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   542篇
  免费   63篇
  国内免费   29篇
安全科学   48篇
废物处理   2篇
环保管理   131篇
综合类   143篇
基础理论   174篇
环境理论   4篇
污染及防治   18篇
评价与监测   25篇
社会与环境   58篇
灾害及防治   31篇
  2023年   8篇
  2022年   21篇
  2021年   12篇
  2020年   20篇
  2019年   30篇
  2018年   27篇
  2017年   28篇
  2016年   25篇
  2015年   31篇
  2014年   20篇
  2013年   36篇
  2012年   23篇
  2011年   48篇
  2010年   25篇
  2009年   24篇
  2008年   25篇
  2007年   28篇
  2006年   27篇
  2005年   25篇
  2004年   17篇
  2003年   18篇
  2002年   23篇
  2001年   21篇
  2000年   20篇
  1999年   8篇
  1998年   10篇
  1997年   7篇
  1996年   4篇
  1995年   6篇
  1994年   3篇
  1993年   3篇
  1992年   4篇
  1990年   2篇
  1989年   1篇
  1985年   1篇
  1982年   1篇
  1981年   1篇
  1977年   1篇
排序方式: 共有634条查询结果,搜索用时 265 毫秒
41.
Abstract: It is critical to understand the ability of water management to prepare for and respond to the likely increasing duration, frequency, and intensity of droughts brought about by climate variability and change. This article evaluates this ability, or adaptive capacity, within large urban community water systems (CWSs) in Arizona and Georgia. It analyzes interview data on the bridges and barriers to adapting water management approaches in relation to extreme droughts over the past decade. This study not only finds levers for building adaptive capacity that are unique to each state but also identifies several unifying themes that cut across both cases. The interviews also show that a particular bridge or barrier, such as state regulation, is not universally beneficial or detrimental for building adaptive capacity within each state. Such knowledge is useful for improving water and drought management and for understanding how CWSs might prepare for future climate variability and change by removing the barriers and bolstering the bridges in efforts to build adaptive capacity.  相似文献   
42.
分析云南山区公路严峻的交通形势,及山区公路交通事故的特征、事故形态及影响因素,研究山区公路交通事故发生的机理。从人、车、路和环境等方面分析事故产生的原因,提出针对云南山区事故多发路段安全对策措施。分析表明,在云南山区,路况、人员安全素质、车辆性能、安全管理均处于较低水平,是重大事故多发的根本原因。提高系统安全性,实现系统功能最强,应使系统各要素相互匹配,以实现本质安全。  相似文献   
43.
SUMMARY

An assessment is made of various grassroots development initiatives in Latin America which show that agroecological technologies can bring significant environmental and economic benefits to small farmers and rural communities in the region. Examined initiatives offer new ways of enhancing the multifunctional attributes of traditional agriculture through greater per unit area productivity and environmental services obtained in complex, integrated agroecological systems that feature many crop varieties, together with animals and trees. If such experiences were to be scaled up, multiplied, extrapolated, and supported in alternative policy scenarios, the gains in food security and environmental conservation would be substantial. The challenge now is to mobilize science, institutions and the right policies to increase the productivity of smallholder farming systems, while preserving the resource base and at the same time empowering local communities.  相似文献   
44.
The United States is finding it difficult to develop a coherent policy on acid rain. Despite more than a decade of scientific research and policy initiatives, no clear course of action has been identified. This article argues that what is missing is an integrated assessment of the scientific knowledge that will guide the political process. The role of the integrated assessment is described, and a conceptual framework presented that would accomplish the desired goal. Currently available acid rain assessment models are compared against this framework and found to be less than satisfactory. The article concludes by stressing the opportunity now available to the National Acid Precipitation Assessment Program to perform such an assessment and break the logjam.  相似文献   
45.
Morton J  Barton D 《Disasters》2002,26(3):213-228
The idea of externally assisted emergency destocking of pastoralists has gained currency in recent years: increasing the incentives for pastoralists to sell animals, or removing the constraints to selling animals in the early stages of drought. We identify two separate rationales put forward by proponents of destocking: environmental benefits and purchasing power/welfare benefits. We consider whether specific recent critiques of 'new range ecology' and specifically of 'tracking policies' do in fact provide arguments against emergency destocking in pastoralist areas. We illustrate some of these themes with a case study of a successful destocking exercise in northern Kenya where a very specific form of support was requested and received by pastoralists themselves. The sorts of destocking that work are likely to have significant effects on pastoralist purchasing power at key points of the drought cycle, but minimal effects on the environment. Clarifying these points will make it easier to promote destocking as a drought-mitigation policy.  相似文献   
46.
介绍了国内外碳酸钙行业生产、应用技术发展现状和池州市碳酸钙资源开发现状,找出了池州市碳酸钙资源开发中存在的问题和解决措施,提出了池州市碳酸钙工业发展需要实施的各种措施。  相似文献   
47.
48.
49.
The success of government programs to control nonpoint source pollution depends upon attitudes toward those programs and the availability of technical and financial assistance. Applicants for the Rural Clean Water Program cost-share funding in Virginia possess different personal and operational characteristics than do nonapplicants. Factors associated with participation in the Rural Clean Water Program differed from those associated with the more traditional soil conservation programs. Discriminant analysis was used to differentiate between other farmers who may become applicants and nonapplicants. Farmers' attitudes toward various policy options for inducing implementation of nonpoint source management practices varied greatly. Farmers were most favorable to cost sharing, low-interest loans and tax credits, and least favorable to a soil loss tax. They were either very favorably or very unfavorably inclined toward cross-compliance between pollution control and other agricultural programs.  相似文献   
50.
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