全文获取类型
收费全文 | 185篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
航空 | 83篇 |
航天技术 | 33篇 |
航天 | 70篇 |
出版年
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2014年 | 9篇 |
2013年 | 4篇 |
2012年 | 9篇 |
2011年 | 11篇 |
2010年 | 9篇 |
2009年 | 12篇 |
2008年 | 6篇 |
2007年 | 10篇 |
2006年 | 5篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 7篇 |
1967年 | 4篇 |
1966年 | 3篇 |
1963年 | 1篇 |
排序方式: 共有186条查询结果,搜索用时 15 毫秒
161.
Y. Le Coq J.A. Retter S. Richard A. Aspect P. Bouyer 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
We analyze the advantages of using ultra-cold coherent sources of atoms for matter-wave interferometry in space. We present a proof-of-principle experiment that is based on an analysis of the results previously published in Richard et al. (2003) from which we extract the ratio h/m for 87Rb. This measurement shows that a limitation in accuracy arises due to atomic interactions within the Bose–Einstein condensate. Finally we discuss the promising role of coherent-matter-wave sensors, in particular inertial sensors, in future fundamental physics missions in space. 相似文献
162.
Mioara Mandea Richard Holme Alexandra Pais Katia Pinheiro Andrew Jackson Giuliana Verbanac 《Space Science Reviews》2010,155(1-4):147-175
The secular variation of the core field is generally characterized by smooth variations, sometimes interrupted by abrupt changes, named geomagnetic jerks. The origin of these events, observed and investigated for over three decades, is still not fully understood. Many fundamental features of geomagnetic jerks have been the subject of debate, including their origin internal or external to the Earth, their occurrence dates, their duration and their global or regional character. Specific tools have been developed to detect them in geomagnetic field or secular variation time series. Recently, their investigation has been advanced by the availability of a decade of high-quality satellite measurements. Moreover, advances in the modelling of the core field and its variations have brought new perspectives on the fluid motion at the top of the core, and opened new avenues in our search for the origin of geomagnetic jerks. Correlations have been proposed between geomagnetic jerks and some other geophysical observables, indicating the substantial interest in this topic in our scientific community. This paper summarizes the recent advances in our understanding and interpretation of geomagnetic jerks. 相似文献
163.
164.
165.
John Z. Kiss Katherine D.L. Millar Prem Kumar Richard E. Edelmann Melanie J. Correll 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
In order to effectively study phototropism, the directed growth in response to light, we performed a series of experiments in microgravity to better understand light response without the “complications” of a 1-g stimulus. These experiments were named TROPI (for tropisms) and were performed on the European Modular Cultivation System (EMCS), a laboratory facility on the International Space Station (ISS). TROPI-1 was performed in 2006, and while it was a successful experiment, there were a number of technical difficulties. We had the opportunity to perform TROPI-2 in 2010 and were able to optimize experimental conditions as well as to extend the studies of phototropism to fractional gravity created by the EMCS centrifuge. This paper focuses on how the technical improvements in TROPI-2 allowed for a better experiment with increased scientific return. Major modifications in TROPI-2 compared to TROPI-1 included the use of spaceflight hardware that was off-gassed for a longer period and reduced seed storage (less than 2 months) in hardware. These changes resulted in increased seed germination and more vigorous growth of seedlings. While phototropism in response to red illumination was observed in hypocotyls of seedlings grown in microgravity during TROPI-1, there was a greater magnitude of red-light-based phototropic curvature in TROPI-2. Direct downlinking of digital images from the ISS in TROPI-2, rather than the use of analog tapes in TROPI-1, resulted in better quality images and simplified data analyses. In TROPI-2, improved cryo-procedures and the use of the GLACIER freezer during transport of samples back to Earth maintained the low temperature necessary to obtain good-quality RNA required for use in gene profiling studies. 相似文献
166.
Hans W. Guesgen Joachim Hertzberg Richard Lobb Andrea Mantler 《Spatial Cognition & Computation》2013,13(2-3):207-222
In this paper, we show how standard GIS operations like the complement, union, intersection, and buffering of maps can be made more flexible by using fuzzy set theory. In particular, we present a variety of algorithms for operations on fuzzy raster maps, focusing on buffer operations for such maps. Furthermore, we show how widely-available special-purpose hardware (in particular, z-buffering in graphics hardware) can be used for supporting buffer operations in fuzzy geographic information systems (GIS). 相似文献
167.
168.
169.
Richard H. Battin 《Acta Astronautica》1987,15(12):965-971
The fundamental ellipse of the two-body, two-point orbital boundary-value problem of orbital mechanics is introduced and its key role in the basic geometry of this famous problem is developed. Analytic formulas for the orbital parameters of conjugate orbits are derived together with further interesting properties of the mean point-locus. 相似文献
170.
Basing his comments around a report on the Space Power Systems 1997 conference, ‘Energy and Space for Humanity’, held in Montreal, 24-28 August 1997, Richard Boudreault describes the progress made in getting the concept of power from space accepted by the terrestrial utilities. Increasing worries about the sustainability of current power sources together with deregulation of power distribution make space power more attractive. However, the high cost of access to space is a barrier, though this is starting to fall. 相似文献