全文获取类型
收费全文 | 4958篇 |
免费 | 643篇 |
国内免费 | 248篇 |
专业分类
电工技术 | 915篇 |
综合类 | 569篇 |
化学工业 | 359篇 |
金属工艺 | 340篇 |
机械仪表 | 706篇 |
建筑科学 | 685篇 |
矿业工程 | 165篇 |
能源动力 | 142篇 |
轻工业 | 64篇 |
水利工程 | 132篇 |
石油天然气 | 66篇 |
武器工业 | 99篇 |
无线电 | 144篇 |
一般工业技术 | 1121篇 |
冶金工业 | 59篇 |
原子能技术 | 23篇 |
自动化技术 | 260篇 |
出版年
2024年 | 30篇 |
2023年 | 66篇 |
2022年 | 160篇 |
2021年 | 178篇 |
2020年 | 191篇 |
2019年 | 157篇 |
2018年 | 154篇 |
2017年 | 220篇 |
2016年 | 224篇 |
2015年 | 234篇 |
2014年 | 291篇 |
2013年 | 268篇 |
2012年 | 349篇 |
2011年 | 376篇 |
2010年 | 295篇 |
2009年 | 292篇 |
2008年 | 258篇 |
2007年 | 323篇 |
2006年 | 286篇 |
2005年 | 206篇 |
2004年 | 204篇 |
2003年 | 174篇 |
2002年 | 142篇 |
2001年 | 128篇 |
2000年 | 110篇 |
1999年 | 87篇 |
1998年 | 73篇 |
1997年 | 58篇 |
1996年 | 80篇 |
1995年 | 49篇 |
1994年 | 41篇 |
1993年 | 22篇 |
1992年 | 27篇 |
1991年 | 25篇 |
1990年 | 21篇 |
1989年 | 7篇 |
1988年 | 13篇 |
1987年 | 11篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
排序方式: 共有5849条查询结果,搜索用时 15 毫秒
1.
K.K. Padmanabhan 《Tribology International》1992,25(5)
Metallic mating surfaces in structural joints offer a good source of frictional energy dissipation resulting in a damped dynamic structural response. This paper reports the results of experiments where the energy dissipation per cycle occurring at a preloaded flat metallic annular interface subjected to cyclic tangential forces is measured. The effects of certain pertinent joint variables on this frictional energy dissipation are investigated by the application of Response Surface Methodology. A central composite rotatable design was utilized for developing empirical expressions for energy loss. The methodology presented suggests a useful technique for tribological research. 相似文献
2.
3.
This paper analyzes the formulation of energy preserving/decaying schemes for dynamics problems. We argue that any energy preserving/decaying scheme can always be seen as composed of an underlying temporal discretization, that is then slightly modified in order to prove a discrete energy bound within a time step. While the details of the modified scheme depend in a critical way on the governing equations, the underlying discretization can in principle be applied to a variety of models. We review some of the temporal underlying schemes recently proposed in the literature, presenting them with a common notation. We show their similarities and highlight their differences. 相似文献
4.
5.
6.
7.
In this paper, a method to calculate derivatives of eigenvectors of damped discrete linear dynamic system with respect to the system parameter is presented. Due to the non-proportional nature of the damping, the eigenvectors become complex, and as a consequence, the derivatives also become complex. The derivatives are calculated using small damping assumption, and the method avoids using the state-space approach. The results are obtained in terms of complex modes and frequencies of the second-order system, which in turn are related to the eigensolutions of the undamped system using perturbation method. Based on the derivatives, an expression for total change of the complex eigenvectors is obtained for a more general case when all the elements of mass, stiffness and damping matrices are varying. Application and accuracy of the derived expressions are demonstrated by considering numerical examples. 相似文献
8.
9.
介绍了系统总阻尼的概念,对低频振荡中系统总阻尼进行了数学推导,分析了与系统阻尼有关的参数及如何通过调整某些参数达到使系统总阻尼增加,且不会造成其他振荡模式阻尼的减小。通过电力系统分析综合程序(PSASP)仿真计算进行了验证。 相似文献
10.
LUBRICATION FILM FORMATION MECHANISM OF SLIPPER PAIRS IN LOW SPEED HIGH TORQUE HYDRAULIC MOTORS 总被引:2,自引:0,他引:2
LI Yong SHI Guanglin CHEN Zhaoneng Research Institute of Mechatronics Shanghai Jiaotong University Shanghai China 《机械工程学报(英文版)》2007,20(1):31-35
Pressure-flow analytical formulas of lubrication film of slipper pairs on camshaft connect- ing rod type low speed high torque (LSHT) hydraulic motors are put forward. The bottom surface of slipper pairs is rectangle, and the effect of squeeze flow and pressure differential flow is considered. The dynamic process of lubrication film formation through squeezing is numerically studied by com- puter simulation. Effects of supply pressure, initial lubrication film thickness, velocity damping coef- ficient, loading impact and gravity, etc are studied. Advantages of novel slipper pairs with large oil cavity area are pointed out. 相似文献