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On the Mechanism of Condensation between 5-Amino-4, 6-dichloro- 2-methylpyrimidine and 1-Acetyl-2-imidazolin-2-one

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Chinese Chemical Letters 2002年第3期13卷 207-210页

作者： Bin SU Hui LI meng shen cai Zhong Jun LI Department of Chemical Biology School of Pharmaceutical sciencePeking UniversityBeijing 100083

The condensation reaction between 5-amino-4, 6-dichloro-2-methylpyrimidine and 1-acetyl-2-imidazolin-2-one using POCl3 as solvent gave 4, 6-dichloro-2-methyl-5-(1-acetyl-tetra- hydro-imidazo-2-ylidene)-aminopyrimidine predominantly and 4, 6-dichloro-2-methyl-5-{1-[1-(2- oxo-tetrahydro-imidazolyl)]-acetyene}-aminopyrimidine as by-product. No 4, 6-dichloro-2- methyl-5-(1-acetyl-2-imidazolin-2-yl)-aminopyrimidine was found. The result indicated an esterifi- cation-addition-elimination mechanism.

关键词： Moxonidine X-ray single crystal diffraction GHMBC.

STUDIES ON CARBOHYDRATES *** STEREOSELECTIVE SYNTHESIS OF 1-O-α-ACYL-D-MANNOPYRANOSE FROM THE CORRESPONDING MANNOSYL TRIMETHYLSILYL ETHER

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Chinese Chemical Letters 1995年第4期6卷 275-278页

作者： He Qing HUANG Zhong Jun LI meng shen cai School of Pharmaceutical Sciences Beijing Medical UniversityBeijing 100083

In the presence of ***2, 1-O-trimethylsilyi-2,3,4,6-tetra-O-benzyl-α-D-mannopyranose (1)reacted stereoselectively with a series of carboxylic acids to give the corresponding α-mannosyl carboxylates in good yields. T... 详细信息

关键词： t?

Studies on Carbohydrates ⅩⅩⅧ. Synthesis of Key Intermediates of Oligosaccharides Related to Serratia marcescens O10 Antigen

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Chinese Chemical Letters 1998年第5期9卷 435-437页

作者： Ke Qin ZHANG Jian Min MAO Hong Min CHEN meng shen cai(School of Pharmaceutical Sciences, Beijing Medical University, Beijing 100083) School of Pharmaceutical Sciences Beijing Medical University Beijing 100083 China

In the continuation of our study on the Serratta marcescens O-antigen, two disaccharides8 and 13, corresponding to the key intermediates of oligosaccharides related to the S. marcescensO10 antigen, were srythesized by the trichloroacetate method. Their structures and compositionswere characterized by H NMR, C NMR, 2D NMR and IR, FAB-MS spectra.

关键词： synthesis Serratia marcescens O10 antigen trichloroacetate

Mapping the Antigenic Peptides of Sm26/2 in Glutathione S-Transferases of Schistosoma Mansoni

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Chinese Chemical Letters 1998年第4期9卷 377-379页

作者： Jia Xi XU meng shen cai(College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (School of Pharmaceutical Sciences, Beijing Medical University, Beijing 100083) Coll. of Chem./Molec. Engineering Peking University Beijing 100871 China School of Pharmaceutical Sciences Beijing Medical University Beijing 100083 China

Six antigenic peptides of Sm26/2 glutathione S-transferase of schistosoma mansoni have been predicted according to their hydrophilicity, flexibility, accessibility, charge distribution and beta-turn in the secondary structure by the determination of its primary structure, and synthesized by solid phase method. Two of them showed good antigenicity by Dot-ELISA. They would be candidate peptides of synthetic anti-schistosomal vaccine.

关键词： schistosoma mansoni glutathione S-transferase antigenic peptide peptide vaccine

Prediction, Synthesis and Antigenicity of the Antigenic Peptides of 26kDa Glutathione S-Transferasc of Schistosoma Japonicum (Sj26)

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Chinese Chemical Letters 1999年第1期10卷 27-28页

作者： Jia Xi XU meng shen cai(College of Chemistry and Molecular Engineering, Peking University, Beijing 100871)(School of Pharmaceutical Sciences, Beijing Medical University. Beijing 100083) Coll. of Chem. and Molec. Eng. Peking University Beijing 100871 China School of Pharmaceutical Sciences Beijing Medical University Beijing 100083 China

Six antigenic peptides of 26 kDa glutathione S-transferase of Schistosoma japonicum(Sj26) have been predicted according to their hydrophilicity, flexibility. accessibility. chargedistribution and β -turn in the secondary structure by the determination of its primary structure andsynthesized by solid phase method. All of them showed antigenicity with anti-schistosomajaponicum immunoglobulin polyclonal antibody, anti-Sj-lgG PcAb by Dot-ELISA. Three of themshowed good antigenicity. They would serve as candidates of synthetic anti-schistosomal vaccine.

关键词： SchistosomajQPonicum glutathione S-transferase antigenic peptide peptide vaccine.

Studies on the Total Synthesis of the Repeat Unit of Candida kefyr IFO 0586 Strain

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Chinese Chemical Letters 1998年第9期9卷 819-822页

作者： Ping Yu DING Cheng He ZHOU Wu Yan ZHANG meng shen cai (Department of Bio-organic Chemistry, School of Pharmaceutical Sciences,Beijing Medical University, Beijing 100083) Department of Bio-organic Chemistry School of Pharmaceutical Sciences Beijing Medical University Beijing 100083 China

The repeat unit of Candida kefyr IFO 0586 strain was designed, and a protected pentasaccharide was synthesized by thirteen-step reactions. Trichloroacetoxy was used as leaving group at anomeric carbon.

关键词： mannose glycoside oligosaccharide synthesis

Synthesis of the Acetate of a New Phenolic Glycoside,Anacardoside,from Semecarpus anacardium and its Diastereomer

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Chinese Chemical Letters 1998年第6期9卷 533-536页

作者： Yu Lan WANG Cheng He ZHOU meng shen cai (Institute of Chemical Metallurgy, Chinese Academy of Sciences, Bejing 100080)( School of Pharmaceutical Sciences, Beijing Medical University, Beijing 100083) Institute of Chemical Metallurgy Chinese Academy of Sciences Beijing 100080 China School of Pharmaceutical Sciences Beijing Medical University Beijing 100083 China

the acetate of a novel phenolic glycoside, 1-O-beta-D-glucopyranosyl-( 1-->6)-beta-D-glucopyranosyloxy-3-hydroxy-5-methylbenzene anacardoside, from the fruits of Semecarpus anacardium, and its diastereomer were first ... 详细信息

关键词： acetate of anacardoside diastereomer synthesis phenolic glycoside

Optimization in Machine Learning:a Distribution-Space Approach

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Communications on Applied Mathematics and Computation 2024年第2期6卷 1217-1240页

作者： Yongqiang cai Qianxiao Li Zuowei shen School of Mathematical Sciences Laboratory of Mathematics and Complex SystemsMOEBeijing Normal UniversityBeijing 100875China Department of Mathematics National University of Singapore21 Lower Kent Ridge RoadSingapore119077Singapore

We present the viewpoint that optimization problems encountered in machine learning can often be interpreted as minimizing a convex functional over a function space,but with a non-convex constraint set introduced by model *** observation allows us to repose such problems via a suitable relaxation as convex optimization problems in the space of distributions over the training *** derive some simple relationships between the distribution-space problem and the original problem,e.g.,a distribution-space solution is at least as good as a solution in the original ***,we develop a numerical algorithm based on mixture distributions to perform approximate optimization directly in the distribution *** of this approximation is established and the numerical efficacy of the proposed algorithm is illustrated in simple *** both theory and practice,this formulation provides an alternative approach to large-scale optimization in machine learning.

关键词： Machine learning Convex relaxation Optimization Distribution space

STERESOSELECTIVE　AND　MILD　METHOD　FOR　THE　SYNTHESIS　OF　α－D－MANNOPYRANOSIDES　AND　RELATED　OLIGOSACCHARIDES　IN　HIGH　YIELD￣1

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Chinese Chemical Letters 1994年第6期5卷 477-480页

作者： Zhong Jun LI He Qing HUANG and meng shen cai (School of Pharmaceutical Sciences, Beijing Medical University, Beijing 100083)

Model reaction Of I-O-(3.5-dinitrobenzcyl)-2,3.4,6-tetra-O-benzyl-a-D-mannopyranose I with a series of carbaxylic acids, phenols, alcohols and saccharides respectively demonstrated that stereocontrolled mannosyl transfer with the retention of configuration at the anomeric center was best carried out in dichloromethane (-20℃→r.t.) with TMSOTf as the Lewis acid catalyst. DBMP as a deprotic agent and powdered 3A molecular steres as a desiccating. agent. Under these conditions. a-D-mannopyanosides and related oligosaccharides were obtained in good yields.

关键词： MILD METHOD STERESOSELECTIVE AND