全文获取类型
收费全文 | 2658篇 |
免费 | 164篇 |
国内免费 | 300篇 |
专业分类
安全科学 | 479篇 |
废物处理 | 37篇 |
环保管理 | 583篇 |
综合类 | 778篇 |
基础理论 | 672篇 |
环境理论 | 11篇 |
污染及防治 | 152篇 |
评价与监测 | 90篇 |
社会与环境 | 217篇 |
灾害及防治 | 103篇 |
出版年
2024年 | 7篇 |
2023年 | 47篇 |
2022年 | 77篇 |
2021年 | 102篇 |
2020年 | 105篇 |
2019年 | 89篇 |
2018年 | 97篇 |
2017年 | 123篇 |
2016年 | 147篇 |
2015年 | 136篇 |
2014年 | 147篇 |
2013年 | 296篇 |
2012年 | 110篇 |
2011年 | 153篇 |
2010年 | 103篇 |
2009年 | 115篇 |
2008年 | 103篇 |
2007年 | 134篇 |
2006年 | 127篇 |
2005年 | 109篇 |
2004年 | 93篇 |
2003年 | 98篇 |
2002年 | 70篇 |
2001年 | 66篇 |
2000年 | 58篇 |
1999年 | 56篇 |
1998年 | 37篇 |
1997年 | 24篇 |
1996年 | 23篇 |
1995年 | 42篇 |
1994年 | 32篇 |
1993年 | 20篇 |
1992年 | 13篇 |
1991年 | 14篇 |
1990年 | 13篇 |
1989年 | 17篇 |
1988年 | 13篇 |
1987年 | 11篇 |
1986年 | 7篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 12篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1973年 | 5篇 |
1972年 | 10篇 |
1971年 | 9篇 |
1970年 | 4篇 |
排序方式: 共有3122条查询结果,搜索用时 216 毫秒
241.
Thomas M. Bonnicksen 《Environmental management》1985,9(5):379-391
Initial decision analysis (IDA) is a microcomputer based decision-making technique that is organized so that a rational, step-by-step, procedure can be followed to use existing knowledge to develop resource policies. The IDA process provides a systematic way for participants to define their own problem and to explore jointly alternative solutions. IDA is particularly suited to resolving complex problems involving many groups with conflicting interests. IDA is illustrated with data from the US Forest Service's Draft Environmental Impact Statement for the 1985 to 2030 Resource Planning Act Program for the United States. Four policy options are evaluated: maximization of timber production, of grazing, and of wilderness, and a dominant use policy that concentrates timber management on productive sites. Policies were evaluated using a new mathematical satisficing procedure. Mathematical satisficing of simulated policy consequences showed that, for selected performance standards, current RPA policies are superior to the four alternative policies examined. 相似文献
242.
ABSTRACT: The domestic sewage of the city of Beer-Sheva, Israel, which is located in an arid region, is treated in a series of facultative ponds. The treated effluent is stored temporarily in an open surface earthen reservoir (about 0.5 ± 106 m3 in volume) and then used for irrigation. The effluent is applied via sprinkler and trickle irrigation systems. The main crops irrigated are cotton, wheat, alfalfa, and corn. Total cotton yield is over 5500 kg/ha, and the wheat grain yield is over 7500 kg/ha. The amount of effluent applied is about 6500 m3/ha for cotton (including preplant irrigation), and the wheat receives about 4500 m3/ha via irrigation and an additional 2000 m3/ha from precipitation. Due to the nutrient content in the effluent, the above yields are obtained without any additional fertilization. 相似文献
243.
Robert G. Bailey 《Environmental management》1988,12(1):11-17
As part of the planning process, maps of natural factors are often superimposed in order to identify areas which are suitable or unsuitable for a particular type of resource management. Overlay maps may also be used to identify analysis areas for predictive modeling of resource productivity and ecological response to management. Current interest in applying computer-assisted mapping technology to making overlay maps is drawing attention to geographic information systems for this purpose. The resultant maps, however, may be so inaccurate or unable to capture significant units of productivity and ecological response that they could lead to imperfect or false conclusions. Recommendations are made on how to proceed in light of these problems. 相似文献
244.
Ernest T. Smerdon John A. Gronouski Judith M. Clarkson 《Journal of the American Water Resources Association》1988,24(6):1257-1262
ABSTRACT: Texas is one of the states in which limitations in water supplies could severely constrain economic growth in certain areas. The traditional planning approach for addressing this problem has involved devising schemes for large water development projects, which for many years included the importation of water from other states. Now the attitude towards water resource management is changing, and it is generally agreed that better management of existing supplies is the preferred approach. In this paper we review some of the changes that have recently occurred in Texas, including attempts to streamline the water institutions in such a way that they might be more responsive to the need for more comprehensive management of water resources statewide, with greater emphasis on social and environmental concerns. 相似文献
245.
Allan R. Ruff 《Journal of Environmental Planning and Management》1988,31(1):53-60
In Canada, increasing costs of maintenance, a shifting perception of what makes a city beautiful, a recognition of the needs and the importance of urban wildlife, and changing recreational demands are all contributing to a pressure for change in current practice. This study examines the extent to which the ecological approach has influenced the design and management of urban green space in Canada, focusing on the city of Toronto and its surrounding region as an example. 相似文献
246.
Robert Leconte Rangesan Narayanan Trevor C. Hughes 《Journal of the American Water Resources Association》1988,24(2):247-253
ABSTRACT: A general methodology to study the economics of dual water systems (defined here as a separate distribution system for untreated low quality local surface Water for outdoor municipal water supply) is summarized and the application of the method to a rapidly growing city is presented. In the first step, a cost-benefit criterion for evaluating dual systems is developed. The criterion is then extended to a dynamic case where the population to be served increases with time and where the dual system is allowed to expand. The optimal investment time to introduce the dual water supply project is obtained by maximizing social welfare. The model is applied to the city of West Jordan, Utah, where a dual system is currently being proposed. Model results indicate that for the city as a whole dual supply is not economically feasible. However, when the model is applied to a part of the city, it is found feasible and the optimal time to initiate the project would be in the year 1989. 相似文献
247.
Deborah Slicer 《Journal of Agricultural and Environmental Ethics》1995,8(2):161-170
I offer a very qualified argument to the effect that rights are grounded in a certain sort of prejudice that privileges individualistic and perhaps masculinist ways of thinking about moral life. I also propose that we look carefully at other conceptions of social ontology and moral life, including the much discussed care conception. 相似文献
248.
Rameshwar S. Kanwar 《Journal of the American Water Resources Association》2006,42(6):1493-1501
Abstract: Diverse cropping systems can have significant impacts on nutrient losses through tile drain systems and to surface water bodies (rivers and streams). Increased transport of nitrogen to water bodies can reduce dissolved oxygen and enrich the supply of nutrients, resulting in hypoxic zones. With the objective of reducing the transport of nutrients from agricultural watersheds, long term studies (1990 to 1998) were conducted in Iowa to investigate the impact of tillage, crop rotation, and N-management practices on NO3 -N leaching losses to tile drain water. Results of these studies indicated that continuous corn production systems required higher input of nitrogen fertilizers and resulted in significantly higher NO3 -N leaching losses compared to rotated corn in plots either fertilized with manure or urea ammonium nitrate. Also, rotated corn gave higher corn yields, 8 megagrams per hectare (Mg/ha) versus 6 Mg/ha, than continuous corn. The higher N application rates resulted in increased NO3 -N concentrations in tile water. A strip cropping system with alfalfa lowered NO3 -N concentrations in tile water to less than 10 mg/l. These studies indicated that better land use practices can reduce NO3 -N leaching losses to surface and ground water systems and will help in mitigating environmental concerns of the production agriculture. 相似文献
249.
Francisco Olivera Milver Valenzuela R. Srinivasan Janghwoan Choi Hiudae Cho Srikanth Koka Ashish Agrawal 《Journal of the American Water Resources Association》2006,42(2):295-309
This paper presents ArcGIS‐SWAT, a geodata model and geographic information system (GIS) interface for the Soil and Water Assessment Tool (SWAT). The ArcGIS‐SWAT data model is a system of geodatabases that store SWAT geographic, numeric, and text input data and results in an organized fashion. Thus, it is proposed that a single and comprehensive geodatabase be used as the repository of a SWAT simulation. The ArcGIS‐SWAT interface uses programming objects that conform to the Component Object Model (COM) design standard, which facilitate the use of functionality of other Windows‐based applications within ArcGIS‐SWAT. In particular, the use of MS Excel and MATLAB functionality for data analysis and visualization of results is demonstrated. Likewise, it is proposed to conduct hydrologic model integration through the sharing of information with a not‐model‐specific hub data model where information common to different models can be stored and from which it can be retrieved. As an example, it is demonstrated how the Hydrologic Modeling System (HMS) ‐ a computer application for flood analysis ‐ can use information originally developed by ArcGIS‐SWAT for SWAT. The application of ArcGIS‐SWAT to the Seco Creek watershed in Texas is presented. 相似文献
250.
通过对四川省科技人力资源的潜力、结构变化的分析,提出建立统一规范的科技人才培养经费投入政策,加强科技人才资源的再开发,不拘一格引进科技人才,建立四川省科技人力资源监测系统等对策。 相似文献