简介:Asanimportantmulti-functionalmaterialappliedinsurfaceacousticwavedevices,opticalcommunications,laserandoptoelectronicsduetoitsgoodphotoelectricandpiezoelectricproperties,lithiumtantalate(LiTaO3)hasdrawnextensiveinterests[1].NumerousphysicalpropertiesofLiTaO3,suchasacoustical,electronicstructures,opticalpropertiesandeffectivemass,thermodynamicproperties,havebeenreportedinseveralpapers.Pointdefectswillaffecttheelectronicstructurewhichshouldberesponsibleformanyphysicalproperties,especiallyopticalproperties.
简介:【摘要】本文通过简要介绍河北省丰宁抽水蓄能电站施工项目中选购装载机方法,对国内外装载机进行分析研究,结合实际施工要求总结出了选购中注意事项。
简介:YbAl3(BO3)4crystalofgoodopticalqualitywasgrownbythefluxmethod.ThestructureofYbAl3(BO3)4crystalwasdeterminedbysingle-crystalX-raydiffraction.TheexperimentshowsthatYbAl3(BO3)4belongstothedoubleborateswithatrigonalstructure.ThespacegroupisR32anditsunitcellconstantsweremeasuredtobea=0.92965nm,c=0.72129nm,V=0.53673nm3,Z=3.Thetransmittancespectraweremeasured.Thecut-offofYbAl3(BO3)4crystalis216nm,andtherearetwoabsorptionpeakslocatedat940and975nmfrom190nmto2600nm.ThethermalpropertiesofYbAl3(BO3)4crystalwerestudiedforthefirsttime.Theaveragethermalexpansioncoefficientsweredeterminedtobe2×10-6/℃,9.5×10-6/℃alonga-andc-direction.ThespecificheatofYbAl3(BO3)4crystalwasmeasuredtobe0.6695J·(g·℃)-1atroomtemperature.AllresultsindicatethattheYbAl3(BO3)4crystalisanexcellentstoichioimetriclasermaterial.
简介:摘要:社会需求,教学手段的发展,教学技术的更新,教学教育功能的开发,教学设计者的态度和思想,都在影响着当前教育教学效果,提倡以学生发展为目标,建立更加适应学生的教育思想,教学载体多样化,让各具个性的学生,在集中教学中都受益,达到学生全面提升的效果,是我们所追求的课堂教学目标。本文提出,对于每次课的主体知识点,不能“昙花一现”,也不要单线联系,要在“双案——四线”中同时并进,各条线不是互相取代,更不是相互抵触,而是“从A地到B地的并联”关系,知识结构中有,问题练习中有,课本中有,学案中有,ppt课件中仍然有,预习时涉及,互动探究时深入,收尾训练时巩固,坚持每一节课的节奏都是“合奏”与“混响”,这些“自助餐”式的学习载体,总有合适的“音频”或“食品”能够引起学生的“食欲”或“共鸣”。老师就是“编创者兼音乐指挥”,舞台上各个声源如何更和谐,何时发声,发什么样的调子,要融入作曲创编者和指挥者的才智,才可以欣赏到优美的交响乐。一节课的内容看起来不多,但学生的理解情况多,要让每个学生都得到最好的教育,教师就必须坚持多角度付出,无论“课本画块描线”“系统制作课件”“精心编制学案”“知识分层主线”“问题例题训练”“音像动画图片”“生生动态答辩”“引导学生会战”等等,这一宗才构成备课的教学方案,才能为一节优质课创造稳固的基础。在教学管理与实施中,教育的节点和情景信息都不是固定的,更不可能把学情都看作是一致的,在分层教育活动时,无论是人、事、资源、行为,多采用“3+3+3”的划分去操作,又可以将教育的精准度提升三倍以上。
简介:Reactionsofthe6-hydroxy-thiopyrano[3,4-c]pyridine-5-carbonitrilederivative1withα-halo-carbonylcompoundsgavetheortho-substitutedintermediates2a-cwhichwereconvertedintofuro[2,3-b]thiopyrano[4,3-d]pyridines3a-cbyfusionofafuranmoietyunderbasicconditions.Furthercyclizationof3a-cledtoafusionofapyrimidinering,yieldingthetetracyclicproducts6,7and8.Inaddition,condensationof6withvariousaromaticaldehydesaffordedthecorrespondingimines9a,b.Mannichreactionof7gaveproducts10a,b.
简介:本文通过高分辨X射线衍射及掠入射(GID)的实验方法对生长在SrTiO3衬底上的LLa2/3Ca1/3MnO3和YBaCu3O7单层膜及YBa2Cu3O7-x/La2/3Ca1/3MnO3异质结构双层薄膜的微结构进行了研究。结果发现,所有薄膜都呈c向生长。由于热膨胀系数的不同而引起的热应力使得LCMO膜的晶格参数与靶材的相差较大。La2/3Ca1/3MnO3在单层腹及双层膜中都由靶材的立方结构变成了薄膜状态的四方结构。YBa2Cu3O7在单层膜及双层膜中都由靶材的正交结构变成了薄膜状态的四方结构。La2/3Ca1/3MnO3膜与YBa2Cu3O7膜在不同的样品中处于不同的应力状态。
简介:1IntroductionTherareearthcobaltalloyshavethepotentialformakingthemagneticandmagnetoopticalmaterials.Sofar,therareearthcobaltalloyfilmsaresubstantiallyproducedbysputteringorvacuumplating.Ifsuchfilmsarepreparedbyelectrodepositioninstead,productionefficiencywouldbeimprovedandthecompositionofthealloycouldbecontrolled.Becausetheoxidationreductionpotentialsofrareearthelementsareverynegative,organicsolventsmaybeusedaselectrolyticmedia.ElectrodepositionofGdCoandSmCoinorganicsolutionshasbeenreporte...
简介:Er3+-Tm3+-Yb3+tri-dopedBaMoO4phosphorsweresynthesizedbyco-precipitationtechniqueandcharacterizedbyX-raydiffractionanalysis,absorptionstudyandfieldemissionscanningelectronmicroscopyanalysis.Upconversionaswellasdownconversionluminescencestudieswereperformedbyusingnearinfrared(980nm)andultraviolet(380nm)excitations.Energyleveldiagram,pumppowerdependenceandcolourcoordinatestudywereutilizedtodescribethemulticolorupconversionemissionproperties.Undersingle980nmdiodelaserexcitationthedualmodesensingbehaviourisrealizedviaStarksublevelsandthermallycoupledenergylevelsoftheTm3+andEr3+ionsinthepreparedtri-dopedphosphors.AcomparativefluorescenceintensityratioanalysisforintegratedemissionintensitiesarisingfromtheStarksublevels{1G4(a)and1G4(b)}andthermallycoupledenergylevels{2H11/2and4S3/2}oftheTm3+andEr3+ions,respectivelywascarriedoutinthepreparedtri-dopedBaMoO4phosphors.ThemaximumsensitivityforthermallycoupledenergylevelsoftheEr3+andStarksublevelsoftheTm3+ionwasreported.Thedevelopedphosphorscouldbeusefulinthedisplaydevicesandopticalthermometricapplications.