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161.
Junho Shin Takashi Sakurai 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
In order to better understand the characteristics of Yohkoh Soft X-ray Telescope (SXT) mirror, we have analyzed the in-flight overexposed image (the starburst image) obtained during the solar flare observation. It has been revealed from our study that the intensity distribution inside the shadows shown in the scattering difference image contains little of the scattered component of the PSF and matches almost correctly the extension of the PSF core profile. Also it is found that the scattering wing of the SXT PSF is connected smoothly to the PSF core within the distance of about 100–200 arcsec from the peak. With numerical simulations we have shown that an increase in energy affects not only the level of scattering wing, but also both the shape and the absolute level of the PSF core. The results have revealed, however, that the energy dependence for the SXT PSF cannot be easily estimated with the data obtained from one filter alone, which implies that the data analysis using multiple filters will enable us to determine the absolute amount of scattered component as well as the energy dependence of the SXT PSF. Details on the analysis of starburst image and the results from numerical simulations will be introduced and discussed thoroughly. 相似文献
162.
为量化分析Crab脉冲星X射线波段光子到达时间(TOA)测量误差和自转频率误差对脉冲TOA估计的影响,仿真生成了13 200组带有不同光子TOA测量误差的光子TOA数据。采用含有不同大小自转频率误差的Crab脉冲星星历,通过历元折叠建立积分脉冲轮廓,与标准脉冲轮廓作互相关运算获得各组仿真观测的脉冲TOA测量误差,进一步计算出各误差参数组的仿真观测脉冲TOA测量误差均方根(RMS)。仿真结果表明,为使Crab脉冲星脉冲TOA短期测量精度达到30 ~300 μs量级的要求,有效面积为6 000 cm2和30 cm2的探测器脉冲星自转频率误差均应小于3×10-6 Hz,30 cm2的探测器光子TOA的偶然误差同时应控制在500 μs以内。 相似文献
163.
T. Kallman 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2004,34(12):2673-2677
In this paper I will review the motivation for measuring polarization in the X-ray band from astrophysical sources. Emission models designed to reproduce X-ray spectra can be tested using polarization, and polarization detected in other wavelength bands makes clear predictions as to the X-ray polarization. Polarization is a powerful tool to infer geometrical properties of sources which are too small to be spatially resolved. At the same time, there has been recent progress in instrumentation which is likely to allow searches for X-ray polarization at levels significantly below what was possible for early detectors. This paper will review the history of X-ray polarimetry, discuss some experimental techniques and the scientific problems which can be addressed by future experiments. 相似文献
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David N. Burrows J. E. Hill J. A. Nousek J. A. Kennea A. Wells J. P. Osborne A. F. Abbey A. Beardmore K. Mukerjee A. D. T. Short G. Chincarini S. Campana O. Citterio A. Moretti C. Pagani G. Tagliaferri P. Giommi M. Capalbi F. Tamburelli L. Angelini G. Cusumano H. W. Bräuninger W. Burkert G. D. Hartner 《Space Science Reviews》2005,120(3-4):165-195
he Swift Gamma-Ray Explorer is designed to make prompt multiwavelength observations of gamma-ray bursts (GRBs) and GRB afterglows.
The X-ray telescope (XRT) enables Swift to determine GRB positions with a few arcseconds accuracy within 100 s of the burst onset.
The XRT utilizes a mirror set built for JET-X and an XMM-Newton/EPIC MOS CCD detector to provide a sensitive broad-band (0.2–10 keV) X-ray imager with effective area of > 120 cm2 at 1.5 keV, field of view of 23.6 × 23.6 arcminutes, and angular resolution of 18 arcseconds (HPD). The detection sensitivity
is 2×10−14 erg cm−2 s−1 in 104 s. The instrument is designed to provide automated source detection and position reporting within 5 s of target acquisition.
It can also measure the redshifts of GRBs with Fe line emission or other spectral features. The XRT operates in an auto-exposure
mode, adjusting the CCD readout mode automatically to optimize the science return for each frame as the source intensity fades.
The XRT will measure spectra and lightcurves of the GRB afterglow beginning about a minute after the burst and will follow
each burst for days or weeks.
Dedicated to David J. Watson, in memory of his valuable contributions to this instrument. 相似文献
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170.
王金良 《北京航空航天大学学报》2005,31(1):1-4
过渡金属与硅的接触系统一直被人们所关注,是因为它们在界面处具有肖特基势垒的形成、过渡金属硅化物的外延生长、制作器件的稳定和耐高温等重要性.因此在硅基底上形成金属硅化物薄膜也被广泛应用于半导体工业.对硅衬底上蒸发的Cr、Fe、Mn薄膜进行热处理,通过固相反应法(SPR)制备过渡金属硅化物薄膜,即经过对过渡金属硅化物(薄膜)/Si系统进行各种温度、不同时间的热处理,制备出各种过渡金属硅化物薄膜.对于制成的各种硅化物薄膜,用X射线衍射法(XRD)和软X射线发射分光光谱法(SXES)对它们的组成成分进行了分析和确认.并且,由这两种分析方法表明:各种过渡金属硅化物薄膜在硅衬底上各形成了单一相的均匀层硅化物薄膜. 相似文献