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   547篇
  免费   4篇
  国内免费   4篇
安全科学   1篇
废物处理   9篇
环保管理   25篇
综合类   300篇
基础理论   89篇
污染及防治   97篇
评价与监测   21篇
社会与环境   12篇
灾害及防治   1篇
  2018年   5篇
  2017年   8篇
  2016年   11篇
  2015年   8篇
  2013年   17篇
  2012年   8篇
  2011年   21篇
  2010年   13篇
  2009年   15篇
  2008年   20篇
  2007年   18篇
  2006年   6篇
  2005年   13篇
  2004年   14篇
  2003年   15篇
  2002年   12篇
  2001年   7篇
  1999年   13篇
  1998年   14篇
  1997年   8篇
  1996年   6篇
  1995年   7篇
  1994年   6篇
  1993年   5篇
  1975年   5篇
  1973年   6篇
  1972年   5篇
  1970年   8篇
  1967年   8篇
  1966年   4篇
  1965年   11篇
  1964年   4篇
  1963年   13篇
  1962年   10篇
  1961年   9篇
  1960年   10篇
  1959年   13篇
  1958年   9篇
  1957年   7篇
  1956年   9篇
  1955年   7篇
  1954年   5篇
  1953年   6篇
  1952年   5篇
  1951年   4篇
  1938年   4篇
  1930年   4篇
  1926年   6篇
  1914年   6篇
  1913年   10篇
排序方式: 共有555条查询结果,搜索用时 0 毫秒
301.
302.
A methodology for regional application of forest simulation models has been developed as part of an assessment of possible climate change impacts in the Federal state of Brandenburg (Germany). Here we report on the application of a forest gap model to analyse the impacts of climate change on species composition and productivity of natural and managed forests in Brandenburg using a statistical method for the development of climate scenarios. The forest model was linked to a GIS that includes soil and groundwater table maps, as well as gridded climate data with a resolution of 10 × 10 km and simulated a steady-state species composition which was classified into forest types based on the biomass distribution between species. Different climate scenarios were used to assess the sensitivity of species composition to climate change. The simulated forest distribution patterns for current climate were compared with a map of Potential Natural Vegetation (PNV) of Brandenburg.In order to analyse the possible consequences of climate change on forest management, we used forest inventory data to initialize the model with representative forest stands. Simulation experiments with two different management strategies indicated how forest management could respond to the projected impacts of climate change. The combination of regional analysis of natural forest dynamics under climate change with simulation experiments for managed forests outlines possible trends for the forest resources. The implications of the results are discussed, emphasizing the regional differences in environmental risks and the adaptation potentials of forestry in Brandenburg.  相似文献   
303.
304.
Urban water infrastructure expenditures cause a major financial burden to municipalities. In the opinion of many policy-makers, public funds may alleviate this burden and facilitate environmental policies. However, practice has shown that despite ambitious policies, funding often follows traditional cost-dominated thinking. In Austria, national policy-makers were interested in new guidelines for funding that increase the transparency of the planning, ensure the adequate treatment of ecological problems, and foster stakeholder involvement, but keep the process as simple as possible, and require minimal changes of the current guidelines. An interdisciplinary project team conducted such a study. Its outcome was tested in two pilot projects. Based on these experiences, policy-makers finally implemented the recommended guidelines for the funding of communal urban water infrastructure projects. A general observation about the policy-making process was a conservative attitude of policy-makers. They prefer simple constraints (precautionary principle) and flexible negotiations (delegation) to complex assessment and decision-aid methodologies.  相似文献   
305.
306.
307.
308.
Based on a recent survey of German composting plants an evaluation of costs and benefits of composting was attempted. In this regard, several economical, ecological and legal aspects and some interrelations are discussed in this paper. A special emphasis is placed on the fees and compost prices of composting plants. It is also shown how the legal framework provides the economic basis for composting in Germany, how economical and ecological costs and benefits could be assessed, and why it is so difficult to determine the value of composting.  相似文献   
309.
    
In Sweden there is a strong tradition of using nature areas for outdoor recreation. This paper reports on a study which explored preferences and willingness to pay for outdoor recreation close to home (≤100 km away from home and ≤24 hours stay at a recreation site) using the contingent valuation method. The data originated from a mail survey that involved Swedish residents who were randomly selected from a national register. An ordinary least squares regression model was used to account for factors influencing willingness to pay. The results showed that approximately 50% of the respondents used nature areas close to their home for recreation and their average frequency of visits to these areas was 74 times annually. Areas dominated by forests were the most preferred, followed by water. The respondents were willing to pay approximately 7200 SEK (US$1080) annually. Their willingness to pay was influenced by factors such as type of nature area, distance to and time spent at the recreation site and income. The results provide one input to the land use planning process by considering the demand for nature-based outdoor recreation close to home.  相似文献   
310.
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