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Resolution of α-cyclohexyl-mandelic acid enantiomers by two-phase (O/W) recognition chiral extraction

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science china Chemistry 2007年第6期50卷 764-769页

作者： TANG KeWen1,2, ZHANG GuoLi2, HUANG KeLong2, LI Yuanjian3 & YI JianMin1,2 1 Department of Chemistry and Chemical Engineering, Hunan Institute of science and technology, Yueyang 414000, china 2 college of Chemistry and Chemical Engineering, Central South university, changsha 410083, china 3 college of Pharmaceutical science, Central South university, changsha 410078, china Department of Chemistry and Chemical Engineering Hunan Institute of Science and Technology Yueyang China college of Chemistry and Chemical Engineering Central South University Changsha China college of Pharmaceutical science Central South University Changsha China

This paper presents a new chiral separation technology:two-phase(O/W)recognition chiral *** behavior of alpha-cyclohexyl-mandelic acid enantiomers was studied in the extraction system with D(L)-isobutyl tartrate in 1,2-dichloroethane organic phase and beta-CD derivatives in aqueous phase,and the influence of the kind and concentration of extractant and pH on extraction performance was *** experimental results indicate that two-phase(O/W)recognition chiral extraction is of strong chiral separation ***-^-CD,HE-beta-CD and Me-beta-CD have higher recognition ability for S-CHMA than that for R-CHMA,among which HP-beta-CD has the strongest ability;whereas,D-isobutyl tartrate has reversed recognition ability for *** the extraction system containing HP-beta-CD and D-isobutyl tartrate,e.e.% of S-CHMA in aqueous phase reached 27.6% by one stage extraction,and the distribution ratio for R-CHMA(k_R)and for S-CHMA(k_S)and separation factor(alpha)are 2.44,0.89 and 2.49,***,pH and concentration of extractant have great effects on chiral separation ***-phase(O/W)recognition chiral extraction has great significance for preparative separation of racemic compounds.

关键词： two-phase(W/0)recognition chiral extraction alpha-cyclohexyl-mandelic acid enantiomers

Fractal Structure of the Core Loss Spectrum of Co-based Amorphous Soft Magnetic Alloy with Constant Permeability

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International Journal of Minerals,Metallurgy and Materials 1999年第1期13卷 54-56页

作者： Yiping Chen (Applied science School, university of science and technology Beijing, Beijing 100083, china) Applied science School University of Science and Technology Beijing Beijing 100083 China

In order to check the traditional core loss formula, the core loss spectrum P(f) of Co-based amorphous soft magnetic alloy with constant permeability has been studied. It is found that within a high frequency range from 10 kHz to 200 kHz and at Bm = 0. 1 T,the P(f) has the fractal structure P (f) = Po, and with the increasing of induced anisotropy energy Ku, the fractal dimension Dfrises, thus the total power loss at high frequency increases and the frequency characteristic of P(f) becomes worse.

关键词： amorphous soft magnetic alloy constant permeability core loss fractal

A Discrete Spectral Problem and Related Hierarchy of Discrete Hamiltonian Lattice Equations

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Communications in Theoretical Physics 2007年第8期48卷 193-198页

作者： XU Xi-Xiang college of science,Shandong Uniersity of science and technology,Qingdao 266510,chinaCAO Wei-Li college of science,Uniersity of Shanghai for science and technology,Shanghai 200093,china college of science Shandong University of Science and Technology college of science University of Shanghai for Science and Technology

Staring from a discrete matrix spectral problem,a hierarchy of lattice soliton equations is presentedthough discrete zero curvature *** resulting lattice soliton equations possess non-local Lax *** structures are esta... 详细信息

关键词： lattice soliton equation zero curvature representation Hamiltonian structure Liouville integrability

Distribution of Nb atom in the TiAl+Nb system

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Rare Metals 2001年第1期20卷 5-12页

作者： Xiaodong Ni, Xidong Hui, Guoliang Chen (Applied science School, university of science and technology Beijing, Beijing 100083, china State Key Laboratory for Advanced Metals and Materials, university of science and technology Beijing, china) Appl. Sci. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

Based on MEAM (the modified embedded atom method) potential and an average atom model similar to B-W (Bragg-Williams) method, the distribution of Nb atoms in TiAl+Nb compounds with various composition was calculated. The calculation results showed that Nb atoms prefer to occupy the Ti sublattice of L10 structure for all compounds in question. With increasing atomic fraction of Nb and Al, Nb atoms exhibited a trend of ordered distribution on the Ti sublattice and result in a new L10 derivative superlattice structure.

关键词： Computer simulation Intermetallics Superlattices Ternary systems

Carbon Solubility and Mass Action Concentrations of Fe-Cr-C Melts

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International Journal of Minerals,Metallurgy and Materials 2000年第2期14卷 86-91页

作者： Jtan Zhang(Metallurgy School, university of science and technology Beijing, Beijing 100083, china) Metallurgy School University of Science and Technology Beijing Beijing 100083 China

An empirical equation of carbon solubility in Fe-Cr-C melts is regressed based on the experimental data from references. Acalculating model of mass action concentrations for these melts is formulated on the basis of the coexistence theory of metaIlic melts in-volving compound formation, the phase diagram of Cr-C system as well as thermodynamic data of Fe-Cr-C melts. According to the mod-el, the standard Gibbs free energies of formation of CrC and Cr3C2 are obtained. Satisfactory agreement between the calculated and me-asured values shows that the model can reflect the structural characteristics of Fe-Cr-C melts.

关键词： activity, coexistence theory mass action concentration saturated state

Applicability of mass action law to sulphur distribution between slag melts and liquid iron

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Journal of university of science and technology Beijing 2002年第2期9卷 90-98页

作者： Jian Zhang Metallurgy School, university of science and technology Beijing, Beijing 100083, china Metall. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

According to the mass action law and the coexistence theory of slagstructure, the calculating models of mass action concentration for CaO-MgO-FeO-Fe_2O_3-SiO_2,CaO-MgO-MnO-FeO-Fe_2O_3-P_2O_5-SiO_2 and CaO-MgO-MnO-FeO-Fe_2O_3-Al_2O_3-P_2O_5-SiO_2 slag melts areformulated and sulphur distribution between the slag melts and liquid iron is treated. It is foundthat CaO, MnO and FeO promote desulphurization, while MgO is detrimental to desulphurization. Inaddition, the sulphur distribution coefficients between the slag melts and liquid iron andpresented.

关键词： mass action law coexistence theory of slag structure activity massaction concentration

Some new results about Jacobi forms

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Chinese science Bulletin 1997年第3期42卷 181-183页

作者： WANG JupingDepartment of Mathematics, university of science and technology of china, Hefei 230026, china Department of Mathematics University of Science and Technology of China Hefei China

THE one-dimensional Jacobi forms were first systematically investigated by Eichler and Zagier, and a similar theory in a higher-dimensional case was developed by Ziegler, who gave the precise definition and some basic properties of higher-dimensional Jacobi forms. This note tries to give a satisfactory classification for a large kind of spaces of Jacobi forms. To be a little more explicit, we get a rank formula for Jacobi forms and then show that either all the

关键词： Jacobi forms rank coefficient estimation.

Sidelobe reduction based on spectrum reshaping in microwave imaging

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science china(Information sciences) 2011年第1期54卷 204-212页

作者： WANG HuaiJun,SU Yi,XU HongBo & ZHU YuTao School of Electronic science and Engineering,National university of Defense technology, changsha 410073,china School of Electronic science and Engineering National University of Defense Technology

Sidelobe artifacts are a common problem in image reconstruction from finite-extent Fourier data obtained by microwave imaging *** order to enhance the image quality,sidelobe reduction must be *** the sidelobe reduction in microwave imaging as the research subject,this paper presents Fourier imaging technique *** the point spread function is obtained through Fourier inversion of rectangular spectral support data and the changing effect of sidelobe direction due to reshaping spectral support is *** reshaping makes that the sidelobes of two Fourier images do not *** on the idea of separating sidelobes from mainlobe,a nolve method that reduces sidelobe levels while maintaining the imaging resolution is *** performance of this method is ***,the simulated and measured data of typical microwave imaging systems such as synthetic aperture radar(SAR),inverse synthetic aperture radar(ISAR)and real aperture radar are used to demonstrate the validity of the proposed method.

关键词： microwave imaging Fourier imaging sidelobe reduction spatial spectrum point spread function

EXAMINATION OF CARBON DIFFUSION IN NIOBIUM CLAD STEEL COMPOSITE

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Journal of Central South university 1999年第1期11卷 2-4页

作者： Xia Changqing Jin Zhanpeng (Department of Materials science and Engineering, Central South university of technology, changsha 410083, china) Department of Materials science and Engineering Central South University of Technology Changsha 410083 China

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Ｔｈｅｎｉｏｂｉｕｍｃｌａｄｓｔｅｅｌｃｏｍｐｏｓｉｔｅｉｓａｃｌａｄｓｔｅｅｌｐｌａｔｅ，ｉｎｗｈｉｃｈｔｈｅｂａｓｅｍｅｔａｌｉｓｓｔｅｅｌｗｉｔｈ０．２０％ｃａｒｂｏｎａｎｄｔｈｅｃｌａｄｄｉｎｇｍｅｔａｌｉｓｎｉｏｂｉｕｍｗｉｔｈｅｘｃｅｌ...

关键词： Nb 2C phase carbon activity stationary diffusion