全文获取类型
收费全文 | 6001篇 |
免费 | 328篇 |
国内免费 | 35篇 |
专业分类
电工技术 | 210篇 |
综合类 | 263篇 |
化学工业 | 917篇 |
金属工艺 | 135篇 |
机械仪表 | 1896篇 |
建筑科学 | 110篇 |
矿业工程 | 196篇 |
能源动力 | 609篇 |
轻工业 | 51篇 |
水利工程 | 42篇 |
石油天然气 | 539篇 |
武器工业 | 25篇 |
无线电 | 101篇 |
一般工业技术 | 836篇 |
冶金工业 | 247篇 |
原子能技术 | 12篇 |
自动化技术 | 175篇 |
出版年
2024年 | 22篇 |
2023年 | 34篇 |
2022年 | 107篇 |
2021年 | 157篇 |
2020年 | 124篇 |
2019年 | 61篇 |
2018年 | 56篇 |
2017年 | 85篇 |
2016年 | 133篇 |
2015年 | 187篇 |
2014年 | 520篇 |
2013年 | 302篇 |
2012年 | 533篇 |
2011年 | 574篇 |
2010年 | 352篇 |
2009年 | 384篇 |
2008年 | 279篇 |
2007年 | 361篇 |
2006年 | 417篇 |
2005年 | 319篇 |
2004年 | 252篇 |
2003年 | 251篇 |
2002年 | 216篇 |
2001年 | 127篇 |
2000年 | 136篇 |
1999年 | 84篇 |
1998年 | 56篇 |
1997年 | 59篇 |
1996年 | 42篇 |
1995年 | 44篇 |
1994年 | 18篇 |
1993年 | 11篇 |
1992年 | 16篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 4篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1981年 | 1篇 |
排序方式: 共有6364条查询结果,搜索用时 15 毫秒
61.
A comprehensive simulation model of a novel rotating spool compressor is presented. The spool compressor provides a new rotary compression mechanism with easily manufactured components. A detailed analytical geometry model of the spool compressor is presented, which includes the geometry of the vane. This geometry model is included in an overall comprehensive compressor model that includes sub-models for friction, leakage, and heat transfer. The results of the comprehensive model were validated using experimental data from a prototype compressor. The prototype compressor has an overall displacement of 23.9 cm3, and was operated using R410A as the working fluid. The model predicts the volumetric efficiency, discharge temperature, and shaft power of the prototype compressor to within 3.13% MAE, 16.5 K and ?13.2 W average deviation, respectively. The trends and spread in the data indicate that additional effort should be focused on the operation of the active sealing elements within the compressor. 相似文献
62.
63.
《Advanced Powder Technology》2022,33(7):103648
MoS2 nanoparticles have been considered valuable materials in lubricating applications due to their layered morphology. This work synthesized spherical MoS2 nanoparticles that held many nanosheets through the hydrothermal method. The thickness of these sheets is between 10 and 25 nm, and their length is estimated to be about 200 nm. The effect of nanoparticles concentration on wear properties was investigated in this research. The four-ball test measured the wear performance of nano lubricants. The results showed that all nano lubricants had better wear performance than the base lubricant (Behran Compressor 68). However, molybdenum disulfide nanoparticles synthesized as nanosheets with a thickness of 10 nm had the best performance. At a concentration of only 0.05 wt-%, the resulting nano lubricant reduced the wear width and friction coefficient by about 50%. The thermal conductivity coefficient results also showed that nanoparticles increased this coefficient. As the lubricant temperature increases, the difference between the nano and base lubricant's thermal conductivity increases. 相似文献
64.
65.
As turbocharging diesel engines for vehicle application are applied in plateau area, the environmental adaptability of engines has drawn more attention. For the environmental adaptability problem of turbocharging diesel engines for vehicle application, the present studies almost focus on the optimization of performance match between turbocharger and engine, and the reliability problem of turbocharger is almost ignored. The reliability problem of compressor impeller of turbocharger for vehicle application when diesel engines operate in plateau area is studied. Firstly, the rule that the rotational speed of turbocharger changes with the altitude height is presented, and the potential failure modes of compressor impeller are analyzed. Then, the failure behavior models of compressor impeller are built, and the reliability models of compressor impeller operating in plateau area are developed. Finally, the rule that the reliability of compressor impeller changes with the altitude height is studied, the measurements for improving the reliability of the compressor impellers of turbocharger operating in plateau area are given. The results indicate that when the operating speed of diesel engine is certain, the rotational speed of turbocharger increases with the increase of altitude height, and the failure risk of compressor impeller with the failure modes of hub fatigue and blade resonance increases. The reliability of compressor impeller decreases with the increase of altitude height, and it also decreases as the increase of number of the mission profile cycle of engine. The method proposed can not only be used to evaluating the reliability of compressor impeller when diesel engines operate in plateau area but also be applied to direct the structural optimization of compressor impeller. 相似文献
66.
67.
分析了河北津西钢铁股份有限公司AV45-11轴流压缩机形成喘振工况的原因,该系统采用过程控制软件对防喘阀进行了有效控制,满足了高炉对风压、风量的要求. 相似文献
68.
Compressors are used all over the world for various individual applications; the current application concerns their use in the ozone process of water treatment. Technical data on different mineral and synthetic lubricants are given. In particular, a new oil was chosen for investigation. Field testing was undertaken over more than 6000 h on two different locations. Used oil monitoring was conducted by sampling during the experiment; analyses of physical and chemical parameters were made and their kinetics are described. Wear, viscometrics and ozone process interaction are discussed in this study. 相似文献
69.
介绍了干气密封的工作原理,通过对现场条件的论证,选用串联式干气密封;阐述了干气密封结构的设计;成功地完成EC-1301的干气密封国产化改造;填补了国内该项技术的空白,标志着我国干气密封设计制造技术达到了国际先进水平,有推广价值. 相似文献
70.