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简介：Thedomainoflinearfunctionf(x)=ax+b(a≠0)isR,itsrangeisR.Thedomainofinverseproportionfunctionf(x)=(k/x)(k≠0)is{x|x≠0},itsrangeisB={y|y≠0}.Thedomainofquadraticfunction,f(x)=ax~2+bx+c(a≠0)isR,itsrangeisB.B={y|y≥(4ac-b~2)/4a},whena>0;B={y|y≤(4ac-b~2/4a)},

简介：Wehavelearnedtheconceptofthefunc-tioninthejuniorhighschool.Itiswhatde-scribeslikethis:Establishtohavetwovariablesxandyinavarietyofprocess.Ifyisauniqueelementassignedtoeveryx,sayingyisafunctionofx;xiscalledtheindependentvariable.

简介：Whenyoufindthetangentlinetoacurveatonepointandthevelocityofanobject,youwillfindbothoftheminvolvingthesametypeoflimit.Let’sstartwiththedifferencequotient.

简介：Thesteady-stateelectricalconductivity,aswellasthedielectricpropertiesbetween2×10-4Hzand100kHz,andat1GHz,arereportedforureasecompressedpowdersamplesoflowhydration.Theresultsshowthatthelarge,lowfrequencydielectricdispersion,knownasα-dispersion,isduetothebuild-upofaspacechargeofprotonsatthesample-electrodeinterfaces.Asmallerdispersion,appearingathigherfrequencies,isconcludedtobeassociatedwithhinderedmotionsofthepeptideresiduesinthemolecularstructureofurease.Theextentofthesepolypeptidebackbonemotionsisshowntobestronglydependedontheextentofenzymehydration.Thisworkiscontributedtothede-velopmentofconductimetricbiosensors.

简介：Background:Childrenareaffectedbydisordersthathaveanimpactontherespiratorymuscles.Inspiratorymusclefunctioncanbeassessedbymeansofthenoninvasivetension–timeindexoftheinspiratorymuscles(TTImus).OurobjectivesweretoidentifythedeterminantsofTTImusinhealthychildrenandtoreportnormalvaluesofTTImusinthispopulation.Methods:Wemeasuredweight,height,upperarmmusclearea(UAMA),andTTImusin96childrenaged6–18years.Thelevelandfrequencyofaerobicactivitywasassessedbyquestionnaire.Results:TTImuswassignificantlylowerinmalesubjects(0.095±0.038,mean±SD)comparedwithfemalesubjects(0.126±0.056)(p=0.002).TTImuswassignificantlylowerinregularlyexercising(0.093±0.040)comparedwithnonexercisingsubjects(0.130±0.053)(p<0.001).TTImuswassignificantlynegativelyrelatedtoage(r=-0.239,p=0.019),weight(r=-0.214,p=0.037),height(r=-0.355,p<0.001),andUAMA(r=-0.222,p=0.030).MultivariatelogisticregressionanalysisrevealedthatheightandaerobicexerciseweresignificantlyrelatedtoTTImusindependentlyofage,weight,andUAMA.ThepredictiveregressionequationforTTImusinmalesubjectswasTTImus=0.228-0.001×height(cm),andinfemalesubjectsitwasTTImus=0.320-0.001×height(cm).Conclusion:Gender,age,anthropometry,skeletalmuscularity,andaerobicexercisearesignificantlyassociatedwithindicesofinspiratorymusclefunctioninchildren.NormalvaluesofTTImusinhealthychildrenarereported.

简介：Theeffectofacuteexercise,asingleboutofexercise,oncognitiveperformancehasattractedmuchattention.ThefirstnarrativereviewofthisliteraturewasconductedbyTomporowskiandEllis.1Intheirsummary,theauthorsconcludedthatacuteexercisefacilitatescognitiveperformance;however,theyemphasizedthatthestudiesatthattimewereatheoreticaland

简介：Purpose:Thepurposeofthisstudywastoestablishtherelationshipbetweenvariousexpressionsofrelativeexerciseintensitypercentageofmaximaloxygenuptake(%VO_(2max)),percentageofmaximalheartrate(%HR_(max)),%VO_2reserve(%VO_2R),and%HRreserve(%HRR))inordertoobtainthemoreappropriatemethodforexerciseintensityprescriptionwhenusinganimmersibleergocycle(IE)andtoproposeapredictionequationtoestimateoxygenconsumption(VO_2)basedonIEpedalingrate(rpm)foranindividualizedexercisetrainingprescription.Methods:Thirty-threehealthyparticipantsperformedincrementalexercisetestsonIEanddrylandergocycle(DE)atequalexternalpoweroutput(Pext).ExerciseonIEbeganat40rpmandwasincreasedby10rpmuntilexhaustion.ExerciseonDEbeganwithaninitialloadof25Wandincreasedby25W/minuntilexhaustion.VO_2wasmeasuredwithaportablegasanalyzer(COSMEDK4b~2)duringbothincrementaltests.OnIEandDE,%VO_2R,%HRmax,and%HRRatequalPextdidnotdiffer(p>0.05).Results:The%HRRvs.%VO_2RregressionforbothIEandDEdidnotdifferfromtheidentityline%VO_2RIE=0.99×HRRIE(%)+0.01(r~2=0.91,SEE=11%);%VO_2RDE=0.94×HRRDE(%)+0.01(r~2=0.94,SEE=8%).Similarmeanvaluesfor%HRmax,%VO_2R,and%HRRatequalPextwereobservedonIEandDE.PredictedVO_2obtainedaccordingtorpmonIEisrepresentedby:VO_2(L/min)=0.000542×rpm2-0.026×rpm+0.739(r=0.91,SEE=0.319L/min).Conclusion:The%HRR–%VO_2RrelationshipappearstobethemostaccurateforexercisetrainingprescriptiononIE.Thisstudyoffersnewtoolstobetterprescribe,control,andindividualizeexerciseintensityonIE.

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简介：Naturaladultagingisassociatedwithmanyfunctionalimpairmentsofthehumanneuromuscularsystem.Oneofthemoreobservablealterationsisthelossofcontractilemusclemass,termedsarcopenia.Thelossofmusclemassoccursprimarilyduetoaprogressivelossofviablemotorunits,andaccompanyingatrophyofremainingmusclefibers.Notonlydoesthelossofmusclemasscontributetoimpairedfunctioninoldage,butalterationsinfibertypeandmyosinheavychainisoformexpressionalsocontributetoweaker,slower,andlesspowerfulcontractingmuscles.Thisreviewwillfocusonmotorunitlossassociatedwithnaturaladultaging,age-relatedfatigability,andtheage-relateddifferencesinstrengthacrosscontractilemuscleactions.

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简介：GoldMedalsinSummerQlympicsMeasuresA1)Programtodevelopjuniorathletestotoplevel2)NationalTrainingCenter3)NationalCoachAcademyB1)Sportsmedicineandsciences(JISS)2)Anti-doping3)Toholdinternationalcompetitions

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简介：Background:Physicalactivity(PA)hasbeenshowntobenefitcognitivefunctioninolderadults.However,thecognitivebenefitsofexercisingforolderChineseadultshavenotbeensystematicallydocumented.ThisstudywastoconductasystematicreviewonevidencethatPAisbeneficialforcognitivefunctioninginolderChineseadults.Methods:Majordatabases,includingPubMed,EMBASE,CochraneLibrary,WanFang,CNKI,andVIP,weresearchedforstudiespublishedinEnglishorChinesebetweenJanuary2000andDecember2015.Randomizedandnon-randomizedcontrolledtrials(RCTsandnon-RCTs),cohort,case-controlandcross-sectionalstudiesthatevaluatedPAandcognitivefunctionamongolderChineseadultswereincludedinthisreview.Results:Of53studiesincludedandreviewed,33wereobservational(22cross-sectional,7case-control,and4cohort)and20wereexperimental(15RCTs,5non-RCTs).Observationalstudiesshowedanassociationofreducedriskofcognitive-relateddiseases(i.e.,mildcognitiveimpairment,Alzheimer’sdisease,anddementia)throughPA,whereasexperimentalstudiesreportedexercise-inducedimprovementinmultipledomainsofcognitivefunction(i.e.,globalcognitivefunction,memory,executivefunction,attention,language,andprocessingrecourse).Conclusion:ThissystematicreviewprovidesinitialevidencethatPAmaybenefitcognitioninolderChineseadults.FurtherstudiesofindividualswithcognitiveimpairmentsandprospectiveandRCTstudieshavinghighscientificrigorareneededtocorroboratethefindingsreportedinthisreview.

简介：Background:Cognitiveimpairmentisprevalentamongolderadultsandresultsindegradedqualityoflifeforolderadults.Asthepopulationages,thismaycauseahugeburdentosociety.Researchhasdemonstratedthatphysicalexerciseisbeneficialtocognitivefunction.Thepurposeofthismeta-analysiswastocriticallyassesstheeffectofTaiChiexerciseonglobalcognitive,executive,andmemoryfunctionsinolderadults.Methods:Afterathoroughelectronicsearchandselection,eightstudieswereincludedinthismeta-analysiswithtwocross-sectionalandsixinterventionstudies.Ninevariablesincludedinthismeta-analysiswere:minimentalstatusexamination(MMSE),Alzheimer’sdiseaseassessmentscale-cognitivesubscale(ADAS-cog),trailmakingtestpartA(TMA),trailmakingtestpartB(TMB),digitspantestforward(DSF),digitspantestbackward(DSB),visualspantestbackward(VSB),verbalfluencytest(VFT),andworddelayrecalltest(WDR).Theeffectsizesandforestplotsoftheseninevariablesweregenerated.Results:Four(MMSE,DSB,VSB,andVFT)outofninevariablesweresignificantlyimprovedafterTaiChiexercisewiththeeffectsizesrangedfrom0.20to0.46(smalltomedium).MMSErepresentedglobalcognitivefunction,andDSB,VSB,andVFTrepresentedmemoryfunction.Conclusion:TaiChiasamind-bodyexercisehasthepositiveeffectsonglobalcognitiveandmemoryfunctions,andmoreconsistentpositiveeffectswerefoundonmemoryfunction,especiallyverbalworkingmemory.

简介：Thestressintensityfactor(SIF)isacriticalparameterassociatedwiththefracturebehaviourofmaterials.Inthispaper,weselectthedisplacementfunctionaroundacracktipastheshapefunctionofthedigitalimagecorrelation(DIC),whichmakesitpossibletodirectlycalculatetheSIFbythecorrelationscheme.Moreover,weuseanon-rectangularsubset,whichcanreducetheinfluenceofplasticdeformationandcrackwidthontheDICmeasurementaccuracy.WemeasuredtheSIFofamodeIcrackinasuper-hardaluminiumalloyspecimentoverifytheperformanceoftheproposedmethod.OurexperimentalresultsshowthataDICwithaspecificshapefunctioncanbeusedtoaccuratelyandefficientlycalculatetheSIF.Furthermore,wealsopresentapracticalapplicationofourproposedmethodfordeterminingtheSIF,crackpropagationangleandcracktipdisplacement.

简介：Purpose:Acuteexercisehasbeenlinkedtothefacilitationofexecutivefunction,butlittleisknownregardingexecutivefunctionassessedbytheWisconsinCardSortingTest(WCST).ThepresentresearchconsistedoftwoexperimentsaimedtodeterminewhetheracuteaerobicexerciseinfluencessuccessiveWCSTperformance.Methods:InStudy1,27youngadultswererandomlyassignedtotheexerciseorreadingcontrolgroupandtheninstructedtoperformtheWCSTbeforeandafterassignedtreatment.Inexercisegroup,participantscompletedasingleboutaerobicexercisewithmoderateintensityfor20minonastationarybike.AsimilarexperimentalprotocolwasreplicatedinStudy2with24latemiddle-agedadultstolookforagedifferencesduringadulthoodandcontrolforapotentialceilingeffectatyoungadultage.Results:Althoughasignificanttimeeffectwasobservedinyoungadults,bothstudiesrevealedthattherewasnomaineffectfortreatmentoraninteractionbetweentreatmentandtimeonanyoftheWCSTindices.Conclusion:AcuteaerobicexercisefailedtoinfluenceexecutivefunctionasassessedbytheWCST,revealingthatthisclassicalneuropsychologicaltesttappingexecutivefunctionmaynotbesensitivetoacuteexercise.Ourfindingssuggestthatacuteexercisedoesnotbroadlyaffecttheentirefamilyofexecutivefunctions,oritseffectonaspecificaspectofexecutivefunctionmaybetask-dependent,asproposedbyEtnierandChang(2009).

简介：Neuromuscularactivityissuppressedduringmaximaleccentric（ECC）musclecontractioninuntrainedsubjectsowingtoattenuatedlevelsofcentralactivationandreducedspinalmotorneuron（MN）excitabilityindicatedbyreducedelectromyographysignalamplitude,diminishedevokedH-reflexresponses,increasedautogenicMNinhibition,anddecreasedexcitabilityindescendingcorticospinalmotorpathways.MaximumECCmuscleforcerecordedduringmaximalvoluntarycontractioncanbeincreasedbysuperimposedelectricalmusclestimulationonlyinuntrainedindividualsandnotintrainedstrengthathletes,indicatingthatthesuppressioninMNactivationismodifiablebyresistancetraining.Insupportofthisnotion,maximumECCmusclestrengthcanbeincreasedbyuseofheavy-loadresistancetrainingowingtoaremovedordiminishedsuppressioninneuromuscularactivity.Prolonged（weekstomonths）ofheavy-loadresistancetrainingresultsinincreasedH-reflexandV-waveresponsesduringmaximalECCmuscleactionsalongwithmarkedgainsinmaximalECCmusclestrength,indicatingincreasedexcitabilityofspinalMNs,decreasedpresynapticand/orpostsynapticMNinhibition,andelevateddescendingmotordrive.Notably,theuseofsupramaximalECCresistancetrainingcanleadtoselectivelyelevatedV-waveresponsesduringmaximalECCcontraction,demonstratingthatadaptivechangesinspinalcircuitryfunctionand/orgainsindescendingmotordrivecanbeachievedduringmaximalECCcontractioninresponsetoheavy-loadresistancetraining.