检索结果-南通市图书馆

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

在线全文

学校读者我要写书评

暂无评论

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 TechnologyYueyang 414000China college of Chemistry and Chemical engineering Central South UniversityChangsha 410083China

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

Coherent coupling of vibrational states in the MEH-PPV film investigated through Multi-Color Photon Echo

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2010年第6期53卷 1020-1023页

作者： YU GuoYang 1 ,SONG YunFei 1 ,WANG YingHui 1 ,LIU YuQiang 1 ,MO YueQi 2 & YANG YanQiang 1 1 Center for Condensed Matter Science and technology,Department of Physics,Harbin institute of technology,Harbin 150001,china 2 college of Materials Science and engineering,South china University of technology,Guangzhou 510640,china 1. Center for Condensed Matter Science and technology Department of Physics Harbin Institute of Technology Harbin 150001 China2. College of Materials Science and Engineering South China University of Technology Guangzhou 510640 China

The poly-[2-methoxy,(5-2′-ethyl-hexyloxy)-p-phenylene vinylene](MEH-PPV) film is investigated by means of the Multi-Color Photon Echo(MCPE) technique. Under the three-order nonlinear response theory,the reason for the occurrence of the quantum beats in the time domain and the relations among signal wavevector,pulse sequence and response function are discussed. The analysis of the Raman spectrum of MEH-PPV and the fast Fourier transformation(FFT) results of photon echo(PE) signal dynamics demonstrate the coherent coupling between the C==C bonds and the CC-H bonds and the coherent coupling between the C-C stretching of the phenyl group and the C==C stretching of the vinylene group.

关键词： MCPE quantum beats coherent coupling

Base－Catalyzed　Rearrangement　of　11－Isopropylidene－anti－4，5－Epoxyendo－Tricyclo［6．2．1．0^（2，7）］　Undeca－4，9－Diene－3，6－Dione

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1996年第10期7卷 902-904页

作者： Xiao Pei GUAN Jian Guang SUN and Yong Zhong YU(college of Chemical engineering and Materials Science, Beijing institute of technology, 100081 Beijing) Coll. of Chem. Eng. and Mat. Science Beijing Institute of Technology 100081 Beijing

Treatment of 11-isopropylidene-anti-4, 5-epoxy-endo-tricyclo[6. 2. 1. 02.7] undeca-4, 9-diene-3,6-dione(6) with methanolic sodium hydroxide results in Favorskii-type ring contraction with concomitant Cope rearrangement and Haller-Bauer cleavage, thereby affording dimethyl9-isopropxlidene-cis-bicyclo[4. 3. 0 ] nonane-(2S)-2, 3-dicarboxylate(7) as the ultimate product. The structure of 7 was confirmed by single crystal X-ray analysis

关键词： Rearrangement Isopropylidene Base Catalyzed

An Anthropomorphic Robot Hand Developed Based on Underactuated Mechanism and Controlled by EMG Signals

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic engineering 2009年第3期6卷 255-263页

作者： Da-peng Yang~1 Jing-dong Zhao~1 Yi-kun Gu~1 Xin-qing Wang~1 Nan Li~1 Li Jiang~1Hong Liu~(1,2) Hai Huang~3 Da-wei Zhao~41.State Key Laboratory of Robotics and System,Harbin institute of technology,Harbin 150001,P.R.china2.institute of Robotics and Mechatronics,German Aerospace Center,Munich 82230,Germany3.college of Shipbuilding engineering,Harbin engineering University,Harbin 150001,P.R.china4.college of Automation,Harbin engineering University,Harbin 150001,P.R.china [a]State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 P. R. China [b]Institute of Robotics and Mechatronics German Aerospace Center Munich 82230 Germany [c]College of Shipbuilding Engineering Harbin Engineering University Harbin 150001 P. R. China [d]College of Automation Harbin Engineering University Harbin 150001 P. R. China

When developing a humanoid myo-control hand,not only the mechanical structure should be considered to afford a high dexterity,but also the myoelectric (electromyography,EMG) control capability should be taken into account to fully accomplish the actuation *** paper presents a novel humanoid robotic myocontrol hand (AR hand Ⅲ) which adopted an underac- tuated mechanism and a forearm myocontrol EMG *** AR hand Ⅲ has five fingers and 15 joints,and actuated by three embedded *** can be found within each finger and between the rest three fingers (the middle finger,the ring finger and the little finger) when the hand is grasping *** the EMG control,two specific methods are proposed:the three-fingered hand gesture configuration of the AR hand Ⅲ and a pattern classification method of EMG signals based on a statistical learning algorithm-Support Vector Machine (SVM).Eighteen active hand gestures of a testee are recognized ef- fectively,which can be directly mapped into the motions of AR hand Ⅲ.An on-line EMG control scheme is established based on two different decision functions:one is for the discrimination between the idle and active modes,the other is for the recog- nition of the active *** a result,the AR hand Ⅲ can swiftly follow the gesture instructions of the testee with a time delay less than 100 ms.

关键词： humanoid hand underactuated mechanism EMG control suppon vector machine

Electronic structure and magnetism of Fe-doped SiC nanotubes

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1582-1589页

作者： ZHANG WeiHu1,2,3,ZHANG FuChun3,ZHANG ZhiYong4,LU ShuYuan5 & YANG YanNing3 1 Xi’an institute of Optics and Precision Mechanics,Chinese Academy of Sciences,Xi’an 710068,china 2 Graduate University of Chinese Academy of Sciences,Beijing 100049,china 3 college of Physics and Electronic Information,Yan’an University,Yan’an 716000,china 4 Information Science and technology Institution,Northwest University,Xi’an 710127,china 5 Department of Telecommunications,Xi’an institute of Posts and Telecommunications,Xi’an 710121,china 1. Xi’an institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi’an 710068 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. College of Physics and Electronic Information Yan’an University Yan’an 716000 China4. Information Science and Technology Institution Northwest University Xi’an 710127 China5. Department of Telecommunications Xi’an Institute of Posts and Telecommunications Xi’an 710121 China

The electronic structure and magnetic properties of Fe-doped SiC nanotubes are investigated by using the first-principles method based on density functional theory(DFT) in the local spin density approximation(LSDA).The calculation results indicate that the SiC nanotube of Fe substitution for C exhibits antiferromagnetism while ferromagnetism features prominently when Fe substitutes *** is a kind of half-metal magnetic *** formation energy calculation results show that the formation energy of ferromagnetic structure is 3.2 eV lower than that of antiferromagnetic *** atoms are more likely to replace Si ***-orbit coupling induces electron spin polarization in the ground ***,the doping Fe atoms make relaxation towards the outside of the tube to some extent and larger geometric distortion occurs when Fe substitutes C,but the whole geometric structure of SiC nanotubes is not damaged due to the *** is revealed in the calculation of energy band structure and density of states that more dispersed distribution of energy levels is produced near the Fermi *** Fe substitution for Si,obviously there are spin-split and intense p-d hybrid effects by Si 3p electron spins and Fe 3d electron spins localized at the exchanging interactions between magnetic transitional metal(TM) *** electronic density results indicate that system magnetic moments are mainly generated by the unpaired 3d electrons of Fe *** these results show that the transition metal doping SiC nanotube could be a potential route to fabricating the promising magnetic materials.

关键词： SiC nanotube the first-principles doped magnetic properties

A new method to improve surface morphology of Ni-Fe-Mo-Co alloy electrode and its catalytic activity for HER

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2007年第3期26卷 205-212页

作者： LUO Beiping REN Buye XU You ZHENG Yajie Department of Chemistry and Chemical engineering Hunan Institute of Science and Technology Yueyang 414000 China college of Metallurgical Science and engineering Central South University Changsha 410083 China Research institute of Materials Science South China University of Technology Guangzhou 510640 China

A new pretreatment method has been developed to improve the catalytic activity of the Ni-Fe-Mo-Co alloy electrode for hydrogen evolution reaction （HER）. The procedure involves pre-electrolyzing the Ni-Fe-Mo-Co alloy electrode in 30% KOH solution containing 10% potassium sodium tartrate at 70℃ for 2 h, until some of the Mo and Fe elements are leached out. The surface morphology of the Ni-Fe-Mo-Co alloy demonstrates a unique hive-like structure after the pre- treatment, which has the pore size in a nanometer range （about 50 nm）, a very large real surface area, and good stability. The results of the electrochemical studies show that compared to other similar electrode materials and the treated Ni-Fe-Mo-Co electrode by leaching method, the pre-treated Ni-Fe-Mo-Co electrode has a much lower overpotential and much higher exchange current density for HER. In addition, a long-term continuous electrolysis test with a current interruption shows that the Ni-Fe-Mo-Co alloy has excellent catalytic stability.

关键词： catalytic activity surface treatment Ni-Fe-Mo-Co alloy hydrogen evolution electrodeposition

Functions for patch test in finite element analysis of the Mindlin plate and the thin cylindrical shell

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2009年第5期52卷 762-767页

作者： CHEN WanJi 1,2 ,WANG JinZhi 1,3 &ZHAO Jie 1 1State Key Laboratory for Structural Analysis of Industrial Equipment,Dalian University of technology,Dalian 116023,china 2institute for Structural Analysis of Aerocraft,Shenyang institute of Aeronautical engineering,Shenyang 110136,china 3 college of Science,institute of Dalian Nationalities,Dalian 116022,china State Key Laboratory for Structural Analysis of Industrial Equipment Dalian University of Technology Dalian 116023 China institute for Structural Analysis of Aerocraft Shenyang Institute of Aeronautical Engineering Shenyang 110136 China college of Science Institute of Dalian Nationalities Dalian 116022 China

Current patch test for Mindlin plate element only satisfies the zero shear deformation *** patch test of non-zero constant shear for Mindlin plate problem cannot be *** shell element, the patch test does not even *** on the theory of enhanced patch test proposed by Chen W J (2006),the authors proposed the enhanced patch test function for Mindlin plate and thin cylindrical shell *** enhanced patch test function can be used to assess the convergence of the Mindlin plate and cylindrical thin shell elements.

关键词： Mindlin plate thin cylindrical shell finite element enhanced patch test test function

薯蓣皂苷元生物合成途径及其关键基因研究进展

在线全文

学校读者我要写书评

暂无评论

植物生理学报 2024年第8期60卷 1221-1228页

作者：李文砚黄静丽李长洲黄金梅肖冬詹洁王爱勤张平刚何龙飞广西大学农学院南宁530004 广西农业环境与农产品安全重点实验室南宁530004 广西高校作物栽培与生理重点实验室南宁530004 广西大学农牧产业发展研究院南宁530004

薯蓣皂苷元属甾体皂苷类化合物,是薯蓣属植物中代表性的药用成分,具多重药理学活性,也是300多种甾体激素类药物的重要前体物质。本文简要概述了薯蓣皂苷元在植物中的分布,薯蓣皂苷元生物合成过程及关键酶基因角鲨烯环氧酶、环阿屯醇合... 详细信息

薯蓣皂苷元属甾体皂苷类化合物,是薯蓣属植物中代表性的药用成分,具多重药理学活性,也是300多种甾体激素类药物的重要前体物质。本文简要概述了薯蓣皂苷元在植物中的分布,薯蓣皂苷元生物合成过程及关键酶基因角鲨烯环氧酶、环阿屯醇合酶、细胞色素P450酶和尿苷二磷酸糖基转移酶的研究进展,并解读它们参与薯蓣皂苷元合成途径的催化机制,以便为提高植物中薯蓣皂苷元含量,促进薯蓣遗传育种与栽培提供参考。

关键词：薯蓣皂苷元甾体皂苷生物合成次生代谢物

Role of inositol 1,4,5-trisphosphate receptors in α1-adrenergic receptorinduced cardiomyocyte hypertrophy

在线全文

学校读者我要写书评

暂无评论

Acta Pharmacologica Sinica 2006年第7期27卷 895-900页

作者： Da-li LUO~(2,3,5) Jian GAO~2 Xiao-mei LAN~3 Gang WANG~4 Sheng WEI~4 Rui-ping XIAO~4 Qi-de HAN~32 Department of Pharmacology,School of Chemical Biology & Pharmaceutical Sciences,Capital University of Medical Sciences,Beijing 100069,china 3 institute of Cardiovascular Science at Health Science Center,Peking University Beijing 100083,china 4 institute of Molecular Medicine and college of Life Science,Peking University,Beijing 100871,china Department of Pharmacology School of Chemical Biology & Pharmaceutical Sciences Capital University of Medical Sciences Beijing 100069 China institute of Cardiovascular Science at Health Science Center Peking University Beijing 100083 China institute of Molecular Medicine and college of Life Science Peking University Beijing 100871 China

Aim:Intracellular Ca2+plays pivotal roles in diverse cellular functions,includinggene transcription that underlies cardiac remodeling during stress ***,the role of inositol 1,4,5-trisphosphate receptors（IP3Rs）in the media-tion of cardiac intracellular Ca2+and hypertrophic growth remains *** with neonatal rat ventricular myocytes suggests that activation of IP3Rsmay be linked to α1adrenergic receptor（α1AR）increased stereotyped Ca2+sparkoccurrence and global Ca2+***,we hypothesized that Ca2+releasethrough IP3Rs was necessary for α1AR-stimulated cardiac ***:We used myoinositol 1,4,5-trisphosphate hexakis（butyryloxymethyl）ester（IP3BM）,a membrane-permeant ester of IP3,to activate IP3Rs directly,and Fluo 4/AM tomeasure intracellular Ca2+***:IP3BM(10μmol·L-1)mimicked theeffects of phenylephrine,a selective agonist of α1AR,in increments in local Ca2+spark release（especially in the perinuclear area）and global Ca2+*** importantly,IP3R inhibitors,2-aminoethoxydiphenyl borateand Xestospongin C,abolished the IP3BM-induced Ca2+responses,and signifi-cantly suppressed α1AR-induced cardiomyocyte hypertrophy assayed by cellsize,[3H]leucine incorporation and atrial natriuretic factor gene expression,dur-ing sustained（48 h）phenylephrine ***:These results,therefore,provide cellular mechanisms that link IP3R signaling to α1AR-stimulatedgene expression and cardiomyocyte hypertrophy.

关键词： inositol 1,4,5-trisphosphate receptors Ca2+sparks α1 adrenergic stimulation cardiac hypertrophy