简介:针对多种类不锈钢多元素成分解析问题,应用X射线荧光光谱分析软件UniQuant,采用扩展基本参数法对多元不锈钢、双相不锈钢进行光谱干扰校正和基体校正,重新设定和优化多元不锈钢基体元素的测试条件,计算背景因子、杂质因子、谱线灵敏度系数和光谱重叠系数,测定Si、Mn、S、P、Ni、Cr、Cu、Mo、V、Al、Ti、Nb、Co、Ta、Fe的相对标准偏差在0.04%-3.8%,Ca、Zr、W、As、Sb、Sn的相对标准偏差在5.4%-20.3%,未知样品检测值与认定值比对结果相当理想,Ni、Cr的平均偏差小于0.05%,可以用很少标准样品实现各类型不锈钢多元素成分准确检测,检测范围宽,适用性好。
简介:AnefficientroutetoprepareL-glucoseandL-galactoseisdescribed.TheL-sugarsareachievedbyusingthestrategyofswitchingthefunctionalgroupsatC1andC5ofD-glucoseandD-mannose.TheoxidationandreductionofthesilylenoletheratC1andthelead(IV)tetraacetatemediatedoxidativedecarboxylationatC5arethekeysteps.L-GlucoseandL-galactosearepreparedinaconvenientandinexpensiveway.
简介:NineteenL-N-2-hydroxyethylaminoacidsandL-N,N-bis(2-hydroxyethyl)aminoacidswerepreparedfromthereactionofchlorohydrinwithL-alanine,L-valine,L-leucine,L-isoleucine,L-phenylalanine,L-serine,L-thrcunine,L-glutamicacid,L-asparticacidandglycine.L-N,N,N’,N’-tetra(2-hydroxyethyl)cystinewaspreparedbythereactionofL-cystinewithchlorohydrin.
简介:ByusingOH-terminatedpolyaryletherdendrimerandN-Fmoc-glycineasrawmaterials,thedendriticpolyarylether2-aminoacetate(G3-NH2)wassynthesizedviatwostepreactions.G3-NH2asamacroinitiatorforthering-openingpolymerizationofγ-benzylL-glutamateN-carboxyanhydridewasinvestigated.Itisfoundthattheresultingcopolymerspossessedrelativelyhighmolecularweightandnarrowmolecularweightdistribution(1.12
简介:ConformationofL-lysineinaqueoussolutionwasinvestigatedbylanthanideshiftprobes(Dy,Ho,Er,TmandYb).Reilley’smethodwasemployedtoseparatethecontactanddipolarcom-ponentsofthe13Cparamagneticshifts.ThisstudyrevealsthatCαshifthasthelargestcontactcon-tributionwhiletheothercarbonshiftsaredominatedbythedipolarcontribution.TheaverageoverallconformationofL-lysineinaqueoussolutionisextendedwiththemolecularbackboneintransform.Inthecomplex,lanthanideioncoordinatestothecarboxylgroupwithLn—Obondlength2.2/nandthewholeligandislocatedoutsidethezero-dipolarshiftconeofthelanthanideion.Theelectronicspindensitydistributionontheligandnucleishowsthatthespinpolarizationisthepredominantmech-anismofthecontactinteractionfornucleiincloseproximitytotheboundlanthanideion.
简介:ThesolidcomplexesofCr(AA)2Cl3·nH2OofCrCl3withL-α-aminoacids(AA=Val,Len,Thr,Met,Arg,Phe,TryandHis)havebeenpreparedin95?EtOHmedium,andcharacterizedstructurallybyelementalanalysis,chemicalanalysis,IRspectraandTG-DTG.Theconstant-volumecombustionenergiesofthecomplexeshavebeendetermimedbyRBC-Ⅱtyperotating-bombcalorimeter.Thestandardenthalpiesofformationofthecomplexeshavebeencalculatedaswell,hwichare(-2543.16±3.71)(Val),(-2561.32±4.06)(Leu),(-2284.02±2.95)(Thr),(-1418.77±4.60)(Met(,(-3218.91±4.67)(Arg),(-2643.90±5.02)(Phe),(-1707.18±3.23)(Try)and(-2838.05±3.45)(His)kJ/mol,respectively.
简介:OpticallypureL-butyllactatewassynthesizedbynormaltransesterificationusingnafion-Hcatalystinmoderateyield.Variousreactionconditionswereinvestigated,includingthereactiontemperature,reactiontime,ratioofthestartingmaterialandamountofthenafioncatalyst.
简介:新alkylenedihydrofuranglycoside(1)从根被孤立桑属albaL.吠叫,与moracinM-3鈥?O-尾-一起d-glucopyranoside(2),和moracinM-6,3鈥?di-O-尾-d-glucopyranoside(3)。化合物1作为2-methylene-3-methoxy-2被识别,5-dihydrofuran-4-O-尾-d-glucopyranoside根据包括1D和2DNMR的化学、分光镜的数据光谱分析。另外,1的抗氧化剂活动用1,1-diphenyl-2-picrylhydrazyl(DPPH)和2,2鈥?azinobis-3-ethylbenzothiazoline-6-sulphonic被评估酸(ABTS)试金。IC50价值分别地是2.49和0.45mg/mL。
简介: Enantioimericallypure1,l'-bi-2-naphthol(BINOL)1anditsderivativesareimportantchiralligandsandauxiliariesforanumberofasymmetrictransformations1suchasaldolcondensations,alkylations,Diels-Alderreactions,Michaeladditions,epoxidations,etc.Opticallypure1andtheirderivativeshavealsobeenusedextensivelyinchiralrecognition,chiralseparationandintheconstructionoffunctionalisedmaterials2.Furthermore,(R)-and(S)-BINOLarealsofundamentalstartingmaterialsforthesynthesisofalargevarietyofotherchiralbinaphthylssuchasMOP(2c),NOBIN(2d)andBINAP(2e).Asaresultthedevelopmentofefficientandeconomicmethodsforthepreparationofopticallypure1hasattractedmuchattentioninrecentyears3andnovelmethodsfortheresolutionof(±)-1continuetobedeveloped.……
简介:TwoseriesofterritremBanalogues(10a-10cand18)havebeendesignedandsynthesizedfromjujubogenin5awhichwaspreparedfromjujubogeninglycosides5bobtainedfromtheleavesofZizyphusjujuba.Thestructuresofthenewcompoundswereconfirmedby1H-,13C-NMRandMSdata.Compounds10cand18showedweakinhibitoryeffectonAChEat10^-4mol/E.
简介:由di-(2,4,4-trimethylpentyl)的L本氨基丙酸的抽取行为phosphinic酸,di-(2,4,4-trimethylpentyl)-monothiophosphinic酸和di-(2-ethylhexyl)磷的酸分别地在二阶段、三阶段的系统被学习。为这些抽取反应的平衡常数是计算的。
简介:GinsenosidesRg1,Re,Rb1,Rc,Rb2,Rb3,andRdindifferentpartsoftheAmericanginsengplantwereinvestigated.Theextractionprocesswasapressurizedmicrowave-assistedextraction(PMAE).Thesevenginsenosideswereseparatedanddeterminedbyhigh-performanceliquidchromatography(HPLC)withaultraviolet(UV)detector,at203nm.TheexperimentresultsshowedsignificantvariationsintheindividualginsenosidecontentsoftheAmericanginsengindifferentpartsandagesoftheplant.Theresultsdemonstratedthattheleaves,roothairs,andrhizomesofPanaxquinquefoliusL.containedhigherginsenosidecontents,followedbythemainrootsandstems.TheleavescontaineddramaticallyhigherlevelsofginsenosideRg1,Rb3,andRdthantheotherfourparts.HighercontentsofRb1andRewerepresentinthemainroots,roothairs,andrhizomes.Theamountofginsenosidecontentinthestemswasthelowest.Thetotalcontentofthesevenginsenosidesinmainroots,roothairsandrhizomesincreasedwiththeageoftheplant.Incontrast,theginsenosidecontentsintheleavesandstemsdecreasedwithayearofgrowth.