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   2566篇
  免费   210篇
  国内免费   282篇
安全科学   356篇
废物处理   87篇
环保管理   651篇
综合类   1095篇
基础理论   254篇
环境理论   19篇
污染及防治   114篇
评价与监测   38篇
社会与环境   385篇
灾害及防治   59篇
  2024年   5篇
  2023年   39篇
  2022年   53篇
  2021年   60篇
  2020年   103篇
  2019年   98篇
  2018年   98篇
  2017年   163篇
  2016年   173篇
  2015年   143篇
  2014年   108篇
  2013年   284篇
  2012年   221篇
  2011年   268篇
  2010年   178篇
  2009年   142篇
  2008年   97篇
  2007年   136篇
  2006年   101篇
  2005年   78篇
  2004年   63篇
  2003年   62篇
  2002年   46篇
  2001年   55篇
  2000年   49篇
  1999年   48篇
  1998年   21篇
  1997年   18篇
  1996年   20篇
  1995年   15篇
  1994年   24篇
  1993年   9篇
  1992年   8篇
  1991年   8篇
  1990年   12篇
  1989年   4篇
  1988年   2篇
  1985年   2篇
  1984年   6篇
  1982年   4篇
  1981年   3篇
  1980年   4篇
  1979年   9篇
  1978年   5篇
  1977年   3篇
  1976年   2篇
  1974年   1篇
  1973年   1篇
  1971年   2篇
  1969年   1篇
排序方式: 共有3058条查询结果,搜索用时 683 毫秒
991.
论中国可再生能源发展机制   总被引:8,自引:0,他引:8  
中国可再生能源存在着成本高和市场狭小两大问题,要根本解决这两大问题必须制定新政策,形成新机制。中国的可再生能源政策的多目标性决定了新出台政策应该是一个政策体系,具体应包括目标机制、定价机制、交易机制、选择机制和补偿机制五种运行机制。  相似文献   
992.
张仕友 《四川环境》1996,15(4):51-52
本文对人类最清洁的能源核聚变能作了简单的介绍。  相似文献   
993.
Global energy demand is expected to increase from the current 400 ExaJ per year to as much as 700–1,000 ExaJ per year by the middle of this century. If fossil carbon resources continue to make up the bulk of the energy supply, not only will atmospheric carbon dioxide increase to levels not seen for the past 30–35 million years, but depleting fossil carbon resources will become increasingly less available for other purposes, particularly the production of chemicals on which society now depends. The chemical process industries are heavily dependent on the availability of low-price petroleum as a feedstock. Recent life-cycle analyses suggest that pursuing both strategies of renewable energy sources and renewable feedstocks (i.e. biomass) will be required to meet these competing demands. Reducing the global use of both energy and manufactured chemicals will be a challenge for sustainable development. Education of the next generation of chemists and chemical engineers will have to change significantly from its current emphasis on petrochemical-based manufacturing to include a much greater emphasis on renewable resources and bio-based processes.Brief accounts of this work were presented at the 7th International Symposium on Green Chemistry in China (Zhuhai, People’s Republic of China, May 2005) and at the Joint US–China Green Chemistry Workshop (Beijing, People’s Republic of China, May 2005; this workshop was supported by US National Science Foundation grant CHE-0522369).  相似文献   
994.
The current and future projections of energy utilisation and related environmental impact has been given. Due to the heavy dependance on low grade lignites and imported hard coal, Turkey is going to have problems in the control of CO2 emissions. Turkey was at first included as an Annex I country according to Kyoto Protocol. Later, it has been removed from the list which is justified considering the previous international environmental impact control applications and relatively much lower energy utilisation in Turkey, compared to Annex I countries. Therefore, Turkey has been removed from the Annex I list.Turkish power generation, industrial and transportation sector will be facing a difficult challenge over the coming 20 yr in complying with environmental impact levels. The developments in the liberalisation of Turkish energy sector since the 1980's is a positive step to overcome the problems.  相似文献   
995.
The selection and recovery of two or more solvents (i.e. co-solvents) are studied because of their importance in environmentally responsible processing. A particularly challenging problem arises when the contaminants (or solutes) are comprised of a mixture of volatile and nonvolatile compounds. The nonvolatile components present difficulties in solvent selection while the volatile components give rise to solvent recovery challenges. Traditional approaches such as the Kauri-Butanol test and predictions based on solubility parameters from regular solution theory can result in poor solvent selection when some of the contaminants are nonvolatile. A simple, graphical and rigorous procedure based on Gibbs energies of mixing for all binary mixtures of solvents and contaminants is proposed for choosing solvent/contaminant pairs. This selection procedure is based on the choice of solvent resulting in the lowest solvent/contaminant Gibbs free energy of mixing for a given contaminant. Nonvolatile contaminants are often easily separated in a single-stage flash vessel. Volatile contaminants, on the other hand, can form homogeneous or heterogeneous azeotropes with commonly used solvents, give rise to distillation boundaries and result in a challenging co-solvent recovery problem. A systematic procedure for the synthesis, design and economic analysis for co-solvent recovery is presented. Residue curve maps are used to identify distillation boundaries and to generate a conceptual process flow sheet for co-solvent recovery. Equipment sizes for the separators and auxiliaries (i.e. condensers, reboilers, decanters, etc.) are determined and capital investment, installation and operating costs are calculated. The removal of oil-water emulsions from the surface of machined metal parts using n-propyl bromide (NPB) and isopropyl alcohol (IPA) in a closed-loop degreaser is used to illustrate the proposed methodology of co-solvent selection and recovery. Analysis shows that the Kauri-Butanol test and the use of solubility parameters can result in poor solvent selection. In contrast, the proposed methodology shows that NPB is competitive with banned solvents like chlorodifluoro, fluorodichloroethane and trichloroethane and highly regulated solvents such as perchloroethylene, trichloroethylene and is a good solvent for the removal of machining oils while IPA is a good solvent for removing water. Separation of mixtures of NPB/IPA/water is difficult because of the presence of three binary and one ternary azeotrope that create three distinct distillation regions as well as regions of vapor-liquid-liquid behavior. It is shown that these distillation boundaries preclude direct water separation and that a two-distillation sequence with decantation is required to cross boundaries and recover both solvents. A variety of geometric illustrations are presented to elucidate key concepts.  相似文献   
996.
大亚湾大鹏澳海域C、N、BSi的沉积记录研究   总被引:3,自引:0,他引:3  
研究了大亚湾大鹏澳海域鱼类养殖区、贝类养殖区以及核电站附近3个站位50~78 cm的柱状沉积物中生物硅(BSi)、总有机碳(TOC)、总氮(TN)等生源要素的垂直变化,以揭示人类活动对海洋环境影响的沉积记录。位于近岸海水养殖区的两个沉积柱中,近年来TOC含量呈明显上升趋势,而核电站附近海域略有下降。从TOC/TN比值判断(三个沉积柱平均分别为9.54、7.42、7.9),该海域TOC是陆源和水生两种来源的混合物。此外,养殖区上表层沉积物中水生有机碳(TOCa)含量呈明显下降趋势,而TOC/TN比值则上升,说明养殖区水生初级生产力及其对总初级生产力的贡献下降;相反,陆源污染所造成的陆源有机碳(TOCt)含量明显增加。在核电站附近海域,TOCa含量明显上升,TOC/TN和TOCt值下降,表明核电站的运行使水体初级生产力上升,陆源有机碳输入则减少。BSi、BSi/TOCa的垂直分布表明,海水养殖区硅藻对总初级生产力的贡献逐年上升,而核电站海域硅藻的贡献则下降。  相似文献   
997.
分析了尿素水解装置存在的问题及采取的改进措施,提高了水解装置处理能力与处理效果,实现了清洁生产、节能降耗、保护环境的目的。  相似文献   
998.
高校节能减排的潜力与效益实证研究   总被引:2,自引:0,他引:2  
高校节能减排的潜力和效益非常可观。但是,要想达到预计的节能减排效益,高校必须建立和健全节能减排制度,加大节能技术和设施设备改造力度,引导师生采取有效的节能减排措施,加强对学生资源忧患意识和节约习惯的养成教育。  相似文献   
999.
能源供应安全视角下中印生物质能源利用的比较   总被引:1,自引:0,他引:1  
徐向阳 《自然资源学报》2010,25(10):1806-1812
中国和印度是世界上两个人口最多的国家,中印两国作为世界上两个能源消费大国,如何满足众多人口和经济快速增长对能源的需求,以及提供安全的能源供应是中国和印度都在考虑并试图解决的紧迫问题,分析印度的生物能源利用政策对我国有重要的现实意义和参考价值。我国在1993年成为石油净进口国,1994年我国进口的原油仅为290×104t,进口依赖度为1.9%。到2009年我国石油净进口量为21 888.5×104t,进口原油的依赖度上升到了52.5%。我国日益增加的对国际石油市场的依赖对我国能源安全供应构成了极大的风险和挑战。我国在"十一五"期间,在生物质能源的利用上取得了很大的成绩。但还存在一些问题,主要问题是原料来源和成本不稳定、缺乏统筹规划、发电上网制度不完善、相关政策配套措施和实施细则不完善等因素在一定程度上影响了生物质能产业的发展。印度政府积极支持的生物质利用技术,包括利用清洁发展机制大量开发的生物质能CDM项目,这类项目大约占印度全部注册CDM项目的三分之一左右。印度从能源多元化供应的角度和扶持乡村可持续发展的角度上开发利用生物质能项目的实践是值得我国借鉴的。  相似文献   
1000.
电力行业节能减排途径探讨   总被引:2,自引:0,他引:2  
为实现电力行业十一五节能20%,二氧化硫削减22%的行业目标,电力行业面临严峻的节能减排形势。根据清洁生产源头控制以及废弃物资源化利用的原理,介绍了七种具有明显经济效益和环境效益的节能减排技术,为电力行业清洁生产审核中节能减排方案的提出提供借鉴作用。  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