全文获取类型
收费全文 | 214篇 |
免费 | 92篇 |
国内免费 | 65篇 |
专业分类
航空 | 240篇 |
航天技术 | 36篇 |
综合类 | 41篇 |
航天 | 54篇 |
出版年
2023年 | 10篇 |
2022年 | 15篇 |
2021年 | 17篇 |
2020年 | 10篇 |
2019年 | 12篇 |
2018年 | 15篇 |
2017年 | 14篇 |
2016年 | 9篇 |
2015年 | 10篇 |
2014年 | 26篇 |
2013年 | 22篇 |
2012年 | 18篇 |
2011年 | 18篇 |
2010年 | 13篇 |
2009年 | 8篇 |
2008年 | 14篇 |
2007年 | 4篇 |
2006年 | 10篇 |
2005年 | 8篇 |
2004年 | 4篇 |
2003年 | 9篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 11篇 |
1998年 | 14篇 |
1997年 | 12篇 |
1996年 | 12篇 |
1995年 | 6篇 |
1994年 | 9篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
排序方式: 共有371条查询结果,搜索用时 312 毫秒
51.
52.
针对飞行器在高速飞行时受气流干扰、惯性数据易发散等问题,从传感器数据融合角度出发,提出了通过无迹卡尔曼滤波(UKF)融合嵌入式大气数据观测系统(FADS)和惯性导航系统(INS)估计飞行器实时大气数据的算法。算法使用高维度非线性方程对惯性系统和大气系统间的关系建模,结合FADS与INS的数据,计算飞行器速度和高度,进而估算出攻角、侧滑角等参数。实验结果显示,与INS直接解算、扩展卡尔曼滤波(EKF)融合等原有估计方法相比,文章所述的算法在估计精度和系统稳定性方面均有所提高。 相似文献
53.
近几年,随着小卫星市场的蓬勃发展,小型卫星发射市场持续升温,以飞马座XL和运载器一号火箭为代表的空射火箭完成多次发射任务,将数十颗卫星送入近地轨道。空射运载火箭具备快速响应、机动灵活、发射成本低、任务适应性强等技术特点。运载火箭从空中发射可以充分利用载机的飞行高度和飞行速度,在相同的系统运载能力下,火箭的起飞质量更小;在相同的火箭起飞质量下,系统运载能力更高;同时,对于规模星座快速部署,空中发射的灵活优势显著。围绕空射火箭的上述技术特点,基于空射火箭模型开展仿真分析研究及不同发射方式的结果对比,结果表明空射方式对提升系统效益效果显著。 相似文献
54.
55.
56.
民航无线电陆空通话语言是以英语为载体的一种空地交流的特殊语言。本文在应用语言学的研究成果之上,提出了该语言的交际能力模型,该模型包括语言能力、策略能力、背景知识和心理生理机制四个部分。笔者结合民航陆空通话实际,对模型各个部分进行了分析,重点解析了策略能力在模型中的核心功能。 相似文献
57.
Mark Azzam 《中国航空学报》2017,30(2)
Analyzing airports' role in global air transportation and monitoring their development over time provides an additional perspective on the dynamics of network evolution. In order to understand the different roles airports can play in the network an integrated and multi-dimensional approach is needed. Therefore, an approach to airport classification through hierarchi-cal clustering considering several parameters from network theory is presented in this paper. By applying a 29 year record of global flight data and calculating the conditional transition probabil-ities the results are displayed as an evolution graph similar to a discrete-time Markov chain. With this analytical concept the meaning of airports is analyzed from a network perspective and a new airport taxonomy is established. The presented methodology allows tracking the development of airports from certain categories into others over time. Results show that airports of equal classes run through similar stages of development with a limited number of alternatives, indicating clear evolutionary patterns. Apart from giving an overview of the results the paper illustrates the exact data-driven approach and suggests an evaluation scheme. The methodology can help the public and industry sector to make informed strategy decisions when it comes to air transportation infras-tructure. 相似文献
58.
梁曼 《西安航空技术高等专科学校学报》2010,28(3)
以空中交通管制员职业特征为依据,深入探讨了适用于空管人才选拔的人为因素实验室的若干重要问题。构建了航空人为因素软件测试平台,并通过统计分析确定实验项目,以达到有效选拔空管人才的目的。 相似文献
59.
郭文君 《西安航空技术高等专科学校学报》2008,26(1):33-34
目的正确分析、准确判断空气压缩机的常见故障。方法通过观察、测量、试验等方法判断故障部位和类型。结果故障主要是活塞环严重磨损、活门密封性降低、偏心轮扭断、润滑油路堵塞和活门严重故障等。结论迅速快捷地排除空压机故障。 相似文献
60.
M. Nelson W.F. DempsterJ.P. Allen 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(5):675-683
Development of reliable and robust strategies for long-term life support for planetary exploration must be built from real-time experimentation to verify and improve system components. Also critical is incorporating a range of viable options to handle potential short-term life system imbalances. This paper revisits some of the conceptual framework for a Mars base prototype which has been developed by the authors along with others previously advanced (“Mars on Earth®”) in the light of three years of experimentation in the Laboratory Biosphere, further investigation of system alternatives and the advent of other innovative engineering and agri-ecosystem approaches. Several experiments with candidate space agriculture crops have demonstrated the higher productivity possible with elevated light levels and improved environmental controls. For example, crops of sweet potatoes exceeded original Mars base prototype projections by an average of 46% (53% for best crop) ultradwarf (Apogee) wheat by 9% (23% for best crop), pinto bean by 13% (31% for best crop). These production levels, although they may be increased with further optimization of lighting regimes, environmental parameters, crop density etc. offer evidence that a soil-based system can be as productive as the hydroponic systems which have dominated space life support scenarios and research. But soil also offers distinct advantages: the capability to be created on the Moon or Mars using in situ space resources, reduces long-term reliance on consumables and imported resources, and more readily recycling and incorporating crew and crop waste products. In addition, a living soil contains a complex microbial ecosystem which helps prevent the buildup of trace gases or compounds, and thus assist with air and water purification. The atmospheric dynamics of these crops were studied in the Laboratory Biosphere adding to the database necessary for managing the mixed stands of crops essential for supplying a nutritionally adequate diet in space. This paper explores some of the challenges of small bioregenerative life support: air-sealing and facility architecture/design, balance of short-term variations of carbon dioxide and oxygen through staggered plantings, options for additional atmospheric buffers and sinks, lighting/energy efficiency engineering, crop and waste product recycling approaches, and human factor considerations in the design and operation of a Mars base. An “Earth to Mars” project, forging the ability to live sustainably in space (as on Earth) requires continued research and testing of these components and integrated subsystems; and developing a step-by-step learning process. 相似文献