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   577篇
  免费   26篇
  国内免费   39篇
安全科学   30篇
废物处理   26篇
环保管理   134篇
综合类   104篇
基础理论   142篇
环境理论   2篇
污染及防治   132篇
评价与监测   47篇
社会与环境   19篇
灾害及防治   6篇
  2023年   9篇
  2022年   5篇
  2021年   14篇
  2020年   11篇
  2019年   17篇
  2018年   21篇
  2017年   21篇
  2016年   39篇
  2015年   32篇
  2014年   28篇
  2013年   39篇
  2012年   21篇
  2011年   42篇
  2010年   37篇
  2009年   26篇
  2008年   42篇
  2007年   28篇
  2006年   21篇
  2005年   14篇
  2004年   17篇
  2003年   16篇
  2002年   20篇
  2001年   5篇
  2000年   6篇
  1998年   3篇
  1997年   11篇
  1996年   16篇
  1995年   8篇
  1994年   4篇
  1993年   8篇
  1992年   8篇
  1991年   4篇
  1990年   2篇
  1989年   2篇
  1987年   4篇
  1985年   3篇
  1984年   2篇
  1982年   4篇
  1981年   3篇
  1978年   2篇
  1962年   2篇
  1960年   1篇
  1959年   1篇
  1957年   5篇
  1953年   1篇
  1950年   1篇
  1947年   1篇
  1925年   1篇
  1920年   5篇
  1917年   1篇
排序方式: 共有642条查询结果,搜索用时 31 毫秒
131.
Robinson LA  Frid CL 《Ambio》2008,37(5):362-371
The organisms living on and in the sea floor, the benthos, represent an important ecological group. Although some (shellfish) have an economic value, most do not, and so little long-term data are available. We have identified three sources of historic benthic data for the North Sea, a regional sea that has been subjected to multiple human impacts for at least several hundred years. Each dataset has its limitations, but by their use together some issues emerge. Wider community shifts were observed in the shorter term and a number of extirpations at the scale of the North Sea were seen over longer time scales. The extirpated taxa share a number of characteristics consistent with an effect of fisheries such as fragile morphology. We must concentrate now on furthering our understanding of the ecological significance of shifts in dominance of particular functional units and protecting those habitats and species most vulnerable to fisheries-driven extirpation.  相似文献   
132.
For effective monitoring in social–ecological systems to meet needs for biodiversity, science, and humans, desired outcomes must be clearly defined and routes from direct to derived outcomes understood. The Arctic is undergoing rapid climatic, ecological, social, and economic changes and requires effective wildlife monitoring to meet diverse stakeholder needs. To identify stakeholder priorities concerning desired outcomes of arctic wildlife monitoring, we conducted in-depth interviews with 29 arctic scientists, policy and decision makers, and representatives of indigenous organizations and nongovernmental organizations. Using qualitative content analysis, we identified and defined desired outcomes and documented links between outcomes. Using network analysis, we investigated the structure of perceived links between desired outcomes. We identified 18 desired outcomes from monitoring and classified them as either driven by monitoring information, monitoring process, or a combination of both. Highly cited outcomes were make decisions, conserve, detect change, disseminate, and secure food. These reflect key foci of arctic monitoring. Infrequently cited outcomes (e.g., govern) were emerging themes. Three modules comprised our outcome network. The modularity highlighted the low strength of perceived links between outcomes that were primarily information driven or more derived (e.g., detect change, make decisions, conserve, or secure food) and outcomes that were primarily process driven or more derived (e.g., cooperate, learn, educate). The outcomes expand monitoring community and disseminate created connections between these modules. Key desired outcomes are widely applicable to social–ecological systems within and outside the Arctic, particularly those with wildlife subsistence economies. Attributes and motivations associated with outcomes can guide development of integrated monitoring goals for biodiversity conservation and human needs. Our results demonstrated the disconnect between information- and process-driven goals and how expansion of the monitoring community and improved integration of monitoring stakeholders will help connect information- and process-derived outcomes for effective ecosystem stewardship.  相似文献   
133.
Opportunity costs can represent a significant portion of the costs associated with conservation projects and frequently outstrip other kinds of cost. They are typically understood to refer to the benefits someone would have obtained if conservation projects had not required them to give up current activities, such as farming or hunting or if the land had been available for uses other than conservation. This familiar way of identifying opportunity costs is flawed, however, because it threatens to condone, or take advantage of, the injustices that many people face that affect their opportunities. I integrated ideas from the political theory of global justice to examine how the analysis of opportunity costs illustrates the importance of considering conservation and issues of global justice together, rather than thinking about them in isolation. I distinguish four baselines for defining opportunity costs. A status quo baseline defines opportunity costs by asking what people would have earned had a conservation project not happened. A willingness to accept baseline defines them by asking people what it would take to make them indifferent to whether a conservation project takes place or not. An antipoverty baseline suggests that opportunity costs have been met when people affected by a project are not left in poverty. An egalitarian baseline suggests opportunity costs have been met when people are not left in relative disadvantage, with worse than average opportunities. I argue that the egalitarian baseline is the most acceptable from the point of view of justice. Such a baseline would suggest that, in practice, many of the world's poor are being unjustly treated, or even exploited, as a result of conservation activities.  相似文献   
134.
135.
As the U.S. auto industry tries to remain competitive in the face of evolving environmental rules, the new administration is presented with the opportunity to achieve environmental and economic goals through an industry-government partnership. The authors suggest a policy of total environmental quality as a starting point.  相似文献   
136.
All models used in activated sludge design and analysis use parameters to characterize process performance. The values of these parameters are often assumed based on default values recommended in the literature, but to date, no quantitative estimates of the parameter uncertainties have been published. Similarly, little attention has been given to quantifying site-specific parameter variability, even though its occurrence has been observed several times in the literature. In this paper, universal uncertainty distributions of the model parameters from Activated Sludge Model No. 1 are developed from a database of parameter values reported in the literature using Bayesian statistics. Site-specific distributions of parameter variability were developed using the same techniques. All parameter distributions developed demonstrated that significant uncertainty and variability exist, which could lead to overdesign or plant failure if not considered during the design process.  相似文献   
137.
The most successful corporate environmental programs regard environmental compliance as an opportunity to improve productivity and profits and seek to integrate environmental information management systems (EIMS) into line information functions. Integrated EIMS should provide timely, accurate data to support all three types of environmental management responsibilities: results and comparison reports for source management; material and waste transaction and emission reports for materials management; and compliance, summary, exception, and trend data for risk managers at every level.  相似文献   
138.
139.
140.
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