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   210篇
  免费   1篇
  国内免费   2篇
安全科学   11篇
废物处理   9篇
环保管理   30篇
综合类   39篇
基础理论   23篇
污染及防治   76篇
评价与监测   22篇
社会与环境   2篇
灾害及防治   1篇
  2023年   1篇
  2022年   2篇
  2021年   4篇
  2020年   2篇
  2019年   2篇
  2018年   4篇
  2017年   5篇
  2016年   5篇
  2015年   1篇
  2014年   7篇
  2013年   20篇
  2012年   12篇
  2011年   17篇
  2010年   11篇
  2009年   11篇
  2008年   15篇
  2007年   11篇
  2006年   7篇
  2005年   12篇
  2004年   9篇
  2003年   5篇
  2002年   6篇
  2001年   12篇
  2000年   3篇
  1999年   2篇
  1998年   1篇
  1997年   2篇
  1995年   3篇
  1994年   1篇
  1992年   1篇
  1991年   3篇
  1989年   3篇
  1988年   2篇
  1987年   2篇
  1984年   4篇
  1983年   2篇
  1982年   2篇
  1981年   1篇
排序方式: 共有213条查询结果,搜索用时 0 毫秒
211.
ABSTRACT Operational cloud seeding projects, those designed to produce a desired change in the weather and that are nonexperimental in nature, continue to be pursued widely in the United States. A recurring question by scientists, project sponsors, and cloud seeders has been, “was the weather altered and if so, by how much?” Evaluation of such projects is now recognized as having scientific benefits, and a four-year study has addressed various techniques and statistical methods to perform evaluations and to learn more about how to modify the weather. Most such evaluations hinge on some type of space-time comparisons, but valid comparisons can be obtained only avoiding biases in the project design and operation. Through simulated changes in weather conditions, it was determined that the principal component regression techniques were used to evaluate selected rain and hail modification projects, revealing modification in certain projects and none in others. Various relevant issues have been examined such as use of other weather variables (covariates) to increase detection power, the validity of using historical data as controls for discrete operational periods, possible randomization options during cloud seeding operations, and analyses of individual rain events versus that based on monthly or seasonal units.  相似文献   
212.
Parasites may, in multi-parasite systems, block the defenses of their hosts and thus thwart host recognition of parasites by frequency-dependent selection. Nest defenses as frontline may block or promote the subsequent stage of defenses such as egg recognition. We conducted comparative studies of the defensive strategies of a host of the Oriental cuckoo Cuculus optatus, the yellow-bellied prinia Prinia flaviventris, in mainland China with multiple species of cuckoos and in Taiwan with a single cuckoo species. Cuckoo hosts did not exhibit aggression toward cuckoos in the presence of multiple cuckoo species but showed strong aggressive defenses of hosts directed toward cuckoos in Taiwan. Furthermore, the cuckoo host in populations with a single cuckoo species was able to distinguish adults of its brood parasite, the Oriental cuckoo, from adult common cuckoos (Cuculus canorus). This represents the first case in which a cuckoo host has been shown to specifically distinguish Oriental cuckoo, from other Cuculus species. Hosts ejected eggs at a higher rate in a single cuckoo species system than in a multi-species cuckoo system, which supports the strategy facilitation hypothesis. Granularity analysis of variation in egg phenotype based on avian vision modeling supported the egg signature hypothesis in hosts because Taiwanese prinias increased consistency in the appearance of their eggs within individual hosts thus favoring efficient discrimination against cuckoo eggs. This study significantly improves our knowledge of intraspecific variation in antiparasitism behavior of hosts between single- and multi-cuckoo systems.  相似文献   
213.
Adaptation to climate change has been recognized as very important in developing countries that face the greatest threats from global warming. In proposing various adaptation approaches, the United Nations Intergovernmental Panel on Climate Change required nations to prepare adaptation plans of action. However, the areas of priority in climate change adaptation have not been considered. This study has developed a new prioritization methodology for climate change adaptation in developing countries. Five categories and 25 approaches in climate change adaptation were adopted through a thorough and detailed analysis of pertinent literature related to the National Adaptation Program of Action (NAPA) in the Gambia. A fuzzy analytic hierarchy process-based questionnaire survey was designed and presented to 12 experts chosen from the committee members of the Gambia’s NAPA. The survey was made to determine the relative importance of the strategies for climate change adaptation. The results indicate that the five most important adaptation categories are health (0.223), forestry (0.213), water (0.210), food (0.181), and energy (0.174), with health as the number one priority in climate change adaptation. Further findings show that the prioritization order of the adaptation approaches to climate change in the Gambia is as follows: “Health education,” “public sensitization,” “water supply infrastructure development,” “microfinance,” and “infrastructure and technology enhancement.”  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