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1.
Bioenergy in the United States: progress and possibilities   总被引:27,自引:0,他引:27  
Concerns about global climate change and air quality have increased interest in biomass and other energy sources that are potentially CO2-neutral and less polluting. Large-scale bioenergy development could indeed bring significant ecological benefits — or equally significant damage — depending on the specific paths taken. In particular, the land requirements for biomass production are potentially immense.

Various entities in the United States have performed research; prepared cost–supply assessments, environmental impact assessments, life cycle analyses and externality impact assessments; and engaged in demonstration and development regarding biomass crops and other potential biomass energy feedstocks. These efforts have focused on various biomass wastes, forest management issues, and biomass crops, including both perennial herbaceous crops and fast-growing woody crops. Simultaneously, several regional and national groups of bioenergy stakeholders have issued consensus recommendations and guidelines for sustainable bioenergy development.

It is a consistent conclusion from these efforts that displacing annual agricultural crops with native perennial biomass crops could — in addition to reducing fossil fuel use and ameliorating associated ecological problems — also help restore natural ecosystem functions in worked landscapes, and thereby preserve natural biodiversity.

Conversely, if forests are managed and harvested more intensively — and/or if biomass crops displace more natural land cover such as forests and wetlands — it is likely that ecosystem functions would be impaired and biodiversity lost.  相似文献

2.
新型近零排放煤气化燃烧利用系统   总被引:14,自引:1,他引:13  
王勤辉  沈洵  骆仲泱  岑可法 《动力工程》2003,23(5):2711-2715,2675
以CO2接受体法气化技术为基础构建了新型的近零排放煤气化燃烧利用系统。煤被加入压力循环流化床气化炉里以水蒸汽为气化介质进行部分气化产生H2、CO和CO2在以CaO作为接受体吸收CO2并放出气化反应所需的热量的同时,CO也通过水煤气变换反应被转化。气化过程所产生高纯度氢气供给固体氧化物燃料电池发电。煤经部分气化后所剩的低活性焦碳和吸收CO2后产生的CaCO2一起被送入循环流化床燃烧炉,焦炭和燃料电池所排出的舍氢尾气燃烧提供CaCO2分解所需的热量。燃烧炉产生的高浓度CO2与其他污染物(SOk、NOx等)一起经余热发电后综合处理,从而实现整个系统的近零污染物排放。经计算,以烟煤为燃料的系统发电效率可达65.5%左右。  相似文献
3.
CaO循环吸收CO2的实验研究   总被引:14,自引:3,他引:11  
对CaO与CO2的循环反应特性进行实验研究,分析了影响CaO转化率的因素及CaO转化率随循环次数的变化趋势,实验结果表明:CaO转化率随温度和CO2体积分数的增加而增加,颗粒粒径对其影响较大;CaO转化率随循环次数的增加而降低,在循环次数达到一定值后,CaO转化率降低到某一值后不再发生较大的变化,在不同温度下,CaO转化率随循环次数的增加而降低的趋势有所不同。  相似文献
4.
Catalytic effects observed during the co-gasification of coal and switchgrass   总被引:12,自引:0,他引:12  
We are investigating catalytic gasification of coal char using biomass-derived potassium salts. Alkali metal salts, especially those containing potassium, are excellent promoters of gasification reactions but are generally considered too expensive for commercial use. Fast-growing biomass, which contains large quantities of potassium, may prove to be an excellent source of inexpensive gasification catalyst. A series of CO2-char gasification tests were performed in a thermogravimetric analyzer (TGA) to evaluate the catalytic activity of alkali-rich biomass-derived materials. Both switchgrass char and switchgrass ash displayed catalytic activity in mixtures with coal char produced from Illinois No. 6 coal. The results obtained with switchgrass ash were especially impressive, with an almost eight-fold increase in coal char gasification rate at 895°C in a 10:90 mixture of coal char and switchgrass ash. These results give encouragement that biomass could be the source of inexpensive, coal gasification catalysts.  相似文献
5.
O2/CO2气氛下循环流化床煤燃烧污染物排放的试验研究   总被引:12,自引:0,他引:12  
富氧燃烧技术不仅能使分离收集CO2和处理SO2容易进行,还能减少NOX排放,是一种能够综合控制燃煤污染物排放的新型洁净燃烧技术。进行了O2/CO2气氛和O2/N2气氛下的循环流化床煤燃烧试验,重点分析了煤燃烧生成的污染物NOX、SO2的排放规律及石灰石脱硫效率,进行了循环流化床富氧燃烧系统的平衡分析并得到了相关试验的证实,为循环流化床富氧燃烧技术的工业应用做了基础和重要的准备。图9表2参9  相似文献
6.
Anaerobic co-digestion of food waste and sewage sludge for hydrogen production was performed in serum bottles under various volatile solids (VS) concentrations (0.5–5.0%) and mixing ratios of two substrates (0:100–100:0, VS basis). Through response surface methodology, empirical equations for hydrogen evolution were obtained. The specific hydrogen production potential of food waste was higher than that of sewage sludge. However, hydrogen production potential increased as sewage sludge composition increased up to 13–19% at all the VS concentrations. The maximum specific hydrogen production potential of 122.9 ml/g carbohydrate-COD was found at the waste composition of 87:13 (food waste:sewage sludge) and the VS concentration of 3.0%. The relationship between carbohydrate concentration, protein concentration, and hydrogen production potential indicated that enriched protein by adding sewage sludge might enhance hydrogen production potential. The maximum specific hydrogen production rate was 111.2 ml H2/g VSS/h. Food waste and sewage sludge were, therefore, considered as a suitable main substrate and a useful auxiliary substrate, respectively, for hydrogen production. The metabolic results indicated that the fermentation of organic matters was successfully achieved and the characteristics of the heat-treated seed sludge were similar to those of anaerobic spore-forming bacteria, Clostridium sp.  相似文献
7.
天然气热、电、冷三联供的热经济性分析   总被引:10,自引:0,他引:10  
李芳芹  魏敦崧 《动力工程》2004,24(1):143-146
提出系统Yong经济系数方法,对天然气热、电、冷三联供系统,天然气发电系统和天然气热电联供系统进行分析,计算出三系统的Yong经济系数,对其进行比较分析,指出天然气热、电、冷三联供系统具有较高的热经济性。进一步对天然气价格进行灵敏度分析,得出三系统在不同天然气价格下的Yong经济系数。图4表8参5  相似文献
8.
生物质混合物与褐煤共热解特性的试验研究   总被引:10,自引:0,他引:10  
阎维平  陈吟颖 《动力工程》2006,26(6):865-870,893
选取秸秆、稻壳、玉米芯、木屑、沙柳枝和叶、旱柳枝和叶、紫花苜蓿、芦苇、碱草等13种农业和林业废弃物、草木类等生物质,按相同比例混合为生物质混合物,采用热重分析仪分析研究该生物质混合物与某典型褐煤在不同混合比例下的共热解特性,计算了生物质挥发分析出终止温度并合理定义了褐煤挥发分析出温度。热解试验表明:不同比例的生物质混合物与褐煤在共热解过程中,热解产物的产率基本等于单独热解生物质和褐煤的产率加权平均值;生物质混合物的比例在20%~400%时,褐煤挥发分析出温度低于褐煤单独热解时挥发分析出温度,生物质中的高碱金属和CaO含量及H/C比较大等因素的存在具有一定的促进作用;生物质混合物的比例在50%以上时,由于生物质密度较小且易软化,阻碍煤挥发分的选出和扩散,使褐煤挥发分析出温度显著高于褐煤单独热解时挥发分初始析出温度,生物质对褐煤热解有抑制作用。  相似文献
9.
O2/CO2气氛下煤粉燃烧反应动力学的试验研究   总被引:10,自引:2,他引:8  
在热重分析仪上进行了模拟空气气氛及不同O2浓度(21%、30%、40%、80%)的O2/CO2气氛下3种不同品质煤粉(龙岩无烟煤、贵州烟煤、元宝山褐煤)的燃烧特性试验,确定了3种煤粉的燃烧特征参数并进行了动力学分析.结果表明,O2/CO2气氛下煤粉的燃烧分布曲线与O2/N2气氛下有明显不同,在相同O2浓度的条件下,O2/CO2气氛下煤粉燃烧速率低,燃尽时间长;随着O2浓度的增加,燃烧DTG曲线向低温区偏移,着火温度及燃尽温度降低,燃尽时间缩短,可燃性指数及燃尽指数明显提高;O2/CO2气氛下煤粉燃烧基本属于一级反应,动力学参数随燃烧气氛与煤质变化的不同有较大差异.  相似文献
10.
This paper applies the cointegration theory to examine the causal relationship between electricity consumption and real GDP (Gross Demostic Product) for China during 1978–2004. Our estimation results indicate that real GDP and electricity consumption for China are cointegrated and there is only unidirectional Granger causality running from electricity consumption to real GDP but not the vice versa. Then Hodrick–Prescott (HP) filter is applied to decompose the trend and fluctuation component of the GDP and electricity consumption series. The estimation results indicate that there is cointegration between not only the trend components, but also the cyclical components of the two series, which implies that, the Granger causality is probably related with the business cycle. The estimation results are of policy implication to the development of electric sector in China.  相似文献
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