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   126篇
  免费   1篇
  国内免费   2篇
安全科学   4篇
废物处理   7篇
环保管理   54篇
综合类   10篇
基础理论   20篇
环境理论   1篇
污染及防治   13篇
评价与监测   14篇
社会与环境   1篇
灾害及防治   5篇
  2023年   1篇
  2021年   1篇
  2020年   2篇
  2019年   2篇
  2018年   5篇
  2017年   5篇
  2016年   5篇
  2015年   4篇
  2014年   2篇
  2013年   15篇
  2012年   3篇
  2011年   7篇
  2010年   6篇
  2009年   5篇
  2008年   2篇
  2007年   6篇
  2006年   3篇
  2005年   6篇
  2004年   9篇
  2003年   2篇
  2002年   4篇
  2001年   4篇
  2000年   2篇
  1999年   2篇
  1998年   3篇
  1997年   4篇
  1996年   5篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1987年   3篇
  1985年   1篇
  1979年   1篇
  1978年   1篇
  1969年   1篇
排序方式: 共有129条查询结果,搜索用时 15 毫秒
121.
A nation-wide ecosystem science network for Canada was formed in 1994. At that time, mercury was a re-emerging issue in Canada and the Coordinating Office for the networksought collaboration to assess the issue. The key mechanismsby which the network has added value in addressing this issue are: 1) Information Dissemination, the network has organised, facilitated and co-hosted a number of regional,national and international mercury events (meetings, conferences and workshops) which have served to bring theexpertise together, the network also disseminates informationon it's web page, and the Coordinating Office hosts an annualNational Science Conference; 2) Collaborative Mercury Monitoring, network partners advocated the need for a singlehemispheric mercury network which resulted in the developmentof a compatible Canada–U.S. mercury deposition network, whichmay also be expanded into Mexico, and 3) Environmental Reporting, the network has collaborated with others to reporton current mercury findings through initiatives such as the 1998 Northeast States and Eastern Canadian Mercury Study, a 1999 Mercury Case Study and is presently a partner in the University of Quebec's proposal to form a Collaborative Mercury Ecosystem Research Network in Canada.  相似文献   
122.
This paper draws upon the DISCUS (Developing Institutional and Social Capacity for Sustainable Development) research project, co-funded by the European Commission. The project was undertaken during 2001 – 2004 and involved an in-depth study of 40 European towns and cities in order to understand the institutional and social factors and conditions that might contribute to policy ‘achievement' or ‘failure' in local sustainable development policy and practice. Based on the findings of this research it proposes a conceptual framework for local sustainable development, linking the concepts of institutional capital, social capital and governance to provide a model for understanding the governing of local sustainability. The research shows that in those cases that exhibit sustainable development policy achievements, there are also greater levels of civil society activity and knowledge regarding sustainability issues, and high levels of institutional capacity. Confident local government is crucial to the development of institutional capacity and to institutional learning. One aspect of this is local authorities being equipped to address the longer-term issues and to have a strategic vision for a sustainable future.  相似文献   
123.
124.
Mate choice is not just a female preoccupation. Under some circumstances, males may also be choosy. However, studies of male mate choice have generally been confined to situations where males can make direct comparisons between potential partners. In contrast, sequential male mate choice has largely been overlooked despite its biologically importance, especially if current investment in mate attraction diminishes a males future mating opportunities. Using the Pacific blue-eye fish Pseudomugil signifer, we show that males are capable of exercising sequential mate choice. When presented sequentially with large and small females, males spent more effort courting the former. However, males did not appear to modify the time spent courting a given female based on the size of the female encountered previously. We suggest that greater attention to the sequential choice problem in males may help illuminate similarities and differences between the sexes when it comes to mating decisions.Communicated by T. Czeschlik  相似文献   
125.
This paper identifies criteria for efficient public utilization of designated wildlife sites. It describes a survey of the major wildlife sites in Scotland in order to determine the site management objectives and extent to which sites are utilized by visitors. Substantial differences were found to exist between organizations as regards site management objectives, promotion and the provision of visitor facilities. Explanations for the apparent variability in efficiency of site utilization are discussed in terms of organization ideology, funding and structure. It is argued that trusts funded through membership may be best able to reconcile the benefits from current site utilization with the conservation of long‐term use and existence values.  相似文献   
126.
At the end of the 20th century, business finds itself in a period of transformation and a new emphasis on environmentally responsible practices. Leading-edge companies are now integrating environmental concerns into everyday business activities. Competitive issues, which led to the formation of just-in-time production processes, are now forcing companies to better understand their effects on the environment. Business leaders must now look at environmental issues as opportunities, not burdens. With innovative use of “industrial ecology,” companies can set the stage for long-term growth into the next century. “Business men go down with their businesses because they like the old way so well they cannot bring themselves to change.” Henry Ford.  相似文献   
127.

Objective

In gastroschisis, there is evidence to suggest that gut dysfunction develops secondary to bowel inflammation; we aimed to evaluate the effect of maternal antenatal corticosteroids administered for obstetric reasons on time to full enteral feeds in a multicenter cohort study of gastroschisis infants.

Methods

A three center, retrospective cohort study (1992-2013) with linked fetal/neonatal gastroschisis data was conducted. The primary outcome measure was time to full enteral feeds (a surrogate measure for bowel function) and secondary outcome measure was length of hospital stay. Analysis included Mann-Whitney and Cox regression.

Results

Of 500 patients included in the study, 69 (GA at birth 34 [25-38] weeks) received antenatal corticosteroids and 431 (GA at birth 37 [31-41] weeks) did not. Antenatal corticosteroids had no effect on the rate of reaching full feeds (Hazard ratio HR 1.0 [95% CI: 0.8-1.4]). However, complex gastroschisis (HR 0.3 [95% CI: 0.2-0.4]) was associated with an increased time to reach full feeds and later GA at birth (HR 1.1 per week increase in GA [95% CI: 1.1-1.2]) was associated with a decreased time to reach full feeds.

Conclusion

Maternal antenatal corticosteroids use, under current antenatal steroid protocols, in gastroschisis is not associated with an improvement in neonatal outcomes such as time to full enteral feeds or length of hospital stay.  相似文献   
128.
129.
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