全文获取类型
收费全文 | 580篇 |
免费 | 80篇 |
国内免费 | 116篇 |
专业分类
航空 | 327篇 |
航天技术 | 169篇 |
综合类 | 130篇 |
航天 | 150篇 |
出版年
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 12篇 |
2020年 | 14篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 9篇 |
2014年 | 40篇 |
2013年 | 28篇 |
2012年 | 34篇 |
2011年 | 42篇 |
2010年 | 52篇 |
2009年 | 35篇 |
2008年 | 31篇 |
2007年 | 26篇 |
2006年 | 27篇 |
2005年 | 27篇 |
2004年 | 18篇 |
2003年 | 18篇 |
2002年 | 27篇 |
2001年 | 27篇 |
2000年 | 44篇 |
1999年 | 31篇 |
1998年 | 28篇 |
1997年 | 20篇 |
1996年 | 24篇 |
1995年 | 23篇 |
1994年 | 12篇 |
1993年 | 16篇 |
1992年 | 13篇 |
1991年 | 10篇 |
1990年 | 12篇 |
1989年 | 15篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有776条查询结果,搜索用时 31 毫秒
622.
针对传统空中交通流量仿真过程中灵活性和智能性的不足,将分布式人工智能Multi—Agent的理论和方法应用到空中交通流量管理领域中,提出了基于Muhi-Agent的空中交通流量仿真方法。介绍了空中流量管理的体系结构和流量管理的具体措施,详细设计了与流量仿真相关的重要Agent,包括航班Agent、航路Agent、机场终端区Agent和区域流量管理Agent等,探讨了各Agent的内部运行机制和在流量管理中的职能,构建了基于Multi.Agent的空中交通流量仿真子系统的整体框架.为实际空中交通流量管理系统的建设提供重要的指导和拳者。 相似文献
623.
L.F. Chernogor K.P. Garmash Q. Guo V.T. Rozumenko Yu Zheng Y. Luo 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(8):2439-2469
The purpose of the present paper is to describe the observations of the variations in the parameters of HF radio waves propagating through the ionosphere when the action of the super typhoon Hagibis on 6–13 October 2019 occurred. The observations have been made with the Harbin Engineering University (the People's Republic of China) multi-frequency multiple path radio system involving the software-defined technology. The action of the super typhoon has been shown to be accompanied by enhanced atmospheric wave activity acting to generate wave processes with periods of 10 to 120 min. Coupling in the atmosphere–upper-atmosphere–ionosphere system has been confirmed to be carried out with atmospheric gravity waves. The ionosphere underwent the greatest impact on those days when the supertyphoon had maximum energy, on 8, 10, and especially 9 October 2019, and when it was found to be in an ~2,500–3,000-km distance range from the propagation path midpoints. Under the action of wave processes, the height of the reflection region was observed to oscillate within the ±(30–90 km) limits. The amplitude of the quasi-periodic variations in the ionospheric F-region electron density was estimated to be 10–12% for periods of ~20 min, and 30–60% for periods of ~60–120 min. The joint action of the dusk terminator and the supertyphoon has been confirmed to enhance wave activity in the ionosphere. Similar effects for the dawn terminator have not been detected. 相似文献
624.
625.
罗红霞 《中国民航飞行学院学报》2011,22(4):32-33
针对冬季机场容易出现的恶劣天气特点,主要从降雪跑道结冰、大雾低能见两个主要恶劣天气着手,分析飞行签派员放行攻略。 相似文献
626.
The rendezvous and docking mission is usually divided into several phases, and the mission planning is performed phase by phase. A new planning method using mixed integer nonlinear programming, which investigates single phase parameters and phase connecting parameters simultaneously, is proposed to improve the rendezvous mission’s overall performance. The design variables are composed of integers and continuous-valued numbers. The integer part consists of the parameters for station-keeping and sensor-switching, the number of maneuvers in each rendezvous phase and the number of repeating periods to start the rendezvous mission. The continuous part consists of the orbital transfer time and the station-keeping duration. The objective function is a combination of the propellant consumed, the sun angle which represents the power available, and the terminal precision of each rendezvous phase. The operational requirements for the spacecraft–ground communication, sun illumination and the sensor transition are considered. The simple genetic algorithm, which is a combination of the integer-coded and real-coded genetic algorithm, is chosen to obtain the optimal solution. A practical rendezvous mission planning problem is solved by the proposed method. The results show that the method proposed can solve the integral rendezvous mission planning problem effectively, and the solution obtained can satisfy the operational constraints and has a good overall performance. 相似文献
627.
扰动因子与结构信息在飞机选型中的应用 总被引:1,自引:0,他引:1
罗德娥 《中国民航学院学报》1993,11(3):31-38
本文提出在飞机选型中利用结构信息,使合成排序更符合客观实际。文中还提出利用扰动因子改善判断矩阵一致性的方法,克服了调整判断矩阵时的盲目性。为满足飞机选型需要,编制了相应的软件。实践证明,扰动因子与结构信息的运用,对于解决层次分析法在飞机选型中应用的某些实际问题、为航空公司飞机选型提供可靠的科学依据是有益的。 相似文献
629.
630.
Simulation-based training is a promising way to train a carrier flight deck crew because of the complex and dangerous working environment. Quantitative evaluation of simulation-based training quality is vital to make simulation-based training practical for aircraft carrier marshalling.This paper develops a personal computer-based aircraft carrier marshalling simulation system and a cave automatic virtual environment(CAVE)-based immersive environment. In order to compare the training effectiveness of simulation-based training and paper-based training, a learning cubic model is proposed and a contrast experiment is carried out as well. The experimental data is analyzed based on a simplified Kirkpatrick’s model. The results show that simulation-based training is better than paper-based training by 26.80% after three rounds of testing, which prove the effectiveness of simulation-based aircraft carrier marshalling training. 相似文献