剖析河南省上市公司资金占用的特征与危害

大股东及关联方占用上市公司巨额资金问题成为证券市场各方关注的焦点.结合河南省上市公司大股东及关联方占款的现状,分析了上市公司资金占用的特征和危害.     

Pattern formation in diffusion-limited reactions

The conditions for macroscopic segregation ofA andB in a steady-stateA+B 0 reaction are studied in infinite systems. Segregation occurs in one and two dimensions and is marginal ford=3. We note the dependence of these results on the precise experimental conditions assumed in the theory. We also note the difference between these results and our earlier ones for finite systems where the critical dimension isd=2.     

The Büttiker-Landauer model generalized

Büttiker and Landauer studied scattering off an oscillating rectangular barrier in order to shed light on the time aspects of tunneling. The expression for the traversal time resulting from this study is controversial. In addition, doubts have recently been expressed on technical aspects of their work. In an attempt to clarify these issues, we investigate a generalization of their model to arbitrary oscillating barriers,V(x, t)=V ₀(x)+V ₁(x)cos t. In the process, we confirm that Büttiker and Landauer's work is technically sound. However, we show, by several examples, that no direct general relation exists between the characteristic frequency of an oscillating barrier and the duration of the tunneling process. For a wide range of realistic parameters this characteristic frequency does not even exist.This paper is dedicated to E. G. D. Cohen.     

Liénard方程极限环的电子计算机计算分析

本文提供了用电子计算机计算分析和绘制Ｌｉｅｎａｒｄ方程极限环的方法及其ＢＡＳＩＣ 语言程序,并利用此方法构造了具有三个极限环的两个Ｌｉｅｎａｒｄ方程,绘制了极限环 图形,指明了Ｃ．Ｃ．Ｐｕｇｈ猜想中极限环的存在性与特征函数的二阶导数Ｆ（Ｚ）的变号 有相当的关系。     

克拉霉素漂浮-生物粘附微囊的制备及性能研究

选用乳化-溶剂挥发法制备乙基纤维素载药微球(EMs), 并通过内部凝胶化法进行包衣制得海藻酸钠-乙基纤维素载药微囊(AEMs), 最后通过离子交联法进一步包衣制得壳聚糖-海藻酸钠-乙基纤维素载药微囊(CAEMs). 研究克拉霉素漂浮\|生物粘附微囊的制备工艺, 并考察微囊的体外漂浮性能、 粘附性能及体内滞留性能. 结果表明, CAEMs球形度较好, 药物包封率为72.3%~78.2%, 载药量为7.1%~12.7%. 在pH=5的醋酸缓冲液中, 6 h时的累积释放率为56.6%~70.6%, 漂浮率大于70%, 4 h时的体内滞留率为60.5%. CAEMs有望通过延长药物胃内滞留时间, 在临床用于根除幽门螺旋杆菌, 从而降低消化道溃疡的复发率.     

沸石中阳离子对氮/氧吸附性能影响的研究进展

基于制氧吸附剂在变压吸附空分制氧工业应用的重要性，从沸石分子筛的氮／氧吸附性能方面，介绍了低硅沸石LSX、钙沸石、锂沸石、锂银沸石等的研究进展。讨论了沸石分子筛骨架结构和其中阳离子的种类、位置、数量与其吸附特性的关系，探讨其在变压吸附空分制氧中的应用前景。     

二组分混合物的最小流化特性 Ⅰ.混合/分离状态与最小流化空隙率

分析了二组分混合物的３种混合／分离状态及在完全混合时发生连续相转变的极限组成。提出一个判别非等密度体系混合／分离状态的法则与确定混合物空隙率简易可行的随意松散堆积方法。     

On the Permanental Polynomials of Some Graphs

Let G be a simple graph with adjacency matrix A(G) and (G,x) the permanental polynomial of G. Let G × H denotes the Cartesian product of graphs G and H. Inspired by Kleins idea to compute the permanent of some matrices (Mol. Phy. 31 (3) (1976) 811–823), in this paper in terms of some orientation of graphs we study the permanental polynomial of a type of graphs. Here are some of our main results.1.If G is a bipartite graph containing no subgraph which is an even subdivision of K _2,3, then G has an orientation G ^e such that (G,x) = det (xI-A(G ^e )), where A(G ^e ) denotes the skew adjacency matrix of G ^e.2.Let G be a 2-connected outerplanar bipartite graph with n vertices. Then there exists a 2-connected outerplanar bipartite graph with 2n+2 vertices such that (G,x) is a factor of .3.Let T be an arbitrary tree with n vertices. Then , where ₁ , ₂ , ..., _n are the eigenvalues of T.     

Segregation in zirconia: equilibrium versus non‐equilibrium segregation

The present work considers the differences between the following two phenomena: equilibrium segregation, which is a thermodynamic phenomenon where the driving force is excess interfacial energy; and non‐equilibrium segregation, which can be produced by phenomenological shocks applied to the solid surface. Fully stabilized cubic yttria‐stabilized zirconia (YSZ) is used as the exemplar for these considerations. Equilibrium segregation in YSZ results in enrichment of the surface and near‐surface layers in constituent elements, typically yttria and impurities. This segregation is an intrinsic material property and has an impact on the performance of zirconia at elevated temperatures. On the other hand, non‐equilibrium segregation leads to a complex distribution of properties (structure and concentration gradients) that are determined by the experimental procedures used rather than being a material property. However, such non‐equilibrium segregation can result in localized structural changes. The present paper also considers the effect of the gas phase on surface properties of metal oxides, including YSZ, and the surface dynamics of YSZ at temperatures below that required to reach equilibrium. Copyright © 2005 John Wiley & Sons, Ltd.     

Monte‐Carlo simulation of spatial distribution of characteristic x‐rays in multi‐film targets: source size of Al Kα x‐rays in W/Al film targets

A Monte‐Carlo simulation approach has been applied to describe the spatial distribution of characteristic x‐rays in W/Al film targets of different combinations of film thicknesses for the optimal design of a small‐sized x‐ray source having a high x‐ray intensity. The result has led to optimal combinations of W and Al film targets for 100 kV electrons, e.g. W(1 µm)/Al(20 µm), W(3 µm)/Al(15 µm) and W(5 µm)/Al(8 µm). These Al/W targets could be used as x‐ray sources for a medical instrument currently under development. Copyright © 2004 John Wiley & Sons, Ltd.