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   7篇
  免费   0篇
环保管理   1篇
综合类   1篇
社会与环境   5篇
  2009年   1篇
  2006年   1篇
  2005年   2篇
  2002年   1篇
  2001年   1篇
  1993年   1篇
排序方式: 共有7条查询结果,搜索用时 15 毫秒
1
1.
Specific features of progressive succession in the vegetation of anthropogenically transformed landscapes in southeastern Belarus have been studied in permanent test plots. Using phytoindication scales proposed by Ellenberg (1974) and Tsyganov (1983), trends of changes in ecological conditions in the first years of succession have been revealed.  相似文献   
2.
3.
Population heterogeneity in cespitose, fibrous-rooted, brevirhizomatous, stoloniferous, and tap-rooted herbaceous and woody plants is described. This heterogeneity is caused by the multivariant character of plant ontogeny (i.e., its dimensional, morphological, rhythmological, and temporal multiversality), which is regarded as the main adaptation mechanism operating in plant populations because it provides for the diversity of ontogenetic pathways under different ecological conditions.  相似文献   
4.
层次分析法在城市生态环境质量评价中的应用   总被引:29,自引:1,他引:29  
喻良  伊武军 《四川环境》2002,21(4):38-40
根据层次分析法的基本原理,在城市生态环境质量评价中建立各层次模型,并以福州市为例,通过对该市近年来城市生态环境质量的评价结果分析,对今后城市规划提出建议,为以后建设生态城市提供直接服务。  相似文献   
5.
The results of studies on transformations of the floristic diversity of forest ecosystems under the effect of human activity in the southern and middle taiga subzones of the Komi Republic are reviewed. It is shown that the change of dominants in the tree layer leads to the formation of specific biotopes and, as a consequence, to changes in floristic complexes and the cenotic roles of species in the lower layers of forest communities. In the study region, the -diversity of forest communities is determined mainly by two environmental factors: soil fertility and acidity. The factor of illumination has only a slight effect on the -diversity of taiga forests, which is especially clear in the group of deciduous forest formations.__________Translated from Ekologiya, No. 3, 2005, pp. 180–185.Original Russian Text Copyright © 2005 by Degteva.  相似文献   
6.
黄河流域是中华古文明的重要发祥地之一.地处黄河中游的山西省运城市拥有灿烂的文化与数千年的农耕发展史.然而,伴随着社会经济的不断发展,对自然生态环境的污染和破坏以及它所面临着的严峻生态环境形势正在影响与制约着其自身经济社会的可持续发展与进步.本文通过对山西省运城市生态环境的现状调查并针对运城市生态环境的现状与问题,分析了造成生态环境破坏的主要原因,从多方面提出了加强和改进生态环境保护的若干对策与措施.  相似文献   
7.
四川省中低产田土的综合治理   总被引:1,自引:0,他引:1  
本文以四川中低产田土综合治理实况为例,着重论述了自然灾害对农业生态系统的严重危害,从而阐明了改造中低产田土对提高经济、生态、社会三大效益的重要性和紧迫性,并从省情出发,总结提出当前乃至今后相当一个时期,农业部门所应采取的几项行之有效的措施,展望了2000年前景。  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