Isolation of Trichoderma reesei pyrG Negative Mutant by UV Mutagenesis and Its Application in Transformation

Two uridine auxotrophic mutants of Trichoderma reesei were isolated by resistance to 5-fluoroorotic acid after UV mutagenesis. One mutant, called M23, was complemented with the Aspergillus niger pyrG gene carried by plasmid pAB4-1. A mutated pyrG gene of M23 was cloned and DNA sequencing analysis indicated that a cytosine was inserted into the 934―939 oligo dC position of the pyrG coding region, resulted in a frameshift mutation. Transformation efficiency was approximately 200―300 transformants per microgram of DNA with plasmid pAB4-1. Stable transformants were obtained by monosporic culture and showed to be prototroph after successive propagation. Vitreoscilla hemoglobin expression plasmid pUCVHb was cotransformed with plasmid pAB4-1 and attained a transformation efficiency of 71.8% or of 26.1% with pAN7-1. Southern blot analysis of the transformants demonstrated that plasmid pUCVHb was integrated into the chromosomal DNA. The experimental results demonstrated that the pyrG-based system was more efficient and timesaving than the conventional hygromycin B resistance-based transformation system.     

一类Valterra积分方程正解的存在性

利用Banach空间锥上的不动点指数证明了Volterra积分方程: μ(x)= integral from n=0 to x a(x—s)g(μ(s))ds正解的局部存在性,然后延拓到[0,十∞)上     

4NH_2－TPP－Co溶解度的测定及溶解热的计算

用Ｒｅｉｌｌｙ和Ｒａｅ’ｓ方法测定了不同温度下氨基卟啉钴的溶解度，得到了溶解度随温度变化的关系式：１ｎｍ＿ｓ＝一３５１．３８２３＋２．４４３７Ｔ一５．４６５５×１０￣（－３）Ｔ￣２＋３．７２７３×１０￣（－６）Ｔ￣３根据Ｖａｎ’ｔＨｏｆｆ方程建立了溶解热随温度变化的经验式：     

Nd：YAG晶体1．064μm受激发射截面随温度变化特性研究

测量了Nd：YAG晶体从-70℃到 80℃不同温度下的荧光发射光谱和荧光寿命，计算了该晶体在不同温度下1．064μm受激发射截面，首次获得在此温度变化范围内受激发射截面随温度的线性变化关系．     

IMPLICIT-EXPLICIT MULTISTEP FINITE ELEMENT-MIXED FINITE ELEMENT METHODS FOR THE TRANSIENT BEHAVIOR OF A SEMICONDUCTOR DEVICE

The transient behavior of a semiconductor device consists of a Poisson equa-tion for the electric potential and of two nonlinear parabolic equations for the electrondensity and hole density.The electric potential equation is discretized by a mixed finiteelement method. The electron and hole density equations are treated by implicit-explicitmultistep finite element methods. The schemes are very efficient. The optimal order errorestimates both in time and space are derived.     

广州地区四所高等院校253例正常老年人心电图分析及正常值探讨

本文对广州地区四所高等院校253例正常老人(60—84岁)心电图进行了分析,其中60—69岁207人(占81.8％),男:女为3.28:1。其心电图特点:除2例心房纤颤外,皆为窦性心律,心率偏慢,各波传导间期稍延长,P—R间期可长达0.22秒,各波波幅比正常成人标准要低;低电压也多见。波形多见错折及小切迹,异常心电图的发现率也较高(64％)。其原因可能与心肌老化,退行性变,心脏转位,胸廓变形及肺组织弹性减弱有关。     

20世纪80年代以来国内关于美国进步运动的研究综述

进步运动是一个颇有争议且富于魅力的历史课题。涉及进步运动本身的一些问题在国内外迄今尚无定论。与美国史学界璀璨夺目的著述相比，中国史学界对进步运动的研究成果可谓寥若晨星。本文简要介绍了中国学者对进步运动的研究状况。进步运动作为一个具有重大历史和现实意义的课题，应引起读者的关注和重视。     

PARALLEL SCHWARZ ALGORITHMS FOR PARABOLIC EQUATIONS AND ERROR ESTIMATES

In this paper we introduce two kinds of parallel Schwarz domain decomposition me thods for general, selfadjoint, second order parabolic equations and study the dependence of their convergence rates on parameters of time-step and space-mesh. We prove that the, approximate solution has convergence independent of iteration times at each time-level. And the L~2 error estimates are given.     

Synthesis and Two-photon Absorption Properties of s-Triazine Derivatives

Two new s-triazine derivatives, which belong to linear dipolar type and triangle octupolar type respectively, have been synthesized. The structure of the dipolar compound has been determined by X-ray diffraction. The two-photon absorption cross-section σ, and the two-photon excited fluorescence (TPEF) intensities are increased significantly from dipolar compound to octupolar compound.     

硒对慢性活动性肝炎的影响

５０例慢性活动性肝炎（慢活肝）随机分为治疗组和对照组。２５例治疗组接受１２周补硒治疗，结果显示，治疗组与对照组比较，血清ＡＬＴ显著下降，谷胱甘肽过氧化物酶活力明显升高，提示补硒能防治自由基引起的肝损伤，防止慢性肝病的发展。