- Selective activation of glycosyl donors utilising electrochemical techniques: A study of the thermodynamic oxidation potentials of a range of chalcoglycosides
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A series of six chalcoglycosides (phenyl-2,3,4,6-tetra-0-benzoyl-1-seleno-β-D-glucopyranoside, phenyl-2,3,4,6-tetraO-benzyl-1-seleno-β-D-glucopyranoside, phenyl-2,3,4,6-tetra-O-benzyl-1-thio-β-D-glucopyranoside, p-tolyl-2,3,4,6-O-benzoyl-1-thio-β-D-glucop
- France, Robert R.,Rees, Neil V.,Wadhawan, Jay D.,Fairbanks, Antony J.,Compton, Richard G.
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Read Online
- Automated Quantification of Hydroxyl Reactivities: Prediction of Glycosylation Reactions
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The stereoselectivity and yield in glycosylation reactions are paramount but unpredictable. We have developed a database of acceptor nucleophilic constants (Aka) to quantify the nucleophilicity of hydroxyl groups in glycosylation influenced by the steric, electronic and structural effects, providing a connection between experiments and computer algorithms. The subtle reactivity differences among the hydroxyl groups on various carbohydrate molecules can be defined by Aka, which is easily accessible by a simple and convenient automation system to assure high reproducibility and accuracy. A diverse range of glycosylation donors and acceptors with well-defined reactivity and promoters were organized and processed by the designed software program “GlycoComputer” for prediction of glycosylation reactions without involving sophisticated computational processing. The importance of Aka was further verified by random forest algorithm, and the applicability was tested by the synthesis of a Lewis A skeleton to show that the stereoselectivity and yield can be accurately estimated.
- Chang, Chun-Wei,Lin, Mei-Huei,Chan, Chieh-Kai,Su, Kuan-Yu,Wu, Chia-Hui,Lo, Wei-Chih,Lam, Sarah,Cheng, Yu-Ting,Liao, Pin-Hsuan,Wong, Chi-Huey,Wang, Cheng-Chung
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supporting information
p. 12413 - 12423
(2021/05/03)
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- Synthesis method of voglibose
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The invention provides a synthesis method of voglibose, and solves the technical problems that in an existing synthesis method of voglibose, raw materials are difficult to obtain, high in price, large in investment, low in yield and not suitable for industrial production. The synthesis method comprises the steps: synthesizing a compound V by taking glucose monohydrate and sodium acetate as raw materials through eleven reaction steps; and preparing a compound VIII from the compound V through an addition reaction, a ring-opening reaction and an aldol condensation reaction, and thus obtaining voglibose through amination reduction of the compound VIII. The synthesis method of voglibose can be widely applied to the technical field of voglibose synthesis methods.
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Paragraph 0060- 0061; 0068-0070-0071
(2021/08/07)
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- Mapping mechanisms in glycosylation reactions with donor reactivity: Avoiding generation of side products
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The glycosylation reaction, which is key for the studies on glycoscience, is challenging due to its complexity and intrinsic side reactions. Thioglycoside is one of the most widely used glycosyl donors in the synthesis of complex oligosaccharides. However, one of the challenges is its side reactions, which lower its yield and limits its efficiency, thereby requiring considerable effort in the optimization process. Herein, we reported a multifaceted experimental approach that reveals the behaviors of side reactions, such as the intermolecular thioaglycon transformation and N-glycosyl succinimides, via the glycosyl intermediate. Our mechanistic proposal was supported by low temperature NMR studies that can further be mapped by utilizing relative reactivity values. Accordingly, we also presented our findings to suppress the generation of side products in solving this particular problem for achieving high-yield glycosylation reactions.
- Wang, Cheng-Chung,Chang, Chun-Wei,Lin, Mei-Huei,Wu, Chia-Hui,Chiang, Tsun-Yi
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p. 15945 - 15963
(2021/01/18)
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- Establishment of Guidelines for the Control of Glycosylation Reactions and Intermediates by Quantitative Assessment of Reactivity
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Stereocontrolled chemical glycosylation remains a major challenge despite vast efforts reported over many decades and so far still mainly relies on trial and error. Now it is shown that the relative reactivity value (RRV) of thioglycosides is an indicator for revealing stereoselectivities according to four types of acceptors. Mechanistic studies show that the reaction is dominated by two distinct intermediates: glycosyl triflates and glycosyl halides from N-halosuccinimide (NXS)/TfOH. The formation of glycosyl halide is highly correlated with the production of α-glycoside. These findings enable glycosylation reactions to be foreseen by using RRVs as an α/β-selectivity indicator and guidelines and rules to be developed for stereocontrolled glycosylation.
- Chang, Chun-Wei,Wu, Chia-Hui,Lin, Mei-Huei,Liao, Pin-Hsuan,Chang, Chun-Chi,Chuang, Hsiao-Han,Lin, Su-Ching,Lam, Sarah,Verma, Ved Prakash,Hsu, Chao-Ping,Wang, Cheng-Chung
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supporting information
p. 16775 - 16779
(2019/11/03)
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- Simple and Practical Real-Time Analysis of Solid-Phase Reactions by Thin-Layer Chromatography
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Solid-phase synthesis is a practical approach for simplifying the time-consuming and routine purification steps in the preparation of numerous naturally occurring molecules; however, studying such reactions is difficult due to the lack of a convenient monitoring method. By using thin-layer chromatography in conjunction with a photolabile linker on a resin, we developed a convenient and simple method for monitoring solid-phase reactions in real time by thin-layer chromatography. This method provides a user-friendly protocol for examining reaction conditions for solid-state syntheses.
- Wu, Chia-Hui,Chen, Chun C.,Lin, Su-Ching,Wang, Cheng-Chung
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supporting information
p. 1430 - 1436
(2018/05/15)
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- Stereoretentive C(sp3)-S Cross-Coupling
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We report a stereoretentive cross-coupling reaction of configurationally stable nucleophiles with disulfide and N-sulfenylsuccinimide donors promoted by Cu(I). We demonstrate the utility of this method in the synthesis of thioglycosides derived from simple alkyl and aryl thiols, thioglycosides, and in the glycodiversification of cysteine residues in peptides. These reactions operate well with carbohydrate substrates containing common protective groups and reagents with free hydroxyl and secondary amide functionalities under standardized conditions. Competition experiments in combination with computational DFT studies established that the putative anomeric intermediate is an organocopper species that is configurationally stable and resistant to epimerization due to its short lifetime. The subsequent reductive elimination from the Cu(III) intermediate is rapid and stereoretentive. Taken together, the glycosyl cross-coupling is ideally suited for late stage glycodiversification and bioconjugation under highly controlled installation of the aliphatic carbon-sulfur bonds.
- Zhu, Feng,Miller, Eric,Zhang, Shuo-Qing,Yi, Duk,O'Neill, Sloane,Hong, Xin,Walczak, Maciej A.
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supporting information
p. 18140 - 18150
(2019/01/04)
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- Urea–hydrogen peroxide prompted the selective and controlled oxidation of thioglycosides into sulfoxides and sulfones
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A practical method for the selective and controlled oxidation of thioglycosides to corresponding glycosyl sulfoxides and sulfones is reported using urea–hydrogen peroxide (UHP). A wide range of glycosyl sulfoxides are selectively achieved using 1.5 equiv of UHP at 60 °C while corresponding sulfones are achieved using 2.5 equiv of UHP at 80 °C in acetic acid. Remarkably, oxidation susceptible olefin functional groups were found to be stable during the oxidation of sulfide.
- Singh, Adesh Kumar,Tiwari, Varsha,Mishra, Kunj Bihari,Gupta, Surabhi,Kandasamy, Jeyakumar
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supporting information
p. 1139 - 1144
(2017/06/20)
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- Glycosylated Platinum(IV) Complexes as Substrates for Glucose Transporters (GLUTs) and Organic Cation Transporters (OCTs) Exhibited Cancer Targeting and Human Serum Albumin Binding Properties for Drug Delivery
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Glycosylated platinum(IV) complexes were synthesized as substrates for GLUTs and OCTs for the first time, and the cytotoxicity and detailed mechanism were determined in vitro and in vivo. Galactoside Pt(IV), glucoside Pt(IV), and mannoside Pt(IV) were highly cytotoxic and showed specific cancer-targeting properties in vitro and in vivo. Glycosylated platinum(IV) complexes 5, 6, 7, and 8 (IC50 0.24-3.97 μM) had better antitumor activity of nearly 166-fold higher than the positive controls cisplatin (1a), oxaliplatin (3a), and satraplatin (5a). The presence of a hexadecanoic chain allowed binding with human serum albumin (HSA) for drug delivery, which not only enhanced the stability of the inert platinum(IV) prodrugs but also decreased their reduction by reductants present in human whole blood. Their preferential accumulation in cancer cells compared to noncancerous cells (293T and 3T3 cells) suggested that they were potentially safe for clinical therapeutic use.
- Ma, Jing,Wang, Qingpeng,Huang, Zhonglv,Yang, Xiande,Nie, Quandeng,Hao, Wenpei,Wang, Peng George,Wang, Xin
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supporting information
p. 5736 - 5748
(2017/07/22)
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- Dehydrative glycosylation with cyclic phosphonium anhydrides
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Cyclic phosphonium anhydrides generated from bis-phosphine oxides and trifluoromethanesulfonic anhydride are shown as general coupling reagents in a dehydrative glycosylation reaction of C1-hemiacetals. This reaction protocol is characterized by a broad substrate scope and high yields, including reactions of O-, C-, N-, and S-based nucleophiles with furanose, pyranose, and deoxysugar donors.
- Dyapa, Rajendar,Dockery, Lance T.,Walczak, Maciej A.
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supporting information
p. 51 - 55
(2016/12/27)
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- Preparation 2, 3, 4, 6-tetra-O-benzyl-D-pyran semi-acetyllactosyl method
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The invention relates to the field of saccharide compounds, particularly a method for preparing 2,3,4,6-tetra-oxy-benzyl-D-galactopyranose. The method comprises the following steps: preparing benzothiazolyl thioacetyl galactose from galactose under the ac
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Paragraph 0044; 0046
(2017/02/17)
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- Total synthesis of mangiferin, homomangiferin, and neomangiferin
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Total synthesis of mangiferin, homomangiferin, and neomangiferin, three C-glycosyl xanthone natural products with a wide spectrum of pharmacological effects, has been achieved starting from 2,3,4,6-tetra-O-benzyl-α/β-d-glucopyranose. The key steps involve a stereoselective Lewis acid promoted C-glycosylation of protected phloroglucinol with tetrabenzylglucopyranosyl acetate and a highly regioselective base-induced cyclization for the construction of the core xanthone skeleton.
- Wei, Xiong,Liang, Danlin,Wang, Qing,Meng, Xiangbao,Li, Zhongjun
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supporting information
p. 8821 - 8831
(2016/10/03)
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- Synthesis of a poly-hydroxypyrolidine-based inhibitor of Mycobacterium tuberculosis GlgE
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(Chemical Equation Presented). Long treatment times, poor drug compliance, and natural selection during treatment of Mycobacterium tuberculosis (Mtb) have given rise to extensively drug-resistant tuberculosis (XDR-TB). As a result, there is a need to iden
- Veleti, Sri Kumar,Lindenberger, Jared J.,Thanna, Sandeep,Ronning, Donald R.,Sucheck, Steven J.
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p. 9444 - 9450
(2015/02/19)
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- Exploring glycosylation reactions under continuous-flow conditions
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The industrial development of carbohydrate-based drugs is greatly thwarted by the typical challenges inherent in oligosaccharide synthesis. The practical advantages of continuous-flow synthesis in microreactors (high reproducibility, easy scalability, and fast reaction optimization) may offer an effective support to make carbohydrates more attractive targets for drug-discovery processes. Here we report a systematic exploration of the glycosylation reaction carried out under microfluidic conditions. Trichloroacetimidates and thioglycosides have been investigated as glycosyl donors, using both primary and secondary acceptors. Each microfluidic glycosylation has been compared with the corresponding batch reaction, in order to highlight advantages and drawbacks of microreactors technology. As a significant example of multistep continuous-flow synthesis, we also describe the preparation of a trisaccharide by means of two consecutive glycosylations performed in interconnected microreactors.
- Cancogni, Damiano,Lay, Luigi
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supporting information
p. 2873 - 2878
(2015/01/16)
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- SYNTHETIC OLIGOSACCHARIDES FOR MORAXELLA VACCINE
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The present invention provides synthetic Moraxella catarrhalis lipooligosaccharide (LOS)-based oligosaccharides and conjugates containing various M. catarrhalis serotype-specific oligosaccharide antigens or various core M. catarrhalis oligosaccharide structures or motifs corresponding to one or more of the three major serotypes and/or members within a given serotype. The oligosaccharides may be synthesized by a chemical assembly methodology relying on a limited number of monosaccharide and disaccharide building blocks. The invention further provides M. catarrhalis LOS-based immunogenic and immunoprotective compositions and antibodies derived therefrom for diagnosing, treating, and preventing infections caused by M. catarrhalis.
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- Mannopyranosyl uronicaAcid donor reactivity
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The reactivity of a variety of mannopyranosyl uronic acid donors was assessed in a set of competition experiments, in which two (S)-tolyl mannosyl donors were made to compete for a limited amount of promoter (NIS/TfOH). These experiments revealed that the reactivity of mannuronic acid donors is significantly higher than expected based on the electron-withdrawing capacity of the C-5 carboxylic acid ester function. A 4-O-acetyl-β-(S)-tolyl mannuronic acid donor was found to have similar reactivity as per-O-benzyl-α-(S)-tolyl mannose.
- Walvoort, Marthe T. C.,De Witte, Wilbert,Van Dijk, Jesse,Dinkelaar, Jasper,Lodder, Gerrit,Overkleeft, Herman S.,Codee, Jeroen D. C.,Van Der Marel, Gijsbert A.
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p. 4360 - 4363
(2011/10/18)
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- 'Click' preparation of carbohydrate 1-benzotriazoles, 1,4-disubstituted, and 1,4,5-trisubstituted triazoles and their utility as glycosyl donors
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Glycosyl triazoles can be prepared from readily available anomeric azides through various 'click' methodologies: thermal Huisgen cycloaddition with alkynes, strain-promoted Huisgen cycloaddition of benzynes, and Cu I-catalyzed azide-alkyne cycloaddition of terminal alkynes (CuAAC reaction). Here we investigate the formation of glycosyl 1-benzotriazoles from anomeric and non-anomeric carbohydrate azides using benzynes derived from substituted anthranilic acids. The reactivity of the resulting anomeric 1-benzotriazoles as glycosyl donors was investigated and compared with 1,4-disubstituted glycosyl triazoles (from the CuAAC reaction) and 1,4,5-trisubstituted glycosyl triazoles (prepared by Huisgen cycloaddition of glycosyl azides and dimethyl acetylene dicarboxylate). The 1,4,5-trisubstituted glycosyl triazoles were activated by Lewis acids and could be converted to O-glycosides, S-glycosides, glycosyl chlorides, and glycosyl azides. By contrast, under all conditions investigated, the 1,4-disubstituted glycosyl triazoles were unreactive as glycosyl donors. Glycosyl 1-benzotriazoles were generally inert as glycosyl donors; however, a tetrafluorobenzotriazole derivative, which bears electron-withdrawing substituents on the benzotriazole group, was a moderate glycosyl donor and could be converted to an S-glycoside by treatment with thiocresol and tin(iv) chloride.
- Watt, Jacinta A.,Gannon, Carlie T.,Loft, Karen J.,Dinev, Zoran,Williams, Spencer J.
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experimental part
p. 837 - 846
(2009/04/11)
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- Regioselective benzylation of azido-containing monosaccharides
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A regioselective benzylation or p-methoxybenzylation of diols in azido-containing monosaccharide derivatives was reported, and the reaction was performed under the conventional reaction conditions (NaH/BnBr in DMF). The hydroxyl functionality adjacent to the azido group was benzylated selectively in good yields. Georg Thieme Verlag Stuttgart.
- Fan, Qiu-Hua,Li, Qin,Zhang, Li-He,Ye, Xin-Shan
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p. 1217 - 1220
(2007/10/03)
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- Selective electrochemical glycosylation by reactivity tuning
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Electrochemical glycosylation of a selenoglycoside donor proceeds efficiently in an undivided cell in acetonitrile to yield β-glycosides. Measurement of cyclic voltammograms for a selection of seleno-, thio-, and O-glycosides indicates the dependence of o
- France, Robert R.,Compton, Richard G.,Davis, Benjamin G.,Fairbanks, Antony J.,Rees, Neil V.,Wadhawan, Jay D.
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p. 2195 - 2202
(2007/10/03)
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- Anomeric reactivity-based one-pot oligosaccharide synthesis: A rapid route to oligosaccharide libraries
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The assembly of an oligosaccharide library has been achieved in a practical and efficient manner employing a one-pot sequential approach. With the help of the anomeric reactivity values of thioglycosides, using a thioglycoside (mono- or disaccharide) with one free hydroxyl group as acceptor and donor coupled with another fully protected thioglycoside, a di- or trisaccharide is selectively formed without self-condensation and subsequently reacted in situ with an anomerically inactive glycoside (mono- or disaccharide) to form a tri- or tetrasaccharide in high overall yield. The approach enables the rapid assembly of 33 linear or branched fully protected oligosaccharides using designed building blocks. These fully protected oligosaccharides have been partially or completely deprotected to create 29 more structures to further increase the diversity of the library.
- Ye, Xin-Shan,Wong, Chi-Huey
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p. 2410 - 2431
(2007/10/03)
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- THIOGLYCOSIDES AS POTENTIAL GLYCOSYL DONORS IN ELECTROCHEMICAL GLYCOSYLATION REACTIONS. PART 1: THEIR PREPARATION AND REACTIVITY TOWARD SIMPLE ALCOHOLS
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Costant potential electrolysis of several glycosyl donors such as substituted phenyl 2,3,4,6-tetra-O-acetyl, benzoyl or benzyl-1-thio-β-D-gluco or galactopyranosides in dry acetonitrile in the presence of various primary, secondary or tertiary alcohols performed in an undivided cell, gave preferentially β-linked saccharides in moderate to good yields according to the nature of the protective groups on the sugar moiety. 2-Deoxy-2-phthalimido-1-thio-β-D-gluco derivatives gave the β-glucosides selectively in excellent yields.It was found, as expected, that substitution of the phenyl group with methoxy or methyl radicals facilitates the electrochemical glycosylation reaction by lowering the oxidation potentials of the corresponding thioglycosides.
- Balovoine, Gilbert,Berteina, Sabine,Gref, Aurore,Fischer, Jean-Claude,Lubineau, Andre
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p. 1217 - 1236
(2007/10/03)
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- Studies on Glycosides VII. A Highly Stereoselective Synthesis of 1-Thioglycosides
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A facile method for the synthesis of 1-thioglycosides using 1-α-O-trimethylsilyl-2,3,4,6,-tetra-O-benzyl-D-gluco- or manno-pyranoside by the promotion of BF3Et2O was reported.The reaction conditions were very mild, and 1-thioglycosides were obtained in hi
- Li, Zhan-Jiang,Liu, Ping-Li,Li, Zhong-Jun,Qiu, Dong-Xu,Cai, Meng-Shen
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p. 2169 - 2175
(2007/10/02)
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