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991.
We investigate the dynamics of a system coupled to an environment byaveraged semiquantum method. The theory origins from the time-dependentvariational principle (TDVP) formulation and contains nondiagonal matrixelements. So it can be applied to study dissipation, measurement, anddecoherence problems in the model (H = hS + hE + hI). In the calculation, the influence of the environment govern by differential dynamical equation is incorporated through a mean field. We have performed averaged semiquantum method for a spin-boson model, which reproduce theresults from stochastic Schrodinger equation method and Hierarchicalapproach quite accurately. The problems, dynamics in nonequilibriumenvironments, have also been studied by our method. 相似文献
992.
Summary: A novel cyclic carbonate monomer 5‐methyl‐5‐(succinimide‐N‐oxycarbonyl)‐1,3‐dioxan‐2‐one (MSTC) was prepared. The copolymers of MSTC with caprolactone (CL) were further synthesized by ring‐opening copolymerization. The copolymers with amido‐amine pendent groups were obtained by aminolysis of poly(MSTC‐co‐CL) with ethylenediamine. These copolymers were characterized by IR, 1H NMR, 13C NMR spectroscopies and GPC. The hydrophilicity and degradability of the copolymers with amido‐amine pendent groups were greatly improved in comparison with the PCL homopolymer.
993.
994.
Absolute band gaps can be created by lifting the degeneracy in the bands of a photonic crystal.To calculate the band structure of a complicated photoinc crystal generated by e.g.symmetry breaking ,general forms of all possible linear operations are presented in terms of matrices and procedure to combine these operations in given.Other forms of linear operations (Such as the addition,subtraction,and translation transforms)are also presented to obtain an explicit expression for the Fourier coefficient of the dielectric function in the plane-wave expansion method.With the present method,band structures for various complicated photoinc crystals(related through these linear operations)can be obtained easily and quickly.As a numerical example,a large absolute and gap for a complicated photonic crystal structure of GaAs is found in the high reglon of normalized frequency. 相似文献
995.
Through measuring high-fold prompt γ- ray coincidence events following the spontaneous fission of 252 Cf with the Gammasphere detector array, new level scheme in the very neutron-rich odd-A 113Ru nucleus has been established. An intruder collective band based on 11/2- level has been identified with spin up to 31/2 k and excitation energy 3.6 MeV. This band most probably originates from vh11/2. intruder orbital. Another collective band probably built on 9/2- level is also observed. Some important characteristics of the collective bands have been systematically discussed. 相似文献
996.
997.
HIPS-g-GMA相容剂对PC/HIPS共混物相容性的影响* 总被引:3,自引:0,他引:3
将两种或两种以上聚合物进行共混是获得性能优异合金材料的简单而有效的途径[1,2 ] .但是大多数聚合物共混时 ,由于混合焓ΔH >0且混合熵ΔS非常小 ,导致混合自由能大于零 ,故大多数共混体系是不相容的 .而对于不相容的共混 ,由于两相间的界面张力大 ,两相间形成锐形界面 ,两相之间的界面粘结力低 ,导致材料性能很差 .为了改善两相间的相容性 ,需要加入相容剂[3 ,4 ] .绝大多数增容剂是嵌段或接枝共聚物 .这类增容剂分子量较大 ,在加工条件下 ,由于其粘度较大往往难于迁移到两相的界面处 ,起不到应有的增容作用 .聚合物反应加工技术是近 2… 相似文献
998.
999.
1000.
Wan Sheng CHEN* Wei Dong ZHANG Gen Jing YANG Hai Sheng CHEN Chuan Zhuo QIAO Department of Pharmacognosy School of Pharmacy Second Military Medical University Shanghai 《中国化学快报》2001,(6)
The root tuber of Polygonum multiflorum Thunb. ( Polygonaceae ) (PM ) is a famous Chinese traditional medicine, which has been used to remedy for treatment many diseases such as cardiovascular and aging diseases for long times. When it is used as a tonic drug, PM must be prepared in order to eliminate its side effects, and the preparation is known as Radix Polygoni multiflori Preparata ( PMP )1. Here we report the isolation of 2,3,5,4'-tetrahydroxystilbene-2-O-(2'-O-feruloyl)-(-D-gluco … 相似文献