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   281篇
  免费   4篇
  国内免费   9篇
安全科学   12篇
废物处理   3篇
环保管理   110篇
综合类   51篇
基础理论   40篇
环境理论   3篇
污染及防治   23篇
评价与监测   6篇
社会与环境   36篇
灾害及防治   10篇
  2023年   4篇
  2022年   5篇
  2021年   4篇
  2020年   4篇
  2019年   3篇
  2018年   6篇
  2017年   17篇
  2016年   15篇
  2015年   8篇
  2014年   6篇
  2013年   15篇
  2012年   18篇
  2011年   12篇
  2010年   14篇
  2009年   29篇
  2008年   16篇
  2007年   20篇
  2006年   15篇
  2005年   10篇
  2004年   10篇
  2003年   4篇
  2002年   6篇
  2001年   9篇
  2000年   6篇
  1999年   6篇
  1998年   4篇
  1997年   1篇
  1996年   5篇
  1995年   1篇
  1994年   2篇
  1993年   1篇
  1992年   2篇
  1989年   3篇
  1988年   1篇
  1987年   4篇
  1984年   6篇
  1983年   1篇
  1968年   1篇
排序方式: 共有294条查询结果,搜索用时 31 毫秒
31.
The literature guides environmental planning and, specifically, how to use ecological rehabilitation projects to achieve long-term planning goals and landscape-scale environmental sustainability. There is, however, a perceived gap between principles in the literature and the use of them by practitioners involved in smaller-scale ecological rehabilitation projects. Using interviews with practitioners involved in 11 projects within the Regional Municipality of Waterloo, Ontario, Canada, we tested whether practitioners used five principles for effective planning and implementation of ecological rehabilitation that we derived from the literature. These five principles were: establishing political and ecological context, using ecologically appropriate objectives and practices, using comparative multidisciplinary and cross-scale approaches, using adaptive planning and implementation, and establishing good communication within and external to projects. Few projects followed all five principles, and practitioners indicated that they used three more project-specific principles: obtaining political/social support, promoting projects and changing attitudes about projects, and securing sufficient and persistent funding to maintain a project's life. While the literature emphasizes that ecological rehabilitation is only effective if projects are coordinated on a watershed basis, most practitioners focused solely on the goals of their specific project. The gap between literature and practice may arise because most practitioners are new to the field of ecological rehabilitation and still are focused on the methods involved. Time pressures force practitioners to obviate the literature and get projects started quickly, lest support evaporate. Complicating these difficulties is decreased support from federal and provincial governments for large-scale environmental planning. It is unclear whether ecological rehabilitation projects in Waterloo Region (at least) will ever become effective at promoting landscape-scale ecological goals or remain smaller-scale stop-gaps.  相似文献   
32.
Environmental pollution and degradation of ecosystems considerably affect the natural resources. The Turkish Government is aware of the importance of the preservation of natural ecology and thereby the environmental conservation of many species in their natural habitat. This paper provides critical assessments of the problems and possible solutions in the identification, implementation and management of the Specially Protected Areas (SPAs) system by giving basic information about stakeholders and their responsibilities that currently offer nature conservation in Turkey. The goals of the article are to analyze how the SPAs interface with the local people, especially the villagers who have dwelt there before SPA designation and how people-SPA conflicts resolved; to show how effective the SPA conservation objectives have been; to outline the significance of informing and empowering people in nature conservation for the protected area management and to show the importance of planning at all levels during protection of the natural, archeological and cultural values of the SPAs.  相似文献   
33.
Air pollution Integrated Assessment Models (IAM) can be used for determining how emissions should be reduced to improve air quality and to protect human health in a cost-efficient way. The application of IAM is also useful to spread information to the general public and to explain the effectiveness of proposed Air Quality Plans. In this paper, the application of the RIAT+ system to determine suitable abatement measures to improve the air quality at a regional/local level is presented for two European cases: the Brussels Capital Region (Belgium) and the Porto Urban Area (Portugal). Both regions are affected with PM10 or NO2 concentrations that exceed the limit values specified by the European Union legislation. To properly assess air quality abatement measures a surrogate model was used, allowing the implementation of an efficient optimization procedure. This model is derived in both cases through a set of simulations performed using a Chemistry Transport Model fed with different emission reduction scenarios. In addition, internal costs (due to the implementation of emission reduction measures) and external costs (due to population exposure to air pollutant concentrations) of policy options were considered. The application of this integrated assessment modelling system in scenario (Brussels case) and optimization (Porto) modes contributes to identifying some advantages and limitations of these two approaches and also provides some guidance when urban air quality has to be assessed.  相似文献   
34.
Coastal flooding affects physical and social place attachments. Values-based approaches to climate change adaptation examine how risks to place attachments are distributed within and among communities, with a view to informing equitable adaptation policies. In this nascent body of research, divergent theoretical frameworks and empirical approaches to measuring social values are evolving. While some studies explore the things people value about their everyday lives generally—the lived values approach, others locate specific social and cultural values in geographic space—the landscape values mapping approach. This study aims to compare the explanatory value of these two approaches for understanding the social risks of sea-level rise, and appraise whether either or both approaches are likely to meet local adaptation planning needs. It does this by examining the potential social impacts of sea-level rise in Kingston Beach, Australia, informed by a mail-out survey of the community. The lived values approach identified that the natural environment, scenery, relaxed lifestyle and safety are highly important to local residents, while the landscape values mapping approach revealed that Kingston Main Beach is the most highly valued of eight coastal landscape units. Incorporating the landscape values mapping into the lived values cluster analysis revealed that while Kingston Main Beach is highly important for its recreational value to some members of the community, for others manmade features such as community halls or sports ovals may be of higher importance because they facilitate social interactions. There is potential to further integrate these two approaches to better inform adaptation policy about how lived and landscape values are distributed among communities, where they are located in space and whether they change over time. A deeper understanding of such assigned values can lead to improved engagement with coastal residents to inform adaptation policy now and into the future.  相似文献   
35.
Multimetric indices based on fish and benthic macroinvertebrate assemblages are commonly used to assess the biological integrity of aquatic ecosystems. However, their response to specific stressors is rarely known. We quantified the response of a fish-based index (Mid-Atlantic Highlands Index of Biotic Integrity, MAH-IBI) and a benthic invertebrate-based index (West Virginia Stream Condition Index, WV-SCI) to acid mine drainage (AMD)-related stressors in 46 stream sites within the Cheat River watershed, West Virginia. We also identified specific stressor concentrations at which biological impairment was always or never observed. Water chemistry was extremely variable among tributaries of the Cheat River, and the WV-SCI was highly responsive across a range of AMD stressor levels. Furthermore, impairment to macroinvertebrate communities was observed at relatively low stressor concentrations, especially when compared to state water quality standards. In contrast to the WV-SCI, we found that the MAH-IBI was significantly less responsive to local water quality conditions. Low fish diversity was observed in several streams that possessed relatively good water quality. This pattern was especially pronounced in highly degraded subwatersheds, suggesting that regional conditions may have a strong influence on fish assemblages in this system. Our results indicate that biomonitoring programs in mined watersheds should include both benthic invertebrates, which are consistent indicators of local conditions, and fishes, which may be indicators of regional conditions. In addition, remediation programs must address the full suite of chemical constituents in AMD and focus on improving linkages among streams within drainage networks to ensure recovery of invertebrate and fish assemblages. Future research should identify the precise chemical conditions necessary to maintain biological integrity in mined Appalachian watersheds.  相似文献   
36.
The implementation of urban sustainability practices is affected by political obstacles, and diverse political ideologies may defend different city models. Sustainable policy design could also be affected by several factors that cause the deflection of resources initially allocated to other groups that are contrary to the concerns pursued and have the power to veto sustainable plans by exerting pressure on the party in power.In this sense, the aim of this paper is to show the impact that political factors have on cities’ sustainability, and the effect of both on cities’ economic development. To do so, we used the 78 Spanish cities with a population over 100,000 studied by MERCO (Spanish Corporate Reputation Monitor) as regards their levels of sustainability for the fiscal years 2008 and 2009. Both relationships have been tested empirically through two dependence models using linear regression techniques.The results obtained show that political competition improves cities’ sustainability, while a leftist ideology has an inverse impact. On the other hand, a significant direct relationship has been observed between urban sustainability and municipal economic activity.  相似文献   
37.
The spatiotemporal structure of the muskrat population has been studied by means of the prenatal radioactive marking of juveniles with 45 Ca and their subsequent recapture in the test area. The muskrat population is characterized by a cyclic type of spatial structure, with seasonal transition from a mosaic type of settling to a diffuse type and, after the breeding season, vice versa.  相似文献   
38.
A review of the use of planning and design briefs by local authorities in the United Kingdom was carried out in 1982–83 to test whether the role of the brief as an instrument of local policy and as a promotional tool in the development process was being fully exploited. The paper provides a state of the art review, presents a summary of the findings and offers some comments on the results. It concludes that most authorities now use briefs as part of their normal planning procedures, but that there is potential which is not yet being exploited.  相似文献   
39.
根据我国宪法和地方组织法等的规定,对地方环境立法中的若干关系问题,从理论和实践的结合上作了探讨。  相似文献   
40.
We review the basic mathematical concepts of random walk particle tracking (RWPT) and its advantages and limitations. Three different numerical approaches to overcome the local mass conservation problem of the random walk methodology are examined: (i) the interpolation method, (ii) the reflection principle, and (iii) the generalized stochastic differential equations (GSDE). Analytical solutions of the spatial moments for a two-layer system are compared to model predictions using the different techniques and results demonstrate that the interpolation method reproduces correctly average velocity, but fails to reproduce macrodispersion at higher hydraulic conductivity contrasts between the two layers. On the contrary, the reflection principle and the GSDE approach underestimate average velocity, but reproduce macrodispersion better for high contrasts. The different behavior is based on an artificial shift of mass for increasing heterogeneities for the GSDE approach and the reflection principle, whereas the interpolation method suffers from the smoothing of the dispersion tensor. The behavior of these approaches was furthermore analyzed in two-dimensional heterogeneous hydraulic conductivity fields, which are characterized by different random function models. Solute transport was simulated correctly by all three approaches for the reference fields having Gaussian structures or non-Gaussian structures with an isotropic spatial correlation, even for a variance of the natural log of hydraulic conductivity of sigma(lnK)(2)=4. However, for the non-Gaussian model with a strong anisotropic spatial correlation and a variance of sigma(lnK)(2)=2 and higher, the interpolation method was the only technique modelling solute transport correctly. Furthermore, we discuss the general applicability of random walk particle tracking in comparison to the standard transport models and conclude that in advection-dominated problems using a high spatial discretization or requiring the performance of many model runs, RWPT represents a good alternative for modelling contaminant transport.  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