全文获取类型
收费全文 | 370篇 |
免费 | 21篇 |
国内免费 | 65篇 |
专业分类
安全科学 | 8篇 |
废物处理 | 3篇 |
环保管理 | 91篇 |
综合类 | 167篇 |
基础理论 | 53篇 |
污染及防治 | 29篇 |
评价与监测 | 26篇 |
社会与环境 | 62篇 |
灾害及防治 | 17篇 |
出版年
2024年 | 2篇 |
2023年 | 5篇 |
2022年 | 8篇 |
2021年 | 18篇 |
2020年 | 12篇 |
2019年 | 8篇 |
2018年 | 6篇 |
2017年 | 16篇 |
2016年 | 24篇 |
2015年 | 19篇 |
2014年 | 11篇 |
2013年 | 32篇 |
2012年 | 23篇 |
2011年 | 26篇 |
2010年 | 14篇 |
2009年 | 22篇 |
2008年 | 23篇 |
2007年 | 32篇 |
2006年 | 19篇 |
2005年 | 22篇 |
2004年 | 13篇 |
2003年 | 13篇 |
2002年 | 9篇 |
2001年 | 12篇 |
2000年 | 6篇 |
1999年 | 12篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 8篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有456条查询结果,搜索用时 15 毫秒
401.
铁路运输安全的产权分析 总被引:1,自引:0,他引:1
由于我国铁路运输安全的复杂性 ,运输安全在改革过程中极有可能沦为“公地悲剧” ,对安全进行产权分析确有必要。分析了一些国家保证铁路运输安全的产权制度安排 ,如英国的“网运分离”后的私有产权路网公司完全负责制、美国的垂直一体化私有产权铁路公司负责和政府安全监管体制、瑞典的非赢利性组织管理和政府安全监管体制以及我国的垂直一体化国有垄断企业 (政府部门 )负责制。笔者认为我国铁路在改革过程中 ,不能忽视运输安全的产权问题 ,应建立适当的运输安全管制体系 ,政府更应该在确保铁路运输安全方面发挥重要作用。 相似文献
402.
403.
成都市区植被变化的遥感动态监测 总被引:4,自引:1,他引:4
利用1987年和2000年的TM影像,对成都市区植被动态变化进行了分析.首先, 利用1:25万数字地形图对2000年的TM影像进行几何校正,并将1987年的TM影像与其配准.其次,利用TM影像的第四和第三波段计算植被指数,根据植被指数提取植被.第三,对成都市区1987~2000年的植被进行了动态变化分析.研究表明,1987~2000年成都市区植被有增有减,但总的趋势是减少:增加部分集中在老城区,是人工绿化的结果;减少部分主要集中在市区西北和西南的面状区域以及因城市道路扩展而占用的线状区域,这是城市化的必然结果. 相似文献
404.
This paper provides a complete case study analysis of environmental impact assessment (EIA) implementation in China from planning to legal challenge, which is typical but rarely reported. The analysis takes an historical perspective on the regulatory and institutional structures through which EIA has been implemented in China, in order to evaluate the extent to which EIA has matured over the last 10 years. The case study relates to a proposed recreation/tourist development at Dianshan Lake, a protected water resource for Shanghai. Legal and administrative challenge began in 1993, when the case was initiated with a letter from the public, and concluded in 1996, when the case was decided in a court judgment. More recent follow-up research indicates that many issues have continued to be problems for EIA implementation in China. Policy implications in terms of regulatory structure, institutional arrangement, EIA procedure, EIA practitioners, and public participation can be drawn, and lessons learned for both the government and the developers. The study emphasizes the problem of relying on reorientation of existing institutions to promote new (environmental) priorities. 相似文献
405.
Duane A. Wells Paul F. Doyle 《Journal of the American Water Resources Association》2004,40(2):477-483
ABSTRACT: Snow course surveys in late winter provide stream‐flow forecasters with their best information for making water supply and flood forecasts for the subsequent spring and summer runoff period in mountainous regions of western North America. Snow survey data analyses are generally based on a 30‐year “normal” period. It is well documented that forest cover changes over time will affect snow accumulation on the ground within forests. This paper seeks to determine if forest cover changes over decades at long term snow courses decrease measured peak snow water equivalent (SWE) enough to affect runoff prediction. Annual peak SWE records were analyzed at four snow courses in two different forest types having at least 25 years of snowpack data to detect any decreases in SWE due to forest growth. No statistically significant decreases in annual peak SWE over time were found at any of these four snow courses. The wide range of annual winter precipitation and correspondingly highly variable peak snowpack accumulation, as well as many other weather and site variables, masked any minor trends in the data. 相似文献
406.
James W. Hornbeck 《Journal of the American Water Resources Association》1975,11(6):1257-1260
ABSTRACT: Experimental cuttings on two small, hardwood-forested watersheds in New England showed that annual streamflow can be increased as much as 41 percent. Most of the increase occurred in summer and early autumn when additional streamflow is most needed. Revegetation caused the annual increases to nearly disappear within 4 years after complete forest clearing. 相似文献
407.
陕西未来50年区域旱涝气候预测研究 总被引:7,自引:0,他引:7
用陕西省近526a的旱涝等级资料,根据超低频气候振动理论和尺度对应原理,通过旱涝气候对天体物理、太阳活动等周期,特别是ENSO对天体物理显著敏感的周期响应关系的物理统计分析,选取周期概率显著的周期,进行外延叠加集成预测,给出了未来50a陕西省不同区域旱涝趋势的预测结果. 相似文献
408.
F. N. Lisetskii 《Russian Journal of Ecology》2007,38(5):311-316
The results of long-term stationary research on the assessment of aboveground phytomass and soil moisture dynamics in a steppe pasture are presented. An analysis of annual and interannual variation in meteorological parameters over the study period has been performed, and, on this basis, the dependence of productivity on climatic changes has been determined. 相似文献
409.
Chen Zhigang Qu Futian Wang Qing 《中国人口.资源与环境(英文版)》2007,5(1):26-32
In China, farmland property rights characterized by the household-responsibility system (HRS) have been improved since the reform and opening-up. The rights of use, transfer and gain become more stable, authorized and complete. This paper firstly analyzes the impact on farmland productivity, which comes from the improvement of farmland property rights. Then, an economet-ric model is built to test the above analysis. It concludes that changes of property rights will affect farmland performance in China. In the end, some policy implications are explored for fur-ther reforms. 相似文献
410.
Kostas Bithas 《Environment, Development and Sustainability》2008,10(3):373-390
The operational designing of Environmentally Sustainable Economic Development (ESED) emerges as an urgent and demanding task.
Even though ESED has paved the way for thought-provoking and constructive scientific dialogue, appeal for designing an operational
ESED is still lagging behind the needs of contemporary societies, leaving much to be desired. With this in mind, the present
paper will aim at delineating principles for the operational application of ESED. First, the preservation of crucial properties
of environmental functions and ecosystems, emerges as a prime condition of ESED. The second condition concerns the provision
of the economic process with sufficient natural inputs; in this context, the paper intends to trace certain operational tenets
governing the use of natural resources. Finally, the appropriate institutional settings for the operational design of ESED
are traced.
Readers should send their comments on this paper to BhaskarNath@aol.com within 3 months of publication of this issue 相似文献