Halonickel 2,4-di-t-butyl-6-(quinolin-8-yliminomethyl)phenolates: Synthesis, characterization and ethylene reactivity

A series of nickel halides bearing 2,4-di-t-butyl-6-(quinolin-8-yliminomethyl) phenolate ligands was synthesized and characterized by IR spectroscopy and elemental analysis.Molecular structures of C1(R = H,X = Br) and C2(R = H,X = Cl) were further confirmed by single-crystal X-ray crystallographic studies,and revealed a distorted square planar geometry at nickel.Upon activation with diethylaluminum chloride(Et 2 AlCl),all nickel pre-catalysts displayed good catalytic activity [up to 9.3 × 10 5 g mol 1(Ni) h 1 ] for ethylene oligomerization with major dimerization.In the presence of methylaluminoxane(MAO),the nickel complex C1 was capable of ethylene polymerization under 3 MPa,and produced polyethylene products with narrow polydispersity(1.16 1.73) and molecular weights in the range of 2.6 4.95 kg/mol.     

Influence of clay on the morphology and phase separation behavior of poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) blends

The effect of clay on the morphology and phase-separation behavior of poly(methyl methacrylate)/poly(styreneco-acrylonitrile)(PMMA/SAN) blends and the variation of clay dispersion have been investigated. With the evolution of phase separation in PMMA/SAN, most of the clays are first located at the boundaries between PMMA and SAN, and then gradually move to the PMMA-rich domain, owing to the affinity of clay to PMMA. The introduction of clay causes the increase of binodal and spinodal temperatures of PMMA/SAN and enlarges their metastable region, indicating the phase stabilizing effect of clay on the matrix. But the influence of clay on the cloud points obviously depends on the composition of PMMA/SAN. The selective adsorption of PMMA on the clay results in the difference between the composition of surface layer and that of polymer matrix. Hence, the clay plays the role of an agent changing the conditions of phase structure formation.     

从一道常微分方程组习题中得到的启示

基于一道微分方程组习题的分析．给出了矩阵指数函数的几个性质以及其行列式的相关结果，并对该习题做了详细的解答．     

On the Decay Property of Solutions of Viscous Burgers Equation with Boundary Feedback

In this article, we will investigate the viscous Burgers equation with boundary feedback. The existence of the solution is proved by constructing a convergence sequence inductively. Moreover, the decay property of the solution is shown based on the maximum principle for nonlinear parabolic equations.     

一种求空间曲线间或曲面间距离的方法

根据空间几何图形距离就是空间几何图形两点之间距离的最小值的定义,利用多元函数求条件极值的拉格朗日数乘法建立空间几何图形距离与法线的关系定理,再根据几何图形上两点之间距离与两点的法线重合的关系找出两几何图形上点,分别求出这些之间的距离,距离最小者即为两几何图形之间距离.     

级数绝对收敛与条件收敛的审敛法研究

由正项级数∞∑n=1 ｜un｜发散一般不能推出级数∞∑n=1 un发散。但是如果正项级数∞∑n=1 ｜un｜的发散性是由比值审敛法或根值审敛法所确定，则原级数∞∑n=1 un必然发散．     

正二十面体、正十二面体研究的历史演进

通过论述柏拉图(Plato,B.C.427-B.C.347)、欧几里得(Euclid,约B.C.330-B.C.275)、帕波斯(Pappus,约300-350)、帕赛利(L.Pacioli,约1445-1517)、梅文鼎(1633-1721)作正二十面体、正十二面体的作图法,指出梅氏作法最为简洁,已蕴含证明,胜于上世纪苏联别列标尔金(Д.И.Перепелкин)方法,为历来最优美解.     

SHORT COMMUNICATION SECTION Some Geometric Flows on Kahler Manifolds

We define a kind of KdV （Korteweg-de Vries） geometric flow for maps from a real line or a circle into a Kahler manifold （N,J,h） with complex structure J and metric h as the generalization of the vortex filament dynamics from a real line or a circle. By using the geometric analysis, the existence of the Cauchy problems of the KdV geometric flows will be investigated in this note.     

中国移动通信市场的利润博弈研究

根据斯塔尔博格博弈原理,研究中国移动通信市场的营销策略,结果表明在多寡头垄断情况下,通过价格战争取客户,在用户数量达到最优,企业不能取得最大利润.只有通过准确的商业战略来指导投资方向,创建可行的商业模式,通过服务差异化等策略才能实现市场的有效竞争.     

Combined effect of modified zeolite 13X and β-nucleating agent on improving β-crystal content and toughening polypropylene random copolymer

Although addition of β-NUCLEATING agent directly into homo-polypropylene(PPH) is a useful method to improve β-CRYSTAL content and toughen PPH, polypropylene random copolymer(PPR) makes this method powerless due to its random structure and low crystallinity. In this study, the-nucleated PPR with high β-CRYSTAL content was prepared by a novel high effective β-NUCLEATING system which consists of-nucleation agent(TMB-5) and modified zeolite 13X(M13X). It was found that M13X and TMB-5 had a synergistic influence on improving β-CRYSTAL content and toughening PPR. The content of β-CRYSTAL in PPR/M13X/TMB-5 was significantly larger than the sum of that in PPR/M13X and PPR/TMB-5. Besides,fracture behavior, phase morphology and relaxation of matrix chain segments were also investigated. The results showed that M13X and TMB-5 improved the mobility of amorphous chain segments at low temperature and contributed to much energy dissipation. This work provides a powerful method to modify PPR.