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简介：TheresearchesonCriticalPeriodHypothesis(CPH)aimstoexplaintheimportanceoftheagefactorintheprocessoflearningasecondlanguage.Inthisessay,acriticalreviewofthetheoreticalissuesandempiricalresearchontheCPHwillspreadout.Meanwhile,thediscussionofimplicationandlimitationoftheCPHresearchwillbeconcernedaswell.

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简介：吸附是为环境补习的最广泛地应用的技术之一。它的动力学意义大评估给定的吸附物和获得卓见的表演进内在的机制。有有关吸附动力学可得到的大量参考书，并且几个数学模型被开发了描述吸附反应和散开过程。然而，这些模特儿经常被雇用适合运动数据在一不合适或不适当举止。这主要是因为到可观的程度，联系模型的边界条件为数据建模被忽略。这里，我们考察了几使用得广泛地的吸附运动模型并且对他们的边界条件给予了更多的注意。我们相信评论为吸附某些意义和改进是运动建模。

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简介：Tocontrolmovement,thebrainhastointegrateproprioceptiveinformationfromavarietyofmechanoreceptors.Theroleofproprioceptionindailyactivities,exercise,andsportshasbeenextensivelyinvestigated,usingdifferenttechniques,yettheproprioceptivemechanismsunderlyinghumanmovementcontrolarestillunclear.Inthecurrentworkwehavereviewedunderstandingofproprioceptionandthethreetestingmethods:thresholdtodetectionofpassivemotion,jointpositionreproduction,andactivemovementextentdiscrimination,allofwhichhavebeenusedforassessingproprioception.Theoriginofthemethods,thedifferenttestingapparatus,andtheproceduresandprotocolsusedineachapproacharecomparedanddiscussed.Recommendationsaremadeforchoosinganappropriatetechniquewhenassessingproprioceptivemechanismsindifferentcontexts.

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简介：让一，b，k，r是有1一b和r的nonnegative整数2。让G是有$n的顺序n的一张图>\tfrac{{(+b)(r(+b)-2)+ak}}{一}$。在这份报纸，我们首先为部分的所有显示出描述(一，b，k)批评的图。然后使用结果，我们证明G都是部分的(一，b，k)批评如果$\delta(G)\geqslant\tfrac{{(r-1)b^2}}{一}+k$并且$|N_G(x_1)\cupN_G(x_2)\cup\cdots\cupN_G(x_r)|\geqslant\tfrac{{bn+ak}}{{+b}}$为任何独立子集{x1，x2，，xr}在G。而且，这被显示出条件$|N_G(x_1)上的更低的界限\cupN_G(x_2)\cup\cdots\cupN_G(x_r)|\geqslant\tfrac{{bn+ak}}{{+b}}$是在某感觉可能的最好，并且它是Lus的延期以前的结果。

简介：ＣＲＩＴＩＣＡＬＳＴＯＰＰＩＮＧＴＩＭＥＳＡＮＤＳＥＭＩＭＡＲＴＩＮＧＡＬＥＳＯＦＳＴＯＣＨＡＳＴＩＣＰＲＯＣＥＳＳＥＳＨｕＢｉｊｉｎ（胡必锦）（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃｓＨＵＳＴＷｕｈａｎ，ＨｕｂｅｉＰ．Ｒ．Ｃ．３．１９９２）Ａ...

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简介：Anembeddedcylinderisalarge-diametercylinderembeddedinasoilfoundation.Thestateoffailureofsuchanembeddedcylindricalstructureshowslargedeflectioninsteadofslideandoverturnofthetraditionalgravitytypeofstructureplacedonarubblebaseorfoundationbase.Thecriticalvalueofdeflectionoftheembeddedcylindricalstructure,whichisthemaximumallowabledeflectionforstabilitycalculationofthecylinder,isavitalcontrolvalue.Throughinvestigationondeflectionandsoilpressuresonanembeddedcylinderbymodelexperiments,thevariationsoftheangleofrotationθofacylinderwitheffectiveanti-overturningratioηandmomentMHofthrustarediscussed.Onthebasisofexperimentalstudy,thecriticalvalueofdeflectionofthecylindricalstructureisproposedinthepaper.Meanwhile,theformulasforcalculatingdeflectionofcylindersarederived.

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简介：目的:对现有的关于研究水合状态对运动员身体活动能力影响的证据进行批判性分析。方法:从多个数据库检索获取符合纳入标准的文献,随后采用唐斯和布莱克协议(DownsandBlackprotocol)对纳入文献进行批判性评估。结果:9篇文章符合入选标准,平均79%在方法论质量上代表高标准的研究。结论:证据表明在持续30s以上的活动中,脱水状态在身体表现中有消极作用:然而在少于15s的持续运动中,脱水状态对身体表现并无显著影响。

简介：Themostsignificantdifferencesbetweencontinuousweldedrails(CWRs)andgeneralsplit-typeconnectorsareaxialcompressioninthelongitudinaldirection,bucklingstabilityandotherissuesgeneratedundertheinfluenceofthermaleffect.Underthermaleffect,adynamicalbehaviorsimilartothatofabeamfixedontwosidesoccursinthecentrallockedareaoftheweldedrail,asthereisaxialcompressionbutnopossibilityofsliding.Continuousweldedrailsdonotcontractorexpand,andaresupportedbythedynamicalsystemmadeupofballastsandrailclips.Therail-supportsystemmentionedabovehasthefeaturesofnon-uniformmaterialdistributionanduncertaintyofconstructionquality.Duetothesefacts,thedynamicsmethodbasedonthelinearelastichypothesiscannotcorrectlyevaluatetherail'sbucklingconditions.ThisstudyisaimedatapplyingFiniteDifferenceMethod(FDM)andMonteCarloRandomNormalVariablesMethodtotheanalysisofweldedrail'sbucklingbehaviorduringthetrain'saccelerationanddeceleration,underthermaleffectanduncertainfactorsofballastandrailclips.Theanalysisresultshowedthatbucklingoccursunderthecombinedeffectofthermaleffectandthetrain'sdecelerationforceco-effectandthevarianceratioofballastandrailclipsisover0.85,orunderthecombinedeffectofthermaleffectandthetrain'saccelerationforcewhenthevarianceratioisover0.88.

简介：Inthispaper,westudythelocalbifurcationofcriticalperiodsnearthenondegeneratecenter(theorigin)ofaclassofLiénardequationswithdegree2n,andprovethatatmost2n-2criticalperiods(takenintoaccountmultiplicity)canbeproducedfromaweakcenteroffiniteorder.Wealsoprovethatitcanhaveexactly2n-2criticalperiodsneartheorigin.