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   320篇
  免费   19篇
  国内免费   31篇
安全科学   2篇
废物处理   1篇
环保管理   136篇
综合类   83篇
基础理论   64篇
环境理论   1篇
污染及防治   28篇
评价与监测   21篇
社会与环境   17篇
灾害及防治   17篇
  2023年   2篇
  2022年   10篇
  2021年   14篇
  2020年   10篇
  2019年   11篇
  2018年   7篇
  2017年   9篇
  2016年   15篇
  2015年   11篇
  2014年   7篇
  2013年   20篇
  2012年   11篇
  2011年   19篇
  2010年   10篇
  2009年   10篇
  2008年   14篇
  2007年   18篇
  2006年   17篇
  2005年   14篇
  2004年   10篇
  2003年   8篇
  2002年   5篇
  2001年   11篇
  2000年   13篇
  1999年   10篇
  1998年   3篇
  1997年   6篇
  1996年   7篇
  1995年   4篇
  1994年   2篇
  1993年   8篇
  1992年   3篇
  1990年   2篇
  1989年   1篇
  1988年   6篇
  1987年   4篇
  1986年   3篇
  1985年   3篇
  1984年   6篇
  1983年   2篇
  1982年   4篇
  1981年   4篇
  1980年   1篇
  1979年   4篇
  1978年   3篇
  1977年   2篇
  1976年   1篇
  1975年   2篇
  1972年   2篇
  1971年   1篇
排序方式: 共有370条查询结果,搜索用时 15 毫秒
221.
The Great Basin Desert lies between the Sierra Nevada Mountains to the west and the Rocky Mountains to the east. Nearly 60% of the area’s deserts and mountains (roughly 30 million ha) are managed by the U. S. Department of Interior’s Bureau of Land Management. This area is characterized by low annual precipitation, diverse desert plant communities, and local economies that depend on the products (livestock grazing, recreation, mining, etc.) produced by these lands. The ecological and economic stability of the Great Basin is increasingly at risk due to the expansion of fire-prone invasive species and increase in wildfires. To stem this loss of productivity and diversity in the Great Basin, the BLM initiated the “Great Basin Restoration Initiative” in 1999 after nearly 0.7 million ha of the Great Basin burned in wildfires. The objective of the Great Basin Restoration Initiative is to restore plant community diversity and structure by improving resiliency to disturbance and resistance to invasive species over the long-term. To accomplish this objective, a strategic plan has been developed that emphasizes local participation and reliance on appropriate science to ensure that restoration is accomplished in an economical and ecologically appropriate manner. If restoration in the Great Basin is not successful, desertification and the associated loss of economic stability and ecological integrity will continue to threaten the sustainability of natural resources and people in the Great Basin.  相似文献   
222.
日本阪神大震灾在应急救灾上的几点教训   总被引:4,自引:1,他引:4  
本文从防灾体制、心理准备和防灾规划等方面分析日本阪神大震灾在应急救灾行动中的教训,并结合我国的情况作了简单的讨论。  相似文献   
223.
This paper presents research currently being conducted in Central Queensland, Australia to understand conflicts between coastal zone resource users and the associated sociocultural and political issues surrounding coastal zone management. Conflict occurs between stakeholders in the coastal zone over values, conservation and development trade-offs, access, and resource use rights. Decisions are currently made within a multi-stakeholder framework where there is limited understanding among stakeholders of each groups values and aspirations, and few, mechanisms for negotiation, or to ensure transparency of decisions and feedback on consultation. This paper reports on the contribution of stakeholder analysis and social mapping to conflict management and findings from their application. As it is applied here, stakeholder analysis and social mapping have been successful participatory tools used to document and feed back the values, interests, attitudes and aspirations of stakeholders. Understanding stakeholder conflict is essential in progressing a whole catchment approach to decision-making that secures the cooperation of a diverse range of social groups.  相似文献   
224.
基于格网GIS的豫北地区干旱灾害风险区划   总被引:4,自引:0,他引:4  
以豫北地区32个市县为研究区域,从造成干旱灾害的4个因子,即致灾因子危险性、承灾体暴露性、脆弱性和防灾减灾能力4个角度出发,选取了包括气象、土壤、人口、社会经济在内的17项指标,在格网GIS技术的支持下,对评价体系中的各指标进行10 km×10 km尺度的网格化表达。应用自然灾害风险指数法,熵组合权重法和加权综合分析法,建立了干旱灾害风险评价模型;通过选取典型案例年,运用最优分割理论确定了干旱灾害风险阈值,并利用GIS技术绘制了豫北地区的干旱灾害风险区划图。结果显示:豫北地区的高风险区主要集中在濮阳市区、濮阳县、清丰县、南乐县、新乡市区;而西部的济源市、孟州市,以及原阳县风险较轻。  相似文献   
225.
Ra isotopes are a powerful tool for quantifying the flux of submarine groundwater discharge (SGD) into the sea. Previous studies of 223Ra and 224Ra mass balances in coastal embayments have shown that the Ra balance is dominated by supply via SGD, exchange with the open ocean and radioactive decay. The current study shows that a single time series over a tidal cycle at the principal inlet to Great South Bay (NY, US) is sufficient to determine the net flux of Ra across the inlet, and also can be used to estimate the decay of short-lived Ra in the bay. Estimates of the net Ra flux obtained from a single tidal time-series by using three different approaches agree with those determined from a more time-consuming survey of Ra within the bay, and may represent a first step of estimating SGD in bays and coastal lagoons.  相似文献   
226.
ABSTRACT: The production of a documentary video in a graduate seminar offers advantages over the traditional term paper. These advantages derive from the nature of the videotape medium. The most distinct difference between a written document and a video production is the use of the video camera to record events. In using the camera, the student is required to become involved both in front of the video camera, for example, as an interviewer, and behind the camera as a camera operator. Next, as an editor, the student is required to review the events that she/he has taped for inclusion in the final product. By participating in these three roles, the student has the opportunity to learn interviewing skills while interacting with professionals in the field, to learn videotaping skills, and to see him/herself as he/she appears to others. The student can use the video feedback to improve his/her professional presentation; posture, dress, gestures, speech, and facial expressions all have an impact on how we are perceived by others. Additionally, the painstaking process of reviewing the taped material leads to an intimate knowledge of the topic, and the process of choosing portions out of entire interviews hones the ability to select the crucial or central themes and ideas from any discussion. Finally, the power of video lies in its ability to communicate information to a wide audience. Although the nature of video for the general public does not permit highly detailed or rigorous coverage of any topic, it is a major source of information. Accordingly, video is an important tool that can be used to inform the public about the importance of wise water resource management.  相似文献   
227.
228.
According to the United States Environmental Protection Agency (US EPA), a significant percentage of residential onsite sewage systems (OSSs) are failing at any given time. The US EPA has therefore issued a set of recommended guidelines for OSS regulatory programs aimed at reducing overall failure rates. We conducted a survey of OSS regulatory program administrators with jurisdictions bordering a Great Lake. Our goal was to determine their programs’ capacities to meet the US EPA’s recommendations. We found that although some local programs meet the US EPA’s recommendations, most do not. In this article, we present our findings and conclusions for one of the US EPA’s models, the baseline “Homeowner Awareness” model. Most areas do not have recommended requirements that systems be inspected when properties transfer between owners. A majority do not track changes in ownership within the computerized databases they use to record information about systems. Although most provide at least “one-time” information to homeowners regarding proper OSS maintenance, most do not contact them periodically with reminders of needed maintenance. We include recommendations for resolving some of the issues that our research identified.  相似文献   
229.
全球气候变暖背景下的局地气候变化特征及其响应,是近年来的研究热点。兴文县是云贵高原北坡的典型石漠化区域,其多年降水变化在一定程度上可以反映该区的气候变化。对兴文县1959~2007年全年和分季节降水量进行Morlet连续小波变换,结果表明:全年与分季节降水总体上均呈减少之势,并具有多尺度波动的特征,不同季节的多年降水具有各自的变化规律。春季和夏季降水量丰贫交替的周期较长(超过9 a),变化相对较缓;秋季、冬季和全年的降水丰贫更替周期较短(少于6 a),变化相对较快。目前兴文县处于降水相对较丰时期的后半程,未来几年将进入降水相对偏少的时期。降水的波动减少趋势,将会加剧该区域水资源的供需矛盾,给农业生产带来不利影响,增加生态系统的脆弱性和影响喀斯特地貌的发育过程,并最终促进石漠化的发展。  相似文献   
230.
In this study,we identified ecological pressures on grassland ecosystems and adaptive countermeasures in Northern China.Our research revealed that the main sources of these pressures included population growth,economic development,resources exploitation,and global climate change,with human-related activities being overriding factors.Overgrazing was an important reason for grassland imbalance,causing soil erosion and desertification,especially during the sensitive spring greening phase.In steppe zones,commercial coal mining was destructive to the ecological environment.Regarding long-term strategies,we recommend that policy-makers devote more consideration to a new conceptual approach for transforming grasslands through shifting the focus from die grassland’s traditional production functions to meir ecological functions.Applying this concept,adaptive countermeasures should be developed to reduce human impacts based on the environmental capacities of grasslands.Moreover,we recommend the development of environment-friendly industries and reduction of pressures from human activities as effective measures for maintaining the balance between sustainable economic development and grassland conservation.Lastly,we suggest that restoration of degraded grasslands should conform to the principle of natural vegetation to further improve the ecological adaptability of plants and ecosystem stability.This study is expected to provide scientific support for policy-makers engaged in grassland protection.  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