全文获取类型
收费全文 | 14331篇 |
免费 | 237篇 |
国内免费 | 196篇 |
专业分类
电工技术 | 203篇 |
综合类 | 80篇 |
化学工业 | 978篇 |
金属工艺 | 693篇 |
机械仪表 | 213篇 |
建筑科学 | 427篇 |
矿业工程 | 44篇 |
能源动力 | 194篇 |
轻工业 | 425篇 |
水利工程 | 75篇 |
石油天然气 | 70篇 |
武器工业 | 1篇 |
无线电 | 692篇 |
一般工业技术 | 762篇 |
冶金工业 | 494篇 |
原子能技术 | 103篇 |
自动化技术 | 9310篇 |
出版年
2023年 | 28篇 |
2022年 | 62篇 |
2021年 | 74篇 |
2020年 | 78篇 |
2019年 | 88篇 |
2018年 | 97篇 |
2017年 | 79篇 |
2016年 | 104篇 |
2015年 | 93篇 |
2014年 | 351篇 |
2013年 | 451篇 |
2012年 | 977篇 |
2011年 | 3310篇 |
2010年 | 1310篇 |
2009年 | 1178篇 |
2008年 | 834篇 |
2007年 | 725篇 |
2006年 | 573篇 |
2005年 | 694篇 |
2004年 | 734篇 |
2003年 | 768篇 |
2002年 | 418篇 |
2001年 | 361篇 |
2000年 | 278篇 |
1999年 | 123篇 |
1998年 | 220篇 |
1997年 | 150篇 |
1996年 | 90篇 |
1995年 | 117篇 |
1994年 | 79篇 |
1993年 | 38篇 |
1992年 | 21篇 |
1991年 | 19篇 |
1990年 | 20篇 |
1989年 | 45篇 |
1988年 | 17篇 |
1987年 | 17篇 |
1986年 | 19篇 |
1985年 | 19篇 |
1984年 | 30篇 |
1983年 | 21篇 |
1982年 | 11篇 |
1981年 | 11篇 |
1980年 | 8篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1976年 | 12篇 |
1974年 | 2篇 |
1965年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
131.
132.
从热力学角度分析了在冲天炉中熔炼铸铁切屑的可行性。指出在铁屑中加入某些添加剂,压制成块,在热风冲天炉中代替金属炉料可直接生产出优质铸铁件。并对其经济效益进行了分析。 相似文献
133.
本文建立了开关式TIG焊电源的离散时域数学模型,分析了电弧引燃过程、引弧性能、电流波形特点和电弧稳定性。试验表明该电源具有良好的焊接性能。 相似文献
134.
IGBT逆变式波形控制CO2弧焊电源的研究 总被引:5,自引:2,他引:5
本文针对IGBT弧焊逆变器,提出并实现了适于短路过渡CO_2气体保护焊的输出波形控制方法。对焊接电弧参数实时采样以及工艺试验均表明,所研制的逆变式波控CO_2弧焊电源对减小金属飞溅和改善焊缝成型均有明显效果。 相似文献
135.
Jae Woong Choi Gil Ho Hwang Won Kyu Han Sung Goon Kang 《Metals and Materials International》2006,12(1):75-80
Ni−B film of 1 μm thickness was electrolessly deposited on an electroplated Cu bus electrode. The film, which encapsulates
the Cu bus electrodes, prevents Cu oxidation and serves as a diffusion barrier against Cu contamination of the transparent
dielectric layer in a plasma display during the firing process at 580 °C. The microstructure of theas-deposited barrier film was amorphous phase and crystallized to Ni and Ni3B after annealing at 300 °C. The good barrier properties observed here can be explained by Ni3B precipitates at the grain boundaries acting as a fast diffusion path via pre-annealing at 300 °C before the firing process
at 580 °C. 相似文献
136.
One issue in the dynamic simulation of flexible multibody system is poor computation efficiency, which is due to high frequency components in the solution associated with a deformable body. Standard explicit numerical methods should take very small time steps in order to satisfy the absolute stability condition for the high frequency components and, in turn, the computational efficiency deteriorates. In this study, a hybrid integration scheme is applied to solve the equations of motion of a flexible multibody system for achieving better computational efficiency. The computation times and simulation results are compared between the hybrid scheme and conventional methods. The results demonstrate that the efficiency of a flexible multibody simulation can be improved by using the hybrid scheme. 相似文献
137.
Logan Molyneux Krishnan Vasudevan Homero Gil de Zúñiga 《Journal of Computer-Mediated Communication》2015,20(4):381-399
Recent research suggests that social interactions in video games may lead to the development of community bonding and prosocial attitudes. Building on this line of research, a national survey of U.S. adults finds that gamers who develop ties with a community of fellow gamers possess gaming social capital, a new gaming‐related community construct that is shown to be a positive antecedent in predicting both face‐to‐face social capital and civic participation. 相似文献
138.
139.
140.
Ricardo Villar-Ribera Francisco Hernández-AbadJosé Ignacio Rojas-Sola David Hernández-Díaz 《Mechanism and Machine Theory》2011,46(6):820-830
The transmission of information has gone through various stages of evolution throughout its history. A stage before that of the electric telegraph was the so-called aerial/optical telegraph. It was developed towards the end of the 18th century and was in service until the middle of the 19th century. Chappe's system was widely used in France, and was the first to be in consistent use. However, a new and technologically superior system was developed soon afterwards which superseded it. Its inventor was Agustín de Betancourt, considered by some authors one of the founders of the Theory of Machines and Mechanisms, who, together with the distinguished clockmaker Breguet, presented it to the French Authorities in the turbulent decade of the 1790s.This article presents a historical review of this telegraph and analyzes its technical characteristics. It presents analytically, numerically and graphically some of the statements made about the telegraph, and corrects other subsequent observations. Lastly, a detailed reconstruction of the telegraph is made using different advanced CAD techniques, which provide an accurate static and dynamic view of each of its parts. 相似文献