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911.
The CAVORT analog radar signal processor for matched filtering of coherent pulse trains from targets displaying significant radial acceleration is described. CAVORT employs a scanning technique to search repeatedly through trial pairs of values for Doppler and Doppler rate. When a target appears, it is detected, and the best-fitting pair of values determined. The principle of operation is illustrated, using photographs of waveforms generated by the equipment. The resuilts of satellite observations are included. It is demonstrated that the experimental CAVORT which integrates half-second segments of signal gives satisfactory estimates of acceleration. 相似文献
912.
G. Li A. Shalchi X. Ao G. Zank O.P. Verkhoglyadova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012,49(6):1067-1075
In gradual solar energetic particle (SEP) events, protons and heavy ions are often accelerated to >100 MeV/nucleon at a CME-driven shock. In this work, we study particle acceleration at an oblique shock by extending our earlier particle acceleration and transport in heliosphere (PATH) code to include shocks with arbitrary θBN, where θBN is the angle between the upstream magnetic field and the shock normal. Instantaneous particle spectra at the shock front are obtained by solving the transport equation using the total diffusion coefficient κ, which is a function of the parallel diffusion coefficient κ∥ and the perpendicular diffusion coefficient κ⊥. In computing κ∥ and κ⊥, we use analytic expressions derived previously. The particle maximum energy at the shock front as a function of time, the time intensity profiles and particle spectra at 1 AU for five θBN’s are calculated for an example shock. 相似文献
913.
High energy density, lithium secondary cells are very attractive for use in many future military applications. However, a number of technical challenges remain. Specifically, the development and qualification of a system capable of withstanding the harsh environmental conditions encountered during normal and abnormal zones of operation. This paper focuses on the environmental extremes that the Eagle-Picher lithium-ion system has tested to date. Emphasis is placed on low temperature performance, high temperature performance, power capability, and cycle life at these extremes. Other areas including safety and environmental issues have also been investigated 相似文献
914.
H G Levine J A Sharek K M Johnson E C Stryjewski V I Prima O I Martynenko W C Piastuch 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2000,26(2):311-314
As part of the GENEX (Gene Expression) spaceflight experiment, protocols were developed to optimize the inflight germination and subsequent growth of 192 soybean (Glycine max cv McCall) seeds during STS-87. We describe a method which provided uniform growth and development of etiolated seedlings while eliminating root and shoot restrictions for short-term (4-7 day) experiments. Final seedling growth morphologies and the gaseous CO2 and ethylene levels present both on the last day in space and at the time of recovery within the spaceflight and ground control BRIC-60 canisters are presented. 相似文献
915.
916.
Gloeckler G. Cain J. Ipavich F.M. Tums E.O. Bedini P. Fisk L.A. Zurbuchen T.H. Bochsler P. Fischer J. Wimmer-Schweingruber R.F. Geiss J. Kallenbach R. 《Space Science Reviews》1998,86(1-4):497-539
The Solar Wind Ion Composition Spectrometer (SWICS) and the Solar Wind Ions Mass Spectrometer (SWIMS) on ACE are instruments
optimized for measurements of the chemical and isotopic composition of solar and interstellar matter. SWICS determines uniquely
the chemical and ionic-charge composition of the solar wind, the thermal and mean speeds of all major solar wind ions from
H through Fe at all solar wind speeds above 300 km s−1 (protons) and 170 km s−1 (Fe+16), and resolves H and He isotopes of
both solar and interstellar sources. SWICS will measure the distribution functions of both the interstellar cloud and dust
cloud pickup ions up to energies of 100 keV e−1. SWIMS will measure the chemical, isotopic and charge state composition of
the solar wind for every element between He and Ni. Each of the two instruments uses electrostatic analysis followed by a
time-of-flight and, as required, an energy measurement. The observations made with SWICS and SWIMS will make valuable contributions
to the ISTP objectives by providing information regarding the composition and energy distribution of matter entering the magnetosphere.
In addition, SWICS and SWIMS results will have an impact on many areas of solar and heliospheric physics, in particular providing
important and unique information on: (i) conditions and processes in the region of the corona where the solar wind is accelerated;
(ii) the location of the source regions of the solar wind in the corona; (iii) coronal heating processes; (iv) the extent
and causes of variations in the composition of the solar atmosphere; (v) plasma processes in the solar wind; (vi) the acceleration
of particles in the solar wind; (vii) the physics of the pickup process of interstellar He in the solar wind; and (viii) the
spatial distribution and characteristics of sources of neutral matter in the inner heliosphere.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
917.
We readily convince ourselves that most achievements can be credited to the construction of powerful jet engines, which enable a spaceship to escape gravity. The principle of jet propulsion seems to work perfectly; jet engines can accelerate a rocket up to an incredible speed of 11 km/sec. Looks like there is nothing left to desire. However, from the physical point of view, 11 km/sec is not such a large value compared, for instance, to the speed of light. Would it be possible to attain half of that speed using gas jets? Unfortunately, the answer is no. Nevertheless, that is not the end of the story. The purpose of this article is to show that it is still possible to use the same principle to remove limitations on attainable speed if instead of gas jets, we employ ultrafast electron beams. The basic idea of our construction was inspired by the paper by H. Morgan (ibid., vol. 13, pp. 5-10, 1998). In that article he experimentally refuted the common premise that nothing can go faster than light and gave some theoretical arguments supporting his experimental data. Although the nature and underlying principles of the Morgan phenomenon are yet to be understood, we can already start thinking of its practical applications 相似文献
918.
Е.А. Deshevaya E.V. Shubralova N.D. Novikova V.V. Borisov O.D. Kononenko N.A. Polikarpov 《Acta Astronautica》2011,68(9-10):1555-1559
In 2008, two experiments – BAR and EXPERT – were performed on the Russian segment (ISS RS) during ISS missions 16 and 17 using diagnostic equipment BAR. The experiments were aimed to enhance ISS safety by proposing means and methods of detecting leaks due to many factors including microdestruction of pressurized modules of the vehicle. The BAR experiment was designed to assess the ultraviolet background in 56 potentially dangerous locations identified by RS ISS designers and engineers. The method for locating sites carrying the risk of microdestruction of pressurized structure was verified. The study showed that the rate of microdestruction is highly affected by level of ultrasound vibrations caused by onboard equipment. The ultrasound measurements in 200 RS ISS sites were performed within the BAR experiment. The method consists of looking for surfaces with atmospheric condensate in the areas of increased levels of ultrasound vibrations. Twenty six sites were added to the nomenclature of potentially risky sites to be monitored on the regular basis. Some of these sites were contaminated by fungi and bacteria. 相似文献
919.
The purpose of this paper is to introduce a new method in the research of radiative and thermal properties of materials with further applications in the design of thermal control systems (TCS) of spacecrafts. In this paper the radiative and thermal properties (emissivity and thermal conductance) of a multilayered thermal-insulating blanket (MLI), which is a screen-vacuum thermal insulation as a part of the TCS for perspective spacecrafts, are estimated. Properties of the materials under study are determined in the result of temperature and heat flux measurement data processing based on the solution of the inverse heat transfer problem (IHTP) technique. Given are physical and mathematical models of heat transfer processes in a specimen of the multilayered thermal-insulating blanket located in the experimental facility. A mathematical formulation of the inverse heat conduction problem is presented as well. The practical approves were made for specimen of the real MLI. 相似文献
920.
SAA drift: Experimental results 总被引:1,自引:0,他引:1
O.R. Grigoryan V.V. RomashovaA.N. Petrov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(1):76-80
According to the paleomagnetic analysis there are variations of Earth’s magnetic field connected with magnetic moment changing. These variations affect on the South Atlantic Anomaly (SAA) location. Indeed different observations approved the existence of the SAA westward drift rate (0.1–1.0 deg/year) and northward drift rate (approximately 0.1 deg/year). 相似文献