Hydrothermal growth and optical properties of doughnut-shaped ZnO microparticles

Doughnut-shaped ZnO microparticles have been grown through a hydrothermal reaction in citrate solution at 120 degrees C. FESEM reveals that these microparticles consist of regular arranged nanoplates, and there is a concave on the surface of each microparticle. The existence of citrate is vital to the formation of the complex microparticles. Room temperature photoluminescence measurements show strong UV band emission. The yellow and green emissions related to the structure defects can be barely observed, indicating the high crystalline perfection of these microparticles.     

教育目的观的成因探析

以知识为中心的教育目的观是导致我国大学生现代适应性差的重要原因,而这种教育目的观的形成也有着多方面的原因。本文从教育发展的历史和现实两个角度对此进行了探讨,提出历史上的“重社会,轻个人”和现实中的“重记忆,轻创造”是重要的两点。为此,作者提出要塑造现代化的人,首先必须更新教育目的观。     

Wave propagation in distributed media

The problem of chemical reaction-diffusion wave propagation through a random, heterogeneous medium is considered using a model based on cubic autocatalysis with decay. The autocatalyst is taken to diffuse and react through a reactant loaded at constant initial concentration in a reaction domain except that there may be gaps of arbitrary width in which the reactant concentration is zero. We first study the propagation of a permanent-form wave across a single gap and determine the critical width of the gap in terms of the kinetic parameters in the system. The numerical results are compared with an analytical estimate. Next, the critical conditions for propagation across two gaps separated by a domain are determined numerically, and this is extended to a series of three gaps. From these results, a series of "rules" is established to allow us to predict whether a wave will pass through an arbitrary random array of gaps of a given size subject to some imposed total void fraction for the material. (c) 2001 American Institute of Physics.     

一维螺旋配合物{[AgL](ClO4)(H2O)}n的合成和晶体结构

二硫醚配体2,3-二苯硫甲基喹喔啉与高氯酸银反应合成出配合物{[AgL](ClO4)(H2O)}n.用X射线衍射方法测定了配合物的晶体结构.配合物为四方晶系,空间群为I4(1)/a,晶体学参数:a=2.375 5(2)nm,b=2.375 5(2)nm,c=2.369 5(4)nm,V=13.371(2)nm3,Z=16.晶体结构研究表明配合物为一维螺旋结构.     

关于刘勰的“变乎《骚》”——《文心雕龙·辨骚》“折衷”解义

“折衷”是刘勰的主要论文方法，《文心雕龙》“变乎《骚》”一语较典型地体现了他的这种“折衷”思维模式。在刘勰看来，体“资于故实”、数“酌于新声”是文“变”之“势”、“理”，而《楚辞》则是对这两者的集中体现。“变乎《骚扩者，实指《骚》（概指《楚辞》）为文“变”之典范。     

The scheduling of deliveries in a production-distribution system with multiple buyers

In a real production and distribution business environment with one supplier and multiple heterogeneous buyers, the differences in buyers’ ordering cycles have influence on production arrangements. Consequently, the average inventory level (AIL) at the supplier’s end is affected by both the production policy and the ordering policy, typically by the scheduling of deliveries. Consequently, the average inventory holding cost is most deeply affected. In this paper, it is proposed that the scheduling of deliveries be formulated as a decision problem to determine the time point at which deliveries are made to buyers in order to minimize the supplier’s average inventory. A formulation of the average inventory level (AIL) in a production cycle at the supplier’s end using a lot-for-lot policy is developed. Under the lot-for-lot policy, the scheduling of deliveries (SP) is formulated as a nonlinear programming model used to determine the first delivery point for each buyer with an objective to minimize the sum of the product of the individual demand quantity and the first delivery time for each buyer. Thus, the SP model determines not only the sequence of the first deliveries to individual buyers, but also the time when the deliveries are made. An iterative heuristic procedure (IHP) is developed to solve the SP model assuming a given sequence of buyers. Six sequence rules are considered and evaluated via simulation.     

试论甲午战争前日本对华的间谍活动

本文将甲午战争前日本对华的间谍活动分成三个阶段论述 ,分析了谍报工作对甲午战争进程的　　影响 ,探讨了日本谍报工作取得成功的原因。     

Experimental study on turbulent features in the negative transport region of asymmetric plane channel flow

Turbulent features of streamwise and vertical components of velocity in the negative transport region of asymmetric plane channel flow have been studied experimentally in details. Experiments show that turbulent fluctuations in negative transport region are suppressed, and their probability distributions are far from Gaussian. Besides, the skewness factors attain their negative maxima at the position of the maximum mean velocity, whereas the flatness factors attain their positive maxima at the same position. The project supported by the National Natural Science Foundation of China (19872043)     

基于AHP方法的湖泊群引水方案综合评价方法

针对湖泊群整治中引水活水方案实施前均需对各方案进行可行性分析,建立一种基于AHP层次分析方法的综合评价方法(ESLI),可以对包含水质改善指标、水动力学指标、经济指标和感观指标等多目标、多层次的湖泊群引水方案进行综合评价,并将ESLI方法用于福州市西湖左海湖泊群水质改善的方案优选中,为设计与决策提供相对较优的方案集.