年 | 698篇 |
2000年 | 580篇 |
1999年 | 356篇 |
1998年 | 257篇 |
1997年 | 267篇 |
1996年 | 273篇 |
1995年 | 313篇 |
1994年 | 265篇 |
1993年 | 256篇 |
1992年 | 213篇 |
1991年 | 216篇 |
1990年 | 211篇 |
1989年 | 207篇 |
1988年 | 188篇 |
1987年 | 162篇 |
1986年 | 183篇 |
1985年 | 169篇 |
1984年 | 214篇 |
1983年 | 180篇 |
1982年 | 216篇 |
1981年 | 192篇 |
1980年 | 153篇 |
1979年 | 172篇 |
1978年 | 118篇 |
1977年 | 124篇 |
1975年 | 96篇 |
1974年 | 100篇 |
1972年 | 104篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
931.
Traditional command-and-control regulations provide few opportunities for total quality environmental management because they usually do not take into account cost and efficiency factors. However, in the past several years both Congress and EPA have shown increasing interest in using incentive-type approaches to regulate the environment. These include taxes, marketable pollution privileges, deposits and refunds, information disclosure provisions, and subsidies. The author details examples of each and discusses how they can effectively complement a quality program. 相似文献
932.
933.
Morris L. Maslia Mustafa M. Aral Robert C. Williams Allan S. Susten Janet L. Heitgerd 《Journal of the American Water Resources Association》1994,30(6):1025-1041
ABSTRACT: Simulation of ground-water flow and fate of contaminants in the subsurface environment constitutes a major phase of most environmental assessment and site remediation studies. These simulation studies yield information on spatial and temporal distributions of contaminants in the subsurface media. An important use of this information is to conduct exposure assessment studies. Spatial and temporal distributions of both chemical concentrations and exposed populations render this integrated exposure analysis task rather difficult. Geographic Information Systems (GIS), on the other hand, provide a platform in which layered, spatially distributed databases can be manipulated with ease, thereby simplifying exposure analysis tasks significantly. In this paper, we describe procedures that combine the simulation models and demographic databases under a GIS platform to automate the exposure assessment phase of a typical health assessment study. Procedures developed herein significantly simplify the post-processing phase of the analysis, and render the overall task more ‘user friendly.’ A site-specific application is included as a demonstration of the proposed process. 相似文献
934.
935.
A review of the research literature suggested that occupational commitment may be an antecedent to employees' commitment to the organization. Although several studies have assessed the general relationship between occupational and organizational commitment, none have attempted to establish the causal priority between the two constructs. In the present study, occupational commitment was viewed as a causal antecedent to organizational commitment. Based on longitudinal data from 100 management information systems professionals, this view was supported through cross-lagged analysis. Further, we examined a longitudinal causal model of the turnover process in which occupational commitment was placed as an antecedent to organizational commitment. Structural equation analysis supported the fit of this model to the data. Implications of the findings are discussed. 相似文献
936.
Teresa N. Malafi Marlene A. Devine Larry L. Lesher 《Journal of Polymers and the Environment》1994,2(4):219-223
This paper summarizes a study evaluating the acceptance and perceived performance of disposable cutlery made from starch-based biodegradable resins relative to nondegradable polystyrene cutlery. Two hundred forty-three sailors onboard three U.S. Navy vessels ate their lunch using either biodegradable cutlery made with resins manufactured by one of two commercial companies or polystyrene cutlery. The cutlery was rated on several sensory and performance dimensions as well as for overall acceptability. Results indicated that sailors rated both the biodegradable and the polystyrene utensils as easy to hold. There were also no differences in the perceived ease of using each of the spoons. However, compared to the polystyrene utensils, both types of biodegradable utensils were viewed as less sturdy, as having a less attractive color, and as being less acceptable overall. The biodegradable forks and knives were also rated as more difficult to use for piercing and cutting food than the polystyrene ones. In addition, several significant differences emerged between the two types of biodegradable cutlery. The results are discussed in terms of the need for continued consumer testing of products developed from biodegradable polymeric materials. 相似文献
937.
The traditional approach to characterizing the extent of groundwater contamination is often phased over a period of several years. A screening method has been developed that allows the investigation process to be reduced to a single phase. Existing data are used to develop a preliminary estimate of the extent of contamination, which is refined by the screening method using groundwater data collected and analyzed in the field. The screening method is applicable at sites with volatile organic compound contamination. Groundwater samples are collected using direct push or drill rig assisted methods, and the groundwater headspace gas is analyzed for the contaminant of interest. The refined estimate is used to locate all of the groundwater monitoring wells necessary to finalize the estimate of the extent of contamination. Therefore, only one investigation phase is required, and time and cost savings are realized with respect to the traditional multiphase approach. The screening method was successfully applied at a CERCLA site in Nebraska with two distinct plumes of TCE-contaminated groundwater. The Nebraska remedial investigation was completed approximately 18 months earlier than the estimated completion of a comparable phased investigation, with a corresponding cost reduction estimated at approximately 10 percent. If data from the screening method were used instead of data from monitoring wells, the estimated cost savings would be over 50 percent. Additional applications and evaluations may lead to industry and regulatory acceptance of the method as a primary characterization tool. 相似文献
938.
During the period of 1972 through 1993, Environmental Concern Inc. (EC) and its recent (1989) affiliate Environmental Construction
Company (ECC) have completed 216 marsh construction projects to control upland bank erosion in tributaries of the Maryland
portion of Chesapeake Bay. Of these projects, 26 have involved marsh construction on unaltered existing shores and 190 have
utilized marsh construction on shores that have been restored to former increased elevations through shoreline filling and
grading. This paper describes the latter restoration technique. Throughout the 21-year period of applying the technique for
long-term upland bank erosion control, refinements to the design standards and criteria for site suitability have been made
so as to optimize its successful application. As a result of this experience, a reliable bioengineering restoration technique
has evolved to control upland bank erosion. This paper describes the details of this successful technique through a review
of: (1) its objectives and benefits, (2) suitability of sites for its application, (3) the design of its shore restoration,
(4) its construction, (5) its maintenance, and (6) comparison of its cost with those of structural techniques for bank erosion
control. Although the technique has only been applied in the Maryland portions of Chesapeake Bay, its applicability should,
with modifications, be broadly applicable to all water bodies. 相似文献
939.
In certain locations, the combination of meteorological conditions and topography are such that persistent fogs cover coastal or interior mountains. The droplets from these fogs are collected by trees or other tall vegetation. They can also be collected by appropriately designed man-made collectors, to provide large volumes of water for domestic, agriculture or forestry uses. The largest project to date has provided, since March 1992, an average of 11 000 litres of water per day (*****l/d) to a village of 330 people in the arid coastal desert of northern Chile. This project and others are reviewed. The impact of the deforestation of high elevation areas, and the subsequent loss of fog water input in a watershed are discussed, as are guidelines for water planners. 相似文献
940.
This study concerns design features of urban parking lots which can increase the perception of such areas as both safe and attractive. College students evaluated the attractiveness and perceived security associated with 180 scenes of parking lots adjacent to commercial and multi-family residential structures in Atlanta and Athens, Georgia, U.S.A. High intergroup correlations (r > 0·90) indicated the reliability of evaluations of both perceived features. Regressions of physical features on perceived security ratings and attractiveness ratings yielded highly predictive models (R2 = 0·76 and 0·80, respectively). For both sets of ratings a Maintenance and Design factor accounted for the most variance. Although attractiveness ratings were higher as the total amount of vegetation increased in a scene, security was in general rated higher only when vegetation was well maintained and appeared to be installed as part of a landscape design. Attractiveness was generally higher for multi-family residential scenes than for commercial scenes. Perceived security was higher for frontal views of structures, especially when entrances were proximate to the viewer. Research implications are discussed in terms of the impact of natural features in urban areas for increasing attractiveness and reducing fear of crime. 相似文献