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101.
对泡沫状多孔聚碳硅烷(PCS)的合成反应条件进行了较为详细的研究,通过控制化学反应的温度、压力和反应时间制备出了熔点高达380℃、相对分子质量Mn>3 000、陶瓷产率达79%(质量分数),密度<0.6 g/cm3的多孔聚合物。对不同反应条件下所制得的多孔PCS的性能进行了表征,并利用IR、TG等手段对泡沫状多孔PCS的热解机理进行了初步探讨。  相似文献   
102.
冲压发动机超薄壁波纹形件的粘性介质压力成形   总被引:1,自引:1,他引:1       下载免费PDF全文
粘性介质压力成形是一种采用具有高粘度并且可流动的半固态介质作为软凸模的成形方法。采用试验和数值模拟方法,研究了高温合金超薄壁波纹形件成形过程坯料形状、应变分布、厚度分布的变化和界面摩擦对板料成形的影响,研究结果表明:成形件尺寸精度高、表面质量好、厚度均匀;与钢凸模成形相比较,可以避免局部较小半径曲面之间的严重颈缩;对于具有局部较小半径曲面的复杂形状薄壁件,粘性介质压力成形显示出其优越性。  相似文献   
103.
The interstellar heliopause probe (IHP) is one of ESA’s technology reference studies (TRS). The TRS aim to focus the development of strategically important technologies of relevance to future science missions by studying technologically demanding and scientifically interesting missions that are currently not part of the science mission programme.

Equipped with a highly integrated payload suite (HIPS), the IHP will perform in situ exploration of the heliopause and the heliospheric interface. The HIPS, which is a standard element in all TRSs, miniaturize payloads through resource reduction by using miniaturized components and sensors, and by sharing common structures and payload functionality.

To achieve the scientific requirements of the mission, the spacecraft is to leave the heliosphere as close to the heliosphere nose as possible and reach a distance of 200 AU from the Sun within 25 years. This is possible by using a trajectory with two solar flybys and a solar sail with characteristic acceleration of 1.1 mm/s2, which corresponds to a 245 × 245 m2 solar sail and a sail thickness of 1–2 μm. The trajectory facilitates a modest sail design that could potentially be developed in a reasonable timeframe.

In this paper, an update to the results of studies being performed on this mission will be given and the current mission baseline and spacecraft design will be described. Furthermore, alternative solar sail systems and enabling technologies will be discussed.  相似文献   

104.
首先给出了中介逻辑ML的二值子系统F^IML,说明了它与经典二值逻辑的子系统F^I同构。其次,利用中介公理集合论MS的相关理论,构造了MS中的自然数系统,证明了Peano5条公理为MS中的定理。最后指出以此五条性质为公理、并以F^IM为配套逻辑,在MS中可推出自然数的所有性质。  相似文献   
105.
In this paper we review the current predictions of numerical simulations for the origin and observability of the warm hot intergalactic medium (WHIM), the diffuse gas that contains up to 50 per cent of the baryons at z∼0. During structure formation, gravitational accretion shocks emerging from collapsing regions gradually heat the intergalactic medium (IGM) to temperatures in the range T∼105–107 K. The WHIM is predicted to radiate most of its energy in the ultraviolet (UV) and X-ray bands and to contribute a significant fraction of the soft X-ray background emission. While O vi and C iv absorption systems arising in the cooler fraction of the WHIM with T∼105–105.5 K are seen in FUSE and Hubble Space Telescope observations, models agree that current X-ray telescopes such as Chandra and XMM-Newton do not have enough sensitivity to detect the hotter WHIM. However, future missions such as Constellation-X and XEUS might be able to detect both emission lines and absorption systems from highly ionised atoms such as O vii, O viii and Fe xvii.  相似文献   
106.
We discuss the different physical processes that are important to understand the thermal X-ray emission and absorption spectra of the diffuse gas in clusters of galaxies and the warm-hot intergalactic medium. The ionisation balance, line and continuum emission and absorption properties are reviewed and several practical examples are given that illustrate the most important diagnostic features in the X-ray spectra.  相似文献   
107.
倾斜分层非均匀介质中磁偶极子场的数值分析   总被引:5,自引:0,他引:5  
研究倾斜分层非均匀介质条件下磁偶极子源在介质空间的电磁响应,给出了场表达式和数值递推算法,提出了在大倾角条件下利用电阻率曲线划分界面和进行前向预测的方法,数值模拟和应用实践证明该方法是有效的,结论具有一定的应用价值.   相似文献   
108.
Complex organic molecules are widely observed in star-forming regions, although their formation mechanisms are not well understood. Solid-state chemistry is thought to play an important role, but the solid-state reaction network is poorly known. We provide a list of purely thermal reactions involving electronically stable reactants to complement existing grain chemistry networks. The kinetic parameters of the reactions are given when available. These reactions lead to the formation of complex organic molecules, which were not considered previously. Eventually, these complex molecules are either released into the gas phase or incorporated into the organic residue found in meteorites. Thermal reactions are important because they are not limited by the UV flux or the slow diffusion of the radicals, and because they involve both surface and mantle molecules. Thermal reactions represent an important step in the formation of complex organic molecules that constitute the primitive material of comets and asteroids.  相似文献   
109.
We present the results of analysis XMM-Newton data of galaxy cluster CL0016+16, which enables us to trace X-ray emission and temperature profile up to the virial radius. We obtained similar results using three different backgrounds. We checked the possibility of detection of cluster emission up to the virial radius with XMM-Newton data with hydrodynamical cosmology simulation from the Adaptive Mesh Refinement technique, code RAMSES by Teyssier [Teyssier, R. Cosmological hydrodynamics with adaptive mesh refinement. A new high resolution code called RAMSES. A&A 385, 337, 2002], convolution with XMM-Newton and the data base of the spectra by Sauvageot et al. [Sauvageot, J.-L., Belsole, E., Pratt, G.W. The late merging phase of a galaxy cluster: XMM EPIC observations of A 3266. A&A, 444, 673, 2005]. For the first time we were able to compute the mass of CL0016 up to R200, we found, assuming hydrostatic equilibrium framework, M200 = (1.15 ± 0.11) × 1015M.  相似文献   
110.
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