含交易成本的分散投资利润研究

投资理论告诉人们，应尽量使投资分散化．但许多投资在实际投资中却常常违背这一原则．本从一个调面分析在一个等均值和有一个无风险资产的均方世界里，交易成本的存在，会使投资产生很强的违背分散化原则的动机。     

我国经济信息网站的现状研究

在搜索与访问国内主要经济信息网站的基础上,对我国近十几年来经济信息网站的开发与维护的状况、所取得的成就做了分析。     

A theoretical model for mid-and low-latitude ionospheric electric fields in realistic geomagnetic fields

The geomagnetic fields, which play important roles in the ionospheric dynamo, can greatly affect the global distribution of ionospheric electric fields, currents and other ionospheric electrodynamics phenomena. In the study of ionospheric electrodynamics phenomena, such as the longitudinal variations of ionospheric electric fields, the non-dipolar component of the geomagnetic fields must be taken into account. In this paper, we deduce a theoretical electric field model for ionospheric dynamo at mid- and low-latitude which adopt a modified magnetic apex coordinates system. In the new electric field model, the geomagnetic fields can be calculated from either the IGRF model or the dipole field model, and the neutral winds and conductivities are calculated based on empirical models. Then the dynamo equation for the electric potential is finally solved in terms of the line-by-line iteration method, and the ionospheric electric fields and currents are derived from the calculated potential. Our model can reproduce the main features of the ionospheric electrodynamics processes, so it will be a useful tool for the investigation of the upper atmosphere and ionosphere.     

合理垂直烧结速度的研究

通过考查气流速度的变化研究垂直烧结速度随烧结过程的变化规律。结果表明:垂直烧结速度并非固定不变,而是随着烧结过程的逐步进行发生显著变化;点火保温后,随烧结物理化学反应的进行,燃烧带逐渐形成并变宽且产生过湿现象,导致料层的透气性显著变差,烧结速度显著下降,直至约25 min后过湿层完全消失,透气性变好,烧结速度迅速上升。根据垂直烧结速度变化规律,通过改变负压烧结,进行烧结速度优化实验,结果表明:在保持转鼓强度及成品率基本不变的情况下,将垂直烧结速度由20.08 mm/min提高到21.82 mm/min,利用系数由1.401 t/(m2-h)提高到1.587 t/(m2-h)。     

闪光Ⅰ号应用于X射线爆轰照相——研究金属射流的穿甲效应

闪光X射线照相技术是研究动载荷及其效应的重要测试手段,特别适用于研究物质在爆炸作用下的瞬变过程,本文介绍了闪光Ⅰ号加速器应用于X射线爆轰照相的基本状况,以及用于观察金属射流穿过高密度物质钨靶的实验技术。     

基于DSP的电子耳蜗语音处理器的研制

电子耳蜗是一项正在迅速发展的聋人康复新技术，其关键是要研制出可靠、灵活、价格低廉的产品。首先介绍电子耳蜗的原理及其进展，然后介绍基于TMS320VC5402 DSP处理器的电子耳蜗语音处理器。实验证明：基于DSP的电子耳蜗系统可以按照患者的实际情况灵活选择各种语音处理方案，并能方便实现语音预处理、噪声抑制和对应各电极的频谱阈值调整，是一种比较好的系统结构。     

Isolation and Structure Elucidation of Nortriterpenoids from Schisandra rubriflora

Seven new highly oxygenated nortriterpenoids, rubriflorins D–J ( 1 – 7 ), were isolated from the leaves and stems of Schisandra rubriflora, and their structures were elucidated on the basis of extensive analysis of spectroscopic data. These new compounds feature the opening of ring A compared with related known nortriterpenoids isolated from the genus Schisandra and showed weak activity against HIV‐1.     

水膜除尘器改造为HSTⅡ型高效脱硫除尘器的应用与实践

介绍了原水膜除尘器改造为HSTⅡ型高效脱硫除尘器的工作原理及改造后的使用情况。说明这一改造不仅可行 ,而且具有投资少、工期短、运行成本和处理效果好的优点     

Chinese (Mainland) teachers’ views of effective mathematics teaching and learning

This study investigates Chinese teachers’ cultural beliefs concerning effective mathematics teaching through semi-structured interview with nine experienced teachers. For the Chinese teachers, an effective teacher should always be passionate and committed to the teaching profession. She should not only understand the knowledge in the textbook thoroughly but also be able to carefully craft the knowledge from the textbook for teaching by predicting possible students’ difficulties. Although Chinese teachers emphasize student participation and flexible teaching, they tend to see the teacher’s ability to design and lead coherent lessons as the key for facilitating students’ understanding. The result of this study helps researchers and educators understand the teacher-designed and content-oriented teaching model in Chinese classrooms.