全文获取类型
收费全文 | 275篇 |
免费 | 3篇 |
国内免费 | 5篇 |
专业分类
航空 | 164篇 |
航天技术 | 58篇 |
综合类 | 3篇 |
航天 | 58篇 |
出版年
2022年 | 1篇 |
2021年 | 5篇 |
2019年 | 3篇 |
2018年 | 35篇 |
2017年 | 18篇 |
2016年 | 1篇 |
2015年 | 8篇 |
2014年 | 4篇 |
2013年 | 12篇 |
2012年 | 8篇 |
2011年 | 14篇 |
2010年 | 16篇 |
2009年 | 15篇 |
2008年 | 10篇 |
2007年 | 14篇 |
2006年 | 6篇 |
2005年 | 14篇 |
2004年 | 8篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1989年 | 2篇 |
1986年 | 2篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 9篇 |
1978年 | 1篇 |
1970年 | 1篇 |
1967年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有283条查询结果,搜索用时 828 毫秒
241.
The success of the Swedish small satellite program, in combination with an active participation by Swedish research groups in major international missions, has placed Sweden in the frontline of experimental space research. The program started with the development of the research satellite Viking which was launched in 1986, for detailed investigations of the aurora. To date, Sweden has developed and launched a total of six research satellites; five for space plasma investigations; and the most recent satellite Odin, for research in astronomy and aeronomy. These fall into three main categories according to their physical dimension, financial cost and level of ambition: nano-satellites, micro-satellites, and mid-size satellites with ambitious scientific goals. In this brief review we focus on five space plasma missions, for which operations have ended and a comprehensive scientific data analysis has been conducted, which allows for a judgement of their role and impact on the progress in auroral research. Viking and Freja, the two most well-known missions of this program, were pioneers in the exploration of the aurora. The more recent satellites, Munin, Astrid, and Astrid-2 (category 1 and 2), proved to be powerful tools, both for testing new technologies and for carrying out advanced science missions. The Swedish small satellite program has been internationally recognized as cost efficient and scientifically very successful. 相似文献
242.
243.
A. Pedersen N. Cornilleau-Wehrlin B. De la Porte A. Roux A. Bouabdellah P. M. E. Décréau F. Lefeuvre F. X. Sène D. Gurnett R. Huff G. Gustafsson G. Holmgren L. Woolliscroft H. ST. C. Alleyne J. A. Thompson P. H. N. Davies 《Space Science Reviews》1997,79(1-2):93-106
In order to get the maximum scientific return from available resources, the wave experimenters on Cluster established the Wave Experiment Consortium (WEC). The WEC's scientific objectives are described, together with its capability to achieve them in the course of the mission. The five experiments and the interfaces between them are shown in a general block diagram (Figure 1). WEC has organised technical coordination for experiment pre-delivery tests and spacecraft integration, and has also established associated working groups for data analysis and operations in orbit. All science operations aspects of WEC have been worked out in meetings with wide participation of investigators from the five WEC teams. 相似文献
244.
Mihail P. Petkov Steven M. Jones Gerald E. Voecks Kenneth J. Hurst Olivier Grosjean Delphine Faye Guillaume Rioland Cecily M. Sunday Emma M. Bradford William N. Warner Jerami M. Mennella Ned W. Ferraro Manuel Gallegos David M. Soules Philippe Lognonné W. Bruce Banerdt Jeffrey W. Umland 《Space Science Reviews》2018,214(8):112
We report on the development of a passive sorption pump, capable of maintaining high-vacuum conditions in the InSight seismometer throughout the duration of any extended mission. The adsorber material is a novel zeolite-loaded aerogel (ZLA) composite, which consists of fine zeolite particles homogeneously dispersed throughout a porous silica network. The outgassing species within the SEIS evacuated container were analyzed and the outgassing rate was estimated by different methods. The results were used to optimize the ZLA composition to adsorb the outgassing constituents, dominated by water, while minimizing the SEIS bakeout constraints. The InSight ZLA composite additionally facilitated substantial CO2 adsorption capabilities for risk mitigation against external leaks in Mars atmosphere. To comply with the stringent particle requirements, the ZLA getters were packaged in sealed containers, open to the SEIS interior through \(1~\upmu\mbox{m}\)-size pore filters. Results from experimental validation and verification tests of the packaged getters are presented. The pressure forecast based on these data, corroborated by rudimentary in situ pressure measurements, infer SEIS operational pressures not exceeding \(10^{-5}~\mbox{mbar}\) throughout the mission. 相似文献
245.
L.I. Fernández P. Salio M.P. Natali A.M. Meza 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
This paper presents PWV estimates from GPS data computed at four continuously operated GPS stations in Argentina established at Buenos Aires, Córdoba, Rosario and Salta over a 1 year period (2006–2007). The objective is to analyze the behaviour of the GPS PWV estimation using mean tropospheric temperature (Tm) values from the Bevis model, Sapucci model and obtained by a numerical integration of variables provided by the operational analysis of the National Centre of Environmental Prediction (NCEP). The results are validated using PWV values from nearest radio soundings. Moreover, a comparison between PWV values determined from microwave sensors deployed on the NOAA-18 satellite and PWV from GPS observations is also presented. 相似文献
246.
Stefano Bertone Christophe Le Poncin-Lafitte Pascal Rosenblatt Valéry Lainey Jean-Charles Marty Marie-Christine Angonin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(1):89-96
Accurate tracking of probes is one of the key points of space exploration. Range and Doppler techniques are the most commonly used. In this paper we analyze the impact of the transponder delay, . the processing time between reception and re-emission of a two-way tracking link at the satellite, on tracking observables and on spacecraft orbits. We show that this term, only partially accounted for in the standard formulation of computed space observables, can actually be relevant for future missions with high nominal tracking accuracies or for the re-processing of old missions. We present several applications of our formulation to Earth flybys, the NASA GRAIL and the ESA BepiColombo missions. 相似文献
247.
G. M. Martínez C. N. Newman A. De Vicente-Retortillo E. Fischer N. O. Renno M. I. Richardson A. G. Fairén M. Genzer S. D. Guzewich R. M. Haberle A.-M. Harri O. Kemppinen M. T. Lemmon M. D. Smith M. de la Torre-Juárez A. R. Vasavada 《Space Science Reviews》2017,212(1-2):295-338
We analyze the complete set of in-situ meteorological data obtained from the Viking landers in the 1970s to today’s Curiosity rover to review our understanding of the modern near-surface climate of Mars, with focus on the dust, CO2 and H2O cycles and their impact on the radiative and thermodynamic conditions near the surface. In particular, we provide values of the highest confidence possible for atmospheric opacity, atmospheric pressure, near-surface air temperature, ground temperature, near-surface wind speed and direction, and near-surface air relative humidity and water vapor content. Then, we study the diurnal, seasonal and interannual variability of these quantities over a span of more than twenty Martian years. Finally, we propose measurements to improve our understanding of the Martian dust and H2O cycles, and discuss the potential for liquid water formation under Mars’ present day conditions and its implications for future Mars missions. Understanding the modern Martian climate is important to determine if Mars could have the conditions to support life and to prepare for future human exploration. 相似文献
248.
Parro V Fernández-Remolar D Rodríguez-Manfredi JA Cruz-Gil P Rivas LA Ruiz-Bermejo M Moreno-Paz M García-Villadangos M Gómez-Ortiz D Blanco-López Y Menor-Salván C Prieto-Ballesteros O Gómez-Elvira J 《Astrobiology》2011,11(1):29-44
The particular mineralogy formed in the acidic conditions of the Río Tinto has proven to be a first-order analogue for the acid-sulfate aqueous environments of Mars. Therefore, studies about the formation and preservation of biosignatures in the Río Tinto will provide insights into equivalent processes on Mars. We characterized the biomolecular patterns recorded in samples of modern and old fluvial sediments along a segment of the river by means of an antibody microarray containing more than 200 antibodies (LDCHIP200, for Life Detector Chip) against whole microorganisms, universal biomolecules, or environmental extracts. Samples containing 0.3-0.5?g of solid material were automatically analyzed in situ by the Signs Of LIfe Detector instrument (SOLID2), and the results were corroborated by extensive analysis in the laboratory. Positive antigen-antibody reactions indicated the presence of microbial strains or high-molecular-weight biopolymers that originated from them. The LDCHIP200 results were quantified and subjected to a multivariate analysis for immunoprofiling. We associated similar immunopatterns, and biomolecular markers, to samples with similar sedimentary age. Phyllosilicate-rich samples from modern fluvial sediments gave strong positive reactions with antibodies against bacteria of the genus Acidithiobacillus and against biochemical extracts from Río Tinto sediments and biofilms. These samples contained high amounts of sugars (mostly polysaccharides) with monosaccharides like glucose, rhamnose, fucose, and so on. By contrast, the older deposits, which are a mix of clastic sands and evaporites, showed only a few positives with LDCHIP200, consistent with lower protein and sugar content. We conclude that LDCHIP200 results can establish a correlation between microenvironments, diagenetic stages, and age with the biomarker profile associated with a sample. Our results would help in the search for putative martian biomarkers in acidic deposits with similar diagenetic maturity. Our LDCHIP200 and SOLID-like instruments may be excellent tools for the search for molecular biomarkers on Mars or other planets. 相似文献
249.
Adaptive combining of experimentally obtained heterodyned pulse position modulated (PPM) signals with pulse-to-pulse coherence, in the presence of simulated spatial distortions resembling atmospheric turbulence, is demonstrated. The adaptively combined PPM signals are phased up via an least-mean-square algorithm suitably optimized to operate with PPM in the presence of additive shot noise. A convergence analysis of the algorithm is presented, and results with both computer simulated and experimentally obtained PPM signals are analyzed. 相似文献
250.
Isotopic ratios in comets provide keys for the understanding of the origin of cometary material, and the physical and chemical
conditions in the early Solar Nebula. We review here measurements acquired on the D/H, 12C/13C, 16O/18O, 14N/15N, 32S/34S ratios in dust and gases, and discuss their cosmogonic implications. The prospects for future measurements from cometary
space missions and remote sensing observations at millimeter and submillimeter wavelengths are presented.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献