全文获取类型
收费全文 | 65篇 |
免费 | 4篇 |
国内免费 | 4篇 |
专业分类
航空 | 44篇 |
航天技术 | 13篇 |
综合类 | 3篇 |
航天 | 13篇 |
出版年
2023年 | 2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 | 2篇 |
2013年 | 2篇 |
2012年 | 1篇 |
2011年 | 1篇 |
2010年 | 1篇 |
2009年 | 3篇 |
2008年 | 5篇 |
2007年 | 10篇 |
2006年 | 6篇 |
2005年 | 2篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1992年 | 2篇 |
排序方式: 共有73条查询结果,搜索用时 406 毫秒
11.
12.
13.
Onur Erturk Orhan Arikan Feza Arikan 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
Electron density distribution is the major determining parameter of the ionosphere. Computerized Ionospheric Tomography (CIT) is a method to reconstruct ionospheric electron density image by computing Total Electron Content (TEC) values from the recorded Global Positioning Satellite System (GPS) signals. Due to the multi-scale variability of the ionosphere and inherent biases and errors in the computation of TEC, CIT constitutes an underdetermined ill-posed inverse problem. In this study, a novel Singular Value Decomposition (SVD) based CIT reconstruction technique is proposed for the imaging of electron density in both space (latitude, longitude, altitude) and time. The underlying model is obtained from International Reference Ionosphere (IRI) and the necessary measurements are obtained from earth based and satellite based GPS recordings. Based on the IRI-2007 model, a basis is formed by SVD for the required location and the time of interest. Selecting the first few basis vectors corresponding to the most significant singular values, the 3-D CIT is formulated as a weighted least squares estimation problem of the basis coefficients. By providing significant regularization to the tomographic inversion problem with limited projections, the proposed technique provides robust and reliable 3-D reconstructions of ionospheric electron density. 相似文献
14.
程健康 《西安航空技术高等专科学校学报》2008,26(4):6-9
人的全面发展理论是马克思主义理论的重要组成部分。人的全面发展的内涵包括人的能力的全面发展、人的社会关系的全面发展、人的需要的全面发展和人的个性的全面发展等内容。人的全面发展理论要求现代教育改革必须树立以人为本的教育理念,重视对学生的全面教育、尊重学生的个性、充分挖掘学生潜能、满足学生需要、营造宽松和谐的教学氛围、构建终身教育体系等。以促进学生的全面发展。 相似文献
15.
量块计量保证方案(MAP)是美国NIST近年来推行的一种科学的量值传递方法。它打破了传统的量值传递方法,采用l检验和F检验对量值传递过程进行控制,并通过数据反馈对参加试验室进行综合考核,以确保量值传递的质量。介绍了在我国推广应用量块计量保证方案的实施情况,并进行了技术分析。 相似文献
16.
关于切顶线三角形有向面积的定值定理及其应用 总被引:1,自引:1,他引:1
喻德生 《南昌航空工业学院学报》2002,16(3):1-3
本文给出切顶线三角形(有向)面积的一些定值定理,并据此推出切顶线共点(其中包括射影几何中著名的Brianchon定理在圆外切三角形中的情形)的结论。 相似文献
17.
介绍了一种新的刚体转动的四元数模型。这些模型可以提高再定向控制的对边界条件的适应能力,在此基础上还介绍了这些模型的一些实际应用。 相似文献
18.
Víctor Puente 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(8):2359-2367
Tropospheric delay is one of the major sources of error in VLBI (Very Long Baseline Interferometry) analysis. The principal component of this error can be accurately computed through reliable surface pressure data —hydrostatic delay— yet there is also a small but volatile component —wet delay— which is difficult to be modelled a priori. In VLBI analysis, troposphere delay is typically modelled in the theoretical delays using Zenith Hydrostatic Delays (ZHD) and a dry mapping function. Zenith Wet Delay (ZWD) is not modelled but estimated in the analysis process. This work studies inter alia the impact of including external GNSS estimates to model a priori ZWD in VLBI analysis, as well as other models of a priori ZWD.In a first stage, two different sources of GNSS troposphere products are compared to VLBI troposphere estimates in a period of 5 years. The solution with the best agreement to VLBI results is injected in the VLBI analysis as a priori ZWD value and is compared to other options to model a priori ZWD. The dataset used for this empirical analysis consists of the six CONT campaigns.It has been found that modelling a priori ZWD has no significant impact either on baseline length and coordinates repeatabilities. Nevertheless, modelling a priori ZWD can change the magnitude of the estimated coordinates a few millimeters in the up component with respect to the non-modelling approach. In addition, the influence of a priori ZWD on Earth Orientation Parameters (EOP) and troposphere estimates —Zenith Total Delays (ZTD) and gradients—has also been analysed, resulting in a small but significant impact on both geodetic products. 相似文献
19.
This paper aims to propose a creep life evaluation method considering the effect of crystallographic orientation. First, the maximum Schmid factor of {111} <112> and the corresponding lattice rotation angle were introduced to form an ‘‘orientation factor". Then the equivalent stress was calculated by multiplying this factor and the nominal stress. Latterly, the LarsonMiller Parameter(LMP) method was adopted as the rupture life evaluation criteria, in which the input variable was the equiva... 相似文献
20.
杨理连 《西安航空技术高等专科学校学报》2007,25(5):62-64
面对我国应用型本科教育不断发展和壮大的新形势,准确把握和正确认识其办学基本定位和办学规律,科学有效地实施应用型本科教育,是高等教育面临的一个重要课题。通过从发展环境、基本现状、努力方向等方面对应用型本科教育进行的论述与剖析,为决策好、研究好、实施好应用型本科教育提供了一定的参考。 相似文献