全文获取类型
收费全文 | 761篇 |
免费 | 181篇 |
国内免费 | 86篇 |
专业分类
航空 | 610篇 |
航天技术 | 120篇 |
综合类 | 61篇 |
航天 | 237篇 |
出版年
2024年 | 10篇 |
2023年 | 10篇 |
2022年 | 24篇 |
2021年 | 33篇 |
2020年 | 42篇 |
2019年 | 29篇 |
2018年 | 47篇 |
2017年 | 41篇 |
2016年 | 55篇 |
2015年 | 50篇 |
2014年 | 44篇 |
2013年 | 62篇 |
2012年 | 60篇 |
2011年 | 44篇 |
2010年 | 61篇 |
2009年 | 44篇 |
2008年 | 43篇 |
2007年 | 38篇 |
2006年 | 30篇 |
2005年 | 24篇 |
2004年 | 22篇 |
2003年 | 24篇 |
2002年 | 43篇 |
2001年 | 27篇 |
2000年 | 11篇 |
1999年 | 23篇 |
1998年 | 12篇 |
1997年 | 13篇 |
1996年 | 9篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 10篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
排序方式: 共有1028条查询结果,搜索用时 15 毫秒
931.
C. Feiler M. Buser E. Kajari W. P. Schleich E. M. Rasel R. F. O’Connell 《Space Science Reviews》2009,148(1-4):123-147
In the present paper we follow three major themes: (i) concepts of rotation in general relativity, (ii) effects induced by these generalized rotations, and (iii) their measurement using interferometry. Our journey takes us from the Foucault pendulum via the Sagnac interferometer to manifestations of gravito-magnetism in double binary pulsars and in Gödel’s Universe. Throughout our article we emphasize the emerging role of matter wave interferometry based on cold atoms or Bose–Einstein condensates leading to superior inertial sensors. In particular, we advertise recent activities directed towards the operation of a coherent matter wave interferometer in an extended free fall. 相似文献
932.
S. Kobayashi N. Hasebe E. Shibamura O. Okudaira M. Kobayashi N. Yamashita Y. Karouji M. Hareyama K. Hayatsu C. d’Uston S. Maurice O. Gasnault O. Forni B. Diez R. C. Reedy K. J. Kim 《Space Science Reviews》2010,154(1-4):193-218
The Kaguya gamma-ray spectrometer (KGRS) has great potential to precisely determine the absolute abundances of natural radioactive elements K, Th and U on the lunar surface because of its excellent spectroscopic performance. In order to achieve the best performance of the KGRS, it is important to know the spatial response function (SRF) that describes the directional sensitivity of the KGRS. The SRF is derived by a series of Monte Carlo simulations of gamma-ray transport in the sensor of the KGRS using the full-fledged simulation model of the KGRS, and is studied in detail. In this paper, the method for deriving absolute abundance of natural radioactive elements based on the SRF is described for the analysis of KGRS data, which is also applicable to any gamma-ray remote sensings. In the preliminary analysis of KGRS data, we determined the absolute abundances of K and Th on the lunar surface without using any previous knowledge of chemical information gained from Apollo samples, lunar meteorites and/or previous lunar remote sensings. The results are compared with the previous measurements and the difference and the correspondence are discussed. Future detailed analysis of KGRS data will provide new and more precise maps of K, Th and U on the lunar surface. 相似文献
933.
席明春 《中国民航飞行学院学报》2012,(1):47-48,53
带培管制学员是一个需要耗费教员大量心力的工作,缺乏经验和技能的学员是工作中主要的风险源。管制教员一方面需要严密监控学员,及时制止学员的失误;另一方面又要掌握合适的教学方式来指导学员,使其尽快掌握正确的工作技巧,养成良好的习惯。因此,带培方法的研究是每一个管制教员必须研究的课题。 相似文献
934.
In this paper, we present the results of the experimental studies of the average heat transfer value in a hemispherical recess
placed in the first, third, and fifth rows of the recess array when varying the frequency of the imposed air velocity fluctuations
in the channel. The range of the Reynolds and Strouhal number variations corresponded to operating conditions of the turbine
blade cooling systems. 相似文献
935.
The results of studying the average and local heat transfer on the surface of hemispherical protrusions arranged on one side
of the flat channel are presented. The experiments were carried out at the turbulent flow regime in varying the density of
protrusions arrangement and the channel height. 相似文献
936.
This summer is Planning a family can partieipate in the tour? With love or family friend with nature for an in-depth exchanges presumably to each other before the feelings of the communication can play a good role.If you can take his family out to sea 《航空港》2011,(9):41-42
这个夏天,有没有筹划一次全家人都可以参与的旅行呢?带着爱人或者家里的小朋友与大自然进行一次深入的交流,想必对于彼此之前感情的沟通能起到不错的作用。如果可以,带着全家去出海吧! 相似文献
937.
M. V. Klimenko V. V. Klimenko Yu. N. Koren’kov F. S. Bessarab I. V. Karpov K. G. Ratovsky M. A. Chernigovskaya 《Cosmic Research》2013,51(1):54-63
A study of the response of the thermosphere and ionosphere to sudden stratospheric warmings (SSWs) which occurred in January of 2008 and 2009 is presented. The Global Self-consistent Model of the Thermosphere, Ionosphere, and Protonosphere (GSM TIP) developed in the West Department of IZMIRAN was a theoretical basis for this study. A comparison of the simulation results of the thermosphere-ionosphere response to SSW events with the observational data over Irkutsk and also with theoretical and experimental studies carried out during the recent years is performed. SSW events were modeled by setting disturbances in the neutral temperature and density at the lower boundary of the GSM TIP model (80 km above the Earth’s surface). It is shown that the disturbances related to SSW lead to substantial global effects in the thermosphere and ionosphere. The analysis of the experimental data showed that, in spite of very similar solar and geophysical conditions on the background of which two considered stratospheric warming events happened, the occurring disturbances in temperature at heights of the mesosphere and lower thermosphere differ substantially from each other, although some common regularities still take place especially at heights of the ionospheric F region. 相似文献
938.
本文用连续方程、稳定不可压缩椭圆型和抛物型时均N-S方程及K-ε双方程湍流模型计算了平面叶栅湍流尾迹。计算表明,上述两种方法都能得到较好的数值结果,但抛物方法可节省大量计算时间和内存空间。 相似文献
939.
940.
大型室内市场火灾危险性及防火设计初探 总被引:1,自引:1,他引:1
陈曦 《沈阳航空工业学院学报》2005,22(6):179-181
本文针对近年来我国大型室内市场的发展趋势以及一些重特大火灾案例,根据当地具体情况,对大型室内市场的火灾危险性进行了全面地分析,并且结合实际消防监督工作。对大型室内市场的消防安全设计从防火分区、安全疏散、防排烟、自动消防设施等多方面进行了探讨,以期对完善我国现阶段消防技术规范有关室内大型市场的设计要求有所借鉴。 相似文献