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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A. Bianconi Y. Busby M. Fratini V. Palmisano L. Simonelli M. Filippi S. Sanna F. Congiu A. Saccone M. Giovannini S. De Negri 《Journal of Superconductivity and Novel Magnetism》2007,20(7-8):495-501
Here we report synthesis and characterization of high quality samples of the superconducting system Mg1−x
Al
x
B2, with a novel optimized preparation method, in a wide range of Al concentration. All the physical properties of the samples
can be tuned continuously with increasing Al content. We have characterized the samples for their structural, morphological
and magnetic properties with high resolution XRD, SEM-EDS and susceptibility measurements. We have prepared a large number
of Al doped MgB2 in the range 0<x<0.57. All the samples are bulk superconductors and the critical temperature show a smooth and regular behavior as a function
of x.
This work was supported by European project 517039 “Controlling Mesoscopic Phase Separation” (COMEPHS) (2005).
An erratum to this article can be found at 相似文献
992.
993.
郑忠祥 《有色冶金设计与研究》2003,(Z1)
通过大量调查资料 ,分析有色金属行业信息化建设的现状、存在的差距和问题 ,探讨了有色信息化建设面临的形势和要求、方向和任务。 相似文献
994.
S. V. Prikhodko Y. Ma A. J. Ardell D. G. Isaak J. D. Carnes S. Moser 《Metallurgical and Materials Transactions A》2003,34(9):1863-1868
The adiabatic elastic stiffness constants C
ij of Ni-Si single-crystal solid-solution alloys of two slightly different compositions, 10.78 and 11.17 at. pct Si, were measured
over the temperature range from 20 °C to 900 °C using the rectangular parallelepiped resonance method. The isotropic elastic
constants of the polycrystalline ordered intermetallic compound Ni3Si containing 23 at. pct Si were also measured over this temperature range. Values of the C
ij for Ni3Si were estimated from the data on the polycrystalline alloy, as well as from published data in the literature on isomorphous
ternary ordered intermetallic compounds containing different amounts of Si. Using measured values and previously published
data, the stiffness constants of Ni3Ti were estimated; these are the only available data on this alloy. The estimated single-crystal elastic constants of Ni3Si, as well as the experimentally measured bulk modulus, are considerably smaller than published values calculated from first-principles
methods. The same is true for the C
ij of Ni3Ti, but the discrepancies are smaller. 相似文献
995.
Cold-rolling texture and partially recrystallized texture of polycrystalline 3 pct Si-Fe were investigated using high-resolution
electron backscattered diffraction (EBSD) method. From the measurement on a deformed grain with {211}〈011〉∼{111}〈011〉 orientations,
deformation bands with {12 4 1}〈014〉 orientation were found. It turned out that the orientation rotation relationship between
deformation bands and surrounding deformed grain can be explained by the activation of the slip system, which has a common
slip plane with an adjacent grain. Oriented nucleation of recrystallized grains with {12 4 1}〈014〉 orientation was observed
in a deformed grain with {211}〈011〉∼{111}〈011〉 orientation. Exactly the same orientation relationship that was observed between
deformed grain and the deformation bands was also observed between the deformed grain and the recrystallized grain. A hypothesis
that recrystallization nuclei are generated directly from the deformation bands formed by an activation of the slip system
that has a common slip plane of neighboring deformed grains was proposed from the present experimental results. 相似文献
996.
Novel floating-patch micro-electro-mechanical system (MEMS) antennas are proposed for millimetre-wave applications. The floating-patch MEMS antennas are fabricated on a high resistivity silicon (HRS) substrate using surface micromachining technology. Simulation and experimental results for reflection coefficients and radiation patterns are presented. 相似文献
997.
X. X. Xi X. H. Zeng A. V. Pogrebnyakov A. Soukiassian S. Y. Xu Y. F. Hu E. Wertz Q. Li Y. Zhong C. O. Brubaker Z.-K. Liu E. M. Lysczek J. M. Redwing J. Lettieri D. G. Schlom W. Tian H. P. Sun X. Q. Pan 《Journal of Superconductivity and Novel Magnetism》2003,16(5):801-806
The recently discovered superconductor MgB2 with T c at 39 K has great potential in superconducting electronics. In this paper, we review the deposition techniques used for MgB2 thin films in the light of a thermodynamic study of the Mg-B system with the calculation of phase diagrams (CALPHAD) modeling technique. This thermodynamic study identifies a growth window in the pressure–temperature phase diagram, in which the magnesium pressure is very high for likely in situ growth temperatures. A Hybrid Physical–Chemical Vapor Deposition (HPCVD) technique that successfully achieves such a high Mg pressure is shown to produce in situ epitaxial MgB2 thin films with bulk superconducting properties. 相似文献
998.
深部调剖驱油交联剂的研究 总被引:3,自引:0,他引:3
为提高非均质性严重的地层原油采出率 ,合成了用于聚合物驱油的 4种交联剂 ,并对聚合物种类、用量和其与交联剂组成的体系进行了评价。 4 0℃下铝交联剂凝胶粘度低 ,酚醛树脂交联剂低温下不成胶 ,而有机铬交联剂 (J2 )和有机复合胺 (J3)交联效果好。当选用HPAM/有机铬交联剂 /有机酸交联体系时 ,其中HPAM相对分子质量为 2 1× 10 7,可通过改变体系pH值调节成胶速度 ,pH值 6 5时 ,14 0 0mg/LHPAM和 4 0 0mg/LJ2组成的体系在 4 0℃、30d可形成粘度为12 0mPa·s以上的凝胶 ,且热稳定性好 ,成胶时间能满足现场施工需要。 14 0 0mg/LHPAM和10 0 0mg/LJ3交联剂组成的体系 ,成胶时间长 ,有利于油田深部调剖驱油 相似文献
999.
1000.
This paper presents experimental and analytical results of four scaled prestressed concrete box-girder bridges with corrugated steel webs. The location of prestressing strands at both ends of the specimens and the thickness of end diaphragms are the two major parameters. Based on the experimental results of all four specimens, their seismic behavior is critically examined, including hysteretic loops, ductility factor, dissipated energy, and failure mode, etc. It was found that both the thickness of end diaphragms and the location of prestressing strands at both ends of the specimens are insignificant when the specimens failed at the mid-span due to concrete crushing, and the proposed analytical model can be used to predict the load-displacement relationship of such bridges. 相似文献