简介:TheVaR,anewappearingfinancialrisk-managetool,havebeenappliedwidely.ManyfinancialsetupshaveaccustomedtomeasuretheriskofaportfoliowiththeVaR.SoitisverynecessarytodiscusstheportfoliochoiceproblemundertheVaRconstraint.Inthispaper,bysettingandsolvingtheportfoliochoicemodelundertheVaRconstraint,weillustratethattheuseoftheVaRconstraintreducesthearrayofchoicetoamoremanageablerange.TheprobabilityoftragetVaR,therefore,canbethoughtofasarisktoleranceassessmenttool(whencoupledwithanothermeasureofrisk).
简介:ChemicalinvestigationontheethanolextractfromtherootsofSpiraeajaponicavar.acutaresultedintheisolationoftwonewditerpenealkaloidsnamedspiratinesAandB(1-2),respectively.
简介:2003年12月全国人大通过了《中华人民共和国银行业监督管理法》,第三条明确了银行监督管理的目标是促进银行业的合法、稳健运行,维护公众对银行业的信心。银行业监督管理应当保护银行业公平竞争,提高银行业竞争能力。这包含了金融监管的两大目标,金融稳定与金融效率,其核心的部分是对风险的控制,只有有效地控
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简介:FamilyoutcrossingratesofPinuscaribaeavar.caribaeapopulationsthatdifferedinoriginandmanagementwereestimatedbyusingisozymemarkers.Thefamilyoutcrossingrateswereestimatedby(1)fixingtheprobabilityofpollengenefrequency(p);(2)allowingpollengenefrequencytovaryamongfamilies.Theestimatesoffamilyoutcrossingratesforallthepopulationsvariedwidelyamongfamilies(clonesoftheseedorchard),rangingfrom0.39to2.0.Theaveragefamilyoutcrossingratesofbothm...
简介:GracilariatenuistipitatavarliuiZhangetXiaiscultivatedattwodifferentsalinities(21,33)inthelaboratoryfor4weeks.Thedailygrowthrateisdetermined.Thetotalagaryieldandfractionalagarcompositionareanalyzed.Resultsshowthatalgaegrowfasterinlowsalinity.Thetotalagaryieldishigherunderhighsalinityconditionsthanunderlowsalinityconditions.Amongtheeightfractionsextracted,theyieldsofcoldwaterextractand40%ethanolextractareaboutthehighest.Inlowsalinitiestheyieldsofautoclavedextractand60%ethanolextractarehigher,whiletheyieldofcoldwaterextractislowerrelativetohighsalinities.
简介:目的从巴西巴豆属药用植物的一新变种复制Muel的叶中分离生物碱成分.方法应用硅胶柱层析法分离和纯化,波谱分析与已知化合物的波谱和理化性质比较得以确定化合物结构.结果分离得到12个生物碱,其中4个为新生物碱,命名为hemiargineA(1),B(5),C(6)和D(7);8个已知生物碱为isocorydine(2),corydine(3),noreorydine(4),salutari-dine(8),glaucine(9),tetrahydropalmatrubine(10),xylopinoine(11)和norlaudanosine(12).结论获得4种新化合物,除生物碱(8),其余生物碱均为首次从该属植物中获得.
简介:DeoxybaccatinⅥ(4α,7β,9α,10β,13α-penta-acetoxy-2α-benzoyloxy-5β,20-epoxytax-11-ene)wasisolatedfromtherootsofTaxuschinensis,Rehd.var.mairei.Thestructuralassignmentsofthecompoundwerebasedontheirspectraldata,including2DNMRexperimentsandchemicalcorrelation.TheX-raycrystallographicanalysisof1-deoxybaccatinⅥprovidedunambiguouscharacterizationforthestructures.Inthestructure,thesix-memberedAringexhibitsboatconformation,theeight-memberedBringadoptsboat-chairconformation,andthesix-memberedCringexhibitsasofaconformation.