全文获取类型
收费全文 | 577篇 |
免费 | 142篇 |
国内免费 | 141篇 |
专业分类
航空 | 430篇 |
航天技术 | 102篇 |
综合类 | 39篇 |
航天 | 289篇 |
出版年
2024年 | 3篇 |
2023年 | 20篇 |
2022年 | 44篇 |
2021年 | 36篇 |
2020年 | 41篇 |
2019年 | 43篇 |
2018年 | 30篇 |
2017年 | 23篇 |
2016年 | 35篇 |
2015年 | 28篇 |
2014年 | 31篇 |
2013年 | 45篇 |
2012年 | 43篇 |
2011年 | 45篇 |
2010年 | 28篇 |
2009年 | 37篇 |
2008年 | 34篇 |
2007年 | 51篇 |
2006年 | 26篇 |
2005年 | 32篇 |
2004年 | 16篇 |
2003年 | 20篇 |
2002年 | 17篇 |
2001年 | 16篇 |
2000年 | 14篇 |
1999年 | 16篇 |
1998年 | 18篇 |
1997年 | 17篇 |
1996年 | 6篇 |
1995年 | 8篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 11篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 2篇 |
排序方式: 共有860条查询结果,搜索用时 234 毫秒
201.
磁悬浮控制力矩陀螺框架伺服系统扰动力矩分析与抑制 总被引:1,自引:0,他引:1
对磁悬浮控制力矩陀螺框架伺服系统,提出了一种基于自适应逆扰动消除控制的设计方法。该控制器采用将被控对象动态控制和对象扰动控制分离处理的方法研究了控制力矩陀螺框架伺服系统的非线性摩擦干扰力矩、陀螺房内部高速磁悬浮转子系统因框架变速转动对框架伺服系统产生的耦合力矩以及航天器姿态改变导致框架伺服系统本身的参数大范围变化等问题。设计的自适应逆扰动消除器大大改善了框架伺服系统的控制性能、提高了系统的速率输出精度。仿真结果表明,提出的扰动力矩抑制方法是可行的,具有很强的鲁棒性。 相似文献
202.
203.
204.
205.
206.
207.
208.
209.
A block-structured adaptive mesh refinement (AMR) method was applied to the computational problem of acoustic radiation from an aeroengine intake. The aim is to improve the computational and storage efficiency in aeroengine noise prediction through reduction of computational cells. A parallel implementation of the adaptive mesh refinement algorithm was achieved using message passing interface. It combined a range of 2nd- and 4th-order spatial stencils, a 4th-order low-dissipation and low-dispersion Runge–Kutta scheme for time integration and several different interpolation methods. Both the parallel AMR algorithms and numerical issues were introduced briefly in this work. To solve the problem of acoustic radiation from an aeroengine intake, the code was extended to support body-fitted grid structures. The problem of acoustic radiation was solved with linearised Euler equations. The AMR results were compared with the previous results computed on a uniformly fine mesh to demonstrate the accuracy and the efficiency of the current AMR strategy. As the computational load of the whole adaptively refined mesh has to be balanced between nodes on-line, the parallel performance of the existing code deteriorates along with the increase of processors due to the expensive inter-nodes memory communication costs. The potential solution was suggested in the end. 相似文献
210.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2023,71(6):2733-2744
A predefined-time attitude stabilization for complex structure spacecraft with liquid sloshing and flexible vibration is investigated under input saturation during orbital maneuver. First, the attitude dynamics model of liquid-filled flexible spacecraft is constructed. Meanwhile, the influence of solar panel vibration and liquid sloshing is treated as a disturbance in the controller design. Next, an adaptive predefined-time control scheme is proposed by applying sliding mode control theory. A predefined-time convergent sliding surface and reaching law are designed to ensure the predefined-time fast convergence rate. Furthermore, a novel adaptive algorithm is developed to handle the disturbances from liquid sloshing and flexible vibration, ensuring that the system converges to a small neighborhood of the equilibrium. Additionally, a new auxiliary system is constructed to deal with the effects of input saturation. At last, one simulation case is performed to verify the feasibility and advantages of the proposed algorithm. 相似文献