Permanence and almost periodic solution of a Lotka–Volterra model with mutual interference and time delays

In this paper, a Volterra model with mutual interference and time delays is investigated. By applying the comparison theorem of the differential equations and constructing a suitable Lyapunov functional, sufficient conditions which guarantee the permanence and existence of a unique globally attractive positive almost periodic solution of the system are obtained. Two suitable examples together with their numeric simulations are given to illustrate our results by using MatLab.     

Nd(OTf)3-catalyzed intramolecular-intermolecular cascade cyclization reaction: An access to phenanthro[9,10-b]furan derivatives

An intramolecular-intermolecular cascade cyclization reaction via multi metal-carbene intermediates has been developed. This reaction uses catalytic amount of Nd(OTf)₃, which actives both alkyne and aldehyde moieties. This protocol provides a novel strategy for the synthesis of phenanthro[9,10-b]furans.     

Robust stability of a class of neural networks with time delays

A stability analysis of the equilibrium position for a given class of Hopfield neural networks with time delays is presented. The robustness of the equilibrium stability with respect to variations in the time delays, system parameters, and interconnection matrix is analyzed. Three approaches are presented which account in various ways for stability of the equilibrium with respect to these perturbations.Work conducted while visiting the University of Bremen, supported by the Deutscheforschungsgemeinschaft.     

Elektronenstoss-induzierter zerfall von benzol-tricarbonyl-chrom- und -wolfram-derivaten; ein vergleich

The Electron impact mass spectra of (CO)₃ MC₆H₅—X complexes (M = Cr, W; X = OCH₃, OC₄H₉, CO₂CH₃, CO₂C₄H₉) were recorded. From metastable transitions and by high-resolution measurements complete fragmentation diagrams were obtained; in some cases comparative structure determinations of fragment ions were carried out by collisional activation. The fragmentation of the tungsten complexes considerably differs from that of the chromium compounds. The differences may be attributed to the stronger-electrophilic character as well as to the more pronounced tendency of tungsten to attain higher oxidation states.     

氖等电子序列2p^5nl（l=s,d）系列的高激发态结构

本文用本征通道量子亏损理论方法（ＥＱＤＴ方法）计算了氖等电子序列２ｐ＾５ｎｌ（ｌ＝ｓ,ｄ）系列的高激发态结构。得到基本结构参量（ＥＱＤＴ参量）随净电荷数Ｚｃ增大的变化规律,并从静电相互作用下自旋－轨道相互作用之间的竞争角度给出确切的物理解释。以ＮｅＩ为实例,给出其高激发态结构的具体数值结果。     

CCl自由基A 2Δ←X 2Ⅱ跃迁REMPI光谱研究

在271～279 nm波长范围内采用REMPI技术研究CCl自由基的A 2Δ光谱.实验观察到12C35Cl以及同位素分子12C37Cl 的A 2Δ←X 2Ⅱ1/2,0-0,1-0和2-1跃迁谱带,其中2-1的跃迁为新观察到谱带.获得了A 2Δ←X 2Ⅱ1/2电子跃迁0-0,1-0,2-1谱带的同位素位移.     

密度泛函理论研究KB_n(n=1-9)团簇的结构和性质

在密度泛函理论的框架下,采用广义梯度近似(GGA)研究了KB_n(n=1-9)团簇的基态几何结构,系统计算了平均结合能Eb、二阶能量差分△2E、劈裂能D(n,n-1)、最高占据轨道(HOMO)与最低未占据轨道(LUMO)之间的能隙,研究表明:KB_n(n=1-9)团簇,随着团簇尺寸的变化,其稳定性逐渐增强,其中KB_3和KB_5为幻数团簇;KB_n(n=1-9)团簇的能隙随团簇总原子数的增加呈现振荡变化,态密度分析得到能隙振荡变化的原因是团簇带隙的差异.