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排序方式: 共有443条查询结果,搜索用时 15 毫秒
391.
392.
Claudia Borries Volker Wilken Knut Stanley Jacobsen Alberto García-Rigo Beata Dziak-Jankowska Guram Kervalishvili Norbert Jakowski Ioanna Tsagouri Manuel Hernández-Pajares Arthur A. Ferreira Mainul M. Hoque 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(2):919-920
393.
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
394.
A. A. Baranov A. F. B. de Prado V. Yu. Razumny Anatoly A. BaranovJr. 《Cosmic Research》2011,49(3):269-279
Four types of optimal solutions are demonstrated to exist for transfers (time of flight is not fixed) between close near-circular
coplanar orbits. One solution is realized with the help of fixed orientation of the propulsion system (PS) along a transversal
in the orbital coordinate system. Another is reached at fixed orientation of the PS in the inertial coordinate system. The
third and fourth types of solutions change the PS orientation in the process of executing the maneuver. Regions of existence
are established for all types of solutions, and algorithms for determination of parameters of these maneuvers are suggested.
The algorithms were used to calculate parameters of the maneuvers of transfer from a launching orbit to a working Sun-synchronous
orbit, and to calculate the maneuvers of supporting the parameters of such an orbit in a specified range. 相似文献
395.
396.
Space Science Reviews - 相似文献
397.
398.
Sanchez-Avila C. Sanchez-Reillo R. de Martin-Roche D. 《Aerospace and Electronic Systems Magazine, IEEE》2002,17(10):3-6
A biometric identification system, based on the processing of the human iris by the dyadic wavelet transform, has been introduced. The procedure to obtain an iris signature of 256 bits has been described, as well as the feature extraction block and the verification system. The results have shown that the system can achieve high rates of security. 相似文献
399.
Between 25 and 30 years ago, the IECEC Proceedings carried a series of papers by the present authors and other members of a JPL team on the problems and the desirable design features associated with the MHW RTGs to be used to power JPL's Voyager I and II spacecraft. The Voyager I and II spacecraft successfully completed their original 12 year missions 10 years ago and are at distances of over 55 AU and 70 AU from the sun. The power systems worked almost precisely as predicted. The Voyager spacecraft seem to have several decades of life left to make measurements outside the solar system. This paper gives a technical overview of the design process and problems 相似文献
400.
M. E. Wiedenbeck W. R. Binns A. C. Cummings A. J. Davis G. A. de Nolfo M. H. Israel R. A. Leske R. A. Mewaldt E. C. Stone T. T. von Rosenvinge 《Space Science Reviews》2007,130(1-4):415-429
The galactic cosmic rays arriving near Earth, which include both stable and long-lived nuclides from throughout the periodic
table, consist of a mix of stellar nucleosynthesis products accelerated by shocks in the interstellar medium (ISM) and fragmentation
products made by high-energy collisions during propagation through the ISM. Through the study of the composition and spectra
of a variety of elements and isotopes in this diverse sample, models have been developed for the origin, acceleration, and
transport of galactic cosmic rays. We present an overview of the current understanding of these topics emphasizing the insights
that have been gained through investigations in the charge and energy ranges Z≲30 and E/M≲1 GeV/nuc, and particularly those using data obtained from the Cosmic Ray Isotope Spectrometer on NASA’s Advanced Composition
Explorer mission. 相似文献