四氯蔗糖及其衍生物的NMR碳氢化学位移完全解析及结构研究

4,6,1′,6′-四氯蔗糖及其两个单酯化衍生物4,6,1′,6′-四氯蔗糖-3-乙酯和4,6,1′,6′-四氯蔗糖-2-乙酯是在合成三氯蔗糖的过程中得到的3种副产物，应用质谱（MS）和核磁共振（NMR）中的¹H-¹H COSY、HSQC等多种二维谱技术对它们的结构进行了研究，报道了四氯蔗糖及其两个单酯衍生物的合成及NMR碳氢化学位移完全解析，并对其氯化产物的立体化学进行了讨论.     

阻抗谱法确定扩散系数

给出了阻抗谱法确定扩散系数的理论和方法;以钒酸盐阴极材料Na_(1+x)V_3O_(?)(L.T.)为例,应用本方法计算给出了Li~+在阴极中的扩散系数为10~(?)-10~(-9)cm~2·s~(-1);最后还对误差来源进行了讨论. 关键词：     

AB INITIO CALCULATIONS OF OPTICAL PHONON DEFORMATION POTENTIALS IN DIAMOND AND ZINC-BLENDE SEMICONDUCTORS

The behavior of the internal lattice vibrational modes in (NH₄)₂Te_xSn_1-xCl₆ mixed crystals has been investigated by Raman scattering. All of the Raman-active [MX₄]^2- internal modes show two-mode property in the mixed crystals with compositions from x =0 to 1, and apart from the sample with x = 0.5, their energy positions are composition-independent, Space group calculations including site symmetry considera-tions and frequency fittings describe a good force field model. It has been demonstrated that the composition-independent two-mode behavior may come from the strong clustering effect, rather than from the character of the gap and local modes of impurities in mixed crystals. For the sample with x=0.5, the two component elements seem to form a pseudo-periodic lattice structure.     

演化诱致突变的计算机模拟

通过对二维微裂纹系统损伤演化的计算机模拟发现,由大量微裂纹级串连接导致的破坏表现出临界行为,且断裂表面具有分形特征,据此提出了演化诱致突变模型,作为断面特征参数的分维仅是演化规则,即微裂纹连接条件的函数,此结果定性解释了实验所发现的分维随断裂韧性的变化规律。     

Unique Continuation on Quadratic Curves for Harmonic Functions*

The unique continuation on quadratic curves for harmonic functions is discussed in this paper. By using complex extension method, the conditional stability of unique continuation along quadratic curves for harmonic functions is illustrated. The numerical algorithm is provided based on collocation method and Tikhonov regularization.The stability estimates on parabolic and hyperbolic curves for harmonic functions are demonstrated by numerical examples respectively.     

Structural Elucidation and Antitumor Activity of Polysaccharide AMP-1 from Atractylodis macrocephalae K.

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The density of states for interacting systems with inelastic transitions and its relation to the collision lifetime

The quantum mechanical excess density of states ρ(E) is shown to be given in terms of the S matrix by (i/2π) Tr{SdS⁺/dE}, giving the relationship ρ(E) = h⁻¹ Tr{Q}, where Q is the collision lifetime matrix of Smith.     

异丁烯聚合催化体系研究 Ⅰ.均聚与共聚反应

用苯甲酰氯(BC)／TiCl4引发异丁烯(IB)聚合及与苯乙烯(St)的共聚反应，得到分子量高、分布窄的聚异丁烯及其共聚物，并控制了BC的高活性。对IB均聚及其与ST共聚反应影响因素(体系浓度、残余水、第3组分三乙胺(TEA))进行优化，得到最佳条件为：[BC]=2．6mmol／L、[TEA]／[BC]=1.0(均聚)和n(TiCl4)／n(BC)=80、[TEA]／[BC=4．0(共聚)，BC／TiCl4／TEA是最佳体系，对水不敏感，可以制备分子量高及分子量分布(MWD)为1．5(均聚)和2．0(共聚)的窄分布聚合物(GPC曲线均为单峰)。     

甲基丙烯酸十六酯溶液聚合

甲基丙烯酸十六酯在有机溶剂中聚合时,溶剂结构对聚合速度没有显著影响。聚合体的平均分子量主要是受溶剂的链转移常数控制的,但在聚合过程中当生成的高聚物分子具有近似平均分子量时,由于高聚物分子在不同溶剂中具有不同的分子形态所产生的不同程度的粘度效应,对高转化率聚合体的平均分子量产生影响;同时,在高转化率聚合过程中聚合体平均分子量的均匀性与高聚物分子在溶剂中的形态有关,而与由聚合物的不同平均分子量在溶剂中所表现的不同粘度无关。