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861.
V. A. Olaev 《Russian Aeronautics (Iz VUZ)》2009,52(2):214-220
The algorithmic support of a small-sized navigation system on the basis of the magnetoinertial course transmitter is considered; the support makes it possible to significantly reduce accumulating errors that are due to incomplete data on wind parameters and decrease requirements for random errors of initial data sensors. 相似文献
862.
I. Sh. Sharafeev 《Russian Aeronautics (Iz VUZ)》2009,52(2):255-258
A set of systems for labor standard computer-aided design is described, namely, initial developments, advance and state-of-the art. 相似文献
863.
Yu. G. Kutsenko 《Russian Aeronautics (Iz VUZ)》2009,52(2):208-213
A modification of the Zimont turbulent combustion model is presented; the modification makes it possible to describe processes in diffusion and homogeneous flame fronts as well as to take into account the influence of different factors that cause flame destabilization. The model is based on the equation for a reaction completeness extent (completeness of combustion). The model realization to simulate the premixed combustion is described and the modification of the turbulent combustion model is applied to simulate a process of flameout downstream of the flameholder. 相似文献
864.
Some experimental data on the process of impulsive ultrasonic machining are presented. Also given are the data on variations in the impulsive vibration frequency of a workpiece and a tool. 相似文献
865.
866.
V. A. Ryabyi V. A. Obukhov A. P. Kirpichnikov P. E. Masherov A. I. Mogulkin 《Russian Aeronautics (Iz VUZ)》2015,58(4):448-453
A technique of integral diagnostics for an RF inductively coupled plasma gas discharge unit of an ion thruster is proposed. This technique includes a priori measurements of antenna coil electrical parameters in free space and in assembled state as well as experimental determination of the antenna coil currents with and without discharge. 相似文献
867.
G. A. Gusev B. N. Lomonosov K. M. Pichkhadze N. G. Polukhina V. A. Ryabov T. Saito V. K. Sysoev E. L. Feinberg V. A. Tsarev V. A. Chechin 《Cosmic Research》2006,44(1):19-38
An estimate of the feasibility of the ultrahigh-energy cosmic ray and neutrino detection using a lunar satellite-borne radio receiver is presented. The data obtained in the proposed experiment will make resolving the current contradictions in the ultrahigh-energy cosmic ray spectra measured with the major ground-based instruments possible. Moreover, they will enable us to considerably extend the accessible energy range and to check predictions of various models of the origin of the highest-energy particles in the Universe. At the same time the lunar radio detector provides a means of searching for ultrahigh-energy neutrinos with a high sensitivity combined with a very large target effective mass. 相似文献
868.
The President's Strategic Defense Initiative (SDI) began in 1983 following his historic March 23, 1983 speech. The SDI program has enjoyed substantial progress since this beginning. As the SDI begins its fourth year, the outlines of a basic system architecture, feasible for deployment in the 1990s, begins to emerge. In addition, SDI technical progress shows great promise not only for an initial strategic defense system, but also for maintaining defense effectiveness into the first decades of the next century against countermeasures designed specifically to defeat defenses. 相似文献
869.
Selected new methods and applications of non-linear apodization for irregularly-shaped and parse coherent apertures and arrays are presented. The benefits include unproved impulse response performance, i.e., reduced peak sidelobes and integrated sidelobe power, along with improved mainlobe resolution, compared to classic windowing techniques. Nonlinear apodization (NLA) techniques can also serve as powerful engines for effective superresolution and bandwidth extrapolation of coherent data for filling sparse apertures. The sparse aperture filling property of superresolution algorithms for radar data forms the basis for a new concept which is introduced here: synthetic multiple aperture radar technology (SMART). Increased swath and/or reduced antenna size are some of the benefits postulated for SMART applied to synthetic aperture radar (SAR) systems. The benefits of these new methods and applications for nonlinear apodization are then demonstrated for two specific applications: 1) sidelobe control for Y-type synthetic aperture radiometers, such as the European Soil Moisture and Ocean Salinity (SMOS) system (Kerr et al.) and JPL's proposed GeoSTAR (Lambrigsten) concept; and, 2) filling of sparse synthetic aperture radar data by exploiting the bandwidth extrapolation properties of nonlinear apodization based superresolution techniques. The methods that have been developed and demonstrated herein have potential application to a wide range of passive and active microwave remote sensing and radar systems. 相似文献
870.
A. Galli P. Wurz S. Barabash A. Grigoriev H. Gunell R. Lundin M. Holmström A. Fedorov 《Space Science Reviews》2006,126(1-4):267-297
We present measurements of energetic hydrogen and oxygen atoms (ENAs) on the nightside of Mars detected by the neutral particle
detector (NPD) of ASPERA-3 on Mars Express. We focus on the observations for which the field-of-view of NPD was directed at
the nightside of Mars or at the region around the limb, thus monitoring the flow of ENAs towards the nightside of the planet.
We derive energy spectra and total fluxes, and have compiled maps of hydrogen ENA outflow. The hydrogen ENA intensities reach
105 cm−2 sr−1 s−1, but no oxygen ENA signals above the detection threshold of 104 cm−2 sr−1 s−1 are observed. These intensities are considerably lower than most theoretical predictions. We explain the discrepancy as due
to an overestimation of the charge-exchange processes in the models for which too high an exospheric density was assumed.
Recent UV limb emission measurements (Galli et al., this issue) point to a hydrogen exobase density of 1010 m−3 and a very hot hydrogen component, whereas the models were based on a hydrogen exobase density of 1012 m−3 and a temperature of 200 K predicted by Krasnopolsky and Gladstone (1996). Finally, we estimate the global atmospheric loss
rate of hydrogen and oxygen due to the production of ENAs. 相似文献