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81.
Phillip C. Chamberlin Thomas N. WoodsFrancis G. Eparvier 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
The solar photon output from the Sun, which was once thought to be constant, varies considerably over time scales from seconds during solar flares to years due to the solar cycle. This is especially true in the wavelengths shorter than 190 nm. These variations cause significant deviations in the Earth and space environment on similar time scales, which then affects many things including satellite drag, radio communications, atmospheric densities and composition of particular atoms, molecules, and ions of Earth and other planets, as well as the accuracy in the Global Positioning System (GPS). The Flare Irradiance Spectral Model (FISM) is an empirical model that estimates the solar irradiance at wavelengths from 0.1 to 190 nm at 1 nm resolution with a time cadence of 60 s. This is a high enough temporal resolution to model variations due to solar flares, for which few accurate measurements at these wavelengths exist. This model also captures variations on the longer time scales of solar rotation (days) and solar cycle (years). Daily average proxies used are the 0–4 nm irradiance, the Mg II c/w, F10.7, as well as the 1 nm bins centered at 30.5 nm, 121.5 (Lyman Alpha), and 36.5 nm. The GOES 0.1–0.8 nm irradiance is used as the flare proxy. The FISM algorithms are given, and results and comparisons are shown that demonstrate the FISM estimations agree within the stated uncertainties to the various measurements of the solar Vacuum Ultraviolet (VUV) irradiance. 相似文献
82.
M. Nuevo S.N. Milam S.A. Sandford B.T. De Gregorio G.D. Cody A.L.D. Kilcoyne 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
Organic residues formed in the laboratory from the ultraviolet (UV) photo-irradiation or ion bombardment of astrophysical ice analogs have been extensively studied for the last 15 years with a broad suite of techniques, including infrared (IR) and UV spectroscopies, as well as mass spectrometry. Analyses of these materials show that they consist of complex mixtures of organic compounds stable at room temperature, mostly soluble, that have not been fully characterized. However, the hydrolysis products of these residues have been partly identified using chromatography techniques, which indicate that they contain molecular precursors of prebiotic interest such as amino acids, nitrile-bearing compounds, and amphiphilic compounds. In this study, we present the first X-ray absorption near-edge structure (XANES) spectroscopy measurements of three organic residues made from the UV irradiation of ices having different starting compositions. XANES spectra confirm the presence of different chemical functions in these residues, and indicate that they are rich in nitrogen- and oxygen-bearing species. These data can be compared with XANES measurements of extraterrestrial materials. Finally, this study also shows how soft X rays can alter the chemical composition of samples. 相似文献
83.
Salvatore Mancuso Alessandro Bemporad 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
We report on the analysis of two fast CME-driven shocks observed with the UltraViolet Coronagraph Spectrometer (UVCS) on board the Solar and Heliospheric Observatory (SOHO). The first event, detected on 2002 March 22 at 4.1 R⊙ with the UVCS slit placed in correspondence with the flank of the expanding CME surface, represents the highest UV detection of a shock obtained so far with the UVCS instrument in the corona. The second one, detected on 2002 July 23 at 1.6 R⊙ with the UVCS slit placed in correspondence with the front of the expanding CME surface, shows an anomalous deficiency of ion heating with respect to what observed in previous CME/shocks observed by UVCS, possibly reflecting the effect of different coronal plasma conditions over the solar cycle. From the two different sets of observations we derived an estimate for the shock compression ratio X, which turns out to be X = 2.4 ± 0.2 and X = 2.2 ± 0.1, respectively, for the first and second event. Comparison between the two events provides complementary perspectives on the dynamical evolution of CME-driven shocks. 相似文献
84.
Ts.N. Gogosheva V.N. Grigorieva Ts.T. Evgenieva B.D. Mendeva N.I. Kolev D.G. Krastev B.H. Petkov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
This presentation deals with the recent investigations of the dynamics of the total ozone content (TOC) and of the lower troposphere ozone over Bulgaria, South-Eastern Europe. 相似文献
85.
速率捷联惯导系统陀螺仪误差分段补偿技术研究 总被引:4,自引:0,他引:4
分析标度因数误差补偿的必要性和可行性,提出了对陀螺按照角速度 大小分段进行标定比例系数的方法,以补偿由于角速度变化而引起的陀螺标度 因数误差。通过计算机仿真验证了误差补偿方法的正确性,为实际应用提供了 理论依据。 相似文献
86.
This paper contains a summary of the topics treated in the working group on abundance variations in the solar atmosphere and
in the solar wind. The FIP bias (overabundance of particles with low First Ionization Potentials over photospheric abundances)
in coronal holes and coronal hole associated solar wind amounts to values between 1 and 2. The FIP bias in the slow solar
wind is typically a factor 4, consistent with optical observations in streamers. In order to distinguish between different
theoretical models which make an attempt to explain the FIP bias, some observable parameters must be provided. Unfortunately,
many models are deficient in this respect. In addition to FIP fractionation, gravitational settling of heavy elements has
been found in the core of long lived streamers. The so-called electron 'freeze in' temperatures derived from in situ observed
ionization states of minor ions in the fast wind are significantly higher than the electron temperatures derived from diagnostic
line ratios observed in polar coronal holes. The distinction between conditions in plumes and interplume lanes needs to be
further investigated. The 'freeze in' temperatures for the slow solar wind are consistent with the electron temperatures derived
for streamers.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
87.
L. Strachan Y-K. Ko A. V. Panasyuk D. Dobrzycka J. L. Kohl M. Romoli G. Noci S. E. Gibson D. A. Biesecker 《Space Science Reviews》1999,87(1-2):311-314
We constrain coronal outflow velocity solutions, resolved along the line-of-sight, by using Doppler dimming models of H I Lyman alpha and O VI 1032/1037 Å emissivities obtained with data from the Ultraviolet Coronagraph Spectrometer (UVCS) on SOHO. The local emissivities, from heliocentric heights of 1.5 to 3.0 solar radii, were determined from 3-D reconstructions of line-of-sight intensities obtained during the first Whole Sun Month Campaign (10 August to 8 September 1996). The models use electron densities derived from polarized brightness measurements made with the visible light coronagraphs on UVCS and LASCO, supplemented with data from Mark III at NCAR/MLSO. Electron temperature profiles are derived from 'freezing-in' temperatures obtained from an analysis of charge state data from SWICS/Ulysses. The work concentrates on neutral hydrogen outflow velocities which depend on modeling the absolute coronal H I Lyα emissivities. We use an iterative method to determine the neutral hydrogen outflow velocity with consistent values for the electron temperatures derived from a freezing-in model. 相似文献
88.
介绍了外设使用USB口进行雷达功率测试的优点,USB通信机制和外设开发过程,一种雷达功率测试模块的设计结构和性能指标,以及应用软件开发及其通信用的两个关键API函数。 相似文献
89.
根据无人机测试要求,详细介绍了由虚拟仪器技术组建的无人机测试系统。该测试设备以PXI总线型高性能计算机为控制核心,采用开关阵技术、程序模式配置测试流程,对无人机机载传感器、飞控计算机性能实施快速检测,具有通用性、智能化和自动化的特点,可实时精确地采集、处理、存储数据。该系统成功运用于某型无人机的检测。 相似文献
90.
We present a preliminary analysis of two quiet Sun transition region areas observed with the SOHO/SUMER spectrometer, using
lines from oxygen, nitrogen and silicon. The average quiet Sun physical parameters are studied as a function of line intensity.
Systematic variations of line position and width with increasing intensity are found. A large number of small-scale active
points have been observed, and preliminary analysis of the physical properties and dynamics of these active features is presented.
A jet-like structure, found in an active point, is also investigated and its velocity along the line of sight determined.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献