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   439篇
  免费   26篇
  国内免费   26篇
安全科学   38篇
废物处理   1篇
环保管理   92篇
综合类   126篇
基础理论   60篇
环境理论   4篇
污染及防治   11篇
评价与监测   8篇
社会与环境   21篇
灾害及防治   130篇
  2023年   8篇
  2022年   9篇
  2021年   17篇
  2020年   17篇
  2019年   17篇
  2018年   19篇
  2017年   15篇
  2016年   26篇
  2015年   26篇
  2014年   9篇
  2013年   33篇
  2012年   16篇
  2011年   23篇
  2010年   23篇
  2009年   20篇
  2008年   13篇
  2007年   23篇
  2006年   28篇
  2005年   21篇
  2004年   12篇
  2003年   17篇
  2002年   15篇
  2001年   13篇
  2000年   18篇
  1999年   13篇
  1998年   3篇
  1997年   5篇
  1996年   6篇
  1995年   6篇
  1994年   7篇
  1992年   3篇
  1991年   2篇
  1990年   1篇
  1987年   2篇
  1984年   1篇
  1983年   2篇
  1981年   1篇
  1980年   1篇
排序方式: 共有491条查询结果,搜索用时 671 毫秒
91.
Few studies on measures for mitigation of damage caused by man-made emissions to the environment have tried to consider all major effects. We illustrate the importance of an integrated approach by estimating costs and benefits of a proposed energy saving program for Hungary, originally designed to reduce CO2 emissions. The dominant benefit of implementing the program is likely to be reduced health damage from local pollutants. Also reduced costs of material damage and to a lesser extent vegetation damage contribute to make the net benefit considerable. Compared to the reduction in these local and regional effects, the benefits from reducing greenhouse gases are likely to be minor. Since local effects in general occur much earlier after measures have been implemented than effects of increased emissions of greenhouse gases, inclusion of local effects makes evaluation of climate policy less dependent on the choice of discount rate. In our opinion, similar results are likely for many measures originally designed to reduce emissions of greenhouse gases particularly in some areas in developing countries with high local pollution levels. Main uncertainties in the analysis, e.g. in the relationships between damage and pollution level, are discussed.  相似文献   
92.
Adaptation is nowrecognized as an inevitable component ofthe overall climate change responsestrategy. For a developing region likesub-Saharan Africa with low greenhouse gasemissions and high vulnerability to theimpacts of climate change, the importanceof adaptation in climate change policy iseven more fundamental. This paper examined alook at the adaptational preparedness ofthe sub-Saharan African region to climatechange. Clearly evident in theenvironmental strategy and developmentfocus of these countries is lack ofrecognition of the need to adapt, poorincentive to adapt and low capacity toadapt to climate change. This furtherexacerbates their vulnerability and hasimplications for the global climate changeresponse strategy. Unfortunately, fewattempts have been made to understand thestructural reasons underlying the pervasivepattern of adaptational unpreparedness inthe region, neither has there been acomprehensive and systematic analysis ofhow to remedy this problem. This paper is acontribution in this regard. It alsohighlights the factors to whichinternational community need to payattention, if it truly wishes to make itsefforts at adaptation more global inscope.  相似文献   
93.
An econometrically estimated family ofresponse functions is developed forcharacterizing potential responses togreenhouse gas mitigation policies by theagriculture and forestry sectors in theU.S. The response functions are estimatedbased on results of anagricultural/forestry sector model. Theyprovide estimates of sequestration andemission reductions in forestry andagriculture along with levels of sectoralproduction, prices, welfare, andenvironmental attributes given a carbonprice, levels of demand for agriculturalgoods, and the energy price. Sixalternative mitigation policiesrepresenting types of greenhouse gasoffsets allowed are considered. Resultsindicate that the largest quantity ofgreenhouse gas offset consistently appearswith the mitigation policy that pays forall opportunities. Restricting carbonpayments (emission tax or sequestrationsubsidy) only to aff/deforestation or onlyto agricultural sequestration substantiallyreduces potential mitigation. Highercarbon prices lead to more sequestration,less emissions, reduced consumer and totalwelfare, improved environmental indicatorsand increased producer welfare.  相似文献   
94.
山东是中国沿海对外开放的主要省份之一,预计在21世纪太平洋时代中占有重要的地位,在迈向21世纪中,面临着发展与减灾协调的抉择。山东地处西太平洋沿岸,不仅灾害种类多,分布广,范围大,灾害重,而且各类灾害具有频繁性、连发性、衍生性等特征,各类灾害目前正步入异常活跃的新时期,灾害对今后区域发展构成了严重威胁。实行减灾与发展协调,是山东迈向太平洋世纪的可行选择。本文在分析世界经济发展给山东带来的机遇、山东减灾与发展的关系、山东灾害特征、规律及趋势的基础上,提出了山东减灾与发展的大框架构思,包括减灾与发展战略目标、指导方针和原则、战略重点及对策建议。  相似文献   
95.
本研究利用太湖区代表站30年和43个一般站25年的降雨资料,改进和完善了降雨侵蚀力新算法,使之与经典法达到90%的一致性,查清了该区降雨侵蚀力时空变化持证,并编制出全区阵雨侵蚀力(R)值分布图。同时,还时R值在水土保持、耕作制度变革和防洪减灾中的应用,尤其对1991年特大洪涝灾害的根本原因,作了讨论。太湖区R值较大,不可忽视水土保持,做好山区、坡耕地的水土保持,是防洪减灾最长久有效的根本措施。  相似文献   
96.
Many proponents of disaster mitigation claim that it offers potential benefits in terms of saved lives and property far exceeding its costs. To provide evidence for this, and to justify the use of public funds, agencies involved in mitigation can use benefit–cost analysis (BCA). Such analysis, if well done, offers a testable, defensible means of evaluating and comparing projects, helps decision-makers choose between mitigation projects, and provides a means to assess the way we spend public funds. In this critical overview of the more contentious issues and latest developments in BCA, I emphasize the pragmatic choices that one can make in accordance with good practice in project evaluation.  相似文献   
97.
Technically, forestry projects have thepotential to contribute significantly tothe mitigation of global warming, but manysuch projects may not be economicallyattractive at current estimates of carbon(C) prices. Forest C is, in a sense, a newcommodity that must be measured toacceptable standards for the commodity toexist. This will require that credible Cmeasuring and monitoring procedures be inplace. The amount of sequestered C that canbe claimed by a project is normallyestimated based on sampling a number ofsmall plots, and the precision of thisestimate depends on the number of plotssampled and on the spatial variability ofthe site. Measuring C can be expensive andhence it is important to select anefficient C-monitoring strategy to makeprojects competitive in the C market. Thispaper presents a method to determinewhether a forestry project will benefitfrom C trading, and to find the optimalmanagement strategy in terms of forestcycle length and C-monitoring strategyA model of an Acacia mangiumplantation in southern Sumatra, Indonesiais used to show that forestry projects canbe economically attractive under a range ofconditions, provided that the project islarge enough to absorb fixed costs.Modeling results indicate that between 15and 38 Mg of Certified Emission Reductions(CERs) per hectare can be captured by thesimulated plantation under optimalmanagement, with optimality defined asmaximizing the present value of profitsobtained from timber and C. The optimalcycle length ranged from 12 to 16 years andthe optimal number of sample plots rangedfrom 0 to 30. Costs of C monitoring (inpresent-value terms) were estimated to bebetween 0.45 (Mg C)-1 to 2.11 (MgC)-1 depending on the spatialvariability of biomass, the variable costsof C monitoring and the discount rate.  相似文献   
98.
Changes towards environmental improvementsare becoming more politically acceptableglobally, especially in developedcountries. Society is slowly moving towardsseeking more sustainable productionmethods, waste minimisation, reduced airpollution from vehicles, distributed energygeneration, conservation of native forests,and reduction of greenhouse gas (GHG)emissions. Modern biomass, when used tosupply useful bioenergy services, has arole to play in each one of theseenvironmental drivers at both the large andsmall scales.This paper describes recent developments inbiomass supply and the technologies for itsconversion to bioenergy including biofuelsfor transport. It examines the economic,environmental and social benefits andidentifies barriers to bioenergy projectimplementation. Future opportunities forbiomass as a carbon (C) sink, a C offsetand a potential source of renewablehydrogen are discussed.Whether or not a bioenergy project iseconomically viable, as well as being trulyrenewable, sustainable and environmentallysound, is determined mainly by the sourceof biomass. The social benefits from usingbiomass are also valuable, though they areoften not clearly presented when proposingnew bioenergy projects or conductinganalyses of existing plants. Employmentrates per MWh or per GJ exceed those whenusing fossil fuel supplies to provide thesame energy service. `Ownership' bystakeholders and local communities at anearly stage in the development process isthe key to successful project developmentin order to share the benefits. Bioenergyhas a significant global role to play inthe mitigation of atmospheric GHG concentrations.  相似文献   
99.
天津大沽南路立交桥工程交通噪声影响问题研究   总被引:1,自引:0,他引:1  
沈伟 《交通环保》2003,24(6):12-14
天津大沽南路立交桥工程周围环境敏感点(居民区和医院)众多,根据预测结果,营运期敏感点除滨海医院和进步里l楼(营运近期)预测值与现状值相比差别不大甚至有所降低外,其它敏感点环境噪声超出现状值昼间0~11.1dB,夜间0.1~13.1dB,普遍超标15dB以上。在比较了声障、减噪路面、通风隔声窗、绿化带、凋整临街建筑物布局等措施的技术经济可行性后,推荐通风隔声窗作为该工程的隔声降噪措施。  相似文献   
100.
Global Biomass Energy Potential   总被引:1,自引:1,他引:1  
The intensive use of renewable energy is one of the options to stabilize CO2atmospheric concentration at levels of 350 to 550ppm. A recent evaluation of the global potential of primary renewable energy carried out by Intergovernmental Panel on Climate Change (IPCC) sets a value of at least 2800EJ/yr, which is more than the most energy-intensive SRES scenario forecast for the world energy requirement up to the year 2100. Nevertheless, what is really important to quantify is the amount of final energy since the use of renewable sources may involve conversion efficiencies, from primary to final energy, different from the ones of conventional energy sources. In reality, IPCC does not provide a complete account of the final energy from renewables, but the text claims that using several available options to mitigate climate change, and renewables is only one of them, it is possible to stabilize atmospheric carbon dioxide (CO2) concentration at a low level. In this paper, we evaluate in detail biomass primary and final energy using sugarcane crop as a proxy, since it is one of the highest energy density forms of biomass, and through afforestation/reforestation using a model presented in IPCC Second Assessment Report (SAR). The conclusion is that the primary-energy potential for biomass has been under-evaluated by many authors and by IPCC, and this under-evaluation is even larger for final energy since sugarcane allows co-production of electricity and liquid fuel. Regarding forests we reproduce IPCC results for primary energy and calculate final energy. Sugarcane is a tropical crop and cannot be grown in all the land area forecasted for biomass energy plantation in the IPCC/TAR evaluation (i.e. 1280Mha). Nevertheless, there are large expanses of unexploited land, mainly in Latin America and Africa that are subject to warm weather and convenient rainfall. With the use of 143Mha of these lands it is possible to produce 164EJ/yr (1147GJ/hayr or 3.6W/m2on average) of primary energy and 90EJ/yr of final energy in the form of liquid fuel (alcohol) and electricity, using agricultural productivities near the best ones already achievable and biomass gasification technology. More remarkable is that these results can be obtained with the operation of 4,000 production units with unitary capacity similar to the largest currently in operation. These units should be spread over the tropical land area yielding a plantation density similar to the one presently observed in the state of São Paulo, Brazil, where alcohol and electricity have been commercialized in a cost-effective way for several years. Such an amount of final energy would be sufficiently large to fulfill all the expected global increase in oil demand, as well as in electricity consumption by 2030, assuming the energy demand of such sources continues to grow at the same pace observed over the last two decades. When sugarcane crops are combined with afforestation/reforestation it is possible to show that carbon emissions decline for some IPCC SRES scenarios by 2030, 2040 and 2050. Such energy alternatives significantly reduce CO2emissions by displacing fossil fuels and promote sustainable development through the creation of millions of direct and indirect jobs. Also, it opens an opportunity for negative CO2emissions when coupled with carbon dioxide capture and storage.  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