~1H NMR确证6-氟-5(或7)-氯-3-苯基-4-(1H)-喹啉酮衍生物的结构

作者合成了６氟３（取代）苯基４（１Ｈ）喹啉酮的５氯衍生物与７氯衍生物，二者极性差异小，难于分离，以混合物形式存在．所合成的化合物均未见文献报道，本文通过１ＨＮＭＲ上的化学位移、积分面积以及偶合常数确证了混合物中两组份的结构．     

柱状装药预制破片缩比战斗部爆炸冲击波和破片的作用时序

针对柱状装药的周向预制破片战斗部,结合无量纲分析方法和爆炸驱动理论,确定了影响破片和冲击波相遇位置的关键参数,给出了由缩比战斗部推广预测原型战斗部爆炸产生的破片冲击波作用时序的方法。采用ANSYS/LS-DYNA有限元软件进行数值模拟,对比验证了理论分析和数值试验结果,分析了战斗部缩比比例对冲击波和破片作用时序的影响。结果表明:缩比模型与原型战斗部爆炸产生的破片和冲击波的相遇位置之比和相遇时间之比主要取决于两模型的质量比,在不考虑破片速度衰减时,两模型中载荷相遇位置之比和相遇时间之比等于其质量比的0.33次方。受破片速度衰减影响,该方法仅适用于质量缩比不小于0.2的模型。     

纳米晶Y_2SiO_5∶Eu的浓度猝灭研究

报道了分别用溶胶－凝胶法合成的Ｙ２ＳｉＯ５∶Ｅｕ纳米晶和用高温固相法合成常规尺度的Ｙ２ＳｉＯ５∶Ｅｕ材料的光致发光光谱和猝灭浓度的实验研究．结果表明：纳米Ｙ２－ｘＥｕｘＳｉＯ５比常规尺度的Ｙ２－ｘＥｕｘＳｉＯ５有更高的猝灭浓度和更高的发光亮度．理论分析认为这是由于在纳米材料中能量共振传递被阻断和猝灭中心在各个纳米晶内分布的涨落造成的．这个结果为高亮度的Ｙ２ＳｉＯ５∶Ｅｕ纳米材料的实际开发应用展示了广阔前景．     

利用一次函数解中考热点试题

随着新课程改革的不断深入,一些贴近学生生活的热点试题应运而生,这些题目设计新颖、形式开放、实用性强,既可以从不同的角度考查学生阅读能力和分析能力以及对数学知识的应用能力,又可以培养学生关心时事热点的习惯,可谓是一石二鸟.现列举与一次函数相关的试题加以说明,让同学们去感受"生活中处处有数学,数学中也处处有生活"的道理.     

关于具有常平均曲率和数量曲率超曲面的Moebius几何的一个注记

设x：M→S^n＋1（n≥23）是n＋1-维单位球中的无脐点超曲面，Moebius不变量G，Ф，A和B分别表示x的Moebius度量，Moebius形式，Blaschke形式和Moebius第二基本形式．本文证明了如果x的Moebius形式圣平行，并且A＋λG＋μB=0，其中λ，μ分别是定义在M上的光滑函数，那么Ф=0，由此及李海中、王长平（2003年）文献中的分类定理给出了眇州中具有平行的Moebius形式及满足A＋λG＋μB=0的超曲面的分类．此结果推广了他们及张廷枋（2003年）文献中的结果．     

Y3Al5O12：Eu^3＋磷光体的溶胶—凝胶法合成及发光特性

以金属烷氧基化合物为原料．采用溶胶-凝胶法在1000℃下合成了Eu^3 掺杂的Y3Al5O12(YAG)磷光体。利用TG-DSC，XRD和发光光谱等对样品进行了表征。结果表明，YAG：Eu^3 的晶相形成温度为991℃。Eu^3 在非晶态和晶态YAG中的发射光谱有明显差异。研究了Eu^3 含量和烧结温度对Eu^3 的^5D0→^7F1和^5D0→^7F2发射峰强度的影响。随煅烧温度的升高和Eu^3 浓度的增加，Eu^3 发射峰强度增强。     

4fN-15d energy levels of lanthanides: aquasi-angular-momentum approach and its application to Cs2NaYF6:Er3+

<正>The spin-orbit interaction of the 5d electron needs to be taken into account to give the proper energy structure for the 4f^N-15d configuration of heavy lanthanide ions occupying a site with ligands forming an octahedron.This paper derives theoretical results for the energy structure by treating the t₂ orbitals as quasi p orbitals and then using angular-momentum coupling techniques.An analytic expression for the electric dipole absorption line strengths between 4f^N multiplets and 4f^N-15d states is given in terms of various angular-momentum quantum numbers and re-coupling coefficients.The result is then applied to interpret the excitation spectrum of Cs₂NaYF₆:Er³⁺.The high-spin and low-spin states of Cs₂NaYF₆:Er³⁺ are discussed in terms of the wavefunctions obtained by using the developed theoretical model.     

FIRST-PRINCIPLE SELF-CONSISTENT PSEUDOPOTENTIAL CALCULATION OF THE ELECTRONIC STRUCTURES OF SHORT-PERIOD (GaAs)m(AlAs)n SUPERLATT1CES

With the local density approximation, the band structares of the short-period (GaAs)₁(AlAs)₁ and (GaAs)₂(AlAs)₁ superlattices are calculated by using the first-principle self-consistent pseudopotential method. The results show that the (GaAs)₁(AlAs)₁ superlattice is an indirect semiconductor, and the lowest conduction band state is at point R in the Brillouin zone; the (GaAs)₂(AlAs)₁ superlattice is a direct semiconductor and the lowest conduction band state is at point Γ. The squared matrix elements of transition are calculated. The pressure coefficients of energy gaps of the (GaAs)₁(AlAs)₁ and (GaAs)₂(AlAs)₁ superlattices are calculated and compared with those obtained by hydrostatic pressure experiments.     

Characteristics of xenon-lamp pumped pyrromethene 567-doped dye laser based on polymethylmethacrylater

The solid-state medium containing pyrromethene 567 (PM567) in a polymethylmethacrylate polymer host is shown to lase under the flash lamp excitation. The experimental setup is an ordinary industrial product without special design. The bulk transmission losses, the output energy, and the other lasing properties are compared. The medium with the lowest transmission loss, measured to be 0.392 %/cm at 633 nm, gives a laser output of 130 mJ with a slope efficiency of 0.082%.