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   3793篇
  免费   247篇
  国内免费   585篇
安全科学   216篇
废物处理   163篇
环保管理   951篇
综合类   1818篇
基础理论   508篇
环境理论   1篇
污染及防治   451篇
评价与监测   78篇
社会与环境   388篇
灾害及防治   51篇
  2024年   8篇
  2023年   61篇
  2022年   94篇
  2021年   103篇
  2020年   107篇
  2019年   116篇
  2018年   93篇
  2017年   138篇
  2016年   143篇
  2015年   154篇
  2014年   170篇
  2013年   273篇
  2012年   297篇
  2011年   280篇
  2010年   199篇
  2009年   217篇
  2008年   150篇
  2007年   282篇
  2006年   229篇
  2005年   194篇
  2004年   169篇
  2003年   147篇
  2002年   132篇
  2001年   104篇
  2000年   131篇
  1999年   102篇
  1998年   76篇
  1997年   63篇
  1996年   50篇
  1995年   49篇
  1994年   57篇
  1993年   49篇
  1992年   30篇
  1991年   29篇
  1990年   16篇
  1989年   12篇
  1988年   10篇
  1986年   6篇
  1985年   4篇
  1984年   7篇
  1983年   5篇
  1982年   7篇
  1981年   4篇
  1980年   7篇
  1979年   13篇
  1978年   5篇
  1977年   4篇
  1973年   7篇
  1972年   5篇
  1971年   8篇
排序方式: 共有4625条查询结果,搜索用时 296 毫秒
121.
西昌地区野生藜蒿资源的开发利用   总被引:5,自引:1,他引:5  
作者根据对四川省西昌地区野生藜蒿资源的调查研究。论述了野生藜蒿的生物学特征,分布、开发利用价值,繁殖特性和经济效益,并提出了开发利用野生藜蒿资源的建议。  相似文献   
122.
榆林地区甘草资源的开发与利用   总被引:1,自引:1,他引:1  
王晓荣 《资源开发与市场》2003,19(6):402-402,414
根据对陕西省榆林地区甘草资源的调查研究,论述了甘草的生物学特征、分布、开发利用价值、栽培技术和经济效益,并提出了开发利用甘草资源的建议。  相似文献   
123.
/ This study intended to explore the perceptions of mountain bikingmanagement through a mail survey of state park directors in all 50 states.With a 100% response rate, it was found that 47 states permit mountainbiking in their state parks, however, few state parks have formalized plansto manage this outdoor activity. The management policies that do exist arenot followed on a statewide basis but vary within each state and at eachstate park. Many states have worked cooperatively with local mountain bikingclubs to develop and maintain mountain bike trails, promote rider education,and provide volunteer patrols on trails. The issue of user conflict surfacedwith almost three-fourths of the managers responding that conflict existedbetween mountain bikers and other trail users. This preliminary study shouldprompt further research with on-site managers focusing on the use ofmanagement plans for mountain biking, cooperation between managers and usergroups, and user conflict. It is recommended that an Internet-basedinformation clearinghouse or discussion group be made available to landmanagers by a national bicycling organization.KEY WORDS: Mountain biking; State parks; State park directors;Recreation resource management  相似文献   
124.
海南特区农村剩余劳动力资源的开发与利用   总被引:1,自引:0,他引:1  
本文论述了海南特区农村剩余劳动力资源的现状及其影响劳动力资源开发利用的主要因素,提出了海南特区农村剩余劳动力资源开发与利用的途径。  相似文献   
125.
湖北旅游资源特征与分区   总被引:1,自引:0,他引:1  
本文在分析湖北省旅游资源的赋存状况和特征基础上,提出了湖北旅游的分区方案,包括鄂东综合旅游,鄂中名胜古迹,鄂西北山岳风光和鄂西南峡谷溶洞与民俗风情4大旅游区,旨在为湖北区域旅游开发与产业布局提供理论依据。  相似文献   
126.
Most writers on resource management presume that local populations, if they act in their self-interest, seldom conserve or protect natural resources without external intervention or privatization. Using the example of forest management by villagers in the Indian Himalayas, this paper argues that rural populations can often use resources sustainably and successfully, even under assumptions of self-interested rationality. Under a set of specified social and environmental conditions, conditions that prevail in large areas of the Himalayas and may also exist in other mountain regions, community institutions are more efficient in managing resources than either private individuals or the central government. In advancing this argument, the paper undermines the often dogmatic belief in the universal superiority of private forms of ownership and management.  相似文献   
127.
Adaptive management: Promises and pitfalls   总被引:3,自引:1,他引:3  
Proponents of the scientific adaptive management approach argue that it increases knowledge acquisition rates, enhances information flow among policy actors, and provides opportunities for creating shared understandings. However, evidence from efforts to implement the approach in New Brunswick, British Columbia, Canada, and the Columbia River Basin indicates that these promises have not been met. The data show that scientific adaptive management relies excessively on the use of linear systems models, discounts nonscientific forms of knowledge, and pays inadequate attention to policy processes that promote the development of shared understandings among diverse stakeholders. To be effective, new adaptive management efforts will need to incorporate knowledge from multiple sources, make use of multiple systems models, and support new forms of cooperation among stakeholders.  相似文献   
128.
ABSTRACT: Protection of ecosystems as entities on the landscape has attracted a wide range of support. Ecosystem-based public policies are claimed to be more effective, efficient, and scientifically sound than other approaches to environmental and natural resource policy. The ecosystem concept was never intended to serve as a public policy guide or to determine landscape units for land management purposes. This paper critically examines the use of the ecosystem concept in public policy and land use management and analyzes the proposed rule to manage the National Forest System according to ecosystem management principles. The concept is found to be unsuitable as a basis for guiding environmental and natural resource public policies in general while the proposed rule to manage the national forests according to ecosystem management principles is shown to be incoherent.  相似文献   
129.
130.
针对胜利电厂皮带输煤系统粉尘浓度高、污染环境、影响职工身体健康的问题,用布袋式除尘器替代原有的静电除尘器,并对布袋除尘器辅助系统进行了多处改进和完善,提高了运行的可靠性。投运后粉尘质量浓度由原来的18.3mg/m^3降低至1.68mg/m^3,除尘效率达到了98%以上。  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