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排序方式: 共有82条查询结果,搜索用时 15 毫秒
21.
SUN Huixian WU Ji DAI Shuwu ZHAO Baochang SHU Rong CHANG Jin WANG Huanyu ZHANG Xiaohui REN Qiongying CHEN Xiaomin OUYANG Ziyuan ZOU Yongliao 《空间科学学报》2008,28(5)
Chang'E-1,the orbiter circling the moon 200km above the moon surface,is the first Chinese Lunar exploration satellite.The satellite was successfully launched on 24th October 2007.There are 8 kinds of scientific payloads onboard,including the stereo camera,the laser altimeter,the Sagnac-based interferometer image spectrometer,the Gamma ray spectrometer,the X-ray spectrom-eter,the microwave radiometer,the high energy particle detector,the solar wind plasma detector and a supporting payload data management system.Chang'E-1 opened her eyes to look at the moon and took the first batch of lunar pictures after her stereo camera was switched on in 20th November 2007.Henceforth all the instruments are successfully switched on one by one.After a period of parameter adjustment and initial check out,all scientific instruments are now in their normal operating phase.In this paper,the payloads and the initial observation results are introduced. 相似文献
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针对偏置动量小卫星的自主飞行问题,提出一种基于不确定项观测器的滑模容错控制方法。应用欧拉-拉格朗日系统的干扰观测方法设计不确定项观测器,对动量轮输出力矩变小、磁力矩器线圈电阻漂移等执行器故障以及小卫星外部环境力矩等不确定项进行估计,理论推导证明该观测器的观测误差一致最终有界(UUB)。基于不确定项观测器的估计值,设计补偿控制项,并与滑模控制器的控制力矩合成实现姿态容错控制。从理论上证明该容错控制方法能够使小卫星姿态快速收敛至滑模面。该容错方法无需做小角度假设,对执行器运行状态信息依赖性低。仿真结果表明,本文建议的容错控制方法具备可行性,实现了对小卫星姿控系统中不确定项的观测估计和容错控制。 相似文献
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弹道-升力式再入飞行器常采用旋成体外形,但其质心偏离对称轴(纵轴)设置。这种飞行器在着陆前要采用降落伞作为主减速手段。研究质心偏离对称轴的旋成体与降落伞组成的系统的运动稳定性是一项有工程实践意义的课题。作为一种初步探索,在把降落伞视作刚体的条件下,按该系统平面运动方程考察其在平衡状态附近的稳定性,给出了运动稳定性判据。 相似文献
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Sudip Bhattacharyya M. Coleman Miller Tod E. Strohmayer Frederick K. Lamb Craig B. Markwardt 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2006,38(12):2765-2767
We discuss millisecond period brightness oscillations and surface atomic spectral lines observed during type I X-ray bursts from a neutron star in a low mass X-ray binary system. We show that modeling of these phenomena can constrain models of the dense cold matter at the cores of neutron stars. We demonstrate that, even for a broad and asymmetric spectral line, the stellar radius-to-mass ratio can be inferred to better than 5%. We also fit our theoretical models to the burst oscillation data of the low mass X-ray binary XTE J1814-338, and find that the 90% confidence lower limit of the neutron star’s dimensionless radius-to-mass ratio is 4.2. 相似文献
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A. Jäggi L. Prange U. Hugentobler 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
Gravity missions are equipped with onboard Global Positioning System (GPS) receivers for precise orbit determination (POD) and for the extraction of the long wavelength part of the Earth’s gravity field. As positions of low Earth orbiters (LEOs) may be determined from GPS measurements at each observation epoch by geometric means only, it is attractive to derive such kinematic positions in a first step and to use them in a second step as pseudo-observations for gravity field determination. The drawback of not directly using the original GPS measurements is, however, that kinematic positions are correlated due to the ambiguities in the GPS carrier phase observations, which in principle requires covariance information be taken into account. We use GRACE data to show that dynamic or reduced-dynamic orbit parameters are not optimally reconstructed from kinematic positions when only taking epoch-wise covariance information into account, but that essentially the same orbit quality can be achieved as when directly using the GPS measurements, if correlations in time are taken into account over sufficiently long intervals. For orbit reconstruction covariances have to be considered up to one revolution period to avoid ambiguity-induced variations of kinematic positions being erroneously interpreted as orbital variations. For gravity field recovery the advantage is, however, not very pronounced. 相似文献
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利用刚体-双刚体模型给出了物体-双伞系统的运动方程与一种简化模式,并按运动稳定性分析的原理求得了该系统的稳定性判据。 相似文献
29.
为了探究火箭煤油热裂解过程以及抗氧化剂对热裂解过程的影响,通过火箭煤油静态热裂解实验研究了火箭煤油在683K~713K条件下裂解转化率、裂解产气率、气相产物组成随温度和时间的变化规律。同时,对比了加入1wt%抗氧化剂邻甲基对苯二酚(THQ)的火箭煤油热裂解行为,发现THQ对火箭煤油热裂解有明显抑制作用。683K~713K下,火箭煤油添加1wt%THQ前后的裂解活化能分别为150.0kJ/mol和210.5kJ/mol,并获得了相应的Arrhenius热裂解方程。对比发现我国火箭煤油裂解速率常数小于美国RP-1,RP-2火箭煤油。 相似文献
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