全文获取类型
收费全文 | 307篇 |
免费 | 1篇 |
国内免费 | 10篇 |
专业分类
航空 | 186篇 |
航天技术 | 84篇 |
综合类 | 1篇 |
航天 | 47篇 |
出版年
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 15篇 |
2013年 | 8篇 |
2012年 | 13篇 |
2011年 | 31篇 |
2010年 | 9篇 |
2009年 | 16篇 |
2008年 | 22篇 |
2007年 | 12篇 |
2006年 | 8篇 |
2005年 | 8篇 |
2004年 | 14篇 |
2003年 | 6篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 11篇 |
1998年 | 7篇 |
1997年 | 2篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有318条查询结果,搜索用时 15 毫秒
91.
Lee J.R. Cho B.H. Kim S.J. Lee F.C. 《IEEE transactions on aerospace and electronic systems》1988,24(3):295-304
Modeling of a complete spacecraft power processing system is presented, using the Boeing EASYS software. Component models are developed, and several system models including a solar array switching system, a partially shunted solar system, and cosmic background explorer (COBE) system are simulated. The modes of operation of the power system, such as shunt mode, battery-charge mode, and battery-discharge mode, are simulated for a complete orbit cycle 相似文献
92.
涡襟翼振动对三角翼涡的影响 总被引:2,自引:0,他引:2
<正> 1.引言 许多实验表明,用主动干扰的方式是控制分离的一个有效方法,而且可以把分离区从一死水区(或紊乱的区域)变成一个有序流动区域。二维流动实验还表明非定常机动可以较大地改变流动结构。三维流态显示表明强迫振动对集中涡的形成过程等有显著影响,并影响涡和物面之间的距离。目前对三维非定常流动特性,以及非定常干扰对机翼绕流中涡破裂等的作用尚未充分了解。 影响集中涡破裂的关键因素是沿涡轴方向的压力梯度。涡环量对破裂的影响是双向的,涡强过大易使涡破裂;涡强过小时涡结构松散,也易于破裂,甚至迅速耗散掉。从二维结果看,非定常强迫扰动可使涡的结构更紧凑、清晰,而且扰动可以改 相似文献
93.
本文中利用三角翼前缘涡襟翼的强制振动来推迟涡破裂。流场显示实验结果表明,在有强制扰动时,集中涡显示出两种不同形式的破裂,可分成六种不同的破裂形态。非定常集中涡的一个破裂过程涉及几种破裂形态之间的转换。涡襟翼振动产生的非定常效应对涡破裂的影响与三角翼后掠角有密切的关系,随后掠角增大非定常效应的影响变小。就实验迎角范围而言(α<35°),对50°后掠角三角翼,涡襟翼振动可显著推迟涡破裂;但对70°后掠角三角翼,振动却能促进涡的破裂。涡襟翼振动改变了集中涡的性态,使集中涡趋向于和前缘平行。振动对涡破裂的作用部分地与这种效应有关。 相似文献
94.
K. T. Lee T. Cleghorn F. Cucinotta L. Pinsky C. Zeitlin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2004,33(12):2211-2214
The charged particle spectrum for nuclei from protons to neon, (charge Z=10) was observed during the cruise phase and orbit around Mars by the MARIE charged particle spectrometer on the Odyssey spacecraft. The cruise data were taken between April 23, 2001 and mid-August 2001. The Mars orbit data were taken March 5, 2002 through May 2002 and are scheduled to continue until August 2004. Charge peaks are clearly separated for charges up to Z=10. Especially prominent are the carbon and oxygen peaks, with boron and nitrogen also clearly visible. Although heavy ions are much less abundant than protons in the cosmic ray environment, it is important to determine their abundances because their ionization energy losses (proportional to Z2) are far more dangerous to humans and to instruments. Thus the higher charged nuclei make a significant contribution to dose and dose equivalent received in space. Results of the charged particle spectrum measurements will be reported. 相似文献
95.
The Juno Radiation Monitoring (RM) Investigation 总被引:1,自引:0,他引:1
H. N. Becker J. W. Alexander A. Adriani A. Mura A. Cicchetti R. Noschese J. L. Jørgensen T. Denver J. Sushkova A. Jørgensen M. Benn J. E. P. Connerney S. J. Bolton The Selex Galileo Juno SRU Team J. Allison S. Watts V. Adumitroaie E. A. Manor-Chapman I. J. Daubar C. Lee S. Kang W. J. McAlpine T. Di Iorio C. Pasqui A. Barbis P. Lawton L. Spalsbury S. Loftin J. Sun 《Space Science Reviews》2017,213(1-4):507-545
The Radiation Monitoring Investigation of the Juno Mission will actively retrieve and analyze the noise signatures from penetrating radiation in the images of Juno’s star cameras and science instruments at Jupiter. The investigation’s objective is to profile Jupiter’s \(>10\mbox{-MeV}\) electron environment in regions of the Jovian magnetosphere which today are still largely unexplored. This paper discusses the primary instruments on Juno which contribute to the investigation’s data suite, the measurements of camera noise from penetrating particles, spectral sensitivities and measurement ranges of the instruments, calibrations performed prior to Juno’s first science orbit, and how the measurements may be used to infer the external relativistic electron environment. 相似文献
96.
M. A. Janssen J. E. Oswald S. T. Brown S. Gulkis S. M. Levin S. J. Bolton M. D. Allison S. K. Atreya D. Gautier A. P. Ingersoll J. I. Lunine G. S. Orton T. C. Owen P. G. Steffes V. Adumitroaie A. Bellotti L. A. Jewell C. Li L. Li S. Misra F. A. Oyafuso D. Santos-Costa E. Sarkissian R. Williamson J. K. Arballo A. Kitiyakara A. Ulloa-Severino J. C. Chen F. W. Maiwald A. S. Sahakian P. J. Pingree K. A. Lee A. S. Mazer R. Redick R. E. Hodges R. C. Hughes G. Bedrosian D. E. Dawson W. A. Hatch D. S. Russell N. F. Chamberlain M. S. Zawadski B. Khayatian B. R. Franklin H. A. Conley J. G. Kempenaar M. S. Loo E. T. Sunada V. Vorperion C. C. Wang 《Space Science Reviews》2017,213(1-4):139-185
97.
T. G. Forbes J. A. Linker J. Chen C. Cid J. Kóta M. A. Lee G. Mann Z. Mikić M. S. Potgieter J. M. Schmidt G. L. Siscoe R. Vainio S. K. Antiochos P. Riley 《Space Science Reviews》2006,123(1-3):251-302
This chapter provides an overview of current efforts in the theory and modeling of CMEs. Five key areas are discussed: (1) CME initiation; (2) CME evolution and propagation; (3) the structure of interplanetary CMEs derived from flux rope modeling; (4) CME shock formation in the inner corona; and (5) particle acceleration and transport at CME driven shocks. In the section on CME initiation three contemporary models are highlighted. Two of these focus on how energy stored in the coronal magnetic field can be released violently to drive CMEs. The third model assumes that CMEs can be directly driven by currents from below the photosphere. CMEs evolve considerably as they expand from the magnetically dominated lower corona into the advectively dominated solar wind. The section on evolution and propagation presents two approaches to the problem. One is primarily analytical and focuses on the key physical processes involved. The other is primarily numerical and illustrates the complexity of possible interactions between the CME and the ambient medium. The section on flux rope fitting reviews the accuracy and reliability of various methods. The section on shock formation considers the effect of the rapid decrease in the magnetic field and plasma density with height. Finally, in the section on particle acceleration and transport, some recent developments in the theory of diffusive particle acceleration at CME shocks are discussed. These include efforts to combine self-consistently the process of particle acceleration in the vicinity of the shock with the subsequent escape and transport of particles to distant regions. 相似文献
98.
N.U. Crooker J.T. Gosling V. Bothmer R.J. Forsyth P.R. Gazis A. Hewish T.S. Horbury D.S. Intriligator J.R. Jokipii J. Kóta A.J. Lazarus M.A. Lee E. Lucek E. Marsch A. Posner I.G. Richardson E.C. Roelof J.M. Schmidt G.L. Siscoe B.T. Tsurutani R.F. Wimmer-Schweingruber 《Space Science Reviews》1999,89(1-2):179-220
Corotating interaction regions (CIRs) in the middle heliosphere have distinct morphological features and associated patterns
of turbulence and energetic particles. This report summarizes current understanding of those features and patterns, discusses
how they can vary from case to case and with distance from the Sun and possible causes of those variations, presents an analytical
model of the morphological features found in earlier qualitative models and numerical simulations, and identifies aspects
of the features and patterns that have yet to be resolved.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
99.
Frequency-hopping signal detection using partial band coverage 总被引:1,自引:0,他引:1
Miller L.E. Lee J.S. Torrieri D.J. 《IEEE transactions on aerospace and electronic systems》1993,29(2):540-553
The performance of a channelized radiometer in detecting a frequency-hopping signal is analyzed for a variable number of parallel radiometers not necessarily covering the entire hopping band. The full band may not be covered because of an attempt to avoid interfering signals, limited radiometer resources, lack of knowledge of the band frequency location, or combinations of these factors. The analysis provides for calculation of the value of the signal-to-noise ratio (SNR) required to achieve a given probability of detection for a specified false-alarm rate, assuming an observation interval equivalent to N hops using either a fixed or a moving observation window. The dependence of the probability of detection on a misalignment of the detector observation intervals with the hop transitions is also analyzed. Numerical results are presented and discussed. Applied to a typical slow-hopping VHF radio, the results imply that a 150-hop transmission can be detected by a channelized radiometer covering half the hopping band when the SNR is about 2 dB 相似文献
100.
J. Park K.W. Min V.P. Kim H. Kil H.J. Kim J.J. Lee E. Lee S.J. Kim D.Y. Lee M. Hairston 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(4):650-654
The global distribution of low-latitude plasma blobs was investigated by in-situ plasma density measurements from the Korea Multi-Purpose Satellite-1 (KOMPSAT-1) and Defense Meteorological Satellite Program (DMSP) F15. In the observations, blobs occurred in the longitude sector where the activity of the equatorial plasma bubble (EPB) was appreciable, and additional blobs were found at the lower (KOMPSAT-1) altitude as in the EPBs. However, several notable differences exist between the distributions of EPBs and blobs. First, KOMPSAT-1 found few blobs around 0°E in March and June, as did DMSP F15 from 30°W to 120°E for every season. Second, the overall occurrences in December and March at the DMSP F15 (840 km) altitude were somewhat lower than expected from those of the EBPs. Third, at the DMSP F15 altitude, the occurrence probability of plasma blobs was less controlled by yearly variations in the solar activity. These results imply that topside ionospheric conditions as well as the existence of EPBs control further development of blobs. Additionally, it was found that the blob latitudes became higher as the yearly solar activity increased. Moreover, most of the blobs were encountered in the winter hemisphere, possibly due to the low ambient density. 相似文献