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131.
Pablo de Len 《Acta Astronautica》2009,65(11-12):1789-1795
One of the most important developers of liquid propellant rocket engines in Argentina was Polish-born Ricardo Dyrgalla. Dyrgalla immigrated to Argentina from the United Kingdom in 1946, where he had been studying German weapons development at the end of the Second World War. A trained pilot and aeronautical engineer, he understood the intricacies of rocket propulsion and was eager to find practical applications to his recently gained knowledge.Dyrgalla arrived in Argentina during Juan Perón's first presidency, a time when technicians from all over Europe were being recruited to work in various projects for the recently created Argentine Air Force.Shortly after immigrating, Dyrgalla proposed to develop an advanced air-launched weapon, the Tábano, based on a rocket engine of his design, the AN-1. After a successful development program, the Tábano was tested between 1949 and 1951; however, the project was canceled by the government shortly after. Today, the AN-1 rocket engine is recognized as the first liquid propellant rocket to be developed in South America. Besides the AN-1, Dyrgalla also developed several other rockets systems in Argentina, including the PROSON, a solid-propellant rocket launcher developed by the Argentine Institute of Science and Technology for the Armed Forces (CITEFA). In the late 1960s, Dyrgalla and his family relocated to Brazil due mostly to the lack of continuation of rocket development in Argentina. There, he worked for the Institute of Aerospace Technology (ITA) until his untimely death in 1970. Ricardo Dyrgalla deserves to be recognized among the world's rocket pioneers and his contribution to the science and engineering of rocketry deserves a special place in the history of South America's rocketry and space flight advocacy programs. 相似文献
132.
We consider transfers with low thrust in an arbitrary field of forces. The modified method of transporting trajectory [1–4] is used for optimization of the transfers. The complexity of finding the transporting trajectory of a preset type can be the main obstacle to application of this method. This challenge is solved for the three-body problem in the Hill motion model. Numerical analysis of the method is performed using an example of the transfers to halo-orbits around the solar-terrestrial libration points. 相似文献
133.
Allan Kardec de ALMEIDA Jr Geraldo Magela Couto OLIVEIRA Antonio Fernando Bertachini de Almeida PRADO 《中国航空学报》2021,34(1):410-423
In the restricted three-body problem, the traditional Lagrange points L1 and L2 are the only equilibrium points near the asteroid 243 Ida. The thrust generated by a solar sail over a spacecraft enables the existence of new artificial equilibrium points, which depend on the position of the spacecraft with respect to the asteroid and the attitude of the solar sail. Such equilibrium points generate new spots to observe the body from above or below the plane of motion. Such points are very good observational locations due to their stationary condition. This work provides a preliminary analysis to observe Ida through the use of artificial equilibrium points as spots combined with transfer maneuvers between them. Such combination can be used to observe the asteroid from more different points of view in comparison to fixed ones. The analyses are made for a spacecraft equipped with a solar sail and capable of performing bi-impulsive maneuvers. The solar radiation pressure is used both to maintain the equilibrium condition and to reduce the costs of the transfers and/or to create transfers with longer duration. This is a new aspect of the present research, because it combines the continuous thrust with initial and final small impulses, which are feasible for most of the spacecraft, because the magnitudes of the impulses are very low. These combined maneuvers may reduce the transfer times of the maneuvers in most of the cases, compared with the maneuvers based only on continuous thrust. Several options involved in these transfers are shown, like to minimize the fuel spent () as a function of the transfer time or to extend the duration of the travel between the points. Extended transfer times can be useful when observations are required during the transfers. 相似文献
134.
135.
P.A. Curran R.L.C. Starling A.J. van der Horst R.A.M.J. Wijers M. de Pasquale M. Page 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The complex structure of the light curves of Swift GRBs (e.g. superimposed flares and shallow decay) has made their interpretation and that of the blast wave caused by the burst, more difficult than in the pre-Swift era. We aim to constrain the blast wave parameters: electron energy distribution, p, density profile of the circumburst medium, k, and the continued energy injection index, q. We do so by comparing the observed multi-wavelength light curves and X-ray spectra of a Swift sample to the predictions of the blast wave model. 相似文献
136.
Y. Sahai R. de Jesus P.R. Fagundes C.L. Selhorst A.J. de Abreu S. Tulasi Ram A. Aragon-Angel V.G. Pillat J.R. Abalde W.L.C. Lima J.A. Bittencourt 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
The main objective of the present investigation has been to compare the ionospheric parameters (NmF2 and hmF2) observed by two ground-based ionospheric sounders (one at PALMAS- located near the magnetic equator and the other at Sao Jose dos Campos-located in the low-latitude region) in the Brazilian sector with that by the satellite FORMOSAT-3/COSMIC radio occultation (RO) measurements during two geomagnetic storms which occurred in December 2006 and July 2009. It should be pointed out that in spite of increasing the latitude (to 10°) and longitude (to 20°) around the stations; we had very few common observations. It has been observed that both the peak electron density (NmF2) and peak height (hmF2) observed by two different techniques (space-borne COSMIC and ground-based ionosondes) during both the geomagnetic storm events compares fairly well (with high correlation coefficients) at the two stations in the Brazilian sector. It should be pointed out that due to equatorial spread F (ESF) in the first storm (December 2006) and no-reflections from the ionosphere during nighttime in the second storm (July 2009), we had virtually daytime data from the two ionosondes. 相似文献
137.
B. Biran F. de Schryver F. Dubois 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1988,8(12):133-136
A new type of differential interferometer based on holographic optical elements is developed, which allows the exact determination of a refractive index gradient field in two orthogonal directions. This interferometer will be used in TEXUS experiments to determine the temperature field in a convective liquid cell in which the temperature may be known at only one point. 相似文献
138.
C de Bergh 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1995,15(3):427-440
Recent progress on measurements of isotopic ratios in planetary or satellite atmospheres include measurements of the D/H ratio in the methane of Uranus, Neptune and Titan and in the water of Mars and Venus. Implications of these measurements on our understanding of the formation and evolution of the planets and satellite are discussed. Our current knowledge of the carbon, nitrogen and oxygen isotopic ratios in the atmospheres of these planets, as well as on Jupiter and Saturn, is also reviewed. We finally show what progress can be expected in the very near future due to some new ground-based instrumentation particularly well suited to such studies, and to forthcoming space missions. 相似文献
139.
J. Jongbloed J. van Diggelen C. de Jager H. Busch J. J. Vos 《Space Science Reviews》1967,6(4):574-576
140.
J. L. Culhane R. C. Catura K. A. Pounds P. de Korte A. Franks G. P. Garmire A. Fabian B. Margon 《Space Science Reviews》1981,30(1-4):581-589
Following the success of Einstein, it is clear that telescopes of very large area (10 cm) with angular resolution (20) are needed for deep X-ray surveys and other observations. After a discussion of these objectives, which form the basis of the NASA LAMAR mission, the design & performance of a five mirror telescope is described. The system was studied for possible flight on Spacelab to undertake observations & to act as a prototype module for LAMAR. Both diamond turning & replication methods of mirror production are discussed. The performance of a single Wolter I telescope with diamond turned mirrors will be described. 相似文献