全文获取类型
收费全文 | 1338篇 |
免费 | 143篇 |
国内免费 | 42篇 |
专业分类
电工技术 | 326篇 |
综合类 | 65篇 |
化学工业 | 490篇 |
金属工艺 | 81篇 |
机械仪表 | 43篇 |
建筑科学 | 13篇 |
矿业工程 | 26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 | 93篇 |
一般工业技术 | 53篇 |
冶金工业 | 56篇 |
自动化技术 | 61篇 |
出版年
2024年 | 5篇 |
2023年 | 20篇 |
2022年 | 35篇 |
2021年 | 48篇 |
2020年 | 68篇 |
2019年 | 45篇 |
2018年 | 58篇 |
2017年 | 43篇 |
2016年 | 53篇 |
2015年 | 46篇 |
2014年 | 108篇 |
2013年 | 68篇 |
2012年 | 92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 | 32篇 |
1999年 | 23篇 |
1998年 | 25篇 |
1997年 | 9篇 |
1996年 | 12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 | 7篇 |
1988年 | 7篇 |
1951年 | 1篇 |
排序方式: 共有1523条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
选择性催化还原(SCR)是一种成熟的电厂烟气脱硝技术,正在国内外得到广泛的应用。液态排渣炉由于其燃烧温度高,其飞灰在粘性、细度及烟气中微量元素的含量等方面与固态排渣炉有较大的不同。文章论述了在液态排渣锅炉上实施SCR时的关键工艺选择,如SCR出口NOx浓度、脱硝率、氨逃逸量的关系;高灰段布置砷中毒的问题;催化剂类型及排列布置方式选择等。文章还提出了SCR改造工程中需要注意的问题,讨论了实施SCR以后对锅炉的影响,提出了具体的解决对策。 相似文献
45.
设计了一种异步电动机节电器 ,采用单片机技术 ,通过双向可控硅控制施加在电机绕组上的端电压 ,使电源电压过零点与绕组电流过零点之间的相位角维持在设定值附近 ,从而使电机维持在较高效率状况下运行 ,达到节约用电的目的 相似文献
46.
47.
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
48.
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
49.
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
50.
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