nanotube
碳纳米管论文
MaterialsChemistryandPhysics134(2012)958e965
ContentslistsavailableatSciVerseScienceDirect
MaterialsChemistryandPhysics
journalhomepage:http://wendang.chazidian.com/loca
内容需要下载文档才能查看te/matchemphys
PrescribedmorphologyandinterfacecorrelationofMWNTs-EP/PSFhybridnano bersreinforcedandtoughenedepoxymatrix
GangLia,b,*,XiaolongJiab,ZhibinHuangb,BoZhub,PengLib,XiaopingYangb,*,WuguoDaic
a
CollegeofMechanicalandElectricalEngineering,BeijingUniversityofChemicalTechnology,Beijing100029,PRChina
StateKeyLaboratoryofOrganiceInorganicComposites,BeijingUniversityofChemicalTechnology,Beijing100029,PRChinac
NantongXingChenSyntheticMaterialsCo.,ChinaBlueStarCo.,Nantong226017,PRChina
b
articleinfo
Articlehistory:
Received21May2011Receivedinrevisedform30January2012
Accepted23March2012
abstract
MWNTs-EPweresuccessfullypreparedbyfunctionalizationofMWNTswithepoxy-basedgroups,andMWNTs-EP/polysulfone(PSF)hybridnano berswerefabricatedtoobtainex-situdispersionandalign-mentofMWNTs-EPbyelectrospinning.Theprescribedmorphologyandinterfacecorrelationofhybridnano bersreinforcedandtoughenedepoxymatrix(RTEP)wereinvestigated.Thealignmentdegreeofhybridnano berswasenhancedwithincreasingMWNTs-EPloadings,andMWNTs-EPwerefoundtobewelldispersedandalignedalongthenano beraxis.ThedispersionandalignmentstatesofMWNTs-EPduringinhomogeneousphaseseparationofRTEPwereproposedandveri ed.MWNTs-EPdispersedandalignedalongtheorginalnano beraxiswereenveloped,bridgedorpinnedbyPSFspheresarrangedinthenano berdirection.TheinterfacechemicalcorrelationbetweenMWNTs-EPandresinmatrixwasgeneratedduetothefurtherreactionofepoxideringsonthesurfaceofMWNTs-EP,whichresultedinsimultaneousimprovementofmechanicalandthermalpropertiesofRTEP.
Ó2012ElsevierLtd.Allrightsreserved.
Keywords:Interfaces
Nanostructures
ElectronmicroscopyFractureandtoughness
1.Introduction
Sincecarbonnanotubes(CNTs)were rstusedas llerinepoxymatrixinthemid1990s,CNTreinforcedepoxymatrixhavebeenexploredasnewprospectsforsuperiorcompositematerialswithhighstrength,lowweightandmulti-functionalfeatures[1e3].However,theatomicallysmoothnonreactivesurfaces,thedistinc-tivelypoorinterfacialbonding,andthespontaneouslyentangledaggregationpropertieshavelimitedtheeffectivenessofCNTs[4,5].Therefore,thestronginterfacialinteractionbetweenCNTsandmatrixaswellasthehomogenousdispersionofCNTsintheepoxymatrixshouldbeapre-requisiteinordertoobtainhighperfor-mancepolymercomposites[6,7].Forthispurpose,chemicalfunc-tionalizationofthesurfaceofCNTshasbeenproposedasanef cientmethod[8e10]toimprovetheinterfacialstresstransferandpositivelyaffectthedispersibilityofCNTs.Epoxy-basedfunc-tionalizationofCNTswasshowntobethemostfavorableduetotheabilityoffurtherreactingofepoxidegroupsgraftedonthesurfaceofCNTs[11].
*Correspondingauthors.StateKeyLaboratoryofOrganiceInorganicComposites,BeijingUniversityofChemicalTechnology,Beijing100029,PRChina.Tel./fax:þ861064412084.
E-mailaddresses:ligang@http://wendang.chazidian.com(G.Li),yangxp@http://wendang.chazidian.com(X.
内容需要下载文档才能查看Yang).
0254-0584/$eseefrontmatterÓ2012ElsevierLtd.Allrightsreserved.doi:10.1016/j.matchemphys.2012.03.098
Anotherimportantaspecttobeconsideredforthesematerialswasthenano-andmicro-morphologyofreinforcementphaseandreinforcedcomposites[2,12].Vaia[13]hassuggestedtheideaof“nanocomposites-by-design”,andtriedtoestablishstructure-performancecorrelationsofcompositesbycontrollingthedistri-butionandarrangementofdispersed,preformedCNTs.Xie[14]andEsawi[15]alsoconsideredthattheenhanceddispersionandalignmentofCNTsinthepolymermatrixweredirectlyrelatedtothemechanicalandfunctionalpropertiesofCNTs/polymercomposites.TooptimizethepropertiesofCNTs/polymercompos-ites,Raravikar[16]andFeng[17]pointedoutthatthedispersionandalignmentofCNTscouldbeachievedpriortocompositefabricationwherealignednanotubesareincorporatedintothepolymermatrixusinganexternalelectric eld.Therefore,variousprocessingtechniqueshavebeenexploitedtoestablishthecouplingbetweenappliedexternalforcesandthedistributionandalignmentofCNTs[18e20].Atpresent, berspinningisconsideredaseffectivemethodtopossesstheabilitytoinduceex-situdispersionandalignmentofCNTsbymechanicaldeformation.TheelectrospinningprocesshasbeensuccessfullyusedtodisperseandalignCNTsinpolymercompositenano bers,inwhichthestabledispersionandhighalignmentofCNTswereobtained[21,22].
Inourpreviouswork,theinhomogeneousphasestructureshavebeenobservedinpolysulfone(PSF)nano berstoughenedepoxy
碳纳米管论文
G.Lietal./MaterialsChemistryandPhysics134(2012)958e965959
matrix[23,24],andPSFspheresgeneratedfromphaseseparationofnano bersexhibitedrandomalignment.Onthebasisoftheinho-mogeneousphaseseparation,theelectrospinning-induceddisper-sionandalignmentofCNTswereintroducedtofabricateCNTs/PSFhybridnano berswithwelldispersedandalignedCNTs,andtopreparereinforcedandtoughenedepoxymatrix(RTEP)usingsuchhybridnano bers.Duringtheinhomogenenousphaseseparationofhybridnano bers,theCNTswerewelldispersedandalignedinthephasestructureduetotheex-situdispersionandalignmentofCNTsinhybridnano bers.Therefore,theprescribedmorphologyofRTEPwasobtainedthatcouldachievethesynergisticeffectsoftheimprovementofstrengthandtoughness.
Toachievethispurpose,(i)MWNTs-EPwerepreparedbycarboxylationandfurtherattachmentofepoxyterminatedmole-cules,andMWNTs-EP/PSFhybridnano berswithwelldispersedandhighlyalignedMWNTs-EPwerefabricatedbyelectrospinning,(ii)aschematicrepresentationofthedispersionandalignmentstateofMWNTs-EPduringtheinhomogeneousphaseseparationofhybridnano berswasproposed,andcomparedwiththeactualmorphologiesofRTEP,(iii)thechemicalcorrelationbetweenMWNTs-EPandepoxymatrixinterfaceswereinvestigated,andthemechanicalandthermalpropertiesofRTEPwerealsodiscussed.2.Experimental2.1.Materials
Multiwalledcarbonnanotubes(MWNTs,purity!95%,diameter10e20nm,length5e15mm)wereproducedbyShenzhenNano-techPortCo.,Ltd,China.Polysulfone(PSF,Udel1700)wassuppliedbyAmocoCo.DiglycidoletherofbisphenolA(DGEBA,EPON828)wasobtainedfromShellChemicalCo.4,40-diaminodiphenylsulfone(DDS)weremanufacturedbyYinshengChemicalCo.N,N0-dimethylformamide(DMF),triphenylphosphorus(TPP),tetrahydrofuran(THF),N,N0-dimethylacetamide(DMAC)andacetonewerepur-chasedfromBeijingChemicalAgentCo.2.2.PreparationofMWNTs-EP
TheschematicofthepreparationprocedureforepoxygraftedMWNTs(MWNTs-EP)isshowninFig.1.ThecarboxylatedMWNTswaspreparedbyfollowingourpreviouslyreportedprocedure[21].Thecarboxylgroupswere rstintroducedontothesurfaceoftheMWNTsbyacidoxidationofas-receivedMWNTsfor1hwithamixtureofconcentratedH2SO4andHNO3(1:1,volumeratio).ThecarboxylatedMWNTsweredispersedinDMFbybathsonicationfor1h.DGEBAwasdissolvedinDMFinaseparatevessel,afterwhichthetwodissolvedmaterialswerefurthermixedandbath-sonicatedforhalfanhour.Thenthemixturewasslowlystirredandheatedto130 C,afteraddingTPPasacatalystforthereaction.Thesystemwasallowedtoreactfor12h.ThereactedMWNTswerewashedwithTHFand lteredthroughaPTFEwitha2mmporesizetoobtaintheepoxygraftedMWNTs(MWNTs-EP).
2.3.FabricationofMWNTs-EP/PSFhybridnano bers
MWNTs-EPweredispersedin20mlmixtureofDMAC/acetone(7:3volumeratio)byultrasonicagitationfor6h,then4.0gPSFpelletswereaddedtoobtainasuspensionforelectrospinning.Thesuspensionwasplacedin30mlmedicalsyringewith12gaugeneedle,andelectrospunat0.5ml/h owrateunder16kVappliedvoltage.TheamountofMWNTs-EPinhybridnano berswascontrolledto5,10,15wt%ofPSF.Forcomparison,PSFnano berswithoutMWNTs-EPwerepreparedbyelectrospinning.2.4.Preparationofhybridnano bersreinforcedandtoughenedepoxy(RTEP)
Epoxymatrixwaspreparedbydissolving100gofDGEBAand30gofDDSbyvigorousstirringat120 Cfor25min,andtheblendwasdegassedundervacuumtoobtainhomogeneoussolution.PSFnano bersandhybridnano berswithvariousMWNTs-EPloadingswerecutandplacedhorizontallyintoalaboratory-mademold.Theepoxymatrixwasthenpouredintothemoldandcuredatthreestages:120 Cfor2h,160 Cfor2h,and180 Cfor1h.Theamountofthenano berswascontrolledto2wt%ofresinmatrix,thatis,theMWNTs-EPloadingswerecontrolledto0.1,0.2and0.3wt%inRTEP,respectively.2.5.Characterization
ChangesofthefunctionalgroupsonthesurfaceofMWNTsweredetectedwithanFTIRspectrometer(Nicolet670).
MorphologiesofPSFnano bers,MWNTs-EP/PSFhybridnano- bersandthenano bersreinforcedandtoughenedepoxymatrix,wereobservedbyscanningelectronmicroscope(SEM,S4700,HITACHI)andtransmissionelectronmicroscope(TEM,JEM100CX,HITACHI),respectively.
ThealignmentofMWNTs-EPinthehybridnano berswascharacterizedusingRamanspectrometer(TY-HR800)withlaserexcitationat532nm.
Thetensilepropertiesweremeasuredbytensiletestingmachine(INSTRON1121)accordingtoGB2568-1995.Thedumbbellspecimensofdimension100mmÂ6mmÂ2.5mmwaspreparedbythenano berdirectionparalleltothelengthofspecimens,andtestedatarateof1mm/minusinga5kNloadcell.The nalvalueswereaveragesof vemeasurements.
Dynamicmechanicalthermalanalysiswasperformedbythree-pointbendingmode(DMTA-V,RheometricsScienti http://wendang.chazidian.comA).ThedimensionofaspecimenforDMTAtestingwas50mmÂ6mmÂ2mm.Theheatingratewas5 C/minfrom50 Cto300 C,andthe xedfrequencywas1Hz.TheTgwasmeasuredfromthepeakofthetandspectrum.
Thecriticalstressintensityfactor(KIC)wasmeasuredbysingle-edgenotchedfracturetoughnesstestinthree-pointbendingmode,accordingtoASTM5045-1999.Thecrossheadratewas1mm/min,andthe nalvalueswereaveragesof ve
内容需要下载文档才能查看measurements.
Fig.1.SchematicofthepreparationprocedureforMWNTs-EP.
碳纳米管论文
960G.Lietal./MaterialsChemistryandPhysics134(2012)958e965
aromaticringsofMWNTs[11],asshowninFig.1.Theseresultsindicatedthattheepoxide-terminatedgroupsweresuccessfullygraftedontothesurfaceofMWNTs.
3.2.MorphologyofMWNTs-EP/PSFhybridnano bers
Fig.3showstheSEMimagesofMWNTs-EP/PSFhybridnano- berswith0,5,10,and15wt%MWNTs-EP.PSFnano berwithoutMWNTs-EPpossessedcoarserdiameterwithmorerandomdistri-butionthanhybridnano berswithMWNTs-EP.WithincreasingMWNTs-EPloadings,theaveragediameterofnano bersdecreasedalongwiththeenhancementofalignmentdegree,asshowninFig.3bed.Ingeneral,theelectricconductivityofMWNT-EP/PSFsuspensionsforelectrospinningincreasedwithincreasingMWNTs-EPloadings,whichledtotheincreaseofnetchargedensitycarriedbythespinningjet[25].Therefore,theliquiddropletofthesuspensionsweresubjectedtothelargerelectrostaticforces,andthespinningjetunderwentthelargerdrawratiosduringtheelectrospinningprocess[26],whichallowedthedis-solvedpolymertobeorientedbytheelongational owofthechargedjet[25], nallyresultingintheincreaseofthedegreeofalignmentofhybridnano bers.
Fig.4showstheTEMimagesofMWNT-EP/PSFhybridnano- berswith5,10,and15wt%MWNTs-EP.TheMWNTs-EPweresuccessfullyembeddedinthePSFnano bers,andwerewelldispersedandhighlyalignedalongthenano beraxis.ThedegreeofalignmentofMWNTs-EPincreasedwithincreasingMWNTs-EPloadings.WhentheloadingofMWNTs-EPinthenano berwasreached15wt%,theMWNTs-EPwerealmoststretchedintostreamlines,whichwasattributedtotheextremelylargeeffectivedrawratioresultedfrombendinginstabilityintheelectrospinningprocess[20].TheincreaseofthedegreeofalignmentofMWNTs-EPinhybridnano bersmightbefavorabletothedispersionandorientationofMWNTs-EPinepoxymatrix.
ThealignmentofMWNTs-EPinhybridnano berswasfurthercharacterizedwithRamanSpectroscopy.Fig.5showsthepolarizedRamanspectraofMWNTs-EP/PSFhybridnano berswith5,10,and15wt%MWNTs-EP,inwhichtheVVcurverepresented
内容需要下载文档才能查看the
Fig.2.FTIRspectraof(a)as-receivedMWNTs,(b)carboxylatedMWNTs,and(c)
内容需要下载文档才能查看MWNTs-EP.
3.Resultsanddiscussion3.1.FunctionalizationofMWNTs
Fig.2showstheFTIRspectraofas-receivedMWNTs,carboxyl-atedMWNTsandMWNTs-EP.Thepeakat1709cmÀ1inthespectraofcarboxylatedMWNTscorrespondedtothecarboxylofthecarboxylicacid,whichindicatedthechangesoffunctionalgroupsonthesurfaceofMWNTsduetothecarboxylation[5].Thispeakwasnotdetectedontheas-receivedMWNTs.InthespectraofMWNTs-EP,thedisappearanceofthepeakat915cmÀ1,whichcorrespondedtotheepoxideringintheDGEBA[5],indicatedthattheepoxideringsopenedandreacted.Thepeakat1100cmÀ1wasrelatedtotheCeObondwhichresultedfromthereactionbetweenthecarboxylicacidandtheepoxidering.Thepeakat1260cmÀ1wasassociatedwithCeOoftheester,whichwasattachedtothe
Fig.3.SEMimagesofMWNTs-EP/PSFhybridnano berswith(a)0,(b)5,(c)10,and(d)15wt%MWNTs-EP.
碳纳米管论文
G.Lietal./MaterialsChemistryandPhysics134(2012)958e965961
Fig.4.TEMimagesofMWNTs-EP/PSFhybridnano berswith(a)5,(b)10,and(c)15wt%MWNTs-EP.(Thewhitecurvesinpartaandbandthewhitearrowsinpartcrepresentthealignmentdirectionsofthe
内容需要下载文档才能查看MWNTs-EP.)
spectrumwhenthepolarizationoftheincidentlaserwasparalleltothenano beraxis,andtheVHcurverepresentedthespectrumwhenthepolarizationoftheincidentlaserwasnormaltothenano beraxis.Thestrongabsorptionpeakat1582cmÀ1wasassignedastheGbandandassociatedwithtangentialCeCbondstretchingmotionthatoriginatedfromtheE2g2modeinthegraphite.Thepeakat1351cmÀ1wasassignedastheDbandandderivedfromdisorderedgraphitestructures[27].Theshoulderpeakat1607cmÀ1wasusuallydenotedastheD0bandandhasalsobeenattributedtodisorder-inducedfeaturesintheCNTs[28].WithincreasingMWNTs-EPloadings,theup-shiftofGandDbandsindicatedthatMWNTs-EPpossessedasubstantialinteraction[27],whichmightbeattributedtobettercompatibilitybetweenPSFandepoxyonthesurfaceofMWNTs-EP.Inaddition,therewasanobviousdifferenceintheintensityoftheGbandfordifferentpolarizationdirectionswithincreasingMWNTs-EPloadings,whichwasassociatedwiththealignmentofCNTsinthehybridnano bers.Ingeneral,thedegreeofalignmentofCNTscanbeevaluatedby
内容需要下载文档才能查看the
Fig.5.PolarizedRamanspectraofMWNTs-EP/PSFhybridnano berswith(a)5(b)10,and(c)15wt%MWNTs-EP.
碳纳米管论文
962G.Lietal./MaterialsChemistryandPhysics134(2012)958e965
depolarizationfactorR,theratioofthepeakintensitiesoftheGbandinthetwopolarizationdirections.TheRvaluesforhybridnano berswith5,10,and15wt%MWNTs-EPwere0.977,1.070,and1.152,respectively,whichweregreaterthanthatofas-receivedMWNTs(ca.0.81)[28].TheincreaseinRvaluecanbeascribedtothebetteralignmentofMWNTs-EPinthehybridnano berswithincreasingMWNTs-EPloadings.
3.3.Prescribedmorphologyofhybridnano bersreinforcedandtoughenedepoxy
Theex-situdispersionandalignmentofMWNTs-EPwereobtainedbyfabricatingMWNTs/PSFhybridnano bersthroughelectrospinning,whichwasassociatedwiththephaseseparationofMWNTs-EP/PSFhybridnano bersreinforcedandtoughenedepoxymatrix(RTEP).Fig.6showstheschematicrepresentationofthedispersionandalignmentstatesofMWNTs-EPduringreaction-inducedphaseseparationinRTEP.
TheepoxymatrixwascompoundedwithMWNTs-EP/PSFhybridnano bers(a).Duringthecuringprocess,PSFnano bersweredissolvedintoepoxymatrix,whereasMWNTs-EPretainedtheoriginaldistributionasinhybridnano bers,asshownin(b).
Withthecuringreactionproceeding,thephaseseparationofhybridnano bersbegantooccur,andPSFspheresweregeneratedduetophaseseparationofnano bers,shownin(c).Herein,thedistributionandalignmentstatesbetweenMWNTs-EPandPSFspheresweresuggested.The rstpossiblestatewasthattheMWNTs-EPwasenvelopedbymanyPSFspheres,whichwasthemostfrequent.AnotherstatewasthatMWNTs-EPmightbepinnedbyonePSFsphere.Inaddition,theMWNTs-EPmightalsobebridgedbysomePSFspheres.However,whateverstatetheMWNTs-EPlocatedamongPSFspheres,theMWNTs-EPwerealmostdispersedandalignedalongtheoriginalnano berdirec-tion,whichwasattributedtothedispersionandalignmentofMWNTs-EPinhybridnano bers.ThedispersionandalignmentofMWNTs-EPandthegenerationofPSFsphereswouldresultinthesynergisticeffectsofhybridnano bersonreinforcingandtough-eningtheepoxy
内容需要下载文档才能查看matrix.
Fig.6.SchematicrepresentationofthedispersionandalignmentstatesofMWNTs-EPduringreaction-inducedphaseseparationinRTEP.(a)Recombinationofepoxymatrixandhybridnano bers,(b)DissolutionofPSFnano bersintoepoxymatrix,and(c)PSFspheresfromthephaseseparationofnano bersand xationofMWNTs-EPinthephase
内容需要下载文档才能查看structures.
Fig.7.SEMimagesofRTEPwith(a)0,(b)0.1,(c)0.2and(d)0.3wt%MWNTs-EP.
下载文档
热门试卷
- 2016年四川省内江市中考化学试卷
- 广西钦州市高新区2017届高三11月月考政治试卷
- 浙江省湖州市2016-2017学年高一上学期期中考试政治试卷
- 浙江省湖州市2016-2017学年高二上学期期中考试政治试卷
- 辽宁省铁岭市协作体2017届高三上学期第三次联考政治试卷
- 广西钦州市钦州港区2016-2017学年高二11月月考政治试卷
- 广西钦州市钦州港区2017届高三11月月考政治试卷
- 广西钦州市钦州港区2016-2017学年高一11月月考政治试卷
- 广西钦州市高新区2016-2017学年高二11月月考政治试卷
- 广西钦州市高新区2016-2017学年高一11月月考政治试卷
- 山东省滨州市三校2017届第一学期阶段测试初三英语试题
- 四川省成都七中2017届高三一诊模拟考试文科综合试卷
- 2017届普通高等学校招生全国统一考试模拟试题(附答案)
- 重庆市永川中学高2017级上期12月月考语文试题
- 江西宜春三中2017届高三第一学期第二次月考文科综合试题
- 内蒙古赤峰二中2017届高三上学期第三次月考英语试题
- 2017年六年级(上)数学期末考试卷
- 2017人教版小学英语三年级上期末笔试题
- 江苏省常州西藏民族中学2016-2017学年九年级思想品德第一学期第二次阶段测试试卷
- 重庆市九龙坡区七校2016-2017学年上期八年级素质测查(二)语文学科试题卷
- 江苏省无锡市钱桥中学2016年12月八年级语文阶段性测试卷
- 江苏省无锡市钱桥中学2016-2017学年七年级英语12月阶段检测试卷
- 山东省邹城市第八中学2016-2017学年八年级12月物理第4章试题(无答案)
- 【人教版】河北省2015-2016学年度九年级上期末语文试题卷(附答案)
- 四川省简阳市阳安中学2016年12月高二月考英语试卷
- 四川省成都龙泉中学高三上学期2016年12月月考试题文科综合能力测试
- 安徽省滁州中学2016—2017学年度第一学期12月月考高三英语试卷
- 山东省武城县第二中学2016.12高一年级上学期第二次月考历史试题(必修一第四、五单元)
- 福建省四地六校联考2016-2017学年上学期第三次月考高三化学试卷
- 甘肃省武威第二十三中学2016—2017学年度八年级第一学期12月月考生物试卷
网友关注
- 火灾来临时教孩子怎样逃生
- 大班三月份班级工作计划
- 如何让宝宝爱上幼儿园
- 校车六定
- 定稿 我想和你一起玩
- 育儿教育
- 儿童情绪处理18种方法
- 吃饭方式与孩子的人格
- 变变变教案
- 2015第二届当代园长论坛
- 热气球教案
- 天空宇宙
- 春季儿童营养饮食对策
- 宝宝乳名大全
- 学会宽容 收获喜悦
- 怎样让孩子懂得感恩
- 母乳喂养注意事项
- 幼儿园中班家长开放日活动方案
- 高宽课程中的一日生活
- 教孩子一天,想孩子一生
- 切勿忽视孩子的“成长烦恼”
- 如何提高孩子社交商
- 生日会小结
- 可爱的小动物教案
- 婴儿奶粉有分段 家长选购需思量
- 我家门前一条路
- 锹峪幼儿园作息时间表
- 大二班——育儿经
- 春季宝宝断奶最佳时机全攻略
- 儿童7岁前不宜穿气垫鞋
网友关注视频
- 冀教版小学数学二年级下册第二单元《租船问题》
- 沪教版八年级下册数学练习册21.4(1)无理方程P18
- 外研版英语七年级下册module1unit3名词性物主代词讲解
- 沪教版八年级下次数学练习册21.4(2)无理方程P19
- 化学九年级下册全册同步 人教版 第22集 酸和碱的中和反应(一)
- 沪教版八年级下册数学练习册21.3(2)分式方程P15
- 【部编】人教版语文七年级下册《逢入京使》优质课教学视频+PPT课件+教案,安徽省
- 七年级下册外研版英语M8U2reading
- 沪教版牛津小学英语(深圳用) 五年级下册 Unit 12
- 3月2日小学二年级数学下册(数一数)
- 沪教版牛津小学英语(深圳用) 四年级下册 Unit 2
- 沪教版牛津小学英语(深圳用) 五年级下册 Unit 7
- 外研版英语七年级下册module3 unit2第一课时
- 苏科版数学 八年级下册 第八章第二节 可能性的大小
- 30.3 由不共线三点的坐标确定二次函数_第一课时(市一等奖)(冀教版九年级下册)_T144342
- 外研版英语三起6年级下册(14版)Module3 Unit2
- 北师大版小学数学四年级下册第15课小数乘小数一
- 沪教版牛津小学英语(深圳用) 四年级下册 Unit 7
- 冀教版小学英语四年级下册Lesson2授课视频
- 北师大版数学四年级下册3.4包装
- 【部编】人教版语文七年级下册《逢入京使》优质课教学视频+PPT课件+教案,辽宁省
- 人教版历史八年级下册第一课《中华人民共和国成立》
- 飞翔英语—冀教版(三起)英语三年级下册Lesson 2 Cats and Dogs
- 冀教版小学数学二年级下册第二周第2课时《我们的测量》宝丰街小学庞志荣.mp4
- 3.2 数学二年级下册第二单元 表内除法(一)整理和复习 李菲菲
- 《空中课堂》二年级下册 数学第一单元第1课时
- 沪教版八年级下册数学练习册21.3(3)分式方程P17
- 苏教版二年级下册数学《认识东、南、西、北》
- 外研版英语七年级下册module3 unit2第二课时
- 六年级英语下册上海牛津版教材讲解 U1单词
精品推荐
- 2016-2017学年高一语文人教版必修一+模块学业水平检测试题(含答案)
- 广西钦州市高新区2017届高三11月月考政治试卷
- 浙江省湖州市2016-2017学年高一上学期期中考试政治试卷
- 浙江省湖州市2016-2017学年高二上学期期中考试政治试卷
- 辽宁省铁岭市协作体2017届高三上学期第三次联考政治试卷
- 广西钦州市钦州港区2016-2017学年高二11月月考政治试卷
- 广西钦州市钦州港区2017届高三11月月考政治试卷
- 广西钦州市钦州港区2016-2017学年高一11月月考政治试卷
- 广西钦州市高新区2016-2017学年高二11月月考政治试卷
- 广西钦州市高新区2016-2017学年高一11月月考政治试卷
分类导航
- 互联网
- 电脑基础知识
- 计算机软件及应用
- 计算机硬件及网络
- 计算机应用/办公自动化
- .NET
- 数据结构与算法
- Java
- SEO
- C/C++资料
- linux/Unix相关
- 手机开发
- UML理论/建模
- 并行计算/云计算
- 嵌入式开发
- windows相关
- 软件工程
- 管理信息系统
- 开发文档
- 图形图像
- 网络与通信
- 网络信息安全
- 电子支付
- Labview
- matlab
- 网络资源
- Python
- Delphi/Perl
- 评测
- Flash/Flex
- CSS/Script
- 计算机原理
- PHP资料
- 数据挖掘与模式识别
- Web服务
- 数据库
- Visual Basic
- 电子商务
- 服务器
- 搜索引擎优化
- 存储
- 架构
- 行业软件
- 人工智能
- 计算机辅助设计
- 多媒体
- 软件测试
- 计算机硬件与维护
- 网站策划/UE
- 网页设计/UI
- 网吧管理