全文获取类型
收费全文 | 3276篇 |
免费 | 602篇 |
国内免费 | 603篇 |
专业分类
航空 | 2124篇 |
航天技术 | 981篇 |
综合类 | 537篇 |
航天 | 839篇 |
出版年
2024年 | 13篇 |
2023年 | 32篇 |
2022年 | 87篇 |
2021年 | 120篇 |
2020年 | 120篇 |
2019年 | 102篇 |
2018年 | 84篇 |
2017年 | 109篇 |
2016年 | 117篇 |
2015年 | 151篇 |
2014年 | 183篇 |
2013年 | 192篇 |
2012年 | 194篇 |
2011年 | 226篇 |
2010年 | 241篇 |
2009年 | 191篇 |
2008年 | 223篇 |
2007年 | 229篇 |
2006年 | 141篇 |
2005年 | 139篇 |
2004年 | 91篇 |
2003年 | 118篇 |
2002年 | 97篇 |
2001年 | 115篇 |
2000年 | 103篇 |
1999年 | 146篇 |
1998年 | 146篇 |
1997年 | 115篇 |
1996年 | 99篇 |
1995年 | 76篇 |
1994年 | 82篇 |
1993年 | 84篇 |
1992年 | 69篇 |
1991年 | 61篇 |
1990年 | 45篇 |
1989年 | 37篇 |
1988年 | 20篇 |
1987年 | 33篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 13篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1966年 | 1篇 |
1965年 | 2篇 |
排序方式: 共有4481条查询结果,搜索用时 15 毫秒
851.
852.
853.
854.
855.
856.
857.
Bian Yushu Gao Zhihui Yun Chao 《中国航空学报》2008,21(1):79-85
In order to suppress vibration in flexible manipulators, a new type of manipulator mechanism with controllable local degrees of freedom is proposed. This mechanism consists of a main chain and some branch links. The main chain is of a flexible open-chain configuration with an end-effector installed at its tip, and the rigid branch links are able to perform active movements. It is proved by kinematics and dynamic analysis that, the branch links bear no direct kinematic relation to the main chain, but their independent motions can strongly affect the dynamic behavior and performance of the flexible manipulator. Then comes a new idea of suppressing vibration, in which independent motions of the branch links are used to suppress the undesired vibration of the flexible main chain through dynamic coupling. On this basis, an optimal method for reducing vibration of flexible manipulators is proposed. Finally, the effectiveness of this method is verified by numerical simulations. 相似文献
858.
基于静强度分布的复合材料疲劳寿命分布的预测模型(英文) 总被引:4,自引:2,他引:2
The reasons of the static strength dispersion and the fatigue life dispersion of composite laminates are analyzed in this article. It is concluded that the inner original defects, which derived from the manufacturing process of composite laminates, are the common and major reason of causing the random distributions of the static strength and the fatigue life. And there is a correlative relation between the two distributions. With the study of statistical relationship between the fatigue loading and the fatigue life in the uniform confidence level and the same survival rate S-N curves of material, the relationship between the static strength distribution and the fatigue life distribution through a material S-N curve model has been obtained. And then the model which is used to describe the distributions of fatigue life of composites, based on their distributions of static strength, is set up. This model reasonably reflects the effects of the inner original defects on the static strength dispersion and on the fatigue life dispersion of composite laminates. The experimental data of three kinds of composite laminates are employed to verify this model, and the results show that this model can predict the random distributions of fatigue life for composites under any fatigue loads fairly well. 相似文献
859.
860.