全文获取类型
收费全文 | 1036篇 |
免费 | 61篇 |
国内免费 | 14篇 |
专业分类
航空 | 102篇 |
航天技术 | 882篇 |
综合类 | 4篇 |
航天 | 123篇 |
出版年
2024年 | 1篇 |
2023年 | 30篇 |
2022年 | 9篇 |
2021年 | 57篇 |
2020年 | 30篇 |
2019年 | 33篇 |
2018年 | 37篇 |
2017年 | 7篇 |
2016年 | 7篇 |
2015年 | 12篇 |
2014年 | 74篇 |
2013年 | 59篇 |
2012年 | 55篇 |
2011年 | 79篇 |
2010年 | 66篇 |
2009年 | 87篇 |
2008年 | 88篇 |
2007年 | 47篇 |
2006年 | 22篇 |
2005年 | 70篇 |
2004年 | 25篇 |
2003年 | 10篇 |
2002年 | 16篇 |
2001年 | 18篇 |
2000年 | 19篇 |
1999年 | 12篇 |
1998年 | 23篇 |
1997年 | 22篇 |
1996年 | 9篇 |
1995年 | 12篇 |
1994年 | 28篇 |
1993年 | 9篇 |
1992年 | 15篇 |
1991年 | 10篇 |
1990年 | 9篇 |
1989年 | 3篇 |
1987年 | 1篇 |
排序方式: 共有1111条查询结果,搜索用时 187 毫秒
991.
为减少帆板驱动机构(SADA)对太阳帆板挠性模态的激励作用,以扰动力矩较小的永磁同步电机(PMSM)作为驱动源,提出一种T-S模糊控制与校正网络相结合的控制方法。利用校正网络增加系统的相位裕度和增益,并通过T-S模糊控制器降低系统的超调和非线性摩擦的影响,从而有效抑制太阳帆板的振动。通过圆判据对带有此控制器的驱动系统进行了稳定性证明,很好地解决了模糊控制系统在摩擦扰动下难以进行频域理论分析的缺陷。仿真结果表明,在非线性摩擦等扰动的影响下,该控制方法能够很好地抑制太阳帆板引起的挠性振动,提高系统的速度精度和稳定度,具有较好的动态性能。 相似文献
992.
993.
Y. -M. Wang 《Space Science Reviews》1994,70(1-2):387-390
Empirical studies have shown that the solar wind speed at Earth is inversely correlated with the areal expansion rate of magnetic flux tubes near the Sun. Recent model calculations that include a self-consistent determination of the coronal temperature allow one to understand the physical basis of this relationship; they also suggest why the solar wind mass flux is relatively constant. 相似文献
994.
N.L. Borodkova J.B. Liu Z.H. Huang G.N. Zastenker 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(8):1220-1225
We present a comparison of large and sharp solar wind dynamic pressure changes, observed by several spacecraft, with fast disturbances in the magnetospheric magnetic field measured by the GOES-8, 9 and 10 geosynchronous satellites. Almost 400 solar wind pressure changes in the period 1996–2003 were selected for this study. Using the large statistics we confirmed that increases (decreases) in the dynamic pressure always results in increases (decreases) in the magnitude of geosynchronous Bz component. The amplitude of the geosynchronous Bz response strongly depends on the location of observer relative to the noon meridian, from the value of solar wind pressure before the disturbance arriving and firstly – from the amplitude of the pressure change. 相似文献
995.
J.-C. Vial F. Auchère J. Chang C. Fang W.Q. Gan K.-L. Klein J.-Y. Prado F. Rouesnel A. Sémery G. Trottet C. Wang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(1):183-189
The SMESE (SMall Explorer for Solar Eruptions) mission is a microsatellite proposed by France and China. The payload of SMESE consists of three packages: LYOT (a Lyman α imager and a Lyman α coronagraph), DESIR (an Infra-red Telescope working at 35–80 and 100–250 μm), and HEBS (a High Energy Burst Spectrometer working in X- and gamma-rays). 相似文献
996.
S. R. Habbal 《Space Science Reviews》1994,70(1-2):37-46
The observational characteristics of the small scale magnetic structures are summarized. The temperature structure and temporal variability of the emission from coronal bright points, that pervade the source region of the solar wind in coronal holes and the quiet sun, and from active regions are shown to be remarkably similar. Particular emphasis is given to observations, potentially feasible with SOHO, that could resolve some of the outstanding issues regarding the role of the small scale magnetic structures in the energy balance and properties of the solar wind. 相似文献
997.
We present a simple technique describing how limits on the helium abundance, , the ratio of helium to proton number density, can be inferred from measurements of the electron density, temperature and their gradients below 1.5R
s. As an illustration, we apply this technique to emission line intensities in the extreme ultraviolet, measured in polar coronal holes. The example indicates that can be significantly large in the inner corona. This technique could be applicable to the more extensive data to be obtained from coordinated ground and space-based observations during the Ulysses south polar passage and the Spartan flight, and subsequently during the SOHO mission. Limits on the helium abundance in the solar wind can thus be derived from its source region and compared to interplanetary values. 相似文献
998.
CBERS-1卫星星载太阳定标器的研制 总被引:2,自引:0,他引:2
文章介绍了CBERS_1卫星IRMSS太阳定标器的主要技术指标要求和工作原理 ,并阐述太阳定标器的设计 ,包括光学设计、机械设计和电学设计等。 相似文献
999.
Sq(Y)的季节变化和场向电流 总被引:4,自引:0,他引:4
本文对中国东部地磁台站链地磁静日变化东向分量进行了分析,有结果表明,在冬、夏季清晨,南北半球之间存在着电离层发电机驱动的场向电流,其方向是从夏季半球到冬季半球;在黄昏,也可能存在方向相反的电流。 相似文献
1000.
AR5395和AR5629X射线事件的太阳射电辐射特征吴洪敖,孙九祯(中同科学院紫金山天文台,南京210008)关键词太阳耀斑,X射线事件,射电事件一、概况本文选用的典型事件是1989年3月的AR5395和8月的AR5629的射电缓变和爆发分量,及其... 相似文献