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   159篇
  免费   6篇
  国内免费   17篇
安全科学   4篇
环保管理   58篇
综合类   47篇
基础理论   25篇
污染及防治   6篇
评价与监测   10篇
社会与环境   29篇
灾害及防治   3篇
  2024年   1篇
  2023年   2篇
  2022年   3篇
  2021年   6篇
  2020年   1篇
  2019年   1篇
  2018年   1篇
  2017年   3篇
  2016年   6篇
  2015年   4篇
  2014年   1篇
  2013年   14篇
  2012年   8篇
  2011年   9篇
  2010年   6篇
  2009年   7篇
  2008年   8篇
  2007年   10篇
  2006年   8篇
  2005年   9篇
  2004年   3篇
  2003年   6篇
  2002年   5篇
  2001年   4篇
  2000年   10篇
  1999年   6篇
  1998年   2篇
  1997年   2篇
  1996年   4篇
  1995年   3篇
  1994年   6篇
  1993年   6篇
  1992年   4篇
  1988年   2篇
  1987年   2篇
  1986年   1篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1980年   1篇
  1978年   2篇
  1975年   1篇
排序方式: 共有182条查询结果,搜索用时 671 毫秒
161.
长江流域区域可持续发展态势与对策   总被引:1,自引:0,他引:1  
提出了一套包括基础系统、协调系统与潜力系统在内的区域可持续发展评价体系。旨在以基础-过程-潜能为主线。资源、经济、社会、生态环境为基本要素单元,并结合外部介入因素对一个地区的可持续发展进行评价。利用这一指标体系.分析了世纪之交长江流域可持续发展的态势.并与沿海经济带及全国其它省区进行了比较。主要结论有:长江流域区域可持续发展总体水平不高。不符合其在国家经济开发中所处的地位;长江流域区域可持续发展状态的内部差异为流域开发带来困难与挑战,但优势互补的潜力也为实现流域资源综合开发与生态环境综合治理带来机遇。最后,针对以上存在的问题提出了建议与对策。  相似文献   
162.
"03.8"渭河下游特大洪涝灾害的"三情"分析   总被引:8,自引:0,他引:8  
应用渭河流域各气象站及下游重灾区华县水文站的资料,对2003年渭河下游特大洪灾的雨情、水情及灾情进行了分析.阐述了大气环流背景,从降水的时间分布、大降水的落区和分类,总结了特大洪灾的降水特点;从洪水的水位、流量、过程线及与历史洪灾过程的对比分析,得出"03.8"洪水具有"峰次多、水位高、历时长、总量大"之特征;通过洪水前后卫星遥感监测图像的对比分析,清楚地看出渭河主河道明显加宽了3~8倍,造成直接经济损失高达40多亿元;经过以上分析,还揭示了本次洪灾形成的主要原因,从而提出了有关治理渭河、减少洪灾的发展对策.  相似文献   
163.
The Lower Rio Grande Valley (LRGV) region in South Texas emerges as a warehouse and transportation center between Central America and the US with positive growth impacts due to the North American Free Trade Agreement (NAFTA). In 10 years time, a 39.8% population increase has resulted in a 25% boost in solid waste per capita disposal rate in the region. A landfill space shortage drives a need for landfill operators to understand their optimal management strategies in this highly-competitive market. Initially, a strategic plan for optimal solid waste pattern distribution minimizes net costs for cities. This is accomplished through a grey integer programming algorithm that encapsulates all uncertainty present in the solid waste system. Secondly, a series of grey integer submodels construct payoff matrices for a zero-sum two-person game. The ensuing game theoretic analysis is critical for evaluating optimal pricing strategies for tipping fees available to the most significant regional landfills (e.g. Browning-Ferris Industries (BFI) and City of Edinburg) as they compete over disposal contracts. The BFI landfill intrinsically benefits from its competitive pricing policy and central location to solid waste generators. The City of Edinburg landfill, on the other hand, wishes to secure its lucrative solid waste management revenue. It desires a gaming strategy backed by optimality that integrates ambiguity in solid waste generation, design capacity boundaries, and unitary shipping costs. Results show that a two-tiered analysis via grey integer programming-based games may pave the way for 'grey Nash equilibria' pricing tactics that will help the Edinburg landfill maintain its waste contracts.  相似文献   
164.
峡谷地形中森林地表火蔓延实验研究   总被引:1,自引:0,他引:1  
在峡谷形的受限结构实验台上进行森林火灾实验,燃料采用与林间可物相似的混合物,观测火蔓延过程在这种地型结构中的特点。改变风速,通过温度时间曲线分析林火蔓延过程以及烟气运动的规律,所得到的结果也将为林火模型进一步的建立提供实验依据。  相似文献   
165.
Abstract: There are four known geothermal resource areas in the Imperial Valley that have a combined potential of over 4,000 megawatts of electrical energy for 25 years. Water resources available to support geothermal enerfy development are imprted Colorado River water, agricultural waste waters, Salton Sea water, and groundwater. In addtion, geothermal power plants can produce their own cooling water from steam condensate. Nevertheless, the relatively high water requirements of geothermal facilities along with a series of real and potential constraints may cause water supply dilemmas involving both the acquistion and use of cooling water. Important constraints are institutional policies, water supply costs, technical problems, and impacts upon the Salton Sea. These constranits and related dilemmas are examined in light of relevanty information on the valley's water resources, geothermal resources and energy technologies, cooling water requrements, and water supply options.  相似文献   
166.
Silicon carbide (SiC) heating elements (siliconits) are widely used at high-temperature fields. The raw materials, manufacture process and application fields of siliconits are all related to heavy energy consumption and pollutions, and bring high environmental loads. The resources consumption and pollution emissions in siliconit manufacture process were quantificationally estimated by input/output method. Difference between two traditional techniques to produce siliconits in China was also compared and analyzed. The results show that siliconit manufacture processes consume large quantities of resources because the furnace is open to environment and too much thermal-protection materials are used. For the thick-end technique is more complicated and the thick-end siliconits have a bigger size and mass, there are more resources and energy consumptions and pollution emissions for thick-end process than that for equal-diameter process. Some suggestions were introduced to improve the traditional techniques and a new process was designed. It is the most important that the open furnace should be replaced by close vacuum furnace. Sintering and siliconizing process can be combined into one high-temperature process. As results of process simplification and vacuum sintering, resources and energy consumption and wastes emission can be decreased remarkably.  相似文献   
167.
通过区内(竹蜓)类化石资料的整理研究,在黄龙组建(?)带三带五亚带,船山组两个带,并简述其分布规律及与国内外相应地层(?)带的对比。  相似文献   
168.
位于四川西北部的黄龙和九寨沟自然地质公园以其独特的高寒岩溶地质景观(钙华景观和层湖叠瀑景观)蜚声中外,被列为世界级风景区.本文介绍了黄龙钙华景观,将其分为钙华滩流、边石坝彩池、钙华瀑布、钙华洞穴和钙华泉;描述了九寨沟优美的层湖叠瀑景观,以及各主要景点的诗情画意。  相似文献   
169.
电机硅钢片冲孔模具在制造及使用中常因各种原因使某个槽孔损坏而需要修补.此文介绍了该类模具的修补技术.实践证明:该技术可延长硅钢片冲孔模具的使用寿命.  相似文献   
170.
ABSTRACT: The objective of this paper is to examine a deficit in water for the Hsinchu area, the location of Taiwan's “Silicon Valley.” The methods suggested in this paper to diagnose water shortage problems are simple and practical. The results show that Hsinchu is in an area without sufficient water to meet demand for domestic and industrial uses. Until the completion of the Baoshan II Reservoir in 2006, the most feasible options for the Taiwan Water Supply Corporation to offset the water deficiency in Hsinchu City over the next five years are: (a) to obtain water gratuitously from the southern Yungheshan Reservoir; (b) to import additional water at an extra charge from other sources such as the northern Shihmen Reservoir and the agricultural sector; and (c) to conduct a comprehensive water conservation program at the Hsinchu Science‐based Industrial Park.  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