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   348篇
  免费   1篇
  国内免费   2篇
安全科学   7篇
废物处理   9篇
环保管理   16篇
综合类   51篇
基础理论   121篇
污染及防治   125篇
评价与监测   10篇
社会与环境   11篇
灾害及防治   1篇
  2022年   1篇
  2021年   2篇
  2019年   1篇
  2018年   2篇
  2016年   3篇
  2015年   1篇
  2014年   3篇
  2013年   9篇
  2012年   10篇
  2011年   15篇
  2010年   11篇
  2009年   24篇
  2008年   14篇
  2007年   22篇
  2006年   21篇
  2005年   11篇
  2004年   10篇
  2003年   20篇
  2002年   11篇
  2001年   4篇
  2000年   18篇
  1999年   23篇
  1998年   16篇
  1997年   17篇
  1996年   17篇
  1995年   11篇
  1994年   8篇
  1993年   11篇
  1992年   3篇
  1991年   1篇
  1990年   3篇
  1989年   2篇
  1988年   2篇
  1987年   2篇
  1986年   1篇
  1983年   2篇
  1982年   2篇
  1981年   2篇
  1979年   2篇
  1978年   2篇
  1977年   1篇
  1967年   3篇
  1965年   2篇
  1961年   1篇
  1959年   1篇
  1958年   1篇
  1955年   2篇
排序方式: 共有351条查询结果,搜索用时 15 毫秒
31.
32.
We present a framework of a scenario-based model that simulates the development of the municipality of Davos (Swiss Alps). We illustrate our method with the calculation of the scenario for 2050 “Decrease in subsidies for mountain agriculture and liberalization of markets.” The main objective was to link submodels of land-use allocation (regression-based approach), material and energy flows submodels (Material and Energy Flux Analysis), and economic submodels (Input–Output Analysis). Letting qualitative and quantitative information flow from one submodel to the next, following the storyline describing a scenario, has proven to be suitable for linking submodels. The succession of the submodels is then strongly dependent on the scenario. Qualitative information flows are simulated with microsimulations of actor choices. Links between the submodels show different degrees of robustness: although the links involving microsimulations are the weakest, the uncertainty introduced by the land-use allocation model is actually advantageous because it allows one possible change in the landscape in the future to be simulated. The modeling results for the scenario here presented show that the disappearance of agriculture only marginally affects the region’s factor income, but that the consequences for the self-sufficiency rate, for various landscape-related indicators and ecosystem services, and for the economy in the long term may be considerable. These benefits compensate for agriculture’s modest direct economic value. The framework presented can potentially be applied to any region and scenario. This framework provides a basis for a learning package that allows potential detrimental consequences of regional development to be anticipated at an early stage.  相似文献   
33.
34.
35.
36.
Conflict are frequently observed when drinking water protection areas are to be defined and when many variants of how to protect these area are to be found. Using ten potential scenarios, a method is presented here which shows how such conflicts concerning these variants may be handled in a systematic manner. The technique is derived from the use of partially ordered sets and their visualization by Hasse diagrams. The first step is to define rankings of different variants according to each aim of protection. A further step is to define an appropriate relationship of order. It is then possible to visualize the extent of consensus and of dissension through the use of a Hasse diagram. The final step is to quantify the importance of each protection aim and the initialization of an iteration. Should a complete consensus be found, this would result in a chain of (connected) variants. Should a complete dissension be found on the other hand, an antichain would then result (i.e. where all variants are isolated).  相似文献   
37.
Zur Unterstützung von Bewertungs- und Entscheidungsprozessen über die Nachhaltigkeit von Managementstrategien, deren Auswirkungen durch unterschiedlich dimensionierte Indikatoren gemessen werden, gibt es verschiedene mathematische Methoden. In diesem Beitrag werden die Prinzipien dieser sog. multikriteriellen Bewertungs- und Entscheidungshilfeinstrumente beispielhaft anhand einer Auswahl von Strategien für ein Nachhaltiges Wassermanagement vorgestellt, sowie Vor- und Nachteile herausgearbeitet. Es wird gezeigt, dass sich die Verfahren insbesondere in Transparenz, Objektivit?t und durch den Grad an Partizipation durch Akteure z.T. erheblich unterscheiden. W?hrend die Hassediagrammtechnik sich an den naturwissenschaftlich begründbaren Datenmatrix orientiert und somit eine objektive und transparente Bewertung und Datenanalyse liefert, haben Konkordanzanalyse, Nutzwertanalyse, PROMETHEE und AHP ihre St?rken in der M?glichkeit, Akteure bzw. Stakeholder am Entscheidungsprozess partizipieren zu lassen. *** DIRECT SUPPORT *** A00OI029 00003  相似文献   
38.
39.
40.
Macro-scale simulations often play an important role in the assessment and remediation of contamination by dense non-aqueous phase liquids (DNAPLs) in the subsurface. Effective parameters for the macro scale are required for these simulations in order to avoid a detailed discretisation of the geological structures. Starting from the observed influence of heterogeneities on multiphase flow processes at the macro scale, we present an upscaling procedure from the local to the macro scale for the derivation of constitutive relationships for multiphase flow processes. The approach is based on the assumption of an equilibrium of (capillary) forces, which allows the application of a percolation model. This results in saturation distributions for different capillary pressures. Averaging these distributions gives rise to a macroscopic capillary pressure-saturation relationship. For the saturation distribution, relative permeabilities and effective conductivities are computed depending on the structure and the flow direction. These are averaged with the help of the renormalisation method. The evolving relative permeability-saturation relationship for the macro scale shows a saturation-dependent anisotropy and pronounced residual saturations of the nonwetting phase (which were not assumed for the local scale). The anisotropy reflects the underlying structure of the considered system that needs not to be known in detail.  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