微生物酶法生产果糖低聚糖

介绍了一种简便易行的制备果三糖标准品的方法。研究得出曲霉６．２２２胞内，胞外酶均具有活性，最佳酶反应条件为：ｐＨ６．０，温度５０℃，时间６０ｍｉｎ。最佳初始蔗糖逍度为２５０ｇ／Ｌ。由曲霉６．２２２发酵制备的酶溶液稳定性良好。     

GUEST EDITORIAL： NEW TRENDS ON SERVICE SYSTEMS AND SERVICE MANAGEMENT

The International Conference on Service Systems and Service Management （ICSSSM06） was held on October 25-27, 2006 in Troyes, France. This conference was sponsored by IEEE Systems, Man and Cybernetics Society. More than 500 articles were submitted to the conference and after a peer-reviewing process, 284 papers were accepted and published in the conference proceedings.     

延迟微分方程θ—方法的稳定性

本文给出了延迟微分方程数值解的稳定性分析。重点解决了单腿θ—方法和线性θ—方法用于求解线性检验方程U(t)=λ(t)U(t)+μ(t)U(t-τ),其中τ>0,λ、μ是从实数域到复数域上的函数,证明了当0<θ<1时两种方法都是不稳定的;而当θ=1时是稳定的。     

GCr15钢球与A3钢板电阻焊工艺参数的研究

本文在试验基础上,确定了GCr15φ5钢球与A3薄板电阻焊的工艺参数,并讨论了各工艺参数与焊后性能、金相组织的关系。     

一种汽车节能采暖系统

本文介绍了一种利用发动机余热的汽车采暖系统的结构、试验结果,这种采暖系统构造简单,改装容易,散热效果基本满意,有节能作用。     

提高激光准直精度的一种有效措施

提出运用三点法补偿激光束不稳定性误差，在时间和空上获得较稳定的激光束。进行了理论分析。实验研究证明运用这种方法可降低准直测量的不确定度近一个数量级。     

不锈钢Ⅲ型试样的氢致开裂和应力腐蚀

研究了奥氏体不锈钢Ⅲ型试样的氢致开裂和应力腐蚀。结果表明,动态充氢时Ⅲ型试样也能发生氢致滞后断裂,且裂纹沿原缺口平面形核和扩展。从而可获得宏观平滑的扭转断口,但断口上存在少量沿45°面的二次裂纹,一系列实验表明动态充氢能促进奥氏体不锈钢室温蠕变,故在恒扭矩下充氢能使扭转角不断增大,直至试样被扭断。奥氏体不锈钢Ⅲ型试样在42％沸腾MgCl_2溶液中也能发生应力腐蚀开裂,且裂纹在与缺口平面成45°的平面上形核和扩展。实验表明,无论是Ⅰ型还是Ⅲ型,应力腐蚀的门槛值均比氢致滞后断裂门槛值要低,例如K_(ⅠSCC)/K_(ⅠX)=0.18,K_(ⅠH/K_(ⅠX)=0.58,K_(ⅢSCC)/K_(ⅢX)=0.13 K_(ⅢH)/K_(ⅢX)=0.62。     

Variation in regulation of aflatoxin biosynthesis among isolates ofAspergillus flavus

Two new phenotypes ofAspergillus flavus which exhibit novel patterns of aflatoxin production have been identified and characterized. In one of the new variants ofA. flavus, aflatoxin is made in the absence of carbohydrate and concomitantly with growth, without a lag period. A second variant did not produce aflatoxin in the presence or absence of carbohydrate. Chemical mutagenesis of this nonaflatoxigenic strain resulted in mutant strains which produced aflatoxin on carbohydrate-containing media. The aflatoxin production pattern observed in these mutants resembled the typical production scheme, with a lag period through log phase growth.     

离体植物细胞分化的调控——植物细胞分化与其本身内在因素的关系

本文对近二十年来国内外关于影响离体植物细胞、组织、器官分化的因素研究进行了综合评述,并提出了一个称之为阶段分化的假说且用这个假说来较合适地解释离体植物细胞的分化.与此同时,本文还指出了一些植物组织培养工作面临急需解决的问题。展望未来创造新的植物种类为人类造福.     

Random walk hypothesis in exchange rate reconsidered

An econometric model for exchange rate based on the behavior of dynamic international asset allocation is considered. The capital movement intensity index is constructed from the adjustment of a fully hedged international portfolio. Including this index as an additional explanatory variable helps to explain the fluctuation of the exchange rate and predict better than the competing random walk model. Supporting empirical evidence is found in Germany–USA, Japan–USA, Singapore–USA and Taiwan–USA exchange markets. Copyright © 2006 John Wiley & Sons, Ltd.