全文获取类型
收费全文 | 345篇 |
免费 | 1篇 |
国内免费 | 5篇 |
专业分类
航空 | 150篇 |
航天技术 | 64篇 |
综合类 | 1篇 |
航天 | 136篇 |
出版年
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 11篇 |
2017年 | 6篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 23篇 |
2011年 | 36篇 |
2010年 | 17篇 |
2009年 | 23篇 |
2008年 | 18篇 |
2007年 | 21篇 |
2006年 | 16篇 |
2005年 | 25篇 |
2004年 | 3篇 |
2003年 | 14篇 |
2002年 | 12篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 4篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1967年 | 6篇 |
1966年 | 2篇 |
排序方式: 共有351条查询结果,搜索用时 16 毫秒
11.
“Mars Direct”, is an approach to the space Exploration Initiative that allows for the rapid initiation of manned Mars exploration, possibly as early as 1999. The approach does not require any on-orbit assembly or refueling or any support from the Space Station or other orbital infrastructure. Furthermore, the Mars Direct plan is not merely a “flags and footprints” one-shot expedition, but puts into place immediately an economical method of Earth-Mars transportation, real surface exploratory mobility, and significant base capabilities that can evolve into a mostly self-sufficient Mars settlement. This paper presents both the initial and evolutionary phases of the Mars Direct plan. In the initial phase, only chemical propulsion is used, sendig 4 persons on conjunction class Mars exploratory missions. Two heavy lift booster launches are required to support each mission. The first launch delivers an unfueled Earth Return Vehicle (ERV) to the martian surface, where it fills itself with methane/oxygen bipropellant manufactured primarily out of indigenous resources. After propellant production is completed, a second launch delivers the crew to the prepared site, where they conduct regional exploration for 1.5 years and then return directly to Earth in the ERV. In the second phase of Mars Direct, nuclear thermal propulsion is used to cut crew transit times in half, increase cargo delivery capacity, and to create the potential for true global mobility through the use of CO2 propelled ballistic hopping vehicles (“NIMFs”). In this paper we present both phases of the Mars Direct plan, including mission architecture, vehicle designs, and exploratory strategy leading to the establishment of a 48 person permanent Mars base. Some speculative thoughts on the possibility of actually colonizing Mars are also presented. 相似文献
12.
13.
Crider Dana H. Brain David A. Acuña Mario H. Vignes Didier Mazelle Christian Bertucci Cesar 《Space Science Reviews》2004,111(1-2):203-221
We examine the magnetic field in the martian magnetosheath due to solar wind draping. Mars Global Surveyor provided 3-D vector magnetic field measurements at a large range of altitudes, local times, and solar zenith angles as the spacecraft orbit evolved. We choose orbits with very clean signatures of draping to establish the nominal morphology of the magnetic field lines at local times of near-subsolar and near-terminator. Next, using a compilation of data from Mars Global Surveyor, we determine the average magnetic field morphology in the martian magnetosheath due to the solar wind interaction. The topology of the field is as expected from previous observations and predictions. The magnetic field magnitude peaks at low altitude and noon magnetic local time and decreases away from that point. The magnetic field has an inclination from the local horizontal of 5.6° on average in the dayside magnetosheath and 12.5° on the nightside. The inclination angle is closest to zero at noon magnetic local time and low altitude. It increases both upward and to later local times. The magnetic field in the induced magnetotail flares out from the Mars—Sun direction by 21°. Finally, we compare the observations to gasdynamic model predictions and find that the shocked solar wind flow in the martian magnetosheath can be treated as a gasdynamic flow with the magnetic pileup boundary as the inner boundary to the flow. 相似文献
14.
David J. Helfand 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,3(10-12)
“With all reserve, we advance the view that a supernova represents the transition of an ordinary star into a neutron star.”This conclusion, reached just 50 years ago in a classic paper by Walter Baade and Fritz Zwicky (1934), was published three decades before the first direct observational evidence for the existence of neutron stars was uncovered. It still informs the standard picture of neutron star production in the Galaxy. We examine herein some recent evidence bearing on this question which has been derived from
Observatory X-ray observations of supernova remnants and radio pulsars. In particular, the discovery that X-ray synchrotron nebulae are found surrounding most young ( 106 yr) pulsars observed to date is discussed. We explore the implications of the lack of such nebulae in the majority of supernova remnants (SNR) for the properties and frequency of neutron star formation in supernova events. 相似文献
15.
López-Valverde Miguel A. Gerard Jean-Claude González-Galindo Francisco Vandaele Ann-Carine Thomas Ian Korablev Oleg Ignatiev Nikolai Fedorova Anna Montmessin Franck Määttänen Anni Guilbon Sabrina Lefevre Franck Patel Manish R. Jiménez-Monferrer Sergio García-Comas Maya Cardesin Alejandro Wilson Colin F. Clancy R. T. Kleinböhl Armin McCleese Daniel J. Kass David M. Schneider Nick M. Chaffin Michael S. López-Moreno José Juan Rodríguez Julio 《Space Science Reviews》2018,214(1):1-31
Space Science Reviews - Time measured by an ideal clock crucially depends on the gravitational potential and velocity of the clock according to general relativity. Technological advances in... 相似文献
16.
17.
David Gubbins 《Space Science Reviews》2010,155(1-4):9-27
This collection of reviews marks the state of the art of geomagnetic data collection, modelling, and interpretation at a time of unprecedented advances in all 3 facets of the subject. For the first time we have excellent satellite data with the prospect of more to come, vast improvements in laboratory techniques, and opportunities to use large scale computing to model the data. In the past, research has been conducted by the separate disciplines largely in isolation; we can hope the subject has now matured enough for progress to be made by genuine collaboration between theoreticians and experimentalists. The purpose of this chapter is to set the historical setting, and I have chosen a starting date of 1980, when vector satellite data first became available and stimulated many new advances in the subject. We can hope for a similar or better stimulus in the next decade. 相似文献
18.
David Kappel Gabriele Arnold Rainer Haus Giuseppe Piccioni Pierre Drossart 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
The successful long-duration radiation measurements performed by the VIRTIS instrument aboard ESA’s Venus Express spacecraft have provided an excellent collection of atmospheric and surface data that stand out due to their high temporal and spatial coverage of the planet and due to a high diversity of measurement and environmental conditions. 相似文献
19.
Remote sensing and the use of satelites to monitor compliance with arms control and disarmament agreements have been among the focal points of the International Space Year. The interdisciplinary research project, Remote Sensing and European Security, is addressing this question. This article gives a brief survey of the latest developments in the field and summarizes the project's findings. 相似文献
20.