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531.
Andrew W. Stephan R. R. Meier Scott L. England Stephen B. Mende Harald U. Frey Thomas J. Immel 《Space Science Reviews》2018,214(1):42
The NASA Ionospheric Connection Explorer Far-Ultraviolet spectrometer, ICON FUV, will measure altitude profiles of the daytime far-ultraviolet (FUV) OI 135.6 nm and N2 Lyman-Birge-Hopfield (LBH) band emissions that are used to determine thermospheric density profiles and state parameters related to thermospheric composition; specifically the thermospheric column O/N2 ratio (symbolized as \(\Sigma\)O/N2). This paper describes the algorithm concept that has been adapted and updated from one previously applied with success to limb data from the Global Ultraviolet Imager (GUVI) on the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission. We also describe the requirements that are imposed on the ICON FUV to measure \(\Sigma\)O/N2 over any 500-km sample in daytime with a precision of better than 8.7%. We present results from orbit-simulation testing that demonstrates that the ICON FUV and our thermospheric composition retrieval algorithm can meet these requirements and provide the measurements necessary to address ICON science objectives. 相似文献
532.
Pulsars are natural cosmic clocks. On long timescales they rival the precision of terrestrial atomic clocks. Using a technique called pulsar timing, the exact measurement of pulse arrival times allows a number of applications, ranging from testing theories of gravity to detecting gravitational waves. Also an external reference system suitable for autonomous space navigation can be defined by pulsars, using them as natural navigation beacons, not unlike the use of GPS satellites for navigation on Earth. By comparing pulse arrival times measured on-board a spacecraft with predicted pulse arrivals at a reference location (e.g. the solar system barycenter), the spacecraft position can be determined autonomously and with high accuracy everywhere in the solar system and beyond. We describe the unique properties of pulsars that suggest that such a navigation system will certainly have its application in future astronautics. We also describe the on-going experiments to use the clock-like nature of pulsars to “construct” a galactic-sized gravitational wave detector for low-frequency (\(f_{GW}\sim 10^{-9} \text{--} 10^{-7}\) Hz) gravitational waves. We present the current status and provide an outlook for the future. 相似文献
533.
风力发电作为清洁能源利用的重要方式,具有无污染、可再生、方便采集等特点,近年来得到快速发展。相对于传统低空风力发电,系留悬浮式风力发电具有容量系数高、发电成本低等优点,拥有更大的开发价值和发展潜力,已有多个国家开展研究并取得一定成果。本文通过对系留悬浮式风力发电技术发展的调研,归纳四种系留悬浮式风力发电技术类型,分析各技术类型的工作原理与特点,总结未来系留悬浮式风力发电需要重点突破的轻质高强系留缆绳设计与制造、高性能囊体复合材料、稳定与智能控制、高效风力发电飞行平台总体设计、便利展开部署五种关键技术,为后续研究提供参考。 相似文献
534.
535.
T. Beuselinck C. Van Bavinchove V. I. Abrashkin A. E. Kazakova V. V. Sazonov 《Cosmic Research》2010,48(3):246-259
The results of reconstruction of rotational motion of the Foton M-3 satellite during its uncontrolled flight in September 2007 are presented. The reconstruction was performed by processing
the data of onboard measurements of the Earth’s magnetic field obtained by the DIMAC instruments. The measurements were carried
out continuously throughout the flight, but the processing technique dealt with the data portions covering time intervals
of a few orbital revolutions. The data obtained on each such interval were processed jointly by the least squares method with
using integration of the equations of satellite motion relative to its center of mass. When processing, the initial conditions
of motion and the used mathematical model’s parameters were estimated. The results of processing 16 data sets gave us complete
information about the satellite motion. This motion, which began at a low angular velocity, had gradually accelerated and
in five days became close to the regular Euler precession of an axisymmetric solid body. At the end of uncontrolled flight
the angular velocity of the satellite relative to its lengthwise axis was 0.5 deg/s; the angular velocity projection onto
the plane perpendicular to this axis had a magnitude of about 0.18 deg/s. 相似文献
536.
F. R. Bouchet R. Gispert N. Aghanim J. R. Bond A. De Luca E. Hivon B. Maffei 《Space Science Reviews》1995,74(1-2):37-43
Here follows a preliminary report on the construction of fake millimeter and sub-millimeter skies, as observed by virtual instruments,e.g. the COBRA/SAMBA mission, using theoretical modeling and data extrapolations. Our goal is to create maps as realistic as possible of the relavant physical contributions which may contribute to the detected signals. This astrophysical modeling is followed by simulations of the measurement process itself by a given instrumental configuration. This will enable a precise determination of what can and cannot be achieved with a particular experimental configuration, and provide a feedback on how to improve the overall design. It is a key step on the way to define procedures for the separation of the different physical processes in the future observed maps. Note that this tool will also prove useful in preparing and analyzing current (e.g. balloon borne) Microwave Background experiments. 相似文献
537.
538.
Alisson Dal Lago Walter D. Gonzalez Aline De Lucas Carlos Roberto Braga Lucas Ramos Vieira Tardelli Ronan Coelho Stekel Marlos Rockenbach 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
In this work, we present a study of the coronal mass ejection (CME) dynamics using LASCO coronagraph observations combined with in-situ ACE plasma and magnetic field data, covering a continuous period of time from January 1997 to April 2001, complemented by few extreme events observed in 2001 and 2003. We show, for the first time, that the CME expansion speed correlates very well with the travel time to 1 AU of the interplanetary ejecta (or ICMEs) associated with the CMEs, as well as with their preceding shocks. The events analyzed in this work are a subset of the events studied in Schwenn et al. (2005), from which only the CMEs associated with interplanetary ejecta (ICMEs) were selected. Three models to predict CME travel time to Earth, two proposed by Gopalswamy et al. (2001) and one by Schwenn et al. (2005), were used to characterize the dynamical behavior of this set of events. Extreme events occurred in 2001 and 2003 were used to test the prediction capability of the models regarding CMEs with very high LASCO C3 speeds. 相似文献
539.