简介：<正>方程(组)的知识是初中数学的核心内容之一,也是历年中考热点.这部分知识内容涉及的考点主要有:一元一次方程、二元一次方程组、可化为一元一次方程的分式方程、一元二次方程的解法以及列方程(组)解决实际问题.一、考点内容知识脉络二、专题考点解析在中考中,考点有如下特点:(1)考查方程(组)的概念和解法的基础知识,类型常以选择题、填空题、解答题形式出现,有时也会与一次函数、不等式相结合出题;(2)一元二次方程是二次函数的一种特殊形式,两者有着密切的关系,在中考题中主要以填空题、选择

简介：Pr原子特殊的电子层结构使其具有多方面的催化特性.实验发现质量分数为0.7%的PrCl3就可使漆酚(U)于110℃固化成膜的时间从5h降低到1h.用可见分光光度法、电子能谱、紫外和红外光谱等方法研究U在PrCl3作用下的固化成膜历程.结果表明,在Pr(Ⅲ)催化U聚合的过程中首先是U与PrCl3发生配位作用,生成U镨配合物(UPr),然后该配合物分子中的Pr(Ⅲ)催化U聚合成体形结构的高分子化合物.

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简介：GeneralizedSteiriertriplesystems,GS(2,3,n,g),areequivalenttomaximumconstantweightcodesoveranalphabetofsizeg+1withdistance3andweight3inwhicheachcodewordhaslengthn.ThenecessaryconditionsfortheexistenceofaGS(2,3,n,g)are(n-1)g≡0(mod2),n(n-1)g2≡0(mod6),andn≥g+2.Thesenecessaryconditionsareshowntobesufficientbyseveralauthorsfor2≤g≤11.Inthispaper,threenewresultsareobtained.First,itisshownthatforanygiveng,g≡0(mod6)andg≥12,ifthereexistsaGS(2.3.n.g)foralln,g+2≤n≤7g+13.thenthenecessaryconditionsarealsosufficient.Next,itisalsoshownthatforanygiveng,g≡3(mod6)andg≥15,ifthereexistsaGS(2,3,n,g)foralln,n≡1(mod2)andg+2≤n≤7g+6,thenthenecessaryconditionsarealsosufficient.Finally,asanapplication,itisprovedthatthenecessaryconditionsfortheexistenceofaGS(2,3,n,g)arealsosufficientforg=12,15.

简介：TheconductivitybehaviorofAl(OH)3-acrylamidehybridpolyacrylamide(hybridPAAm)indistilledwaterwasstudied.Adiscontinuityphenomenonoftheconductivity(k)versusconcentration(c)curveofthehybridPAAminacertainconcentrationregimeisfound.ThisphenomenonisdependentonthemolecularweightofthehybridPAAmandontheparticlesizeandcontentoftheAl(OH)3colloidinthehybridPAAm.ThisphenomenonwasaccountedforassumingionizationofthehybridPAAm.

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简介：本文阐述了Flashcs3AcdonScript课件的优势及如何利用Flashcs3中具有的强大编程功能的AetionScript脚本语言制作大学物理CAI课件。

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简介：Thenonstaggeredgridsareadoptedinthispaperforsolvingthegoverningequationsofflowsinthecurvilinearcoordinatesystems.Thepresentpaperdemonstratesthebasicreasonandcorrespondingeliminatingmethodforthepressureoscillation,anddeducesthecorrectedexpressionsforthecurvilinearvelocitycomponentsinwhichandadditionaltermrepresentingthedifferencebetweenthe1-δand2-δdifferencevaluesforthepressuregradientappears.Thusifanoscillatorypressurefiledwerearisen,themagnitudeofthistermwouldbelargeandwouldacttoremovetheoscillation;whereasfornonoscillatoryfieldthemagnitudeofthistermremainssmall.Asexaminationforthenumericalmethod3-Dturbulentflowinasquareductwith90°bendand3-Dturbulentmixinglowinalobed-mixerwerecalculatiedrespectively.Thenumericalresultsaresatisfactory.

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简介：讨论了一种3度正则网络,这类网络具有较小的网络直径,本文给出了网络直径、网络支撑树和欧拉环游的数目的公式.

简介：Fe2O3/activecarbon(Fe2O3/AC)nanocompositeswerereadilyfabricatedbypyrolyzingFe3+impregnatedactivecarboninanitrogenatmosphere.Theas-preparedcompositeswerestudiedbyX-raypowderdiffraction(XRD),X-rayphotoelectronspectroscopy(XPS)andtransmissionelectronmicroscopy(TEM).Thecapacitivepropertyofthecompositeswasinvestigatedbycyclicvoltammetry(CV)andgalvanostaticcharge-dischargetest.Physicalcharacterizationsshowthattheγ-Fe2O3finegrainsdispersedintheACwell,withameansizeof21.24nm.Electrochemicaltestsin6mol/LKOHsolutionsindicatethattheas-preparednanocompositesexhibitedimprovedcapacitiveproperties.Thespecificcapacitance(SC)ofFe2O3/ACnanocompositeswasupto188.4F/gthatwasderivedfrombothelectrochemicaldouble-layercapacitanceandpseudo-capacitance,whichwas78%largerthanthatofpristineAC.AsymmetriccapacitorwithFe2O3/ACnanocompositesaselectrodeshowedanexcellentcyclingstability.TheSCwasonlyreducedbyafactorof9.2%after2000cyclesatacurrentdensityof1A/g.

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简介：我们为象一个维的p拉普拉斯算符那样的操作符考虑一个三点的边界值问题，并且显示出他们什么时候，并且多少有解决方案。反的操作员被包含零一真实值的功能的各种各样的公式给。他们被显示保存顺序，为为其它珍视的一些参数值，和非单条。操作符被显示在连续函数的空格m消散。关键词边界价值问题-非线性的o.d.e.s-p拉普拉斯算符-三点的边界价值问题-m消散的先生(2000)题目分类34B15-34L30-47H06

简介：Thevisualsystemisvitaltohumanhealth,andtheeffectsofionizingradiationonvisionhavereceivedincreasingattention.Usingazebrafishmodel,thisstudywasdesignedtoinvestigatetheapoptosisineyesinducedbycarbonionirradiation.Zebrafishembryosat12hpost-fertilization(hpf)wereirradiatedusing12C6+ionbeamsatdosesof2,4and8Gy.

简介：Inthispaperweobtainthebestapproximationconstantoffunctionf（x）(∈C2π)bytheJackson’stypeoperatorJπ3（f;x）,i.e.‖Jn,3（f,x）-f（x）‖c≤（4-6/π）ω（f,1/n）,‖Jn,3（f,x）-f（x）‖c≤（8-17/π）ω2（f,1/n）

简介：Themillrollerbeatingismadeupofaninternalring,middlerollsandanexternalring,theanalysisofwhiehisamulti-bodiescontactproblem.Inthispaper,basedonthethree-dimensionalelasticcontactBEMwithoutfriction,andusingthestructuralcharacteristicsofrollerbearings,middlerollsarede-scribedbyelasticplateunitsofdifferentshapes,whichisplacedontheinternalring.Thediscontinuoustractionproblemofthecontactelementcanbedealtwithbythetractionsub-elementmethod.Thereforethecontactproblemcanbechangedfroinoneofmulti-bodiestooneoftwo-bodies.Asanelasticdeformationoftheplateelement,itcanbecalculatedbyanelasticcontactformulaandisregardedananequivalentgaptobeputintothetotalmatrixequality.Theface-to-facecontactconditionofdisplacementandtractionontheelementwillnerveastheconvergencejudgingcondition.Soconvergencesolutioncanbeobtainedbeforeanygeometryinconsistentonthecontactelementmaytakeplace.Therefore,thethree-dimensionaldistributionofloadofthemillrollerbearingcanbeachieved,Ithasbeenprovedthatthecalculatingmodelofthismethodisvisualizedandsimple,haslastconvergencesolutionandhigheraccuracy,makingitaneffectivenumericalmethodofdesigningandanalyzingloadcharacteristicsofthemillrollerbearing.

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