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STUDY ON PYROLYSIS OF POLYPHENYLSILSESQUIOXANE

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chinese Journal of Polymer Science 2002年第6期20卷 573-577页

作者： Jun Ma Liang-he Shi Jian-min Zhang Bai-yu Li De-yan Shen Jian Xu State Key Laboratory of Polymer Physics & Chemistry Center for Molecular Science, Institute of Chemistry,chinese academy of Sciences, {2. 100080 china Center for Molecular Science Institute of Chemistry Chinese Academy of Sciences State Key Laboratory of Polymer Physics & Chemistry 北京 100080

X-ray photoelectron spectroscopy and Raman spectroscopy were' used to determine the chemical change of polyphenylsilsesquioxane (PPSQ) during pyrolysis in flowing nitrogen. Two temperature ranges were found for pyrolysed PPSQ below and above 600degreesC, respectively. The former is related to the rearrangement of PPSQ backbone and the latter reflects that most of backbone structure of PPSQ might be broken down and unorganized. Carbon formed in carbonization of PPSQ sample pyrolysed at 900degreesC should be sp(3) bonded carbon with crystallite size effects or defects.

关键词： pyrolysis polyphenylsilsesquioxane

Characterization of nanoscale iron and its degradation of 2.4-dichlorophenol

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Science Bulletin 2010年第Z1期 350-357页

作者： HOU ChunFeng1,2. gE XiaoPeng1, ZHOU YanMei2. LI Yi3, WANg DongSheng1 & TANg HongXiao1 1 State Key Laboratory of Environmental Aquatic Chemistry, RCEES, chinese academy of Sciences, {2. 100085, china 2.school of Civil Engineering, {2. Jiaotong University, {2. 100044, china 3 Nanotechnology Center, Central Iron and Steel Research Institute, {2. 100081, china

Nanoscale iron was detected by TEM, X-ray diffraction and X-ray photoelectron spectroscopy. It was found that the size of the nanoscale iron particles is in the range of 30?40 nm according to TEM image, and it contains abundant Fe3O4 as passivating layers on the surface of the core-shell structure. To improve its performance, dilute HCl was used for the removal of the passivating layers, and the degradation of 2.4-dichlorophenol (2.4-DCP) was measured for the nanoscale iron samples treated and untreated. Experimental results demonstrated that the removal of 2.4-DCP by untreated nanoscale iron is mainly due to the adsorption of 2. 4-DCP by nanoscale iron, and there are no degradation products detected by HPLC in the process. However, excellent dechlorination of 2.4-DCP was gained by HCl-treated nanoscale iron, and 2.chlorophenol, 4-chlorophenol and phenol were detected during the process. It was concluded that dechlorination is the key reaction pathway for the degradation of 2.4-DCP by activated nanoscale iron, and phenol is found to be the main product.

关键词： nanoscale iron 2 4-dichlorophenol degradation dechlorination

Coexistence of broadband power line communication systems

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The Journal of china Universities of Posts and Telecommunications 2009年第4期16卷 125-128页

作者： YANg Biao ,L Ying-hua,ZHANg Hong-xin school of Electronic Engineering,beijing University of Posts and Telecommunications,beijing 100876,china school of Electronic Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

Recent progress in home networks enhances the application of broadband power line communication （BPL） since it does not require any installation of new communication lines or outlets. However, high-density distribution of BPL devices may bring down the access quality. Besides, the electromagnetic field radiating from the power line may cause interference with other radio systems. Thus, the objective of this study is to investigate the impact of cumulative interference in BPL systems, especially focused on indoor environment. A 2.D model describing the BPL transmission activity is proposed. Based on transmission characteristics of the main networks, it takes into account the coexistence effect of the BPL devices. The maximum acceptable density of BPL devices and the radiation field are finally determined.

关键词： BPL coexistence effect radiating electromagnetic field

Phase separation of ploy(ethylene glycol) + n-butanol mixture induced by supercritical CO_2

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chinese Chemical Letters 2007年第6期18卷 738-740页

作者： Min Qiang Hou, Shu guang Liang, Ji Yuan Song, Xiao Yong Li, Zhao Fu Zhang, Tao Jiang, Bu Xing Han beijing National Laboratory for Molecular Sciences, Institute of Chemistry, chinese {2. of Sciences, beijing 100080, china beijing National Laboratory for Molecular Sciences Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China

The phase behavior of supercritical (SC) CO2.+ PEg 1000 (PEg with average molecular weight of 1000 g/mol) + n-butanol system was studied. It was demonstrated that SC CO2.could induce phase separation of PEg 1000 + n-butanol system under suitable conditions. This hints that SC CO2.has potential applications in the separation of mixtures of PEg + organic compound.

关键词： PEg1000 CO2 n-Butanol Phase behavior Separation

MULTILEVEL CORRECTION FOR COLLOCATION SOLUTIONS OF VOLTERRA NONL INEARINTEgRO-DIFFERENTIAL EQUATIONS

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Systems Science and Mathematical Sciences 2000年第2期13卷 170-180页

作者： HU Qiya (Institute of Computational Mathematics and Scientific/Engineering Computing, chinese academy of Sciences, {2. 100080 Institute for Computing Mathematics and Applied Mathematics, Xiangtan University, Hunan 411105, china) PENg Long (school of 中科院计算数学与科学工程计算所北京 100080 北京外国语大学国际商学院北京 100081

In this paper we give a complete analysis of the convergence acceleration method for collocation solutions of Volterra nonlinear integro-differential equations with smooth kernels. It will be shown that when continuous piecewise polynomials of degree m are used and collocation is based on the Lobatto points, the first derivative of this collocation approximation admits, at the knots, an error expansion in even powers of the step-size h, beginning with a term in h2.. On the basis of this expansion we show that when a correction procedure is applied to this collocation approximation for k times, the global accurary of the corresponding corrected approximation will be increased to O(h2.(k+1)).

关键词： Nonlinear integro-differential equation collocation solution error expansion multilevel correction.

Simulation of g factor for size optimization and coupling in phased array coil design

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Progress in Natural Science:Materials International 2006年第2期16卷 120-124页

作者： SONg Xiaoyu, ZHANg Hongjie, WANg Le, BAO Shanglian, SUN Yanrong and ZU Donglin (beijing Key Laboratory of Medical Physics & Engineering, Peking University, beijing 100871, {2. Physics school, Peking University, beijing 100871, {2.) beijing Key Laboratory of Medical Physics and Engineering Peking University Beijing 100871 China Physics school Peking University Beijing 100871 China

The effect of geometric parameters of the coil element in an array on signal-to-notse ratio (SNR) and g factor of parallel imaging are analyzed, and the optimal parameters for the maximal SNR and minimal g factor are also given in this paper. In addition, the effects of coupling on SNR and g factor have been analyzed. The test results indicate that g factor for parallel imaging is greatly increased and SNR is decreased for coupling. According to the optimization, a six-channel parallel coil has been designed for torso imaging.

关键词： MRI phased array coil SENSE parallel imaging.

Phase Difference Function in Coherent Temporal-spatial Region and Unified Equations of Steady, Non-steady Interference

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Phase Difference Function in Coherent Temporal-spatial Regio...

Stereoselective synthesis of D-α-glucopyranosides,di-and tri-saccharides via 6-O-acetyl-glucopyranosyl bromides

中国光学学会2.04年学术大会

作者： Ji Luo1,2.(1 Institute of High Energy Physics, chinese academy of Sciences, {2., 100039 china) (2.Department of Physics, Dalian University, Dalian, 11662. china)

A phase difference function within the interference temporal-spatial region is obtained by a subtraction with two phase transfer functions, each of which transfers a corresponding phase between time d

关键词： phase transfer function coherent wave information information modulation phase difference function steady and non-steady interference equation beat frequency and interferometry.

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chinese Journal of Chemistry 1995年第5期13卷 454-459页

作者： FEI, Chang-Pei MA, YueInstitute of Chemistry, chinese academy of Science, {2. 100080, chinaCHAN, Tak-HangDepartment of Chemistry, Mcgill University, Montreal, PQ, Canada Institute of Chemistry Chinese Academy of Science Beijing 100080 China Department of Chemistry McGill University Montreal PQ Canada

Acetyl bromide cleaved 2.3,4-tri-O-benzyl-l,6-anhydro-B-D-glucopyranose (la) or 2.3,4-tri-O-benzyl-1,6-anhydro-B-Z)-galactopyranose (1a') to give the corresponding a-D-pyranosyl bromides (2.. Reaction of 2.with ROH/diisopropylethylamine gave the corresponding a-glucopyra-nosides, di- and tri-saccharides with good yield. It was available to use 13C NMR to monitor the glycosidation reaction.

关键词： Stereoselection,α-D-pyranosyl bromide glycosidation 13C NMR

TWO REMARKS ON SCHWARZ FORMULA

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Acta Mathematica Scientia 2005年第1期25卷 1-6页

作者：丁夏畦罗佩珠 Institute of Applied Mathematics academy of Mathematics and System Sciences The chinese academy of Sciences Beijing 100080 China

This paper discusses two problems. Firstly the authors give the Schwarz formula for a holomorphic function in unit disc when the boundary value of its real part is in the class H of generalized functions in the sense of Hua. Secondly the authors use the classical Schwarz formula to give a new proof of the zero free region of the Riemann zeta-function.

关键词： Schwarz formula zero free region Riemann zeta-function