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   63篇
  免费   2篇
安全科学   1篇
废物处理   1篇
环保管理   16篇
综合类   21篇
基础理论   11篇
环境理论   1篇
污染及防治   10篇
评价与监测   2篇
灾害及防治   2篇
  2019年   1篇
  2018年   3篇
  2016年   1篇
  2015年   2篇
  2013年   6篇
  2010年   4篇
  2009年   5篇
  2008年   3篇
  2007年   1篇
  2006年   2篇
  2004年   1篇
  2003年   3篇
  2002年   3篇
  2001年   2篇
  1999年   1篇
  1998年   1篇
  1997年   1篇
  1996年   3篇
  1995年   3篇
  1994年   1篇
  1993年   2篇
  1991年   1篇
  1985年   1篇
  1984年   1篇
  1982年   2篇
  1979年   1篇
  1968年   2篇
  1962年   1篇
  1961年   1篇
  1960年   1篇
  1959年   1篇
  1958年   1篇
  1956年   1篇
  1954年   2篇
排序方式: 共有65条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
Joas M  Kern K  Sandberg S 《Ambio》2007,36(2-3):237-242
Policymaking within and among states is under pressure for change. One feature of this change is empirically observed as an activation of different network structures in the Baltic Sea Region, especially since the collapse of the Iron Curtain, the initiation of the Rio process, and the enlargement of the European Union. The contemporary theoretical debates about governance highlight the changing conditions for policymaking and implementation on all societal levels. This process of change, especially evident concerning environmental policies, includes new types of networks crossing state borders both at the supranational and the subnational levels. This article illuminates this process of change with empirical data from the project "Governing a Common Sea" (GOVCOM) within the Baltic Sea Research Program (BIREME).  相似文献   
7.
Sediment is an important pollutant for Lake Erie and its tributaries as a carrier of other substances and as a pollutant in its own right. Environmental managers have called for major reductions in sediment loadings in Lake Erie tributaries. In this study, 30-yr (1975-2005) datasets with daily resolution are analyzed to identify and interpret trends in sediment concentrations and loads in major US tributaries to Lake Erie. The Maumee and Sandusky Rivers in agricultural northwest Ohio show continual decreases throughout this period, but the River Raisin shows increases, especially in the last decade. The urban and forested Cuyahoga River shows little trend before 2000 but shows increases since then. The mostly forested Grand River shows strong decreases before 1995, little change thereafter until the early 2000s, and then increases. In most cases, the greatest decreases or smallest increases, depending on the river, are associated with summer and fall and with low flow conditions, whereas the smallest decreases or greatest increases are associated with the spring and with high flow conditions. Analysis of concentration-flow relationships indicates that these changes are not due to weather but reflect positive and negative anthropogenic influences. Sediment decreases in the northwestern Ohio tributaries seem to reflect the successful use of agricultural practices to reduce erosion and prevent sediment loss. Opportunities for further reductions in sediment loads and concentrations lie in better management of sediment losses during winter and spring.  相似文献   
8.
Substantial conflict exists over water management and allocation in the Platte River Basin of Nebraska. An interdisciplinary computer simulation model, representing the water quantity, water quality, environmental, and economic dimensions of the conflict, was developed in order to analyze the tradeoffs among allocation scenarios. Most importantly, decisionmakers and interest groups were involved in model development. Simulation results for a base case and two scenarios are presented. One scenario favors protection of instream flow for wildlife; the other favors water diversions for agriculture. Impacts of the instream flow scenario, as measured by the amount of land irrigated, groundwater levels, the amount of wildlife habitat for cranes and catfish, and net agricultural benefits did not differ greatly from those of the base case. However, impacts of the diversion scenario were substantial. On the negative side, instream flows and wildlife habitat declined an average of 39 percent; while, on the positive side, groundwater levels and net agricultural benefits each increased 6 percent. The modeling process was successful insofar as it promoted an understanding among the highly diverse interest groups of the systems nature of the Basin. One agreement on a water diversion schedule among three of the parties has been reached, partly as a result of this process. More comprehensive compromises have not yet been forged. Our experience, however, indicates that modeling success at the policymaking level depends more on the extent to which the policymakers understand the model than it does on model sophistication.  相似文献   
9.
A method for the determination of 16 selected pharmaceuticals in surface water using LC-MS/MS has been developed Methods from literature were adapted within the scope of this study. The limit of quantification of 13 out of 16 analytes is below 10 ng/l. The analysis of samples from the Saale river and lakes around Halle demonstrated that Carbamacepin (Median 207 ng/l) and Diclofenac (Median 196 ng/l) are detectable at various sampling stations along the river. The wastewater path was identified as the most relevant source for pharmaceutical residues entering the environment. Besides, the results reveal increased levels of several substances in some smaller anabranches and brooks.  相似文献   
10.
Australia's 'Landcare' programme is a community-based, participatory programme established by government, to tackle the problem of land degradation. It has been hailed by some as the world's most imaginative sustainable development policy. In light of the agreements reached at the Rio Earth Summit, particularly Agenda 21, the experience of established programmes such as Landcare may be useful to those beginning to grapple with the call for greater community involvement. This paper explores briefly the presentation and enactment of ideas of 'community' and 'ownership' in the Landcare programme and finds that, contrary to the rhetoric, community 'ownership' of Landcare is, in practice, ambiguous.  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