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901.
S.L. Mandelstam A.M. Urnov I.A. Zhitnik 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(7):87-89
Results are given of the study of active regions and flares by a high resolution Mg XI ion spectra obtained aboard rockets and a satellite. It is shown that there is a noticable similarity in the physical conditions in the plasma of active regions and flares. Plasma of both sources consists okf a thermal component with the temperature T ~ 2.?3.106K for active regions and T ~ 1.5?2.5.107K for flares and in both cases of a relatively small number (~ 1–5%) of suprathermal electrons with an energy E ~ 3–6 kT. 相似文献
902.
L.V. Nevzgodina E.N. Maximova Yu.A. Akatov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(14):83-85
We have studied the effects of prolonged (up to 175 days) exposure of seeds to space flight factors, including primary cosmic radiation heavy ions. The data obtained evidence a significant fourfold increase ofs pontaneous mutagenesis in seeds both with regard to the total number of aberrant cells as well as the formation of single cells with multiple aberrations. Comparison of the present experiment with earlier works shows that the frequency of such aberrations increases with the duration of the flight. 相似文献
903.
G Horneck H Bucker K Dose K D Martens A Bieger H D Mennigmann G Reitz H Requardt P Weber 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(10):19-27
Bacterial spores are proper test organisms for studying problems of space biology and exobiology. During the Spacelab 1 mission, studies on the limiting factors for survival of Bacillus subtilis spores in free space have been performed. An exposure tray on the pallet of Spacelab 1 accomodated 316 samples of dry spores for treatment with space vacuum and/or the following selected wavelengths of solar UV: > 170 nm, 220 nm, 240nm, 260nm and 280 nm. After recovery, inactivation, mutation induction, reparability, and photochemical damages in DNA and protein have been studied. The results contribute to the understanding of the mechanisms of increased UV sensitivity of bacterial spores in vacuo and to a better assessment of the chance of survival of resistant forms in space and of interplanetary transfer of life. 相似文献
904.
V.V. Iliukhin V.P. Shalimov S.J. Budurov P.D. Kovachev S.A. Toncheva 《Acta Astronautica》1984,11(9):585-592
Thermodynamics relations have been considered under which gas inclusions may form in melts (closed systems), due to both volatility of components and the presence of dissolved gases. It has been shown that in the melts with sufficient volatility of components, gas inclusions may form under equilibrium conditions if the ampoule is wetted well by the melt, whereas in case of low wettability they form under non-equilibrium state only. The foaming in the tellurium-selenium system has been analysed (“Pirin”, KP-4 experiment).In the melts containing dissolved gases, gas inclusions form under conditions of deviation from equilibrium and it is the main mechanism of outgassing. It has been demonstrated that the melt foaming method using hydrid compounds may be applied to the materials exhibiting a hysteresis of temperature dependence of diluted hydrogen concentration. Production of foam aluminium under zero gravity state has been considered as an example (“Pirin”, SP-3 experiment). 相似文献
905.
A.A. Stepanian 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,3(10-12)
A brief review of very high energy gamma-ray astronomy achievements is presented. The results of observations of the Crab nebula, the Cygnus X-3, Vela pulsar, radiogalaxy Centaurus A and 2CG 195+4 show that all these objects are the sources of very high energy gamma-quanta. The most powerfull source is Cygnus X-3. Its gamma-ray luminosity is no less than 3·1037 erg.s−1. The upper limit of quanta energy is no less than 1016eV. All sources are variable in different time scales, from milliseconds up to years. The nature of all these sources is not known yet, but known ones are pulsars. 相似文献
906.
A control law is presented for asymptotic function reproducibility in a class of nonlinear-systems such that the output of the system asympotically tends to a given function. The controller consists of a prefilter and a servocompensator. Based on this result, a nonlinear feedback control law for the attitude control of a satellite containing symmetric rotors, in a circular orbit, is derived. In the closed-loop system, given trajectories of pitch, yaw, and roll angles are asymptotically followed, and set point control of attitude is accomplished. Digital simulation results are presented to show the capability of the nonlinear controller. 相似文献
907.
B.N. Khare C. Sagan W.R. Thompson E.T. Arakawa F. Suits T.A. Callcott M.W. Williams S. Shrader H. Ogino T.O. Willingham B. Nagy 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(12):59-68
A dark reddish organic solid, called tholin, is synthesized from simulated Titanian atmospheres by irradiation with high energy electrons in a plasma discharge. The visible reflection spectrum of this tholin is found to be similar to that of high altitude aerosols responsible for the albedo and reddish color of Titan. The real (n) and imaginary (k) parts of the complex refractive index of thin films of Titan tholin prepared by continuous D.C. discharge through a 0.9 N2/0.1 CH4 gas mixture at 0.2 mb is determined from x-ray to microwave frequencies. Values of n (1.65) and k (0.004 to 0.08) in the visible are consistent with deductions made by ground-based and spaceborne observations of Titan. Many infrared absorption features are present in k(λ), including the 4.6 μm nitrile band. Molecular analysis of the volatile component of this tholin was performed by sequential and non-sequential pyrolytic gas chromatography/mass spectrometry. More than one hundred organic compounds are released; tentative identifications include saturated and unsaturated aliphatic hydrocarbons, substituted polycyclic aromatics, nitriles, amines, pyrroles, pyrazines, pyridines, pyrimidines, and the purine, adenine. In addition, acid hydrolysis produces a racemic mixture of biological and non-biological amino acids. Many of these molecules are implicated in the origin of life on Earth, suggesting Titan as a contemporary laboratory environment for prebiological organic chemistry on a planetary scale. 相似文献
908.
909.
A. Bertram 《Acta Astronautica》1980,7(10):1179-1190
In this paper some problems are described which are expected to arise during dynamic qualification of future large space structures. It is shown that the methods applied today, are no longer sufficient. As conclusion, the concept of a qualification procedure is proposed, which considers the phase of launching, as well as the phase of mission in orbit. 相似文献
910.
M. A. Azouni W. Kalita 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1988,8(12):219-224
The interaction of inert foreign particles and a solid-liquid interface during solidification is considered. The viscous drag on the particle which produces a force on the interface is calculated under general assumptions as well as the disjoining force for small particles and the buoyancy force for large ones. 相似文献