全文获取类型
收费全文 | 217篇 |
免费 | 23篇 |
国内免费 | 37篇 |
专业分类
航空 | 114篇 |
航天技术 | 56篇 |
综合类 | 41篇 |
航天 | 66篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 6篇 |
2014年 | 9篇 |
2013年 | 14篇 |
2012年 | 18篇 |
2011年 | 21篇 |
2010年 | 14篇 |
2009年 | 13篇 |
2008年 | 16篇 |
2007年 | 13篇 |
2006年 | 13篇 |
2005年 | 14篇 |
2004年 | 15篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 11篇 |
2000年 | 6篇 |
1999年 | 12篇 |
1998年 | 8篇 |
1997年 | 9篇 |
1996年 | 10篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有277条查询结果,搜索用时 218 毫秒
171.
A novel integrated guidance and autopilot design method is proposed for homing missiles based on the adaptive block dynamic surface control approach. The fully integrated guidance and autopilot model is established by combining the nonlinear missile dynamics with the nonlinear dynamics describing the pursuit situation of a missile and a target in the three-dimensional space. The integrated guidance and autopilot design problem is further converted to a state regulation problem of a time-varying nonlinear system with matched and unmatched uncertainties. A new and simple adaptive block dynamic surface control algorithm is proposed to address such a state regulation problem. The stability of the closed-loop system is proven based on the Lyapunov theory. The six degrees of freedom (6DOF) nonlinear numerical simulation results show that the proposed integrated guidance and autopilot algorithm can ensure the accuracy of target interception and the robust stability of the closed-loop system with respect to the uncertainties in the missile dynamics. 相似文献
172.
173.
174.
175.
对电子工艺教学的思考 总被引:1,自引:0,他引:1
电子工艺课程的培养目标决定课程内容的选择.为了达到培养目标,在电子工艺课程中提出了强化实践教学的几个措施,把培养高综合素质人才的理念渗透到教学环节中,突显职业技术教育的优势. 相似文献
176.
Gaussian pigeon-inspired optimization approach to orbital spacecraft formation reconfiguration 总被引:2,自引:0,他引:2
With the rapid development of space technology, orbital spacecraft formation has received great attention from international and domestic academics and industry. Compared with a single monolithic, the orbital spacecraft formation system has many advantages. This paper presents an improved pigeon-inspired optimization(PIO) algorithm for solving the optimal formation reconfiguration problems of multiple orbital spacecraft. Considering that the uniform distribution random searching system in PIO has its own weakness, a modified PIO model adopting Gaussian strategy is presented and the detailed process is also given. Comparative experiments with basic PIO and particle swarm optimization(PSO) are conducted, and the results have verified the feasibility and effectiveness of the proposed Gaussian PIO(GPIO) in solving orbital spacecraft formation reconfiguration problems. 相似文献
177.
Basic performance of BeiDou-2 navigation satellite system used in LEO satellites precise orbit determination 总被引:1,自引:0,他引:1
The visibility for low earth orbit(LEO) satellites provided by the BeiDou-2 system is analyzed and compared with the global positioning system(GPS). In addition, the spaceborne receivers' observations are simulated by the BeiDou satellites broadcast ephemeris and LEO satellites orbits. The precise orbit determination(POD) results show that the along-track component accuracy is much better over the service area than the non-service area, while the accuracy of the other two directions keeps at the same level over different areas. However, the 3-dimensional(3D) accuracy over the two areas shows almost no difference. Only taking into consideration the observation noise and navigation satellite ephemeris errors, the 3D accuracy of the POD is about30 cm. As for the precise relative orbit determination(PROD), the 3D accuracy is much better over the eastern hemisphere than that of the western hemisphere. The baseline length accuracy is 3.4 mm over the service area, and it is still better than 1 cm over the non-service area. This paper demonstrates that the BeiDou regional constellation could provide global service to LEO satellites for the POD and the PROD. Finally, the benefit of geostationary earth orbit(GEO) satellites is illustrated for POD. 相似文献
178.
179.
180.
In view of the complexity of landing on the deck of aircraft carrier, a systematic model, composed of six- degree-of-freedom mathematic model of carrier-based aircraft, four-degree-of-freedom model of landing gears and six-degree-of-freedom mathematic model of carrier, is established in the Matlab-Simulink environment, with damping function of landing gears and dynamic characteristics of tires being considered. The model, where the car- rier movement is introduced, is applicable for any abnormal landing condition. Moreover, the equations of motion and relevant parameter are also derived. The dynamic response of aircraft is calculated via the variable step-size Runge-Kuta algorithm. The effect of attitude angles of aircraft and carrier movement during the process of landing is illustrated in details. The analytical results can provide some reference for carrier-based aircraft design and main- tenance. 相似文献