首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   62篇
  免费   0篇
  国内免费   2篇
安全科学   2篇
废物处理   1篇
环保管理   18篇
综合类   7篇
基础理论   15篇
污染及防治   12篇
评价与监测   4篇
社会与环境   5篇
  2022年   2篇
  2021年   2篇
  2020年   1篇
  2016年   2篇
  2015年   2篇
  2014年   2篇
  2013年   6篇
  2012年   1篇
  2011年   4篇
  2010年   3篇
  2009年   2篇
  2008年   2篇
  2007年   3篇
  2006年   1篇
  2004年   2篇
  2003年   4篇
  2002年   1篇
  2001年   4篇
  2000年   1篇
  1999年   4篇
  1998年   2篇
  1997年   1篇
  1996年   1篇
  1990年   2篇
  1983年   1篇
  1982年   1篇
  1980年   4篇
  1978年   1篇
  1973年   1篇
  1972年   1篇
排序方式: 共有64条查询结果,搜索用时 31 毫秒
41.
42.
43.
It is often stated that social pressures to conform to the norm can help stimulate some individuals into recycling. Whilst this can be intuitively accepted by most people, there have been few scientific studies to show if and how these normative influences can make any significant impact on recycling behaviour within a community. Normative influences, however, are not directly measurable quantities. Their presence may only be supposed either: (1) by showing that models of the expected effects are consistent with observed behaviours; or (2) by questioning individuals on their motivation for recycling. This paper explores both approaches. Measured recycling performance indicators have been examined for evidence that non-chance behaviour is occurring. Results show that if natural normative influence is occurring, its measurable effects are likely to be small and substantially masked by natural random variation. The effects themselves serve more to increase recycling frequency than to increase absolute levels of participation. Simulation studies, based on a new model of normative influence, show that increased overall weight recovery may be achieved, from a recycling scheme, through management interventions to stimulate normative influences. This is, however, at the expense of substantially more pick-ups being required to collect the extra weight. The simulation results are consistent with the hypothesis that there needs to be a certain threshold level of participants within a locality before the normative influences are triggered.  相似文献   
44.
An experimental multitube cyclone facility was constructed and experiments conducted to investigate the influence of hopper evacuation on multitube cyclone performance. The effects of the amount of hopper evacuation and the location of hopper evacuation on individual cyclone tube velocities and particle collection efficiency were determined. Cyclone tube velocities increased with increasing hopper evacuation although hopper evacuation location had little effect on the velocities. Particle collection efficiencies were increased from 89.5 percent to approximately 95 percent with 14 percent hopper evacuation from a location near the center of the hopper. Other hopper evacuation locations were not as effective in increasing collection efficiency. These results suggest that, while the increased velocity in the cyclone tubes is an important effect in the improvement of multitube cyclone performance with hopper evacuation, other factors such as redistribution of gas flow within the hopper are also important.  相似文献   
45.
This paper suggests a number of benefits in identifying urban and regional planners as a public in public participation programs of water resources planning studies. A perspective on public participation is presented. Recent trends and developing concepts are identified: emphasis on the need to coordinate urban and regional planning activities with water resources planning, increasing system complexity, the goals and objectives orientation of planning, planning for multi-objectives, the evaluation of a broader range of alternatives, and the consideration of water alternatives as only one set of measures to further society's aspirations. One way to assist in capitalizing on these trends is to seek out participation of those in other planning efforts who are involved in planning but on a different level. Because of their intimate knowledge of an areas history, growth and development, political climate, local perceptions of needs and desires, and major problems and issues they are able to contribute a great deal of insight in making the water resources planning effort more responsive at the local level. The paper describes one of the first major efforts at working-level public-planner contact which was carried out as part of the Susquehanna River Basin Study. A regional survey team comprised of an engineer and an economist from a federal agency and a state water resources planner met informally with planners, city managers, and local planning commissions to discuss issues related to water resources and the growth and development of local areas. This effort while only part of the overall public participation program yielded a number of benefits and if expanded and refined would be a very useful experience in other studies.  相似文献   
46.
47.
/ Data were collected from 245 farmers within the Darby Creek hydrologic unit in central Ohio to assess perceptions of risk associated with use of farm chemicals. Farmers were asked to evaluate the level of risk associated with use of agricultural chemicals for water quality, food safety, food quality, health of applicator, health of farm animals, wildlife, beneficial plants, beneficial insects, and human health. Study findings revealed that respondents perceived use of farm chemicals posed little or no threat to any of the assessed items. A composite index was formulated from the responses to the nine items and was titled Perceived Risk. Variance in the Perceived Risk index was regressed against social learning variables. The findings revealed that approximately 32% of the variance was explained by the predictive variables included in the model. It was concluded that the theoretical perspective was somewhat useful for understanding perceptions held about agricultural chemical use at the farm level. The findings are discussed in the context of future conservation and educational-information programs within the study region.KEY WORDS: Risk perception; Risk assessment; Groundwater; Pesticide contamination; Food safety; Environmental quality  相似文献   
48.
This project has arisen from the need to produce GFFs (glass fiber filters) bearing a thin and evenly distributed coating of a selected reagent in the equatorial plane for breakthrough studies. However, it has been discovered that today's two general techniques for coating GFFs (total immersion and application of reagent solution to GFFs) have usually produced unevenly distributed coatings of reagent in the equatorial plane. In addition, quantities of reagent on GFFs from commercial sources may vary widely in the same lot of coated GFFs. Consequences are variability in capacity of coated filters at the point of breakthrough and, perhaps, wasted reagent. Although today's reagent-coated filters may be satisfactory for routine air sampling, such filters may be unacceptable for precise breakthrough studies. Research has been conducted successfully to produce nearly evenly distributed coatings of reagents in the equatorial plane of GFFs by application of reagent solutions to the centers of GFFs which are resting on crisscrossing, fine, stainless-steel wire. Distributions of coatings have been determined by punching out twenty-one 5-mm circles from each GFF and analyzing each circle by flow-injection with a UV detector. Lowest achievable relative standard deviations of measurement (RSDs) for reagents in 5-mm circles have been 5 to 7%. Reagents studied have included 1-(2-pyridyl)piperazine (1-2PP), 2,4-dinitrophenylhydrazine (DNPH), and 1-(9-anthracenylmethyl)piperazine (MAP). Factors affecting the distribution of such coatings include choice of reagent and choice of solvent for the reagent solution.  相似文献   
49.
50.
Groundwater and surface water pollution from nonpoint sources are problems of increasing concern. Nitrate transport is a crucial part in the whole process of nitrate loss. Previous methods for simulating the nitrate transport process usually involved solving complex advection–dispersion equations and required large amount of parameters and input data, which makes a model application expensive or invalid in terms of computation and data availability. The aim of this research is to develop a simple conceptual method to simulate the nitrate transport. In this paper, a simple conceptual method utilizing the distribution of nitrate loss against cumulative drainage to simulate the nitrate transport process is introduced. The concept and construction of this method are presented, and its applicability at different spatial scales is demonstrated. Results of model application at laboratory, pilot, and catchment scales show that this method has a good capability to simulate the transport of nitrate. Impact of spatial scales on parameters’ values is also discussed. Compared to conventional methods, this method requires fewer parameters, less computing time, and less input data.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号