简介:<正>利用H2S系统的分组方法,进行第二组阳离子分析时,CdS沉淀不完全,或完全不沉淀,常认为是由于酸度过高,但是在实际中,有时酸度合适,即0.3mol-l-1HCl通H2S或0.2mol-1用5%TAA时CdS也不沉淀或沉淀不完全,北师大分析比学提出:为保证CdS沉淀完全,除了必须调整酸度外,还须控制Cl-的浓度,那么Cl-浓度控制在多大范围内,才不影响CdS的沉淀呢?为此,我们做了如下的实验:1、取三支离心管,各加入0.42mol·l-1Cd(NO3)21.0ml,5%的TAAl.0ml和0.6mol·-1HNO31.9ml,然后向三支离心试管中分别加入1.0ml浓度为1.7mol,l-1,3.4mol.l-1和5.13mol.l的NaCl溶液,此时可以看至三支离心管
简介:Theratioofnonsynonymoussubstitutionrate(Ka)tosynonymoussubstitutionrate(Ks)iswidelyusedasanindicatorofselectivepressureatsequencelevelamongdifferentspecies,anddiversemutationmodelshavebeenincorporatedintoseveralcomputingmethods.Wehavepreviouslydevelopedanewγ-MYNmethodbycapturingakeydynamicevolutiontraitofDNAnucleotidesequences,inconsiderationofvaryingmutationratesacrosssites.WenowreportafurtherimprovementofNG,LWL,MLWL,LPB,MLPB,andYNmethodsbasedonanintroductionofgammadistributiontoillustratethevariationofrawmutationrateoversites.Thenoveltycomesintwoways:(1)weincorporateanoptimalgammadistributionshapeparameteraintoγ-NG,γ-LWL,γ-MLWL,γ-LPB,γ-MLPB,andγ-YNmethods;(2)weinvestigatehowvariablesubstitutionratesaffectthemethodsthatadoptdifferentmodelsaswellastheinterplayamongfourevolutionalfeatureswithrespecttoKa/Kscomputations.Ourresultssuggestthatvariablesubstitutionratesoversitesundernegativeselectionexhibitanoppositeeffectonωestimatescomparedwiththoseunderpositiveselection.WebelievethatthesensitivityofournewmethodshasbeenimprovedthanthatoftheiroriginalmethodsunderdiverseconditionsanditisadvantageoustointroducenovelparametersforKa/Kscomputation.
简介:Usingamicrowavegenerator,chlorinedilutedbyheliumwasdissociatedtochlorineatomsthatsubse-quentlyreactedwithhydrogenazidetoproducetheexcitedstatesofNCl(a1△).Meanwhile,moleculariodinewithcarriergasofheliumreactedwithatomicchlorinetoproduceatomiciodinewhichthenwaspumpedtoexcitedstateofI(2P1/2)byanenergytransferreactionfromNCl(a1△).Inthispaper,thechangesofNCl(a1△)andNCl(bi∑)emissionintensityispresentedwhenI2/HeisintroducedintothestreamofCl/Cl2/He/HN3/NCl(a1△)/NCl(b1∑).ThedependencesofatomiciodineI(2P1/2)onflowratesofgaseswerealsoinvestigated.TheoptimumparametersforI(2P1/2)productionaregiven.
简介:KaKs_Calculator是计算的一个软件包裹非同义(Ka)并且同义(K)替换通过平均的模型选择和模型评价。因为存在,为这个评价的方法采用他们的特定的变化(替换)考虑不同进化特征的模型,导致多样的估计,KaKs_Calculator在一个最大的可能性框架实现一套候选人模型并且采用Akaike信息标准测量在模型和数据之间的健康,试图包括为精确地在编码蛋白质的序列捕获进化信息需要的同样多特征。另外,为精明的Ka和K的几存在方法也被合并到这个软件。包括源代码,编译可执行文件,和文档,KaKs_Calculator为在http://evolution.genomics.org.cn/software.htm的学术使用是自由地可得到的
简介:Inthispaper,weareconcernedwiththeexistenceanduniquenessofglobalsolutionsofthemodifiedKS-CGLequationsforflamesgovernedbyasequentialreaction,wheretheterm|P|~2Pisreplacedwiththegeneralizedform|P|~(2σ)P,see[18].Themainnoveltycomparedwith[18]inthispaperistocontrolthenormsofthefirstorderofthesolutionsandextendtheglobalwell-posednesstothreedimensionalspace.
简介:ConstructingareasonablereactionkineticmodelforCr-containingwasteincinerationisofhighsignificancetostudytheeffectofvariousfactors,suchastemperature,Cl,onitshexavalentchromiumcompounds.Inthispaper,aprimaryCr/H/Air/ClreactionkineticmodelisbuiltandstudiedbyGaussian03codewithquantumchemistrytheory.Numericalresultsshowthattherearetwooverallreactionsinthemodel,eachofthetwooverallreactionsconsistsoftheirrespectivetwoelementaryreactions.Sothetwooverallreactionsshouldbeomittedfromthemodel.Instead,thefourelementaryreactionsshouldbeaddedintheCr/H/Air/Clreactionkineticmodel.Theactivationenergiesofthefourelementaryreactionsarealsocalculated.