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   2452篇
  免费   360篇
  国内免费   408篇
安全科学   1089篇
废物处理   107篇
环保管理   269篇
综合类   1288篇
基础理论   163篇
环境理论   1篇
污染及防治   135篇
评价与监测   76篇
社会与环境   57篇
灾害及防治   35篇
  2024年   5篇
  2023年   36篇
  2022年   77篇
  2021年   82篇
  2020年   66篇
  2019年   103篇
  2018年   94篇
  2017年   138篇
  2016年   119篇
  2015年   152篇
  2014年   136篇
  2013年   180篇
  2012年   220篇
  2011年   216篇
  2010年   126篇
  2009年   155篇
  2008年   95篇
  2007年   159篇
  2006年   152篇
  2005年   120篇
  2004年   85篇
  2003年   115篇
  2002年   97篇
  2001年   83篇
  2000年   88篇
  1999年   72篇
  1998年   61篇
  1997年   32篇
  1996年   28篇
  1995年   23篇
  1994年   20篇
  1993年   12篇
  1992年   13篇
  1991年   3篇
  1990年   3篇
  1989年   4篇
  1988年   3篇
  1987年   4篇
  1986年   3篇
  1985年   7篇
  1984年   5篇
  1983年   6篇
  1982年   6篇
  1981年   3篇
  1980年   1篇
  1979年   4篇
  1978年   3篇
  1977年   3篇
  1976年   1篇
  1971年   1篇
排序方式: 共有3220条查询结果,搜索用时 15 毫秒
971.
在对里彦煤矿采矿地质条件分析的基础上,对安全煤岩柱的化学成分及其阻水性能、岩性及力学特征进行了研究.针对里彦煤矿的具体情况,分析了里彦安全煤岩柱的阻水性能,认为其阻水性能良好,可以适当减小防水防砂煤岩柱宽度,以提高开采上限,释放部分煤炭储量.  相似文献   
972.
介绍了循环流化床锅炉燃用煤泥的燃烧调整方法,阐述了燃用煤泥技术对电厂降低成本,提高经济效益及社会效益的积极意义。  相似文献   
973.
采煤沉陷区生态环境形势严峻,土地复垦势在必行。分析了采煤沉陷对邹城矿区生态环境的影响,并提出了疏干法、就地平整法、挖深垫浅法等实际的土地生态修复措施。  相似文献   
974.
我国煤中微量元素的赋存及开发利用   总被引:2,自引:0,他引:2  
煤中微量元素的赋存规律和综合利用工艺的研究和开发,对于资源的合理利用具有重要意义。在综合国内煤中微量元素研究文献的基础上,分析了煤中微量元素的来源可分为原生、次生和后生,赋存状态主要与有机质的吸附和络合作用有关;开发利用的现状较为落后,表现为研究区域少、研究手段和技术水平差。指出,必须深入对煤中微量元素的赋存规律和综合利用工艺进行深入研究,合理利用资源,使矿区实现可持续发展。  相似文献   
975.
976.
This paper explains how the well-accepted concept of improved stakeholder participation during mineral policy development leads to a national mineral policy that accommodates the diverging views and interests that allows wide acceptance of decisions, enhancing the success of implementation and, ultimately, national benefits. This process is based on lessons learnt during the South African experience and has been successfully applied in the development of the Namibian and Malawian national minerals policies. An effective policy in the SADC will engineer the delicate balance between poverty reduction and an internationally competitive minerals sector. This balance enhances the possibility of long-term economic growth and development in the SADC region. The overriding advantage of this strategy is that it generates ‘home-grown’ policy instruments and implementation of mineral law with which stakeholders can identify. This process presents a new challenge to traditional policy formulation strategies in emerging economies and the bottom-up approach, linked to wide political support, allows the potential realisation of national objectives.  相似文献   
977.
ABSTRACT: The Tucson area is totally dependent on ground water, which is in increasingly short supply due to excessive overdrafts. Tucson area waste water treatment plants discharge material quantities of secondary effluent downstream, which is lost to evapotranspiration and recharge of the ground water basin. The city and the four large mining companies who share the common Santa Cruz basin ground water, recognized the common water supply problem and agreed to fund a feasibility study for mining process use of the effluent to partly alleviate the overdraft of ground water. The study analyzed the projected waste water effluent resources, potential mining company demand for waste water effluent and possible interface of an effluent delivery facility with the proposed Central Arizona Project. The effluent resources were analyzed with respect to potential demand. An optimum alignment was selected. An optimum system was detailed through design schematics, amortized cost and finance requirements, and an implementation schedule. It was concluded that a waste water effluent delivery facility could be implemented which would utilize reclaimed effluent in quantities approximating 35 percent of basin overdraft and which would provide revenue for full cost recovery over a 20 year operation period. The mining companies are studying the internal economic impacts of the project.  相似文献   
978.
ABSTRACT: The concentration of 10 [titanium (Ti), manganese (Mn), copper (Cu), chromium (CR), zinc (Zn), arsenic (As), selenium (Se), cobalt (Co), cadmium (Cd), and mercury (Hg)] toxic elements were measured in the water, benthic sediment, plants, invertebrates, and vertebrates of an ash basin and its drainage system at a coal-fired power plant of the Savannah River Project, Aiken, S.C., over a period of two years. During 12 months of this period the basin was essentially filled and little settling of ash occurred. In the remaining 12 months, dredging had been completed, adequate settling occurred and most of the effluent turbidity was removed. All elements were more concentrated in sediment and biota than in water, and five (Mn, Cu, As, Zn, and Se) were biomagnified by at least one biotic component as compared to concentration in benthic sediment. Plants had high accumulations of Ti, Mn, As, and Hg; invertebrates had high accumulations of Co, Hg, Cu, Cr, Cd, and As; and vertebrates greatly biomagnified Se and Zn. The streamlined biotic community of the system accomplished major removal of Mn, Zn, As, Se, and Cd from the effluent. The magnitude of bioaccumulation of Ti, Mn, Zn, As, Se, Cd, and Hg was increased during the period of adequate settling in the basin.  相似文献   
979.
甲烷-煤尘爆炸波与障碍物相互作用的数值研究   总被引:8,自引:2,他引:6  
为了探讨煤矿瓦斯和煤尘爆炸的物理机制 ,基于对甲烷和煤尘爆炸传播的理论分析 ,采用数值模拟方法研究障碍物对甲烷和煤尘爆炸传播的影响 ;为了更系统地考虑颗粒相各种输运特性、相间滑移和耦合 ,采用双流体模型建立了数学模型 ,该模型的出发点是把颗粒群和气体都作为连续介质 ,两者相互渗透充满整个空间形成没有间隙的“流体”———拟流体 ,在欧拉坐标系下考虑气 -固两相流动 ,气相和颗粒相的计算网格统一 ,易于处理。数值方法采用LU分解和迎风TVD格式分别处理对流项的隐式和显式部分 ,扩散项采用中心差分 ;同时研究了不同形状的障碍物对流场的影响 ,计算结果与实验吻合较好  相似文献   
980.
This paper provides an overview of the initiatives that have been undertaken by the Ghanaian government to promote more sustainable development in resident small-scale gold mining operations, and recommends a series of strategies for perpetuating a pattern of continued improvement. Since the passing of the Small Scale Gold Mining Law (PNDCL 218) in 1989, which effectively legalized small-scale gold mining as an industry in Ghana, the government, in particular, the Minerals Commission, has made a concerted effort to regularize operations, and to provide technical and financial support to miners. Under the auspices of the German non-profit Gesellschaft Technishe Zusannebarbeit (GTZ), a small-scale gold mining registration system has been implemented, district support centres for small miners have been constructed and the Precious Minerals Marketing Corporation (PMMC) has been created, which purchases products from small-scale miners at near-market prices. Careful analysis reveals, however, that these efforts have collectively only had a marginal impact, and that the industry is still in dire need of aid. Specifically, to perpetuate further a pattern of improved sustainability--improvements in both the socio-economic and environmental arenas--additional technical and financial support must be provided, and sound environmental management practices implemented. The Minerals Commission has been burdened with these tasks and challenges but because it is largely understaffed, it is highly unlikely that it will be able to facilitate sufficient improvement in the sector on its own. Nevertheless, marked improvements can be achieved if: (1) avenues for technological dissemination are created and improved; (2) research partnerships are forged with local universities; (3) experienced consultation is hired when needed; and (4) other governmental agencies, namely the Mines Department, Environmental Protection Agency (EPA) and Geological Survey, provide the Minerals Commission assistance with prospecting, monitoring, regulation and environmental auditing activities.  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