全文获取类型
收费全文 | 875篇 |
免费 | 191篇 |
国内免费 | 155篇 |
专业分类
航空 | 847篇 |
航天技术 | 122篇 |
综合类 | 110篇 |
航天 | 142篇 |
出版年
2024年 | 4篇 |
2023年 | 18篇 |
2022年 | 30篇 |
2021年 | 53篇 |
2020年 | 35篇 |
2019年 | 47篇 |
2018年 | 46篇 |
2017年 | 46篇 |
2016年 | 71篇 |
2015年 | 45篇 |
2014年 | 83篇 |
2013年 | 61篇 |
2012年 | 71篇 |
2011年 | 83篇 |
2010年 | 45篇 |
2009年 | 56篇 |
2008年 | 54篇 |
2007年 | 40篇 |
2006年 | 36篇 |
2005年 | 39篇 |
2004年 | 33篇 |
2003年 | 38篇 |
2002年 | 33篇 |
2001年 | 23篇 |
2000年 | 13篇 |
1999年 | 22篇 |
1998年 | 20篇 |
1997年 | 12篇 |
1996年 | 8篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1986年 | 1篇 |
排序方式: 共有1221条查询结果,搜索用时 15 毫秒
161.
Upset condition encountered by an aircraft in flight could pose great threat to flight safety, which is of chief importance in civil aviation. The causal factors have the nonlinear and multiple characteristics, and as a result the conventional envelope protection system cannot successfully do with the condition. So dynamic envelope based on differential manifold theory, which can take more coupling factors into account, is proposed as a basis to design a novel envelope protection system. Then the relationship between the dynamic envelope and the control coefficient or pilot command is obtained, and the result shows that the dynamic envelope can be enlarged with the change of control coefficient. Furthermore, quantification of flight security is realized via defining relative distance between flight state and dynamic envelope, which can detect whether there is a risk for an aircraft in flight. Finally, an envelope protection system based on dynamic envelope enlargement is proposed on the basis. NASA’s Generic Transport Model encountering hazard gust wind in climbing phase is taken as an example to verify the system’s feasibility. The result shows that the system can give a better operation encountering upset condition and to a certain extent reduce the number of accidents or incidents. 相似文献
162.
由于在S-网络上的IMP S-网络接口在线路上存在自身的缺陷,往往使其与主控计算机之间的通信受阻。本文从线路上改进了IMP S-网络接口,从而使通信更加稳定、可靠。 相似文献
163.
164.
林泉 《中国民航学院学报》2009,27(3):37-40
从一般经济学的投入、成本和效益的基本思路进行探讨,阐述了民航安全经济学研究的基本内容、研究方法,指出了民航安全经济学的基本特点,分析了研究民航安全经济学的意义与价值,勾勒了民航安全经济学研究的基本框架。 相似文献
165.
A new safety culture model is constructed and is applied to analyze the correlations between safety culture and SMS. On the basis of previous typical definitions, models and theories of safety culture, an in-depth analysis on safety culture's structure, composing elements and their correlations was conducted. A new definition of safety culture was proposed from the perspective of sub-culture. 7 types of safety sub-culture, which are safety priority culture, standardizing culture, flexible culture, learning culture, teamwork culture, reporting culture and justice culture were defined later. Then integrated safety culture model (ISCM) was put forward based on the definition. The model divided safety culture into intrinsic latency level and extrinsic indication level and explained the potential relationship between safety sub-culture and all safety culture dimensions. Finally in the analyzing of safety culture and SMS, it concluded that positive safety culture is the basis of im plementing SMS effectively and an advanced SMS will improve safety culture from all around. 相似文献
166.
167.
基于CS8900A的工业级嵌入式网络接口实现 总被引:2,自引:0,他引:2
介绍了工业级以太网络控制芯片CS8900A—IQ3在嵌入式Internet中的应用,以实例详细对比说明了其在8位和16位两种运行模式下的硬件和软件实现。 相似文献
168.
INTRODUCTIONThe study on phenomenon of multi- fluid in-terface driven by shock waves include:( 1 ) totrack the motion of multimaterial interfaces;( 2 )to simulate the chemical reaction on the inter-faces. As the pioneering work,chemical reactionis neglected in this paper. The objective is totrack the interfaces. Of course,the fluids aretreated as compressible medium under such ahigh impact.Although Eulerian schemes workwell for most gas flows,they have been shownto be too dissipative nea… 相似文献
169.
多媒体煤矿安全监测管理系统研究 总被引:1,自引:0,他引:1
介绍了现有的煤矿安全监测和安全考勤管理系统的特点及缺陷,探讨了如何将多媒体计算机技术应用于煤矿安全监测管理系统。该系统具有实时监视、紧急救援和事故分析三大特点。 相似文献
170.
李大立 《西安航空技术高等专科学校学报》2008,26(1):3-7
通过介绍我国远西地区的基本情况和战略地位,并就民用航空对该地区经济发展的重要推动作用和通用航空市场需求进行了分析,提出了我国远西地区发展通用航空的资金、组织机构、空管、适用机型等建议、设想以及实施战略。 相似文献