双比例延迟微分方程改进的单支θ-方法的H_α-稳定性

In[13],the author constructes the modified Runge-Kutta method and proves that the modified Runge-Kutta method preserves the order of accuracy of the original one.As a result,it is obtained that theθ-method with 1/2θ1is asymptotically stable.The modified one-legθ-method is a specific form of the modified Runge-Kutta method.This paper deals with H_α-stability for the modified one-legθ-method for system of pantograph equation with two delays.It is proved that the modified one-legθ-method with 0θ≤1 is H_α-stable.Some experiments are given.     

解一类二阶延迟常微分方程连续RKN方法的P-稳定性

In this paper, we study the P-stability of the continuous Runge-Kutta Nystroem method for solving the delayed second order differential equation that does not depend on y′. A general theorem is presented which can be used to obtain complete characterizations of the P-stability regions of these continuous RungeKutta- Nystroem methods. We use the condition to two given RKN methods.     

时滞抛物型方程的高精度精细积分法

对一类时滞抛物型方程初边值问题,提出了关于空间步长是四阶精度的高精度无条件稳定的精细积分法.数值算例表明,本文提出的精细积分法具有很高的精度,因而是一种有效的数值方法.     

PVP存在下液液界面生长法制备硒纳米线(英)

0IntroductionSelenium(Se)iswellknownforitsphotoelectri鄄calandsemiconductorpropertiesandhasbeensuc鄄cessfullyusedinsolarcells,rectifiers,photographicexposuremetersandxerography[1].Itcouldbeexpect鄄edthattheuniquestructureandthequalityofone鄄di鄄mensional(     

二阶延迟微分方程θ-方法的TH-稳定性

This paper is concerned with the TH-stability of second order delay differential equation. A sufficient condition such that the system is asymptotically stable is derived. Furthermore, a sufficient condition is obtained for the hnear θ-method to be TH-stable. Finally, the plot of stability region for the particular case is presented.     

比例延迟微分方程组具有刚性精度Runge-Kutta方法的稳定性分析

该文研究比例延迟微分方程组具有刚性精度变步长Runge-Kutta方法的渐近稳定性，给出了一类普遍意义下的变步长格式。证明当且仅当其稳定函数在无穷远点处的模小于1时，变步长Runge-Kutta方法渐近稳定。     

陵水暗罗有效成分的研究 Ⅰ.天然含锌化合物暗罗素的分离及结构

我们从海南岛产的药用植物陵水暗罗中分得一种含锌化合物(得量0.0008%),经鉴定为2-巯基吡啶-Ⅳ-氧化物锌盐,并经合成确证。该化合物对鼠疟具有抗疟原虫的作用。这种金属化合物存在于高等植物中,可能是一种植物他感物质(allelopathy)。因此对植物生理与植物生化必然有其重要意义。     

线性随机比例方程的渐近均方稳定性

本文目的是研究线性随机比例方程解析解和数值方法（连续θ方法）的渐近均方稳定性．给出了解析解和数值方法渐近均方稳定的条件．     

解对流扩散方程的子域精细积分AGEI方法

Based on subdomain precise integration method, a class of two-levelimplicit schemes containing parameter a＞0 for the initial-boundary value prob-lem of convection-diffusion equation are presented. Their local truncation errorsare O(a△t+△t2+△x2). The implicit schemes are unconditionally stable for all a＞0. Then on the basis of the implicit schemes, an alternating group explicit iter-ative (AGEI) method is proposed, and convergence of the iterative process isproved. Because the whole calculation process is explicit, so the AGEI method isvery suitable to parallel arithmetic. Numerical example shows that the AGEImethod has high accuracy and good practicability.     

聚壳糖模板法制备纳米硒

报道了一种利用天然高分子壳聚糖为软模板水相制备纳米硒的方法。研究了反应时间、反应物浓度、温度、超声等实验条件对产物粒度大小、形貌的影响。结果表明 ,当n(Vc)∶n(H2 SeO3 ) =4∶1、壳聚糖质量分数为 1 2 0× 10 -4、常温下反应 2h时 ,可得到均匀稳定的球形纳米硒颗粒 ,平均粒径约 5 0nm ,并随反应体系的总浓度增加而减小。在 80℃反应时 ,得到了棒状纳米硒。采用紫外光谱、红外光谱、X射线衍射和透射电镜等对产物进行了结构分析和形貌观察。