Catalytic Hydrogenation of α,β-Epoxyketones to β-Hydroxyketones with Two Sulfinyl Analogues of Coenzyme NADH Models

An efficient method for the selective hydrogenation of a series of α,β-epoxyketones to β-hydroxyketones using catalytic amount of two sulfinyl analogues of NAD^＋ model compounds is reported. The lack of any diastereoselectivity for the formation of β-hydroxyketones with optically pure sulfinyl analogue of NAD^＋ model supports the radical mechanism proposed previously.     

[SiMo_2~(Ⅴ)Mo_(10)~(Ⅵ)O_(40)]~(6-)及其钒取代物的量子化学研究

采用SCC－DV－Xα方法对α－Keggin结构硅钼二电子还原态杂多蓝阴离子［SiMo2（V）Mo10（VI）O40］6-和它的混合型钒取代物［SiV2（V）Mo10（VI）O40］6-进行了量子化学计算，获得了轨道能级、费米能级、各原子价电子布居、自由价态密度分析和分子轨道成分等信息．理论分析表明该杂多阴离子中所有原子Si、Mo、V、Oa、Ob、Oc和Od都参与反应，Oc和Od的成键能力较强，化学活性较大，有力地支持了实验结果．中心硅氧四面体结构发生畸变很小，但构成三金属簇的八面体结构都发生了较明显的畸变，其整体仍然保持α－Keggin结构．钒的取代增强了Mo2VO13三金属族中Od的活性．预测这两种杂多阴离子都有被继续还原和取代的趋势，[SiMo2(V)Mo10(VI)O40]6-的趋势更强．     

父代种群参与竞争遗传算法几乎必然收敛

熟知,标准遗传算法如不采用“杰出者记录策略”则必不收敛。本文发现：允许父代种群参与竞争是标准遗传算法几乎必然收敛的条件。特别地,我们运用鞅收敛定理证明：允许父代种群参与竞争型遗传算法能以概率1确保在限步内达到全局最优解,且收敛与种群规模无关。所获结果对该类遗传算法的应用奠定了可靠基础。     

超强激光超热电子激发的Kα X射线发射研究

建立了无色散型X射线谱仪. 利用SILEX-I激光装置的超强激光辐照固体物质，分别在靶前、后定量测量了Cu和Mo物质在不同激光功率密度时的X射线谱和Kα光子产额，推导了不同激光强度时的Kα X射线光子转换效率. 实验发现，打靶激光能量越高，靶后出射的Kα产额越高，100μm Mo靶可获得10^-5量级转换效率.     

Non-linear Semigroup of a Class of Abstract Semilinear Functional Differential Equations with a Non-Dense Domain

In this work, we are concerned with a general class of abstract semilinear autonomous functional differential equations with a non-dense domain on a Banach space. Our objective is to study, using the Crandall-Liggett approach, the solutions as a semigroup of non-linear operators.     

Inverse-Definiteness of the Fourth-Order Symmetric Differential Operator （Ⅰ）

Abstract   We give a linear symmetric differential operator L defined by

Non-expansive Mappings and Iterative Methods in Uniformly Convex Banach Spaces

In this article, we will investigate the properties of iterative sequence for non-expansive mappings and present several strong and weak convergence results of successive approximations to fixed points of non-expansive mappings in uniformly convex Banach spaces. The results presented in this article generalize and improve various ones concerned with constructive techniques for the fixed points of non-expansive mappings.     

Weak Uniform Normal Structure and Fixed Points of Asymptotically Regular Semigroups

Let X be a Banach space with a weak uniform normal structure and C a non–empty convexweakly compact subset of X. Under some suitable restriction, we prove that every asymptoticallyregular semigroup T = {T(t) : t ∈¸ S} of selfmappings on C satisfying

${\mathop {\lim \inf }\limits_{S \mathrel\backepsilon t \to \infty } }{\left| {{\left\| {T(t)} \right\|}} \right|} < {\text{WCS}}(X)$

has a common fixed point, where WCS(X) is the weakly convergent sequence coefficient of X, and\({\left| {{\left\| {T(t)} \right\|}} \right|}\) is the exact Lipschitz constant of T(t).     

Neumann-Bessel级数的线性求和及其收敛性

研究了Neumann-Bessel级数部分和的收敛性及其逼近性质.为进一步改进其收敛性和逼近性质,首先从Neumann-Bessel级数部分和出发,构造了一类新的积分算子Hn(f,z)=1/8πi∮Γ(f(ζih)+2f(ζ)+f(ζe-ih))kn(z,ζ)dζ,其中h=π/(n+1),并证明了:若f(z)在Γ上连续,则Hn(f,z)-f(z)=o(ω(f,1/n)),z∈Γ,其中"0"与n无关,ω(f,δ)为f(z)在Γ上的连续模.进而得出Hn(f;z)在单位圆周Γ(|z|=1)上一致地收敛到每个连续的f(z)且其逼近性质优于Fejer和σn(f,z).     

在单参数双边截断型分布族中参数估计的一种新的渐近效率

为了克服在单参数双边截断型分布族中不能消除参数估计中在Ｂａｈａｒｄｕｒ意义下的超有效病态现象,本文提出了一种新的渐近效率．根据这种效率的定义,对一般 的参数函数,构造了适用的渐近中位无偏的渐近有效估计量．作为全文的理论基础,我们发现了渐近中位无偏估计的最优收敛速度．