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   3篇
  免费   0篇
环保管理   2篇
基础理论   1篇
  2013年   1篇
  2012年   1篇
  1989年   1篇
排序方式: 共有3条查询结果,搜索用时 0 毫秒
1
1.
2.
Contemporary analysis of the food sector has failed convincingly to link production to consumption, and it has not provided a sociological account of such links. This paper makes a provisional attempt to begin such an analysis and does so by examining the case of the market for organic food in Tuscany. It proposes that the ‘pioneers’ of organics in this region constituted a new food movement that succeeded in opening up a new market. However, this market could only be successfully expanded once other actors were enrolled in the market-making process, notably state agencies and supermarkets. The regional government, through new regulations and specific initiatives, integrated organic foods into rural development policy, thereby assisting producers in the process of conversion. Supermarkets co-operated in the implementation of these policies and made space for Tuscan organic products in their stores. So while the ‘pioneers’ began the process of market building, these later entrants were crucial to the stabilization and expansion of the organic sector in Tuscany. Thus, it can be concluded that the emergence of these new ‘markets’ for nature can only be adequately explained by analysing the full range of actors. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
3.
The principal aim of this research is to solve problems of water-budget estimation in particularly indeterminate conditions, of the kind that are frequently encountered in the field, in which absence or insufficiency of hydrographic instrumentation prevents the adequate evaluation of runoff.To do this we have developed techniques that are based on the method of Kennessey (1930), in which the runoff coefficient of a watershed in estimated using three physiographic variables (slope angle, permeability, and vegetation cover) and a parameter that defines the climatic conditions of the local area. Our comparison of the Kennessey method with instrumental records from a wide variety of instrumented drainage basins in central Italy shows that the method provides reliable estimates of runoff. Our analysis also indicates the best criteria for its application, as shown by the examples and results presented in this article.This research enables us to present a new application of the method, namely the runoff coefficient map, which, in addition to its specific usefulness for the evaluation of runoff, has three advantages. First, it supplies a more realistic vision of the local distribution of runoff/rainfall ratios; second, it allows one to overcome the spatial constraints imposed by the narrow frame of reference represented by the watershed; and third, it makes an important contribution to the solution of other hydrogeological problems, such as the evaluation of the amount of water required for adequate recharge of the intake areas of deep aquifers or the maintenance of geothermal processes.Hence we propose this mapping technique as a valuable practical aid to regional hydrogeologic planning.  相似文献   
1
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