蒙特卡罗方法计算定积分的进一步讨论

介绍了蒙特卡罗方法计算定积分的原理和方法.给出了用蒙特卡罗方法计算定积分的一个简单证明,从而揭示了蒙特卡罗方法和定积分定义间的内在联系.针对蒙特卡罗方法收敛慢的特点,提出将蒙特卡罗方法与相应的数值计算方法相结合,提高计算结果的精度.此外,将蒙特卡罗方法推广到反常积分上去.     

GI~X/M~b/1/N排队系统

本文主要研究了顾客一般独立批到达、指数批服务、缓冲器容量有限的单个服务器的排队系统，本文首先使用补充变量和嵌入马氏链的方法，在部分拒绝和全部拒绝情形下，得到系统排队队长的稳态分布，进而得到相应的性能指标，如系统的平均排队长、平均等待时间、损失概率等．其次对等待时间进行了分析．     

溅射Al-C-O/Al太阳选择性吸收涂层

设计计算了以Al为底层的多层Al-C-O的太阳吸收涂层。运用直流磁控溅射制备了这种Al-C-O/Al吸收涂层。理论计算与实验测量的结果基本一致。经真空中烘烤后,涂层的Al-C-O/Al太阳吸收率α≈0.92,室温热发射率ε≈0.04,具有优良的光谱选择性。由于使用单个溅射靶,简化了溅射系统,提高了靶溅射的利用率。 关键词：     

Spin flip inelastic scattering in electron energy loss spectroscopy of a ferromagnetic metal

A model ferromagnetic metal is used to calculate the spin-polarization which occurs during inelastic electron-metal scattering with the production of an electron-hole pair. The polarization is found to have contributions from unequal spin-flip as well as non-flip energy loss rates. Our results indicate an asymmetry of the order of a few percent with parameters roughly modelling iron.     

The computations of Einstein-Kähler metric of Cartan-Hartogs domain

In this paper, we compute the complete Einstein-Kähler metric with explicit formula for the Cartan-Hartogs domain of the fourth type in some cases. Under this metric the holomorphic sectional curvature is given, which intervenes between −2k and −1. This is the sharp estimate.

     

Synthesis and characterization of well‐defined polystyrene and poly(ε‐caprolactone) hetero eight‐shaped copolymers

Well‐defined hetero eight‐shaped copolymers composed of polystyrene (PS) and poly(ε‐caprolactone) (PCL) with controlled molecular weight and narrow molecular weight distribution were successfully synthesized by the combination of ring‐opening polymerization, ATRP, and “click” reaction. The synthetic procedure involves three steps: (1) preparation of a tetrafunctional PS and PCL star copolymer with two PS and two PCL arms using the tetrafunctional initiator bearing two hydroxyl groups and two bromo groups; (2) synthesis of tetrafunctional star copolymer, (α‐acetylene‐PCL)₂(ω‐azido‐PS)₂, by the transition of terminal hydroxyl and bromo groups to acetylene and azido groups through the reaction with 4‐propargyloxybutanedioyl chloride and NaN₃ respectively; (3) intramolecular cyclization reaction to produce the hetero eight‐shaped copolymers using “click” chemistry under high dilution. The ¹H NMR, FTIR, and gel permeation chromatography techniques were applied to characterize the chemical structures of the resulted intermediates and the target polymers. Their thermal behavior was investigated by DSC, and their crystallization behaviors of PCL were studied by polarized optical microscopy. The decrease in chain mobility of the eight‐shaped copolymers restricts the crystallization of PCL and the crystallization rate of PCL is slower in comparison with their corresponding star precursors. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6496–6508, 2008     

单杠教学中心理障碍的分析研究

单杠教学作为体操教学的重点内容在体育系的教学中具有举足轻重的地位,同时因为心理障碍在单杠教学中出现的很多,当然单杠教学中心理障碍的克服对单杠教学效率的提高有很大的作用,在文中针对不同的心理障碍提出了不同的方法进行克服,对单杠教学进行了研究分析.     

Optimization of asymmetric hydrogenation of 3-phenyl-3-butenoic acid catalyzed by rhodium(I)-4,5-bis[(diphenylphosphino)methyl]-2,2-dimethyldioxolane (DIOP)

Enantioselective, homogeneous hydrogenation of 3-phenyl-3-butenoic acid (1) has extensively been examined in the presence of the rhodium(I)/4,5-bis[(diphenylphosphino)methyl]-2,2-dimethyldioxolane (DIOP) catalyst systems. Optimization of the reaction conditions was undertaken mainly by controlling effects of added tertiary amines as well as solvent polarities on the enantio-selectivity of the product. The best asymmetric yield (85.1% e.e.) was attained when the hydrogenation was carried out in the presence of triethylamine (5 mol%) in 75% aqueous methanol using a neutral rhodium-DIOP catalyst.     

氚核磁共振波谱在氚标记甾族化合物制备中的应用

本文介绍了十一种氚化甾族化合物的氚核磁共振谱。我们依照英国放化中心和英国萨里大学报道数据,(甾体骨架上的CH及CH_2各位置的谱线归属,应用了定位标记化合物作为对照)归属了其氚在化合物中标记的位置,根据其积分曲线定出了各位氚的相对百分含量。同时图谱中又提供了立体构型的信息,为氚化甾族化合物制备过程中,催化剂的选择,实验条件的控制及反应机理等研究提供了理论依据。