全文获取类型
收费全文 | 727篇 |
免费 | 161篇 |
国内免费 | 188篇 |
专业分类
航空 | 632篇 |
航天技术 | 125篇 |
综合类 | 94篇 |
航天 | 225篇 |
出版年
2024年 | 6篇 |
2023年 | 7篇 |
2022年 | 21篇 |
2021年 | 28篇 |
2020年 | 33篇 |
2019年 | 37篇 |
2018年 | 40篇 |
2017年 | 28篇 |
2016年 | 38篇 |
2015年 | 45篇 |
2014年 | 35篇 |
2013年 | 35篇 |
2012年 | 55篇 |
2011年 | 58篇 |
2010年 | 40篇 |
2009年 | 40篇 |
2008年 | 47篇 |
2007年 | 51篇 |
2006年 | 44篇 |
2005年 | 34篇 |
2004年 | 33篇 |
2003年 | 35篇 |
2002年 | 26篇 |
2001年 | 33篇 |
2000年 | 27篇 |
1999年 | 25篇 |
1998年 | 24篇 |
1997年 | 23篇 |
1996年 | 11篇 |
1995年 | 21篇 |
1994年 | 18篇 |
1993年 | 11篇 |
1992年 | 18篇 |
1991年 | 16篇 |
1990年 | 4篇 |
1989年 | 11篇 |
1988年 | 13篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有1076条查询结果,搜索用时 31 毫秒
221.
222.
根据战术弹道导弹的特点 ,提出了战术导弹运动偏差状态解耦的联合滤波算法 ,基于该算法相应给出了可有效检测速度跳变的SINS/GPS级联组合制导品质控制措施。仿真结果验证了该方法的有效性。 相似文献
223.
对DATH在复合改性双基推进剂中应用及配装浇 出工艺制DATH-CMDB推进剂药柱过程中出现的较强固化放气问题做了探讨,得出了若干结论。 相似文献
224.
提出了Latin抽样与分层抽样相结合的复合抽样方法,对于提高抽样精度和效率都有较为明显的作用,特别适用于结构裂纹概率的仿真和其它应用工程仿真计算。在复合抽样仿真计算示例中,对某型导弹的燃汽发生器进行了抽样仿真计算,所得的抽样结果的精度和相关差都达到了令人满意的预期效果,与实验结果吻合。 相似文献
225.
226.
227.
Real-time and accurate fault detection is essential to enhance the aircraft navigation system’s reliability and safety. The existent detection methods based on analytical model draws back at simultaneously detecting gradual and sudden faults. On account of this reason, we propose an online detection solution based on non-analytical model. In this article, the navigation system fault detection model is established based on belief rule base (BRB), where the system measuring residual and its changing rate are used as the inputs of BRB model and the fault detection function as the output. To overcome the drawbacks of current parameter optimization algorithms for BRB and achieve online update, a parameter recursive estimation algorithm is presented for online BRB detection model based on expectation maximization (EM) algorithm. Furthermore, the proposed method is verified by navigation experiment. Experimental results show that the proposed method is able to effectively realize online parameter evaluation in navigation system fault detection model. The output of the detection model can track the fault state very well, and the faults can be diagnosed in real time and accurately. In addition, the detection ability, especially in the probability of false detection, is superior to offline optimization method, and thus the system reliability has great improvement. 相似文献
228.
J. Kozicka 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(1):129-137
Technical and architectural problems of a Martian base have been arised in many publications. Usually there is one solution described in detail or general classification is presented. In this paper, a recognition of low-cost solutions for Martian architecture is analyzed. The overview through various building techniques based on previous concepts of extraterrestrial architecture is summarized. Several solutions taking advantages of the shape of terrain, aiming for cost decreasing of human settlement on Mars are proposed. 相似文献
229.
230.
Gaseous cavity at the base of an underwater projectile 总被引:1,自引:0,他引:1
A Dyment J.P Flodrops J.B Paquet D Dupuis D Marchand 《Aerospace Science and Technology》1998,2(8):489-504
The problem of the behavior of the gaseous cavity which is formed at the base of an underwater launched projectile is treated using different approaches. Asymptotic analysis is used to yield expressions for similarity parameters and a simplified hydrodynamic model of the initial stretching phase. A laboratory facility is described, in which launches can be simulated and analyzed by means of pressure measurements and high speed visualizations. Complete calculations are also performed using a numerical “Volume of Fluid” model solving the unsteady Navier-Stokes equations. Results from the three approaches are presented and compared during the cavity stretching phase. Finally, the thermodynamic aspects of the problem are examined. 相似文献