氟化锂团簇基纳米相薄膜的慢正电子研究

用慢正电子束流装置研究了氟化锂团簇沉积在单晶硅衬底上构成的纳米相薄膜,获得了正电子湮没S参数和有效扩散长度L_eff. 讨论了制备条件(如衬底温度、蒸发速率、惰性气体分压等)对薄膜微观结构的影响.     

城市工业企业经济效益的综合评判

本文采用多元统计分析中的主成分分析方法改进型，对城市工业企业的经济效益给予综合评判，然后又对综合评判系数采用系统聚类分析方法对其作了分类，用以找出各类城市的优势和差距，便于针对性地制定提高经济效益的对策．     

Stahl und Eisen

Ohne Zusammenfassung     

Crystallographic report: Bis(4‐nitrobenzoato)bis(pyridine)zinc(II)

The molecular structure of [Zn(O₂CC₆H₄NO₂‐p)₂(pyridine)₂] exhibits a distorted N₂O₂ tetrahedral geometry around the zinc atom owing to the presence of monodentate p‐nitrobenzoate ligands; the molecule has twofold symmetry. Copyright © 2004 John Wiley & Sons, Ltd.     

非锁相Lorenz-Haken方程动力学研究

考虑原子的相干性和经典注入光场，利用随机微分方程给出非锁相条件下的Lorenz-Haken方程，研究失谐量、注入经典光场和原子相干性对非锁相Lorenz-Haken方程动力学特性的影响．在激光运转情形，失谐量造成光场位相的混沌，系统在不同条件下，出现四吸引子、双吸引子及单吸引子混沌状态，且体系的分数维维数较锁相条件下增加．光场失谐量、注入光场和原子相干性可抑制混沌．在双稳态运转下，光场位相为π的偶数倍或奇数倍，使光场稳定于正值和负值，故体系出现对称双稳态对，但无混沌状态． 关键词： 非锁相Lorenz-Haken方程 混沌 原子相干性 注入光场     

Reconfiguring the Logical Topology With Performance Guarantees in WDM Networks

To improve the network performance after traffic demand changes , reconfiguring the logical topology is necessary. We present an ILP algorithm to find out the least lightpath changes needed with guaranteed network performance.     

Microencapsulation of cholesteryl alkanoate by polymerization‐induced phase separation and its association with drugs

A new microencapsulation technique is presented in which cholesteryl nonanoate (CN)/poly(methyl methacrylate) (PMMA) microcapsules are produced by the induction of phase separation between CN and PMMA within the droplets during the polymerization. The concentration of CN is the most important factor determining the final morphology of the microcapsules. For example, a polynuclear type is obtained at a low concentration (<20 wt %), a mononuclear type is obtained at a medium concentration (20–30 wt %), and an irregular phase is obtained at a high concentration (>40 wt %). To evaluate the effectiveness of the technique for stabilizing an unstable drug, we selected retinol (vitamin A) as a model drug and loaded it into the CN/PMMA microcapsules. We used a process called solute codiffusion, in which a fine solvent emulsion containing the retinol was diffused uniformly into the CN/PMMA microcapsules. The loading efficiency of retinol was predicted successfully with the aid of a thermodynamic equation. In the thermal stability test of retinol, we found that an effective association with the CN phase was the most important factor determining the limit of its molecular stability. The technique reported in this article has great potential for the microencapsulation of soft materials via a simple process and for the stabilization of unstable drugs. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2202–2213, 2004     

Adsorption structure and spin polarization of pentacene on a magnetized Fe(1 0 0) substrate: SPMDS and ERDA study

The adsorption structure and spin-resolved electronic structure of pentacene on Fe(1 0 0) surfaces were investigated using elastic recoil detection analysis (ERDA) and spin-polarized metastable deexcitation spectroscopy (SPMDS), respectively. It was found that the pentacene molecule adsorbs with its molecular plane parallel to the surface in the initial stage of growth, while the molecular plane tilted from the surface with the increase of the coverage. In the pentacene-Fe surface interaction, a donation and backdonation interaction was indicated. It was found that the polarity of the spin polarization induced in the pentacene molecular orbitals was opposite to each other between the orbitals contributing to the donation and those contributing to the backdonation.     

脉冲时滞抛物型方程解的振动性

本文研究了两类边界条件下有振动系数的脉冲时滞抛物型方程解的振动性,得到了若干解振动的判别准则。其结果即使用于有固定符号系数的方程,也显著地改进了已有的结果。     

Universal self-similarity of porous media equation with absorption: the critical exponent case

In this paper we study the large time behavior of non-negative solutions to the Cauchy problem of u_t=Δu^m−u^q in R^N×(0,∞), where m>1 and q=q_c≡m+2/N is a critical exponent. For non-negative initial value u(x,0)=u₀(x)∈L¹(R^N), we show that the solution converges, if u₀(x)(1+|x|)^k is bounded for some k>N, to a unique fundamental solution of u_t=Δu^m, independent of the initial value, with additional logarithmic anomalous decay exponent in time as t→∞.