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51.
随着火星探测技术的不断发展和探测任务的不断推进,载人火星探测在未来将会成为火星探测的重要手段。首先,回顾了无人火星探测任务的发展历程,对比分析了部分无人火星探测器进入、下降与着陆(EDL)过程的参数。然后,结合无人火星探测、载人月球探测和载人航天再入过程,梳理了载人火星探测的特点及需求,系统地总结了前苏联/俄罗斯和美国的载人火星探测研究进展以及技术储备。接着,归纳了载人火星探测的体系构成、集结方式和主要的技术挑战。最后,概括了载人火星EDL过程面临的难题,重点阐述了EDL的导航、制导与控制(GNC)关键技术。 相似文献
52.
53.
Ricardo Hueso J. Legarreta J.F. Rojas J. Peralta S. Pérez-Hoyos T. del Río-Gaztelurrutia A. Sánchez-Lavega 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
The observation, characterization, and understanding of planetary atmospheres are key components of Solar System exploration. Their study requires, among other observations, the use of image data acquired from spacecrafts. The basic tasks that are generally used to work with planetary image data are: image navigation, projection, image processing, limb-darkening correction, composition of multiwavelength images and mosaicing. We illustrate the mathematical techniques required for the study of planetary images obtained from spacecrafts using as an example our own software package (PLIA). We present examples of analysis of Galileo SSI, Cassini ISS and Venus Express VIRTIS observations covering a large range of image peculiarities. The paper is organized as a guide for anyone willing to replicate one or several of the capabilities incorporated in the PLIA software. An open source version of PLIA for astronomical image processing is available. 相似文献
54.
A. Sprague J. Warell G. Cremonese Y. Langevin J. Helbert P. Wurz I. Veselovsky S. Orsini A. Milillo 《Space Science Reviews》2007,132(2-4):399-431
Mercury’s surface is thought to be covered with highly space-weathered silicate material. The regolith is composed of material
accumulated during the time of planetary formation, and subsequently from comets, meteorites, and the Sun. Ground-based observations
indicate a heterogeneous surface composition with SiO2 content ranging from 39 to 57 wt%. Visible and near-infrared spectra, multi-spectral imaging, and modeling indicate expanses
of feldspathic, well-comminuted surface with some smooth regions that are likely to be magmatic in origin with many widely
distributed crystalline impact ejecta rays and blocky deposits. Pyroxene spectral signatures have been recorded at four locations.
Although highly space weathered, there is little evidence for the conversion of FeO to nanophase metallic iron particles (npFe0), or “iron blebs,” as at the Moon. Near- and mid-infrared spectroscopy indicate clino- and ortho-pyroxene are present at
different locations. There is some evidence for no- or low-iron alkali basalts and feldspathoids. All evidence, including
microwave studies, point to a low iron and low titanium surface. There may be a link between the surface and the exosphere
that may be diagnostic of the true crustal composition of Mercury. A structural global dichotomy exists with a huge basin
on the side not imaged by Mariner 10. This paper briefly describes the implications for this dichotomy on the magnetic field
and the 3 : 2 spin : orbit coupling. All other points made above are detailed here with an account of the observations, the
analysis of the observations, and theoretical modeling, where appropriate, that supports the stated conclusions. 相似文献
55.
Deep Impact Mission Design 总被引:1,自引:0,他引:1
William H. Blume 《Space Science Reviews》2005,117(1-2):23-42
The Deep Impact mission is designed to provide the first opportunity to probe below the surface of a comet nucleus by a high-speed
impact. This requires finding a suitable comet with launch and encounter conditions that allow a meaningful scientific experiment.
The overall design requires the consideration of many factors ranging from environmental characteristics of the comet (nucleus
size, dust levels, etc.), to launch dates fitting within the NASA Discovery program opportunities, to launch vehicle capability
for a large impactor, to the observational conditions for the two approaching spacecraft and for telescopes on Earth. 相似文献
56.
Michael F. A’Hearn Michael J. S. Belton Alan Delamere William H. Blume 《Space Science Reviews》2005,117(1-2):1-21
The Deep Impact mission will provide the first data on the interior of a cometary nucleus and a comparison of those data with
data on the surface. Two spacecraft, an impactor and a flyby spacecraft, will arrive at comet 9P/Tempel 1 on 4 July 2005 to
create and observe the formation and final properties of a large crater that is predicted to be approximately 30-m deep with
the dimensions of a football stadium. The flyby and impactor instruments will yield images and near infrared spectra (1–5
μm) of the surface at unprecedented spatial resolutions both before and after the impact of a 350-kg spacecraft at 10.2 km/s.
These data will provide unique information on the structure of the nucleus near the surface and its chemical composition.
They will also used to interpret the evolutionary effects on remote sensing data and will indicate how those data can be used
to better constrain conditions in the early solar system. 相似文献
57.
Since its discovery in 1867, periodic comet 9P/Tempel 1 has been observed at 10 returns to perihelion, including all its returns
since 1967. The observations for the seven apparitions beginning in 1967 have been fit with an orbit that includes only radial
and transverse nongravitational accelerations that model the rocket-like thrusting introduced by the outgassing of the cometary
nucleus. The successful nongravitational acceleration model did not assume any change in the comet’s ability to outgas from
one apparition to the next and the outgassing was assumed to reach a maximum at perihelion. The success of this model over
the 1967–2003 interval suggests that the comet’s spin axis is currently stable. Rough calculations suggest that the collision
of the impactor released by the Deep Impact spacecraft will not provide a noticeable perturbation on the comet’s orbit nor
will any new vent that is opened as a result of the impact provide a noticeable change in the comet’s nongravitational acceleration
history. The observing geometries prior to, and during, the impact will allow extensive Earth based observations to complement
the in situ observations from the impactor and flyby spacecraft. 相似文献
58.
空间尘埃等离子体中尘粒电荷的相关涨落对尘埃磁声波的影响 总被引:3,自引:0,他引:3
本文运用自洽的三流体方程组, 考虑了尘埃的充电过程, 得到均匀磁化尘埃等离子体中垂直于磁场传播的尘埃磁声波的色散关系, 结合空间环境讨论了尘埃电荷的相关涨落对尘埃磁声波的影响. 相似文献
59.
本文用Nimbus7 SAM卫星观测的温度资料,分析了突然增温事例中地面地形不同的四个子午圈剖面内的温度分布及变化过程。结果表明,高山地区、平原和海面上空的行星波加热和低平流层突然增温有很大的差别。地形的影响是明显的。 相似文献
60.
结合行星借力飞行技术的小推力转移轨道初始设计 总被引:1,自引:0,他引:1
针对结合行星借力和小推力技术的行星际转移轨道设计问题,提出一种基于形状逼近策略的初始设计方法。采用改进的逆六次多项式策略计算小推力弧段,通过引入B平面参数和推进器开关点时间系数实现行星借力和推滑混合轨道的拼接,将初始设计问题转化为求解混合整数非线性规划问题。为降低规划模型求解难度,通过参数变换对模型进行简化处理,并采用具有全局大范围搜索能力的改进微分进化算法求解最优设计参数。数值结果表明:相比正弦指数曲线设计方法,本文方法可以有效对交会型转移轨道进行设计,并且可以提供更少燃料消耗的探测机会。
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