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921.
922.
考虑随机系数自回归模型Yt =Φtyt-1+ ut,其中 Φt为随机系数,ut为随机误差。在允许Φt与ut相依以及Eut无穷的条件下,构造了误差方差的自加权估计,并证明了该估计的渐近正态性。最后通过数值模拟,说明
自加权估计的稳健和有效性。 相似文献
923.
Thin films of ZnAl2O4:Mn were grown on aluminosilicate ceramic plates using spray pyrolysis of aqueous solutions. The cathodoluminescence (CL) properties of the films under low to medium excitation voltage (<5 kV) were investigated. The films exhibited green CL after being annealed at temperatures above 550 °C, which corresponds to the transition between 4T1 and 6A1 of Mn2+ ions located in the tetra coordination of the Zn2+ site in the spinel structure. The chromaticity coordinates were x=0.150 and y=0.734 with a dominant wavelength of 525 nm and an 82% color purity. The CL luminance and efficiency depended on the excitation voltage and current density. Saturation effects were observed as the current density increased. A luminance of 540 cd/m2 and an efficiency of 4.5 lm/W were obtained at an excitation voltage of 4 kV with a current density of 38 A/cm2. PACS 78.60.Hk 相似文献
924.
Hao?CaiEmail author Feng-Ming?Liu Nian-Ning?Huang 《International Journal of Theoretical Physics》2005,44(2):255-265
The inverse scattering transform for the nonlinear Schrödinger equation in normal dispersion with non-vanishing boundary values is re-examined using an affine parameter to avoid double-valued functions. An operable algebraic procedure is developed to evaluate dark multi-soliton solutions. The dark two-soliton solution is given explicitly as an example, and is verified by direct substitution. The additional motion of the soliton center is given by its asymptotic behavior. 相似文献
925.
926.
927.
928.
Kuriyama M Soeta T Hao X Chen Q Tomioka K 《Journal of the American Chemical Society》2004,126(26):8128-8129
A catalytic asymmetric arylation of sterically tuned imines with arylboroxines was developed by using N-Boc-l-valine-connected amidomonophosphane rhodium(I) catalyst in n-PrOH. The TMS group used for the steric tuning of imines is convertible to other functionalities that are applicable as a key foothold for the carbon-carbon bond-forming coupling reactions. 相似文献
929.
Taking into account the effects of quantum interference and interface scattering, combining the electron current with hole
current contribution to tunnel current, we study the coherent quantum transport in normal-metal/d-wave superconductor/ normal-metal (NM/d-wave SC/NM) double tunnel junctions by using extended Blonder-Tinkham-Klapwijk (BTK) approach. It is shown that all quasiparticle
transport coefficients and conductance spectrum exhibit oscillating behavior with the energy, in which periodic vanishing
of Andreev reflection (AR) above superconducting gap is found. In tunnel limit for the interface scattering strength taken
very large, there are a series of bound states of quasiparticles formed in SC. 相似文献
930.
Hao B Zhao G Kang PT Soares JA Ferguson TK Gallucci J Krzycki JA Chan MK 《Chemistry & biology》2004,11(9):1317-1324
L-pyrrolysine, the 22(nd) genetically encoded amino acid, was previously deduced to be (4R, 5R)-4-substituted-pyrroline-5-carboxylate attached to the epsilon-nitrogen of lysine based on the crystal structure of the M. barkeri monomethylamine methyltransferase (MtmB). To confirm L-pyrrolysine's identity, structures of MtmB have been determined following treatment with hydroxylamine, N-methylhydroxylamine, or dithionite. Analysis of these structures has provided additional support for the presence of the pyrroline ring and, together with previous mass spectroscopy data, has led us to assign the C(4)-substituent to a methyl group. Based on this assignment, synthetic L-pyrrolysine was prepared by chemical methods. Detailed study of this chemically synthesized L-pyrrolysine has allowed us to characterize its physical properties, to study its chemical stability, and to elucidate the role of its C(4) substituent. Future applications of this synthetic L-pyrrolysine include its in vivo incorporation into recombinant proteins. 相似文献