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91.
92.
Transport of a Brownian particle moving in a periodic potential is investigated in the presence of an asymmetric unbiased external force. The asymmetry of the external force and the asymmetry of the potential are the two ways of inducing a net current. It is found that the competition of the spatial asymmetry of potential with the temporal asymmetry of the external force leads to the phenomena like current reversal. The competition between the two opposite driving factors is a necessary but not a sufficient condition for current reversals. 相似文献
93.
WEN De-Hua CHEN Wei LIU Liang-Gang 《理论物理通讯》2007,47(4):653-657
Properties and deformations of the rotating neutron stars in uniform strong magnetic field are calculated. The magnetic field will soften the equation of state of the neutron star matters and make an obvious effect on the structure of the rotating neutron star. If the magnetic field is superstrong (B=10^17 T), the mass, radius, and the deformation will become smaller effectively. 相似文献
94.
设计合成了2-[(2'-芴基)-乙烯基]-8-羟基喹啉(6)、2-[(2'-菲基)-乙烯基]-8-羟基喹啉(7)及其金属锌配合物8和9; 用UV-Vis, FT-IR, ESI-MS, 1H NMR和元素分析确认了化合物6和7的结构; 并用四甲基偶氮唑盐微量酶反应比色法(MTT法)研究了其调控骨髓间质干细胞增殖的作用, 结果表明, 化合物6和7对干细胞有明显的增殖作用. 用FT-IR, FAB-MS和元素分析表征了金属锌配合物结构, 光致发光光谱测试结果表明, 化合物8的发光峰值为602 nm, 发黄光; 化合物9的发光峰值为628 nm, 发橙红色光. 相似文献
95.
For any finite-dimensional semisimple Lie algebra g, a
Z+-graded vertex algebra is construsted on the vacuum
representation Vk(\hat{g}[ θ]) of \hat{g}[θ], which is
a one-dimentional central extension of θ-invariant subspace on the loop algebra
Lg=g\otimes C((t1/p)). 相似文献
96.
On the basis of the interaction between phonons in ionic crystals with anharmonic lattice vibration, we present a laser model on acoustic nondegenerate four-wave mixing. Two beams of highfrequency ultrasound, incident on the acoustic cavity fulfilled with the medium of ionic crystal, play the role of pumping and one of the two side-band modes of the pumping frequency as an acoustic signal mode has a strong interaction with the optical cavity mode, the coupling-out of which wiIl be the light (far-infrared) output of a laser. The problem is treated with quantum-mechanics. The theory shows that there is the threshold phenomenon as usual lasers and a so called "phase-matching" condition is derived, which should be satisfied for stability of the system. 相似文献
97.
In a recent paper [Weng, Z.K., 2004. Coordinating order quantities between the manufacturer and the buyer: A generalized newsvendor model. European Journal of Operational Research 156, 148–161], a newsvendor-type coordination model was developed for a single-manufacturer single-buyer channel with two ordering opportunities. This paper further extends the model to the case where the excess demand after the first order is partially backlogged and both parties share the manufacturing setup cost of the second order (if happened). We show that the decentralized system would perform best if the manufacturer covers utterly the second production setup cost, which is opposite to that obtained in Weng (2004). Another extension in the present paper is that in the centralized system, the second order decision is made by the buyer based on the channel’s benefit rather than based on the buyer’s benefit as in Weng (2004). It is proved that the expected profit of the system in our paper is always larger than that in Weng (2004). In order to maximize the expected profit of the channel, two coordinated policies are proposed to achieve perfect coordination: a two-part-tariff policy for the special case that the buyer pays all the manufacturing setup cost, and a revised revenue-sharing contract for the case that two parties share the manufacturing setup cost. 相似文献
98.
99.
New approach to the synthesis of star-shaped polymers based on calix[8]arene with amphiphilic arms of nonionogenic nature
is described. The ionophore properties of the resulting polymer with respect to ions of alkali metals, europium, and uranium
were studied by an example of a polymer containing residues of ω-cetyloligoethylene oxide as arms. 相似文献
100.
F. Xiao Y.N. Xue Q.Y. Zhang 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,74(2):498-501
Y4MgSi3O13:Bi3+, Eu3+ nanophosphors have been prepared by a facile sol–gel method. The products have been characterized by X-ray diffraction, field-emission scanning electron microscopy and fluorescence measurements. The results show that the nanophosphors are of single phase hexagonal Y4MgSi3O13 with size-distribution of 50–90 nm in diameter. White-light emission has been obtained from Bi3+ and Eu3+ co-doped Y4MgSi3O13 nanophosphors upon excitation of 350 nm ultraviolet light. It is noted that Bi3+ ions can occupy two different Y3+ sites and generate different emissions from the 3p1 → 1s0 transition. Warm white light has been obtained from Y4MgSi3O13:Bi3+, Eu3+ nanophosphors according to Commission International de I’Eclairage (CIE) chromaticity coordinates and color temperature (Tc) with appropriately adjusted contents of Bi3+ and Eu3+. The results indicate that Y4MgSi3O13:0.08Bi3+, 0.04Eu3+ (x = 0.31, y = 0.31, Tc = 6907 K) are potential nanophosphors for white light-emitting diodes (LEDs) applications. 相似文献