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   3410篇
  免费   291篇
  国内免费   364篇
安全科学   606篇
废物处理   131篇
环保管理   820篇
综合类   1495篇
基础理论   327篇
环境理论   19篇
污染及防治   140篇
评价与监测   64篇
社会与环境   396篇
灾害及防治   67篇
  2024年   23篇
  2023年   85篇
  2022年   86篇
  2021年   123篇
  2020年   145篇
  2019年   123篇
  2018年   119篇
  2017年   183篇
  2016年   212篇
  2015年   187篇
  2014年   177篇
  2013年   334篇
  2012年   283篇
  2011年   343篇
  2010年   225篇
  2009年   177篇
  2008年   140篇
  2007年   180篇
  2006年   147篇
  2005年   108篇
  2004年   77篇
  2003年   78篇
  2002年   61篇
  2001年   60篇
  2000年   56篇
  1999年   59篇
  1998年   32篇
  1997年   26篇
  1996年   26篇
  1995年   18篇
  1994年   33篇
  1993年   12篇
  1992年   13篇
  1991年   10篇
  1990年   11篇
  1989年   6篇
  1988年   4篇
  1987年   4篇
  1986年   3篇
  1985年   5篇
  1984年   5篇
  1983年   3篇
  1982年   9篇
  1981年   7篇
  1980年   7篇
  1979年   9篇
  1978年   8篇
  1977年   6篇
  1976年   4篇
  1974年   3篇
排序方式: 共有4065条查询结果,搜索用时 625 毫秒
371.
李创  刘倩斐 《资源开发与市场》2014,30(12):1504-1506
经历了十几年的讨论,燃油税改革方案终于在2009年出台并实施,改革后燃油税究竟会对我国宏观经济及各部门产生怎样的影响,倍受关注.基于此背景,采用环境CGE模型对改革前后的两种不同燃油税税率进行了量化分析,总体研究得出:从长期发展来看,燃油税改革有利于我国经济结构调整,减少能源消耗和降低碳排放;短期内会增加企业生产成本,抑制宏观经济增长,其中交通运输业和石油加工业受到的冲击最大,应引起有关部门重视.  相似文献   
372.
In this paper,the authors have analyzed the relationship between energy intensity gap and GDP per worker gap of China’s western and eastern provinces over the period 1997-2006.Using panel data model with lag adjustment,taking the above provinces and six industrial sectors (agriculture,forestry,animal husbandry,and fisheries,industry,construction industry,transport,storage and post & telecommunications,wholesale and retail trades & catering industry,and other sectors of tertiary industry.) as the investigated subjects,the authors have conducted empirical study on the convergence of GDP per worker gap and the convergence of energy intensity gap with respect to the variation of GDP per worker gap,and have concluded that:First,the GDP per worker gap of the six industrial sectors and provinces are convergent,and of this,the convergence rate of GDP per worker gap of Construction Industry is the fastest,while that of Industry is the slowest.Second,the overall energy intensity gap between eastern and western provinces is convergent,that is,with the narrowing of GDP per worker gap between eastern and western provinces,the energy intensity gap converges,but its convergence rate is slower than that of GDP per worker gap.Third,energy intensity gap between various industrial sectors of the east and the west is either convergent or divergent,and there are differences.The energy intensity gap of agriculture,forestry,animal husbandry,and fisheries,industry,and construction industry is convergent,while that of the other three industrial sectors is divergent.Fourth,the convergence of the overall energy intensity of the western provinces is not in conformity with the convergence of the various industrial sectors,and there are significant differences,indicating that the western provinces and autonomous regions should take measures to more effectively improve their overall energy utilization efficiency at the industrial sector level.  相似文献   
373.
能源强度收敛:对发达国家与发展中国家的检验   总被引:3,自引:0,他引:3  
能源强度是指一个国家或地区生产单位产值所消耗的能源量,它反映了经济系统对能源的依赖程度和能源的使用效率。许多国家的能源强度曲线在直观上表现出收敛的显著特征。为了对这一现象进行严格的证明和检验,该文依据时间序列协整概念,首先提出了能源强度收敛的定义,然后从一个包含能源投入的内生增长模型出发,从理论上证实了能源强度收敛的存在性。为了对能源强度收敛进行实证检验,选取24个国家,并划分组合为5组样本,分别对能源强度收敛进行了σ收敛检验和协整检验,结果表明:高收入国家、高中收入国家、中低收入国家、发展中国家和样本中所有国家都存在能源强度收敛现象;σ收敛检验还揭示出各组样本中能源强度收敛的时间段以及收敛程度的大小排序。  相似文献   
374.
生物质能(Biomass energy)是最为广泛的可再生能源,其中多年生芒属C4植物(Miscanthus)由于具有巨大碳固定能力而成为潜力巨大的生物质能植物。中国是芒属植物芒草起源中心,但相对于欧洲国家应对能源危机和温室效应而采取的芒草研究与应用来说,仍处于起步阶段。我国长期以来传统的草地利用模式,决定了在南方草地的研究显著少于北方,近年来芒草在华南地区的运用研究集中于生态修复,对草本植物群落基于生态系统水平的 CO2气体交换能力的研究仍然相当缺乏,在二氧化碳浓度持续增长及全球变暖背景下,生物质能植物及其碳汇功能的相关研究尤显重要。我国南方近6700万hm2退化丘陵草坡急待恢复或处于恢复中,草坡地芒属植物符合生物质能植物标准,施肥少,害虫少,农药输入少,能够有效地利用光、水等自然资源。考虑到C4植物具有比C3植物更强的光合作用能力,高光能利用率C4芒属植物的碳固定能力及能源潜力值得重视,但缺乏科学的碳动态和碳收支评估。综述了国内外芒草生物量特征与生物质能潜力研究现状,重点论述芒属植物生态系统水平的碳动态和收支能力研究,探讨了系统水平更客观评估芒属碳源汇(Carbon sequestration)功能的方法,基于生物量过程的研究结果及华南地区草坡研究历史和现状,为草坡地生物质能的合理开发利用提出了相关对策,强调在我国南方开发和利用芒属植物资源具有重要能源价值和经济、环境效益。  相似文献   
375.
文章通过综合分析、计算 ,提出用天然气代替煤作主要能源 ,走燃机热电联供道路 ,解决北京市大气环境恶化的问题 ,并对这一工程方案实施的可能性和优越性作了阐述 ,最后提出了多项实施建议。  相似文献   
376.
将河南平顶山煤气公司原煤气输配系统改造成为自动恒压控制系统,从而提高安全系数,降低煤气输配电耗。  相似文献   
377.
Contrary to claims from American politicians, lobbyists, and oil and gas executives, allowing energy development in the Alaskan Arctic National Wildlife Refuge (ANWR) will harm the environment, compromise international law, erode the social significance of wilderness protection, and ultimately fail to␣increase the energy security of the United States. After exploring a brief history of the ANWR controversy, this piece argues that the operation of oil and gas refineries in ANWR will release discharged solids, drilling waste, and dirty diesel fuel into the ecosystem’s food-chain, as they have from oil operations in Prudhoe Bay. Less obvious but equally important, oil and gas exploration in ANWR will violate a number of international treaties on biodiversity protection. In the end, development in ANWR will threaten the concept of wilderness protection, and will do little to end US dependence on foreign sources of energy. About the Author: Benjamin K. Sovacool is a doctoral candidate in the Department of Science and Technology Studies at the Virginia Polytechnic Institute & State University in Blacksburg, Virginia. He works as a research analyst for the Consortium on Energy Restructuring and is a Senior Research Fellow for the Virginia Center for Coal and Energy Research. He also just completed a Graduate Fellowship in Energy Policy at the Oak Ridge National Laboratory in Oak Ridge, Tennessee. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.  相似文献   
378.
The water–energy–food nexus is being promoted as a conceptual tool for achieving sustainable development. Frameworks for implementing nexus thinking, however, have failed to explicitly or adequately incorporate sustainable livelihoods perspectives. This is counterintuitive given that livelihoods are key to achieving sustainable development. In this paper we present a critical review of nexus approaches and identify potential linkages with sustainable livelihoods theory and practice, to deepen our understanding of the interrelated dynamics between human populations and the natural environment. Building upon this review, we explore the concept of ‘environmental livelihood security’ – which encompasses a balance between natural resource supply and human demand on the environment to promote sustainability – and develop an integrated nexus-livelihoods framework for examining the environmental livelihood security of a system. The outcome is an integrated framework with the capacity to measure and monitor environmental livelihood security of whole systems by accounting for the water, energy and food requisites for livelihoods at multiple spatial scales and institutional levels. We anticipate this holistic approach will not only provide a significant contribution to achieving national and regional sustainable development targets, but will also be effective for promoting equity amongst individuals and communities in local and global development agendas.  相似文献   
379.
Mihailovic  D.T.  Kapor  D.  Hogrefe  C.  Lazic  J.  Tosic  T. 《Environmental Fluid Mechanics》2004,4(1):57-77
In grid-based environmental models, the underlying surface consists of patches of solid and liquid parts and different plant communities, creating a very heterogeneous picture in the grid cell. In these cases, numerical modelers usually use a simple arithmetic average to determine the grid-cell albedo, a key variable in the parameterization of the land-surface radiative transfer over the grid cell. The object of this paper is to consider the assumptions for aggregating the albedo over a very heterogeneous surface where various surfaces occur at different heights, and, then propose a method for deriving a general expression for it. The suggested expression for the albedo is compared with the conventional approach, for the two-patches grid-cell with a simple geometrical distribution and different heights of its components. A numerical test is performed to compare the two approaches by numerical simulation of the evolution of the surface temperature over the particular grid-cell. Specifically, a one-dimensional land-surface model was applied to an isolated rocky grid-cell with a hole in the center; the model was forced with meteorological observations taken on July 17, 1999 in Philadelphia, PA.  相似文献   
380.
This study examines ten programmes to advance energy efficiency and retrofitting of existing, private sector buildings in C40 cities in Asia-Pacific and USA. We set out to identify differing policy approaches, together with potential impacts and implementation challenges for each. Findings unearthed six policy models – both mandatory and voluntary – with unique impacts and challenges. We demonstrate that innovation occurs without new policy inventions and largely by necessity, as new features are added and generic models are adapted to local circumstances. Our sample demonstrated experimentation with benchmarking in the USA, comprehensive regulation in Asia, and voluntary approaches in Australia. Overall, environmental impacts are particularly slow to emerge and plagued with attribution challenges. We found limited evidence of benchmarking programme effectiveness in reducing energy consumption in the short-term, but some indication of mid-term outcomes. Driven by unique local circumstances, the cap-and-trade model stood out by fostering large, sustained and attributable GHG emission reductions and retrofitting. Market and social impacts are highly significant across all programmes, highlighting needs to consider non-environmental impacts in policy evaluation. We emphasise the complementary potential of voluntary and regulatory approaches to advancing energy efficiency and climate resilience. We also underscore the potential for reporting or benchmarking programmes to later transition to models mandating performance improvements, such as cap-and-trade.  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