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161.
UCAV任务规划系统的研究进展及发展趋势 总被引:7,自引:0,他引:7
分析了无人作战飞机任务规划系统的特点,按照规划范围和时段对无人作战飞机任务规划系统进行分层研究,讨论和分析了各个层次的作用及发展现状。最后,展望了无人作战飞机任务规划系统的发展趋势。 相似文献
162.
Conte E. De Maio A. Ricci G. 《IEEE transactions on aerospace and electronic systems》2002,38(2):612-621
The subject of detection of spatially distributed targets in non-Gaussian noise with unknown statistics is addressed. At the design stage, in order to cope with the a priori uncertainty, we model noise returns as Gaussian vectors with the same structure of the covariance matrix, but possibly different power levels (heterogeneous environment). We also assume that a set of secondary data, free of signal components, is available to estimate the correlation properties of the disturbance The proposed detector assumes no a priori knowledge about the spatial distribution of the target scatterers and ensures the constant false alarm rate (CFAR) property with respect to both the structure of the covariance matrix and the power levels. Finally, the performance assessment, conducted modeling the disturbance as a spherically invariant random process (SIRP), confirms its validity to operate in real radar scenarios 相似文献
163.
J. P. De Greve 《Space Science Reviews》1986,43(1-2):139-210
The present knowledge on the evolution of semidetached systems is reviewed. Characteristics of observed systems are discussed and general properties tested by the behaviour of theoretical models. New models of mass accreting companion stars are computed. The accretion phase is divided into a fast and slow phase with an accretion rate depending on the initial mass of the mass losing star and on the initial mass ratio, assuming the systems are undergoing a case B of mass transfer. The results are compared with observed systems with masses of the gainers located within the theoretical range. Up to now no computations exist for the evolution of medium mass close binaries including overshooting of the convective core. However some of the influences of extended convective mixing on the interaction of close binaries are investigated. A larger probability for the occurrence of case A of mass exchange and a larger remnant mass at the end of the process are the most important results. Finally the investigation into the origin of individual systems (in mass, mass ratio and period) is discussed, showing that progress both in observations and in theoretical models result in a more detailed and more restricted determination of the initial parameters of the individual systems.Research associate, NFWO, Belgium. 相似文献
164.
Deep space environments for human exploration. 总被引:3,自引:0,他引:3
J W Wilson M S Clowdsley F A Cucinotta R K Tripathi J E Nealy G De Angelis 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2004,34(6):1281-1287
Mission scenarios outside the Earth's protective magnetic shield are being studied. Included are high usage assets in the near-Earth environment for casual trips, for research, and for commercial/operational platforms, in which career exposures will be multi-mission determined over the astronaut's lifetime. The operational platforms will serve as launching points for deep space exploration missions, characterized by a single long-duration mission during the astronaut's career. The exploration beyond these operational platforms will include missions to planets, asteroids, and planetary satellites. The interplanetary environment is evaluated using convective diffusion theory. Local environments for each celestial body are modeled by using results from the most recent targeted spacecraft, and integrated into the design environments. Design scenarios are then evaluated for these missions. The underlying assumptions in arriving at the model environments and their impact on mission exposures within various shield materials will be discussed. 相似文献
165.
166.
Deep and Shallow Solid-Earth Structures Reconstructed with Sequential Integrated Inversion (SII) of Seismic and Gravity Data 总被引:3,自引:0,他引:3
In this paper, the possibility of using simultaneously seismic and gravity data, for the reconstruction of solid-Earth structures,
has been investigated through the use of an algorithm which allows joint efficient and reliable optimisation of compressional
velocity and mass density parameters. We view the measured data as a realisation of a stochastic process generated by the
physical parameters to be sought and we construct a “probability density function” which includes three kinds of information:
information derived from gravity measurements; information derived from seismic travel time inversion and information on the
physical correlation among density and velocity parameters. We show that combining data has a beneficial effect on the inversion
since: it makes the problem more stable and as a consequence, providing that the quality of data is sufficiently high, enables
more accurate and reliable reconstruction of the unknown parameters. In this context, we look forward the GOCE mission, which
promises high spatial resolution (100–200 km) and accurate (1–2 mGals) gravity data.
We show results obtained from data sets calculated for a lateral inhomogeneous earth synthetic model and from seismic and
gravity field data analysed:
— in the framework of TOMOVES (TOMOgraphy of Mt. VESuvius) experiment, an European project aiming at reconstructing the 3-D
image of Mt. Vesuvius volcano and the crust underneath. using high resolution seismic tomography techniques and other geophysical
methods;
— for a profile inserted in a project aiming at reconstructing the crustal structure between Corsica and the Northern Appennines
which crosses the Ligurian Sea and cuts the Ligurian Appennines W of La Spezia, extending up to Parma.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
167.
168.
169.
以一座 2层 44车位立体车库为例 ,介绍了可编程控制器 (PLC)在立体车库中的应用 ,用PLC实现对车库系统的自动化控制。叙述了立体车库的设计、PLC控制系统的构成和程序设计。 相似文献
170.
在GPS短基线相对定位中,可以根据多路径误差周期约为1天的重复性特点建立误差模型,采用坐标域或观测值域滤波的方法进行多路径误差改正.北斗系统由GEO、IGSO和MEO三种卫星类型组成,其中MEO卫星类型接近7天的轨道周期与GEO和IGSO约为1天的轨道周期差异较大,因此对北斗观测值进行多路径误差改正时只能采用观测值域滤波方法.本文以某水库大坝形变监测网为例,对GPS和BDS观测值分别建立多路径误差模型,根据各自卫星轨道周期进行多路径误差改正,结果表明经改正后大坝形变监测精度有较大提高. 相似文献