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   949篇
  免费   22篇
  国内免费   13篇
安全科学   37篇
废物处理   29篇
环保管理   212篇
综合类   143篇
基础理论   191篇
环境理论   1篇
污染及防治   260篇
评价与监测   51篇
社会与环境   40篇
灾害及防治   20篇
  2023年   13篇
  2022年   22篇
  2021年   25篇
  2020年   13篇
  2019年   10篇
  2018年   18篇
  2017年   18篇
  2016年   22篇
  2015年   26篇
  2014年   23篇
  2013年   102篇
  2012年   25篇
  2011年   42篇
  2010年   32篇
  2009年   39篇
  2008年   48篇
  2007年   45篇
  2006年   43篇
  2005年   43篇
  2004年   44篇
  2003年   47篇
  2002年   31篇
  2001年   17篇
  2000年   11篇
  1999年   24篇
  1998年   16篇
  1997年   17篇
  1996年   12篇
  1995年   12篇
  1994年   15篇
  1993年   15篇
  1992年   10篇
  1991年   3篇
  1990年   11篇
  1989年   7篇
  1988年   8篇
  1987年   8篇
  1986年   2篇
  1985年   17篇
  1984年   7篇
  1983年   6篇
  1982年   7篇
  1981年   7篇
  1980年   5篇
  1979年   4篇
  1978年   2篇
  1974年   2篇
  1971年   2篇
  1941年   1篇
  1934年   1篇
排序方式: 共有984条查询结果,搜索用时 323 毫秒
61.
Abstract: Conservation biologists have developed powerful tools for reserve selection and design over the past two decades, yet seldom are protected areas actually designed on scientific grounds. Using fundamental biological and socioeconomic principles of conservation science, we designed a new protected area and its multiple-use zone on the Masoala Peninsula in the humid forest zone of Madagascar. The explicit design criteria determined the data gathered for the work, which included (1) spatial distribution and quality of habitat, (2) the areas and species at greatest risk, (3) the relationship between environmental gradients and species distributions, (4) current and predicted human settlement and land and resource use, and (5) the economic potential of natural forest management as an alternative to deforestation. We used a geographic information system to integrate these data layers and applied the design criteria to develop a park proposal that balanced human and wildlife needs. The proposal won the approval of local residents, and a national decree in 1997 designated 2100 km2 of rainforest and three satellite marine reserves as the Masoala National Park, with a surrounding multiple-use zone of approximately 1000 km2. The new park is Madagascar's largest protected area and protects more lowland (<400 m) humid forest habitat than the entire reserve system combined, a significant step forward in conserving a globally important ecoregion. Consideration of local needs and the national economy was a key element in gaining approval for the Masoala Park. Such an approach toward reserve design could be applied elsewhere to improve chances of establishing and maintaining protected areas over the long term.  相似文献   
62.
Since the completion of the Management of Myelomeningocoele Study, maternal-fetal surgery for spina bifida has become a valid option for expecting parents. More recently, multiple groups are exploring a minimally invasive approach and recent outcomes have addressed many of the initial concerns with this approach. Based on a previously published framework, we attempt to delineate the developmental stage of the surgical techniques. Furthermore, we discuss the barriers of performing randomized controlled trials comparing two surgical interventions and suggest that data collection through registries is an alternative method to gather high-grade evidence.  相似文献   
63.
Hydrologic analysis for coastal wetland restoration   总被引:1,自引:0,他引:1  
Increasing recognition of the value of tidal wetlands has led to interest in how to restore and enhance areas that have been modified by human activity. The policy of recognizing restoration or enhancement as mitigation for destruction of other wetlands is controversial. Once policy questions are separated from technical questions, the steps in a successful project are straightforward A key element in the design of a successful project is quantitative hydraulic and hydrologic analysis of alternatives. Restoration projects at two sites in California used a combination of empirical geomorphic relationships, numerical modeling, and verification with field observations. Experience with these and other wetland restoration projects indicates the importance of longterm postproject monitoring, inspection, and maintenance  相似文献   
64.
65.
Activities in Brazil's forest sector have substantial potential for mitigating global warming as well as additional environmental and other benefits. Silvicultural plantations of different types, reduced impact logging, and deforestation avoidance all have potential mitigation roles. The magnitude of the annual emission from recent rates of deforestation in Amazonia presents an opportunity for carbon (C) benefits through reducing current rates of deforestation. Measures related to Amazonian deforestation have greater potential carbon benefits than do options such as plantation silviculture, but much depends on how benefits are calculated. Procedures are needed for assessing the environmental and social impacts of Clean DevelopmentMechanism (CDM) projects.  相似文献   
66.
67.
This paper presents a case study of negotiations over the combination of a small manufacturing firm into a multi-billion dollar conglomerate following its 'white knight' acquisition. It focuses on the strategic and tactical conflicts between the two firms and traces these to the party's emotional reactions to the combination. Feeling of loss versus gain in the two firms, each party's sense of uncertainty and threat, and their moves toward proactive versus reactive control in the combination are analysed to identify the roots of strategic conflict. These feelings, plus incompatibilities in the two company's managements, business systems, corporate cultures, and goals for combination ramify in conflict in the negotiations themselves. The paper concludes with a more generic model illustrating contextual features of combinations that shape human reactions and conflicts in negotiations after the sale.  相似文献   
68.
69.
In this article, Rohm & Haas' Responsible Care® implementation strategy and management system verification (MSV) experiences are detailed. Recommendations on how to strengthen the verification process are provided.  相似文献   
70.
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