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801.
802.
M. N. Burdaev 《Cosmic Research》2011,49(5):464-467
The paper presents the derivation of two new equations for calculating the time of transfer between two points of the central
gravitational field: for hyperbolic orbits and the universal equation for elliptical and hyperbolic orbits. In the paper we
have used as an independent variable, instead of the linear elements (semimajor axis, focal parameter of orbit or a chord
connecting the ends of boundary radii of transfer), the angular parameter—the angle between the radius vector of an initial
point of transfer and the vector of initial velocity of transfer. Paper’s material is a continuation of that presented in
the “Space research“ Journal, vol. 2, March–April, 2009. 相似文献
803.
A. I. Tkachenko 《Cosmic Research》2011,49(2):150-159
A method to find and identify failures in a spacecraft’s set of sensitive elements that measure vector quantities of different
nature is discussed. 相似文献
804.
Abrevaya XC Paulino-Lima IG Galante D Rodrigues F Mauas PJ Cortón E Lage Cde A 《Astrobiology》2011,11(10):1034-1040
The haloarchaea Natrialba magadii and Haloferax volcanii, as well as the radiation-resistant bacterium Deinococcus radiodurans, were exposed to vacuum UV (VUV) radiation at the Brazilian Synchrotron Light Laboratory. Cell monolayers (containing 10(5) to 10(6) cells per sample) were prepared over polycarbonate filters and irradiated under high vacuum (10(-5) Pa) with polychromatic synchrotron radiation. N. magadii was remarkably resistant to high vacuum with a survival fraction of (3.77±0.76)×10(-2), which was larger than that of D. radiodurans (1.13±0.23)×10(-2). The survival fraction of the haloarchaea H. volcanii, of (3.60±1.80)×10(-4), was much smaller. Radiation resistance profiles were similar between the haloarchaea and D. radiodurans for fluences up to 150?J m(-2). For fluences larger than 150?J m(-2), there was a significant decrease in the survival of haloarchaea, and in particular H. volcanii did not survive. Survival for D. radiodurans was 1% after exposure to the higher VUV fluence (1350?J m(-2)), while N. magadii had a survival lower than 0.1%. Such survival fractions are discussed regarding the possibility of interplanetary transfer of viable microorganisms and the possible existence of microbial life in extraterrestrial salty environments such as the planet Mars and Jupiter's moon Europa. This is the first work to report survival of haloarchaea under simulated interplanetary conditions. 相似文献
805.
Preservation of microbial lipids in geothermal sinters 总被引:1,自引:0,他引:1
Lipid biomarkers are widely used to study the earliest life on Earth and have been invoked as potential astrobiological markers, but few studies have assessed their survival and persistence in geothermal settings. Here, we investigate lipid preservation in active and inactive geothermal silica sinters, with ages of up to 900 years, from Champagne Pool, Waiotapu, New Zealand. Analyses revealed a wide range of bacterial biomarkers, including free and bound fatty acids, 1,2-di-O-alkylglycerols (diethers), and various hopanoids. Dominant archaeal lipids include archaeol and glycerol dialkyl glycerol tetraethers (GDGTs). The predominance of generally similar biomarker groups in all sinters suggests a stable microbial community throughout Champagne Pool's history and indicates that incorporated lipids can be well preserved. Moreover, subtle differences in lipid distributions suggest that past changes in environmental conditions can be elucidated. In this case, higher archaeol abundances relative to the bacterial diethers, a greater proportion of cyclic GDGTs, the high average chain length of the bacterial diethers, and greater concentrations of hopanoic acids in the older sinters all suggest hotter conditions at Champagne Pool in the past. 相似文献
806.
E. P. Kontar J. C. Brown A. G. Emslie W. Hajdas G. D. Holman G. J. Hurford J. Ka?parov�� P. C. V. Mallik A. M. Massone M. L. McConnell M. Piana M. Prato E. J. Schmahl E. Suarez-Garcia 《Space Science Reviews》2011,159(1-4):301-355
X-radiation from energetic electrons is the prime diagnostic of flare-accelerated electrons. The observed X-ray flux (and polarization state) is fundamentally a convolution of the cross-section for the hard X-ray emission process(es) in question with the electron distribution function, which is in turn a function of energy, direction, spatial location and time. To address the problems of particle propagation and acceleration one needs to infer as much information as possible on this electron distribution function, through a deconvolution of this fundamental relationship. This review presents recent progress toward this goal using spectroscopic, imaging and polarization measurements, primarily from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Previous conclusions regarding the energy, angular (pitch angle) and spatial distributions of energetic electrons in solar flares are critically reviewed. We discuss the role and the observational evidence of several radiation processes: free-free electron-ion, free-free electron-electron, free-bound electron-ion, photoelectric absorption and Compton backscatter (albedo), using both spectroscopic and imaging techniques. This unprecedented quality of data allows for the first time inference of the angular distributions of the X-ray-emitting electrons and improved model-independent inference of electron energy spectra and emission measures of thermal plasma. Moreover, imaging spectroscopy has revealed hitherto unknown details of solar flare morphology and detailed spectroscopy of coronal, footpoint and extended sources in flaring regions. Additional attempts to measure hard X-ray polarization were not sufficient to put constraints on the degree of anisotropy of electrons, but point to the importance of obtaining good quality polarization data in the future. 相似文献
807.
808.
Hugh S. Hudson 《Space Science Reviews》2011,158(1):5-41
This article broadly reviews our knowledge of solar flares. There is a particular focus on their global properties, as opposed
to the microphysics such as that needed for magnetic reconnection or particle acceleration as such. Indeed solar flares will
always remain in the domain of remote sensing, so we cannot observe the microscales directly and must understand the basic
physics entirely via the global properties plus theoretical inference. The global observables include the general energetics—radiation
in flares and mass loss in coronal mass ejections (CMEs)—and the formation of different kinds of ejection and global wave
disturbance: the type II radio-burst exciter, the Moreton wave, the EIT “wave”, and the “sunquake” acoustic waves in the solar
interior. Flare radiation and CME kinetic energy can have comparable magnitudes, of order 1032 erg each for an X-class event, with the bulk of the radiant energy in the visible-UV continuum. We argue that the impulsive
phase of the flare dominates the energetics of all of these manifestations, and also point out that energy and momentum in
this phase largely reside in the electromagnetic field, not in the observable plasma. 相似文献
809.
E. M. Kraeva 《Russian Aeronautics (Iz VUZ)》2011,54(2):154-158
Based on the jet-vortex model for flow passage hydrodynamics in a high-speed centrifugal pump with the open-type impeller,
we present the calculated relations for design and optimization of the experimentally verified pump design parameters. 相似文献
810.
In this paper, one of the most possible methods for calculations of ejector devices equipped with the cylindrical mixing chambers
is considered; the method is based on averaging the flow parameters at the chamber inlet. We present the calculation results
and their comparison with the earlier published data, as well as the quantitative assessment of this method and feasibilities
of its use for different technical devices embodying the concept of ejection. 相似文献