全文获取类型
收费全文 | 2660篇 |
免费 | 28篇 |
国内免费 | 15篇 |
专业分类
航空 | 1076篇 |
航天技术 | 960篇 |
综合类 | 12篇 |
航天 | 655篇 |
出版年
2022年 | 13篇 |
2021年 | 31篇 |
2019年 | 28篇 |
2018年 | 85篇 |
2017年 | 68篇 |
2016年 | 50篇 |
2015年 | 23篇 |
2014年 | 87篇 |
2013年 | 110篇 |
2012年 | 80篇 |
2011年 | 156篇 |
2010年 | 108篇 |
2009年 | 153篇 |
2008年 | 158篇 |
2007年 | 85篇 |
2006年 | 72篇 |
2005年 | 87篇 |
2004年 | 85篇 |
2003年 | 85篇 |
2002年 | 58篇 |
2001年 | 78篇 |
2000年 | 41篇 |
1999年 | 48篇 |
1998年 | 52篇 |
1997年 | 51篇 |
1996年 | 42篇 |
1995年 | 60篇 |
1994年 | 35篇 |
1993年 | 40篇 |
1992年 | 52篇 |
1991年 | 14篇 |
1990年 | 17篇 |
1989年 | 41篇 |
1988年 | 19篇 |
1987年 | 17篇 |
1986年 | 16篇 |
1985年 | 63篇 |
1984年 | 52篇 |
1983年 | 41篇 |
1982年 | 44篇 |
1981年 | 60篇 |
1980年 | 36篇 |
1979年 | 16篇 |
1978年 | 19篇 |
1977年 | 10篇 |
1976年 | 16篇 |
1975年 | 16篇 |
1974年 | 13篇 |
1969年 | 7篇 |
1967年 | 8篇 |
排序方式: 共有2703条查询结果,搜索用时 140 毫秒
891.
M. I. Panasuyk V. V. Kalegaev I. N. Myagkova N. V. Kuznetsov M. V. Podzolko 《Cosmic Research》2017,55(6):464-468
Factors of radiation environment in near-Earth space in a period from December 1 to 10, 2014 have been analyzed, which could affect serviceability of the onboard systems of Vernov spacecraft. 相似文献
892.
Analysis of errors in atmospheric density measurements by lidar on board the ISS is performed. It is shown that using as the lidar transmitter a Nd:YAG laser with moderate parameters of emission at a wavelength of 353 nm and a receiving mirror diameter of 0.4 m, it is possible to cover with a 10% measurement error a height range, on average, from 40–60 km and 30–40 km in the nighttime and daytime, respectively, down to the troposphere. Working with emission at 266 nm with a 10% error, it is possible to move to the heights of the mesosphere (70 km) and penetrate the atmosphere down to a height of 40 km. Thus, the use of two harmonics makes it possible to assimilate the height range of atmospheric density measurements from on board the ISS beginning from 70 km and down to the troposphere. 相似文献
893.
Sobolevsky N. M. Latysheva L. N. Kuznetsov H. V. Panasyuk M. I. Podzolko M. V. 《Cosmic Research》2021,59(4):259-267
Cosmic Research - A special version of the SHIELD transport code has been developed intended for radiation protection purposes in space. The calculation of the fluxes of primary and secondary... 相似文献
894.
Beklemishev N. D. Boguslavskii A. A. Belyaev M. Yu. Volkov O. N. Sazonov V. V. Sokolov S. M. Sofinskii A. N. 《Cosmic Research》2021,59(3):183-198
Cosmic Research - The results of the Sreda–MKS space experiment showed that visual data on the vibrations of the ISS structural elements allow one to acquire quantitative characteristics of... 相似文献
895.
N. S. Dushin N. I. Mikheev I. M. Gazizov I. A. Davletshin 《Russian Aeronautics (Iz VUZ)》2017,60(4):583-590
A technique that allows simultaneous heating of the heat-exchange surface and estimation of its local temperature from the corresponding electrical resistance of the heating element is presented. The systematic error in measurements of the local heat transfer coefficient has been analyzed. A relation that takes possible heat loss into account and minimizes the measurement errors has been obtained. 相似文献
896.
The design schemes of cooling for the nozzle blades of high-temperature gas turbines are considered. The results of the thermal and hydraulic tests for the cooling systems of the nozzle vanes are presented. The prospective cooling system of the nozzle vanes of low and high pressure turbines is developed and presented. The test results for the vane with proposed design are presented. 相似文献
897.
Joaquín ABELLAN 《中国航空学报》2018,31(3):529-533
Two types of uncertainty co-exist in the theory of evidence: discord and non-specificity. From 90s, many mathematical expressions have arisen to quantify these two parts in an evidence. An important aspect of each measure presented is the verification of a coherent set of properties. About non-specificity, so far only one measure verifies an important set of those properties. Very recently, a new measure of non-specificity based on belief intervals has been presented as an alternative measure that quantifies a similar set of properties (Yang et al., 2016). It is shown that the new measure really does not verify two of those important properties. Some errors have been found in their corresponding proofs in the original publication. 相似文献
898.
Anny-Chantal Levasseur-Regourd Jessica Agarwal Hervé Cottin Cécile Engrand George Flynn Marco Fulle Tamas Gombosi Yves Langevin Jérémie Lasue Thurid Mannel Sihane Merouane Olivier Poch Nicolas Thomas Andrew Westphal 《Space Science Reviews》2018,214(3):64
This review presents our understanding of cometary dust at the end of 2017. For decades, insight about the dust ejected by nuclei of comets had stemmed from remote observations from Earth or Earth’s orbit, and from flybys, including the samples of dust returned to Earth for laboratory studies by the Stardust return capsule. The long-duration Rosetta mission has recently provided a huge and unique amount of data, obtained using numerous instruments, including innovative dust instruments, over a wide range of distances from the Sun and from the nucleus. The diverse approaches available to study dust in comets, together with the related theoretical and experimental studies, provide evidence of the composition and physical properties of dust particles, e.g., the presence of a large fraction of carbon in macromolecules, and of aggregates on a wide range of scales. The results have opened vivid discussions on the variety of dust-release processes and on the diversity of dust properties in comets, as well as on the formation of cometary dust, and on its presence in the near-Earth interplanetary medium. These discussions stress the significance of future explorations as a way to decipher the formation and evolution of our Solar System. 相似文献
899.
Adrienn Luspay-Kuti Olivier Mousis Jonathan I. Lunine Yves Ellinger Françoise Pauzat Ujjwal Raut Alexis Bouquet Kathleen E. Mandt Romain Maggiolo Thomas Ronnet Bastien Brugger Ozge Ozgurel Stephen A. Fuselier 《Space Science Reviews》2018,214(8):115
The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument onboard the Rosetta spacecraft has measured molecular oxygen (O2) in the coma of comet 67P/Churyumov-Gerasimenko (67P/C-G) in surprisingly high abundances. These measurements mark the first unequivocal detection of O2 in a cometary environment. The large relative abundance of O2 in 67P/C-G despite its high reactivity and low interstellar abundance poses a puzzle for its origin in comet 67P/C-G, and potentially other comets. Since its detection, there have been a number of hypotheses put forward to explain the production and origin of O2 in the comet. These hypotheses cover a wide range of possibilities from various in situ production mechanisms to protosolar nebula and primordial origins. Here, we review the O2 formation mechanisms from the literature, and provide a comprehensive summary of the current state of knowledge of the sources and origin of cometary O2. 相似文献
900.
The algorithms for achieving a practical increase in the rate of data transmission on the space-craft–ground tracking station line has been considered. This increase is achieved by applying spectral-effective modulation techniques, the technology of orthogonal frequency compression of signals using millimeterrange radio waves. The advantages and disadvantages of each of three algorithms have been revealed. A significant advantage of data transmission in the millimeter range has been indicated. 相似文献