简介：在本期的“课例大家评”中,我们刊登了同一课题下的6篇课例供大家点评.2001年第4期,我刊登出了“直线方程的一般形式(第一课时)”课例的征稿启事.截止4月30日,我们收到课例来稿百余篇.这6篇课例就是从这些应征稿件中遴选出来的.为了便于大家点评,我们将6篇课例按学生学习状况的优、中、差分为三组,每组有2篇课例.在撰写点评稿时,您可以对6篇课例进行总评,也可以就学生学习状况相当的两篇课例进行评析,还可以对某一课例做单独的评议.总之,点评的内容应相对集中,以便于编者对稿件进行选择和组构.文稿字数以1000字左右为宜,截稿日期为9月10日.投稿时请在信封左下方注明“课例大家评”字样.欢迎广大数学教师和教研工作者积极参与本次“课例大家评”活动,我们将以较大篇幅集中发表观点新颖、论述深刻、对教学具有较强启发性的优秀来稿.在此,我们还特别对提供“直线方程的一般形式”课例的所有老师表示衷心的感谢.
简介：采用Nb2O3、Y2O3复合稳定剂,制得了高韧性、高强度的四方相ZrO2陶瓷材料,发现在Y2O3-ZrO2材料中加入0.5～1molNb2O3,可使材料在保持原有抗弯强度的同时,一定程度上改善了断裂韧性和相组成。
简介：Throughmeasuringthecoefficientoflinearexpansion,thestructureandpropertiesoftheLi2O-Al2O3-SiO2lowexpansionglassceramicscontainingB2O3arestudiedbyJRandXRD.ItisshoutnthattheIRmethodisefficientinthestudyoftheglass-ceramicsstructure.Thereisa"Boronabnormality"inthesystemwhichhasanimportantinfluenceonthepropertiesoftheglass-ceramics.
简介：Themonomericcobalt-phosphite-thiolatocomplex[Co(mpt)2{P(OCH3)3}2]BF4(Hmpt=2-mercaptothiazoline)hasbeenpreparedandcharacterizedbyX-raycrystallography.ThecomplexcrystallizesinthemonoclinicspacegroupC2/cwitha=0.8078(5),b=2.6020(18),c=1.2191(7)nm,β=99.38(1)°,V=2.528(3)nm3,andZ=4.Thestructurecomprisesdiscretecations[Co(mpt)2{P(OCH3)3}2.]+andanionsBF4-,inwhichthecobalt(Ⅲ)atomiscoordinatedtotwochelatempt-andtwoas-orientedmonodentateP(OCH3)3ligandsinahighlydistortedoctahedralgeometry.ThemostdistortedanglesareS(2)-Co(1)-S(2a)of162.23(10)°andN(1)-Co(1)-S(2)of71.47(13)°,thelatteriscausedbythegeometricconstraintofthebidentateligandmpt-.CyclicvoltammetryhasbeenusedtostudytheelectrochemicalbehaviorofthetitlecomplexontheRelectrodeinMeCNsolutionwith0.1mol·L-1ofBun4NBF4aselectrolyte.TheresultsindicatethatthetitlecomplexisunstableinMeCN.
简介：SiO2-B2O3-Al2O3-CaO在低sintering温度使契约成玻璃，高力量被讨论。FTIR和XRD分析被用来与铝的不同内容描绘基本使成玻璃的契约的结构。弯曲力量和热扩大系数也被测试。同时，在660光线衍射(XRD)的sintering温度的合成标本的微观结构，扫描电子显微镜(SEM)分析和其它工具。结果证明分别地，钾和磷的溶解率在95.64wt%lessthan的一种谷物尺寸的条件下面是70wt%和93.7wt%0.074公里，9.78gg-1硫磺的酸，0.5gg-1铵氟化物，160桴???瑳畲瑣牵獥椠?慭湩慴湩摥映吗？？
简介：TiO2@ZrO2@Y2O3:有coremultishell结构的Eu3+合成粒子通过layer-by-layer(LBL)的联合被综合自己组装方法和一个solgel过程。获得的样品与扫描电子被描绘显微镜学(SEM)，传播电子显微镜学(TEM)，X光检查光电子光谱学(XPS)，X光检查衍射(XRD)，和荧光spectrophotometry。结果证明合成粒子有coremultishell结构，球形的形态学，和狭窄的尺寸分布。TiO2核心上的ZrO2层的存在能有效地阻止在TiO2核心和Y2O3壳之间的反应；为在在TiO2@ZrO2@Y2O3的TiO2核心和Y2O3壳之间的反应的温度:Eucoremultishell黄磷能被300提高
简介：A60%Fe/Al2O3catalystwaspreparedbytheco-precipitationmethod.ItwasreducedbyH2toproducemetallicFe,whichwasthensulfidedbyCS2toFe0.96SandFe3S4orphosphidedbytriphenylphosphine(PPh3)inliquidphasestoFe2PandFeP.Itwasfoundthattheironsulfides(Fe0.96SandFe3S4)exhibitedthelowactivityforthehydrodesulfurization(HDS)reactions.TheHDSactivitywasalsolowontheFe(metal)/Al2O3andFe2P/Al2O3catalystssincetheywereconvertedintoFe0.96SandFe3S4duringtheHDSreactions.Incontrast,theFeP/Al2O3wasfoundtobestableandactivefortheHDSreactions.Inparticular,FeP/Al2O3possessedsignificantlysmallerFePparticlesthanFeP/C,leadingtothesignificanthigherHDSactivityofFeP/Al2O3thanFeP/C.
简介：Reactionof(MeC5H4)3LnwithHOCH2CH2NMe2intetrahydrofuran(THF)givesthenewcomplexes[(MeC5H4)2Ln(μ-OCH2CH2NMe2)]2(Ln=Sm,Y,Nd)withnitrogenfunctionalizedμ-alkoxideligand.ThecomplexeswerecharacterizedbyelementalanalysisandIR,and[(MeC5H4)2Sm(μ-OCH2CH2NMe2)]2wasstructurallycharacterizedbytheX-raydiffractiontobeadimerformedbytwounsymmetricoxygenbridges.ThecomplexhasatricyclicskeletonwiththeadditionaltwoSm-NbondsviaintramolecularcoordinationofOCH2CH2NMe2.ThecoordinationnumberofthecentralmetalSmisnine.Thetitlecomplexesshowgoodcatalyticactivityforring-openingpolymerizationofε-caprolactone.
简介：Temperature-dependentphotoluminescencecharacteristicsoforganic-inorganichalideperovskiteCH3NH3PbI3-xClxfilmspreparedusingatwo-stepmethodonZnO/FTOsubstrateswereinvestigated.Surfacemorphologyandabsorptioncharacteristicsofthefilmswerealsostudied.Scanningelectronmicroscopyrevealedlargecrystalsandsubstratecoverage.Theorthorhombic-to-tetragonalphasetransitiontemperaturewas140K.Thefilms’excitonbindingenergywas77.6±10.9meVandtheenergyofopticalphononswas38.8±2.5meV.TheseresultssuggestthatperovskiteCH3NH3PbI3-xClxfilmshaveexcellentoptoelectroniccharacteristicswhichfurthersuggeststheirpotentialusageinperovskitebasedoptoelectronicdevices.
简介：应用密度泛函理论中的ω-B97XD/6-311＋G（d,p）方法,对甲湛分子团簇[CH2O]n（n=1～4）的空间结构进行了优化,得到了这些团簇的基态结构,并对其红外光谱,核磁共振谱的性质进行了研究.结果表明,当甲醛分子构成稳定的多分子团簇时,团簇中的每个分子仍然为平面结构,分子间将形成氢键,并且团簇中的各个分子共面.与单分子甲醛相比,多分子团簇的红外光谱,会出现许多与分子间氢键振动有关的新的吸收峰.当甲醛分子形成团簇时,13C核和17O核的核磁共振谱线会发生劈裂现象,这与电荷分布的对称性的破缺有关;而1H的核磁共振谱中将会出现新的条纹,这是由分子间的氢键的形成引起的.本文的研究可为甲醛团簇的识别、检测及性质研究提供理论依据.
简介：CrystallineTiO2（P25）andisolatedtitanatespeciesinaZSM-5structure（TS-1）weremodifiedwithAuandAg,respectively,andtestedinthegas-phasephotocatalyticCO2reductionunderhighpurityconditions.Thenoblemetalmodificationwasperformedbyphotodeposition.LightabsorbancepropertiesofthecatalystsareexaminedwithUV–Visspectroscopybeforeandaftertheactivitytest.Inthegas-phasephotocatalyticCO2reduction,itwasobservedthatthecatalystswithAgnanostructuresaremoreactivethanthosewithAunanostructures.Itisthusfoundthattheenergeticdifferencebetweenthebandgapenergyofthesemiconductorandthepositionoftheplasmonisinfluencingthephotocatalyticactivity.Potentially,plasmonexcitationduetovisiblelightabsorptionresultsinplasmonresonanceenergy,whichaffectstheexcitationofthesemiconductorpositively.Therefore,anoverlapbetweenbandgapenergyofthesemiconductorandmetalplasmonisneeded.
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