锗薄膜透射光学二次谐波研究

本文采用固定入射角，改变入射光偏振方位角的方法从实验上了研究了锗薄膜的透射光学二次谐波产生及其变化规律，并从理论上推导了产生透射二次谐波的表达式，最后拟合求得描述面谐波电流的唯象参数ａ。     

水平液─固流中颗粒抑制湍流的行为和条件

用激光多普勒分相测量方法，考察了水平含颗粒水流的主流区，亚毫米颗粒对水流湍流有抑制行为，湍流削弱程度与颗粒浓度、流动发展长度、水流雷诺数等因素有关．按照不出现尾涡脱落和至少能响应一部分大尺度涡的运动这两个基本条件，分析了湍流抑制与有关参量的依赖性．结果表明，流动尺度和颗粒尺寸之比，对于颗粒消耗而不增生湍流起着最主要的作用．在一定的水流雷诺数下，只要这一比值很大，亚毫米颗粒就会表现出对湍流的抑制作用     

BaZr(BO3)2:Eu的合成及发光性能研究

用硝酸盐热分解法成功制备了BaZr(BO3)2:Eu(Eu3+的掺杂量为摩尔分数5%)荧光材料,并研究了其在254及147 nm光束激发下的发光特性.254 nm光束激发下的发射主峰位于612 nm处,归属于Eu3+的5D0-7F2的电偶极跃迁,但在147 nm光束激发下的发射主峰位于592 nm处,归属于Eu3+的5D0-7F1的磁偶极跃迁.通过激发光谱分析,上述现象归因于在紫外激发下占据非对称格位Ba2+的Eu3+被优先激发,而在真空紫外激发下占据对称格位Zr4+的Eu3+被优先激发.结果表明BaZr(BO3)2:Eu并不适合作为等离子平板显示器用红色发光材料.     

Synthesis and characterization of well‐defined cyclodextrin‐centered seven‐arm star poly(ε‐caprolactone)s and amphiphilic star poly(ε‐caprolactone‐b‐ethylene glycol)s

Per‐2,3‐acetyl‐β‐cyclodextrin with seven primary hydroxyl groups was synthesized by selective modification and used as multifunctional initiator for the ring‐opening polymerization of ε‐caprolactone (CL). Well‐defined β‐cyclodextrin‐centered seven‐arm star poly(ε‐caprolactone)s (CDSPCLs) with narrow molecular weight distributions (≤1.15) have been successfully prepared in the presence of Sn(Oct)₂ at 120 °C. The molecular weight of CDSPCLs was characterized by end group ¹H NMR analyses and size‐exclusion chromatography (SEC), which could be well controlled by the molar ratio of the monomer to the initiator. Furthermore, amphiphilic seven‐arm star poly(ε‐caprolactone‐b‐ethylene glycol)s (CDSPCL‐b‐PEGs) were synthesized by the coupling reaction of CDSPCLs with carboxyl‐terminated mPEGs. ¹H NMR and SEC analyses confirmed the expected star block structures. Differential scanning calorimetry analyses suggested that the melting temperature (T_m), the crystallization temperature (T_c), and the crystallinity degree (X_c) of CDSPCLs all increased with the increasing of the molecular weight, and were lower than that of the linear poly(ε‐caprolactone). As for CDSPCL‐b‐PEGs, the T_c and T_m of the PCL blocks were significantly influenced by the PEG segments in the copolymers. Moreover, these amphiphilic star block copolymers could self‐assemble into spherical micelles with the particle size ranging from 10 to 40 nm. Their micellization behaviors were characterized by dynamic light scattering and transmission electron microscopy. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6455–6465, 2008     

氦,氖,氩气体压力对氖光谱和能级填充的影响

以＾２３８Ｐｕ为激发源，测量了不同压力下Ｎｅ、Ｈｅ－Ｎｅ、Ｈｅ－Ｎｅ－Ａｒ体系的氖光谱，并以此为基础计算了Ｎｅ的２ｐ＾５３ｐ的１０个２ｐ能级的辐射率Ⅰ、相对集居数Ｎ、填充率Ｗ，总结出相应的Ｎｅ压力、Ｈｅ压力和Ａｒ压力对Ｎｅ的５８５．２ｎｍ谱线强度和１０个２ｐ能级填充的影响规律。     

一类有迁移的SIS流行病模型

研究一类种群有迁移的流行病模型,得到了这类模型的基本再生数R0,证明了R0＜1无病平衡点是局部渐近稳定的,而当R0＞1时无病平衡点是不稳定的.进一步讨论了疾病持续存在与无病平衡点和地方病平衡点全局稳定的条件.     

随机微分方程终值问题的弱解(英)

设｛Wt．Ft．t∈［0．T］｝为概率空间（Ω，P）上的标准α维Brown运动，为由它生成的自然σ－代数流．本文讨论了如下随机微分方程终值问题弱解的存在性：其中ξ∈L2（Ω，P；Rn），g：［0，T」×Rn×Rnd→Rn为有界可测函数．此外，还讨论了它在金融市场期权定价问题中的应用．     

Study on liquid scintillation technique for bioassay of plutonium

Simple, rapid and sensitive methods are very important for the bioassay of plutonium. In this work, modern liquid scintillation technique combined with selective extraction separation and / pulse decay discrimination were studied and evaluated for the bioassay of plutonium. After sample decomposition and partial evaporation, cyclohexanone and trialkylphosphine oxide (TRPO) were used for the separation of plutonium from matrix. Several different cocktails were tested for liquid scintillation analysis of urine samples. The minimum detectable activity (MDA) of this method was estimated to be 0.01 Bq/500ml urine with 100 minutes measuring time and 3 confident level.     

A New Fluorimetric Reagent for Determination of Trace Amounts of Europium

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