全文获取类型
收费全文 | 1351篇 |
免费 | 143篇 |
国内免费 | 42篇 |
专业分类
电工技术 | 326篇 |
综合类 | 67篇 |
化学工业 | 491篇 |
金属工艺 | 81篇 |
机械仪表 | 43篇 |
建筑科学 | 14篇 |
矿业工程 | 27篇 |
能源动力 | 181篇 |
水利工程 | 8篇 |
石油天然气 | 25篇 |
武器工业 | 2篇 |
无线电 | 96篇 |
一般工业技术 | 53篇 |
冶金工业 | 61篇 |
自动化技术 | 61篇 |
出版年
2024年 | 5篇 |
2023年 | 20篇 |
2022年 | 37篇 |
2021年 | 50篇 |
2020年 | 69篇 |
2019年 | 46篇 |
2018年 | 58篇 |
2017年 | 44篇 |
2016年 | 53篇 |
2015年 | 47篇 |
2014年 | 108篇 |
2013年 | 68篇 |
2012年 | 93篇 |
2011年 | 93篇 |
2010年 | 85篇 |
2009年 | 73篇 |
2008年 | 58篇 |
2007年 | 100篇 |
2006年 | 68篇 |
2005年 | 53篇 |
2004年 | 35篇 |
2003年 | 30篇 |
2002年 | 37篇 |
2001年 | 41篇 |
2000年 | 33篇 |
1999年 | 23篇 |
1998年 | 25篇 |
1997年 | 9篇 |
1996年 | 13篇 |
1995年 | 10篇 |
1994年 | 7篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1951年 | 1篇 |
排序方式: 共有1536条查询结果,搜索用时 15 毫秒
61.
62.
Jeya Jeevahan G. Mageshwaran G. Britto Joseph R. B. Durai Raj R. Thamarai Kannan 《Chemical Engineering Communications》2017,204(10):1202-1223
Energy demand, decreasing fossil fuel reserves, and health-related issues about pollutants have led researchers to search for renewable alternative fuels to either partially or fully replace fossil fuels. Among many alternative fuels, biodiesel became one of the most popular choices due to similar properties to that of conventional diesel. Biodiesel produces slightly lower brake thermal efficiency compared to that of conventional biodiesel, but has an advantage of reduced emissions of CO2, CO, HC, and smoke. However, biodiesel shows higher NOx emission which, when used in increased biodiesel market, may become a serious problem. Various strategies were attempted by different researcher to reduce NOx emissions. In this paper, various strategies, adapted for reducing NOx emissions of biodiesel fuel used in diesel engines for automobile applications, are reviewed and discussed. The strategies are grouped into three major groups, namely combustion treatments, exhaust after-treatments, and fuel treatments. Among various strategies discussed, fuel treatments, such as low temperature combustion, mixing fuel additives and reformulating fuel composition, reduce NOx emission without compromising other emission and performance characteristics and they seem to be promising for future biodiesel fuel. 相似文献
63.
介绍了一种基于dsPIC30F6014单片机控制的三相晶闸管触发实验装置,详细阐述了其软硬件结构。测试实验证明,该装置电路简单,产生的触发脉冲稳定性好、触发精度高、易于调试、操作方便、具有实用价值,能够进一步开发用于实验教学。 相似文献
64.
Selective catalytic reduction as one of the secondary NOx control technologies is widely used in industrial sources including coal-fired power plants and large boilers. The performance of an SCR-DeNOx system is sensitive to the installment of its components such as turning vanes and hybrid grids. In this work, three-dimensional CFD simulations are carried out to analyze the breakage failure of an SCR-DeNOx system for a certain 350 MW coal-fired power plant. Research results are consistent with the phenomena that occur in the industrial application. It reveals that the breakage failure in the industrial application is likely to be caused by the inappropriate installation of the turning vane 3 locating closest to the catalyst, especially the angle of the turning vane 3. The analysis further shows that the lifetime or the breakage of the catalyst layers depends highly on the gas velocity, the fly ash distribution and its particle velocity. 相似文献
65.
Soran Shwan Louise Olsson Magnus Skoglundh Jonas Jansson 《American Institute of Chemical Engineers》2015,61(1):215-223
The focus of this work is to investigate whether a previously developed microkinetic deactivation model for hydrothermally treated Fe‐BEA as NH3‐SCR catalyst can be applied to describe chemical deactivation of Fe‐BEA due to phosphorous exposure. The model describes the experiments well for Fe‐BEA before and after phosphorous exposure by decreasing the site density, representing deactivation of sites due to formation of metaphosphates blocking the active iron sites, while the kinetic parameters are kept constant. Furthermore, the results show that the activity for low‐temperature selective catalytic reduction (SCR) is very sensitive to loss of active monomeric iron species due to phosphorous poisoning compared to high‐temperature SCR. Finally, the ammonia inhibition simulations show that exposure to phosphorous may affect the internal transport of ammonia between ammonia storage sites buffering the active iron sites, which results in a lower SCR performance during transient conditions. © 2014 American Institute of Chemical Engineers AIChE J, 61: 215–223, 2015 相似文献
66.
High activity and wide temperature window of Fe‐Cu‐SSZ‐13 in the selective catalytic reduction of NO with ammonia
下载免费PDF全文
![点击此处可从《American Institute of Chemical Engineers》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jian Liu Daxi Wang Zhen Zhao Kai Cheng Junhua Li 《American Institute of Chemical Engineers》2015,61(11):3825-3837
Fe‐Cu‐SSZ‐13 catalysts were prepared by aqueous solution ion‐exchange method based on the one‐pot synthesized Cu‐SSZ‐13. The catalysts were applied to the selective catalytic reduction (SCR) of NO with NH3 and characterized by the means of XRD, UV‐Vis, EPR, XPS, NH3‐TPD, and so on. The selected Fe‐Cu‐SSZ‐13‐1 catalyst exhibited the high NO conversion (>90%) in the wide temperature range (225–625°C), which also showed good N2 selectivity and excellent hydrothermal stability. The results of XPS showed that the Cu and Fe species were in the internal and outer parts of the SSZ‐13 crystals, respectively. The results of UV‐Vis and EPR indicated that the monomeric Cu2+ ions coordinated to three oxygen atoms on the six‐ring sites and Fe monomers are the real active species in the NH3‐SCR reaction. Furthermore, the influence of intracrystalline mass‐transfer limitations on the Fe‐Cu‐SSZ‐13 catalysts is related to the location of active species in the SSZ‐13 crystals. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3825–3837, 2015 相似文献
67.
煤层气发电是煤层气利用的重要途径之一,但煤层气发电排放的高温尾气中含有大量的氮氧化物(NO_x),会对环境造成污染,需要对其进行脱硝处理,而高温烟气(约500℃)又不宜用V_2O_5/TiO_2蜂窝式催化剂进行直接脱硝处理。为此,在分析比较煤层气发电高温烟气与燃煤发电烟气差别的基础上,应用纳米组装和灌注法研制了GJ-HC-5型催化剂,并通过室内实验确定了脱除NO_x的最佳温度窗口(400~600℃)。之后,在某煤层气电厂进行中间试验,将发电机组高温烟气直接通入到SCR一体化装置进行脱硝处理,在SCR反应器进出口处连续监测,进口NO_x浓度约为620 mg/m~3,出口监测浓度约为20 mg/m~3,对烟气中的NO_x的脱除率始终保持在90%以上。试验结果表明,所研制的高温SCR催化剂符合实际烟气温度条件,且制备方法简单,是一种可行的煤层气发电高温烟气的脱硝方法。 相似文献
68.
提出一种由过零检测电路、可控硅整流电路、高频滤波电路与PWM隔离驱动电路组成的非隔离驱动方式的高效LED驱动电源电路。通过可控硅整流器(SCR)控制角α的程控调节与隔离驱动PWM占空比的自适应负载变化,分别实现LED负载恒流驱动的粗调与细调。对各电路模块的仿真与LED负载电流调节实验均验证了系统设计的正确性。 相似文献
69.