全文获取类型
收费全文 | 397篇 |
免费 | 1篇 |
国内免费 | 2篇 |
专业分类
航空 | 154篇 |
航天技术 | 83篇 |
综合类 | 3篇 |
航天 | 160篇 |
出版年
2021年 | 3篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 8篇 |
2013年 | 16篇 |
2012年 | 7篇 |
2011年 | 38篇 |
2010年 | 15篇 |
2009年 | 31篇 |
2008年 | 20篇 |
2007年 | 19篇 |
2006年 | 19篇 |
2005年 | 11篇 |
2004年 | 7篇 |
2003年 | 17篇 |
2002年 | 9篇 |
2001年 | 5篇 |
2000年 | 15篇 |
1999年 | 10篇 |
1998年 | 9篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1991年 | 4篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 12篇 |
1985年 | 16篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1968年 | 6篇 |
1967年 | 7篇 |
1966年 | 3篇 |
1965年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有400条查询结果,搜索用时 15 毫秒
261.
We review results about protoplanetary disk models, protoplanet migration and formation of giant planets with migrating cores.
We first model the protoplanetary nebula as an α–accretion disk and present steady state calculations for different values
of α and gas accretion rate through the disk. We then review the current theories of protoplanet migration in the context
of these models, focusing on the gaseous disk–protoplanet tidal interaction. According to these theories, the migration timescale
may be shorter than the planetary formation timescale. Therefore we investigate planet formation in the context of a migrating
core, considering both the growth of the core and the build–up of the envelope in the course of the migration.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
262.
263.
264.
265.
266.
The dynamics of shock propagation have been studied theoretically for a variety of two-dimensional lattices. The approach used is based on molecular dynamics and hinges on the exact numerical solution by computer of the equations of motion for the individual atoms or molecules in each lattice. Shocks have been launched into the lattices under study by methods designed to simulate flyer-plate impact. Two different interatomic potentials have been used, one endothermic and one net-exothermic. For both types of potential, a shock launched at one side of the lattice will spall a group of atoms off the other side. However, the subsequent behavior of the two types of lattice is very different. For endothermic potentials, after the initial atomic spall, the residual lattice is quiescent with little further activity. For net-exothermic potentials, the initial atomic spall injects additional energy into the system in such a manner that subsequently further spall occurs at both sides. Once this new spall is initiated, it leads rapidly to further bond breaking and explosive disintegration of the system. 相似文献
267.
268.
A review of the physics and gasdynamics associated with conventional CO2-N2 gasdynamic lasers (GDL's) is given, including a short survey of the state of the art. The role of advanced, downstream mixing GDL's is examined, and the question is addressed: Can such downstream mixing GDL's provide an order-of-magnitude increase in power output over the conventional device? Finally, combustion driven GDL's with unconventional fuels are examined, and new results for gain and maximum available power are given for various fuel-oxidizer combinations. 相似文献
269.
This article examines the long-term ‘Star Wars’ R&D programme initiated by President Reagan - the Strategic Defense Initiative (SDI). The nature of this initiative and the research programme that has been approved are described. There is still considerable uncertainty over where the SDI research will eventually lead - whether it be a limited BMD system designed to protect military targets or a comprehensive shield to protect the USA and its allies. The feasibility and potential implications of the SDI are examined with this caveat in mind. 相似文献
270.