全文获取类型
收费全文 | 1591篇 |
免费 | 32篇 |
国内免费 | 19篇 |
专业分类
电工技术 | 31篇 |
综合类 | 81篇 |
化学工业 | 230篇 |
金属工艺 | 184篇 |
机械仪表 | 174篇 |
建筑科学 | 170篇 |
矿业工程 | 76篇 |
能源动力 | 77篇 |
轻工业 | 23篇 |
水利工程 | 54篇 |
石油天然气 | 181篇 |
武器工业 | 5篇 |
无线电 | 24篇 |
一般工业技术 | 92篇 |
冶金工业 | 150篇 |
原子能技术 | 30篇 |
自动化技术 | 60篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 9篇 |
2021年 | 23篇 |
2020年 | 15篇 |
2019年 | 21篇 |
2018年 | 13篇 |
2017年 | 33篇 |
2016年 | 33篇 |
2015年 | 35篇 |
2014年 | 70篇 |
2013年 | 54篇 |
2012年 | 67篇 |
2011年 | 103篇 |
2010年 | 95篇 |
2009年 | 81篇 |
2008年 | 74篇 |
2007年 | 87篇 |
2006年 | 91篇 |
2005年 | 84篇 |
2004年 | 91篇 |
2003年 | 93篇 |
2002年 | 70篇 |
2001年 | 60篇 |
2000年 | 79篇 |
1999年 | 72篇 |
1998年 | 57篇 |
1997年 | 33篇 |
1996年 | 30篇 |
1995年 | 18篇 |
1994年 | 13篇 |
1993年 | 12篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有1642条查询结果,搜索用时 15 毫秒
1.
结合工程特点及工艺流程,阐述了300 kt/a聚丙烯装置的布置原则,管道、管架设计要点和方法,以及需要注意的问题。 相似文献
2.
S. David Graber 《Canadian Metallurgical Quarterly》2004,130(1):67-80
Numerous types of pipes and channels with spatially increasing flows in environmental engineering applications are identified by type and function and referred to as collection conduits. An overview of methods for designing and analyzing collection conduits is provided. Full conduits with nonuniform and uniform inflow are first considered. Dimensional analysis is then employed to demonstrate the relationship between variables for open channels; that leads to the identification of possibilities for generalized numerical solutions. Prior collection conduit applications are discussed within the framework of the dimensional analysis (which also pertains to some constant-flow applications). A previously unpublished generalized numerical solution for rectangular collection conduits is presented. Subsurface drains are addressed with particular emphasis, including the use of numerical methods to develop a new generalized chart and relation to other design methods. Among the important conclusions for subsurface drains is that the somewhat common practice of using Manning’s equation alone for such problems is not generally adequate. Examples and practical design suggestions are included, and the use of computer-based numerical methods is discussed more generally. 相似文献
3.
4.
5.
6.
介绍一种用于生产聚氨酯泡沫夹克管保温层的新材料聚酯聚醚,报道选用这种材料生产泡沫夹克管的工艺及工要工艺参数和产品达到的技术指标及现场应用情况。 相似文献
7.
气—液式热管换热器在硫酸工业中的应用研究 总被引:4,自引:0,他引:4
本文研制的气-液式热管换热器应用于硫酸生产中SO3气体的余热回收。它具有传热性能好、流动阻力小、寿命长、体积小、节能效果显著和易清垢等优点。 相似文献
8.
Sun Linzhi Luo Yi Zhang Yanan Sun Ping Qin Xinjie Gong ZhenbangPrecision Machinery Institute Shanghai University Shanghai China 《机械工程学报(英文版)》2002,15(4):303-307
An experimental bimorph piezoelectric element (PZT) actuator for small pipe robot is developed. The robot can move in φ20 mm pipe, and can carry a CCD camera for detecting cracks or fine holes on inner surface of pipe. The velocity of the robot can reach 17~22 mm/s for vertical pipe up/down, respectively. Moving principle and its performance characteristics are presented. 相似文献
9.
10.
Erosion is one of the most serious problems in various gas and liquid flow passages such as flow in pipes, pumps, turbines, compressors and many other devices. Sand presence causes loss of pipe wall thickness that can lead to pipe erosion, frequent failures and loss of expensive production time. The importance of this problem is mainly due to many related engineering applications, viz. heat exchangers. In order to reduce the frequency of such pipe erosions, caps in the form of replaceable pipes are protruded in the sudden contraction regions which are exposed to most of the serious erosion rates. In the present work, numerical investigation of the erosion of a pipe protruded in a sudden contraction is presented. The turbulent, steady, 2-D axi-symmetric flow inside an axi-symmetric abrupt contraction pipe with a pipe protrusion embedded in it was solved by steady-state time averaged conservation equations of mass and momentum along with two equation model for turbulence. Particles are tracked using Lagrangian particle tracking. An erosion model was employed to investigate the erosion phenomena for the given geometry. The influence of the different parameters such as the inlet flow velocity (3–10 m/s), the particle diameter (10–400 μm), the protruded pipe geometry (thickness T=1–5 mm and depth H=2–5 mm) and the pipe contraction ratio (Cr=0.25–0.5) on the erosion of pipe protrusion was investigated. Correlations for the influence of inlet flow velocity, depth and thickness of the protruded pipe on the erosion rate are presented. 相似文献