一种产生任意连续型分布伪随机数的方法

本文提出一种产生随机数的方法,该方法通过对随机数取值区间进行等概率划分,将概率密度转化为小区间宽度变化,并通过迭代式数值解法寻求区间的等概率划分,以解决大多数分布函数不能用显示表达的问题,最后讨论了算法并进行了实例研究。图3,表3,参2。     

N,N′-亚烃基脂肪酸双酰胺的合成及其润滑性能

研究了文题化合物的合成,制备了二十一种该类化合物。红外光谱及元素分析数据证实了这些化合物结构的正确性。由混炼塑化仪测定了它们的润滑性能,探讨了其润滑性能与分子结构之间的关系。结果表明,芥酸的双酰胺较硬脂酸的双酰胺具有更好的润滑作用;特别是N,N′-(1,2-亚乙基)双芥酸酰胺,明显优于国内目前生产的N,N′-(1,2-亚乙基)双硬脂酰胺和芥酸酰胺。     

露天矿外部排土场的模拟优化研究

以唐钢石人沟铁矿为背景，进行露天矿岩石排弃的模拟优化研究。采用动态模拟、线性规划、模糊数学等理论和方法，建立了外部排土场模拟模型、目标决策模型、流向流量优化模型。设计了相应的框图，编制了计算机软件，并结合矿山实际进行了模拟优化研究。     

永磁轴向多极场的获得

本文描述了永磁非对称轴向二极场的结构和形态,这种磁场用于替代同轴线圈提供微波ECR等离子体CVD系统所需的磁场;简要分析了磁场对等离子体特性的影响。     

New Parallel Interference Cancellation Scheme for DS／CDMA Systems

This paper proposes a new multi-stage parallel interference cancellation scheme by modifying the conventional multi-stage parallel interference canceller (PIC). At each stage, it first converts the interference-cancelled outputs from previous stage into the a prior information, in terms of which the bit mean values are computed and the multi-access interferenee (MAI) for each user is evaluated, and then an interferenee cancellation is performed to obtain further interference suppression. To reduce the implementation complexity, wegive an approximation expression for bit mean value. The performance over AWGN channel is analyzed and compared to the conventional PIC. The user number K= 7 and spreading factor N= 13 are chosen as simulation parameters. The computer simulation results show that the proposed PIC has better performance than the conventional PIC both with 2 interference cancellation (IC) stages, at bit error rate of 10^-3 , for example, about 3 dB performance gain is obtained by using the proposed PIC. It is also shown that our proposed PIC with 1-stage is superior to the conventional PIC with 2-stage in performance, which is of practical value because PIC with fewer stages can bring about shorter processing delay.     

Effect of bromization on the propertises of a series of substituted 1,8,15,22—tetra（2,4—ditertbutylphenoxy） phthalocyanines

A series of 1,8,15,22-tetra(2,4-ditertbutylphen-oxy) phthalocyanines [α-（oAr）4PcM,M1=(H)2,M2=Pd,M3=Cu,M4=Zn,M5=Pb] were synthesized in this study.Each compound was bromized in two kinds of solvent.One is the solvent mixture of 1,1,2-trichloroethane and water,the other is 1,1,2-trichloroethane alone.The effects of solvent,bromine excess added and reaction duration on the bromization reaction were studied.The shift of maximum absorbance wave-length both is solution and in solid thin film was investigated comparatively,discovering that both were bathochromism but the former was more.TG data showed that the temperature of thermal decomposition decreased continuously with the increase of numbers of bromine.Finally,the fragments produced during the bromization of (OAr)4PcPb in 1,1,2-trichloroethane were characterized by GC/MS.Based on the electronic structure,the possible mechanism of decomposition of these compounds was presented and discussed.     

The c-myc coding DNA sequences of cyprinids （Teleostei： Cypriniformes）： Implications for phylogeny

The family Cyprinidae is one of the largest fish families in the world, which is widely distributed in East Asian, with obvious difference in characteristic size among species. The phylogeneUc analysis of cyprinid taxa based on the functionally important genes can help to understand the speciation and functional divergence of the Cyprinidae. The c-myc gene is an important gene regulating individual growth. In the present study, the sequence variations of the cyprinid c-myc gene and their phylogenetic significance were analyzed. The 41 complete sequences of the c-myc gene were obtained from cyprinids and outgroups through PCR amplification and clone. The coding DNA sequences of the c-myc gene were used to infer molecular phylogenetic relationships within the Cyprinidae. Myxocyprinus asiaticus （Catostomidae）, Misgurnus anguillicaudatus （CobiUdae） and Hemimyzon sinensis （Homalopteridae） were assigned to the outgroup taxa. Phylogenetic analyses using maximum parsimony （MP）, maximum likelihood （ML）, and Bayesian retrieved similar topology. Within the Cyprinidae, Leuciscini and Barbini formed the monophyletic lineage respectively with high nodal supports. Leuciscini comprises Xenocyprinae, CuItrinae, East Asian species of Leuciscinae and Danioninae, Gobioninae and Acheilognathinae, and Barbini contains Schizothoracinae, Barbinae, Cyprininae and Labeoninae. Danio rerio, D. myersi and Rasbora trilineata were supposed to separate from Leuciscinae and Barbini and to form another lineage. The positions of some Danioninae species were still unresolved. Analyses of both amino acid variation with parsimony information and two high variation regions indicated that there is no correlation between variations of single amino acid or high variation regions and characteristic size of cyprinids. In addition, the species with smaller size were usually found to be basal within clades in the tree, which might be the results of the adaptation to the primitive ecology and survival pressure.     

反应气氛对铝热还原氧化钛合成氮化钛的影响

研究在流动氮气和埋炭条件下铝热还原氮化TiO2的反应过程,借助于X射线衍射(XRD)和扫描电子显微镜(SEM)分别测试和观察两种气氛中不同温度下处理后产物的物相组成和显微结构。结果显示,与流动氮气氛下一样,在埋炭气氛下采用铝热还原氮化法可以制备氮化钛复相材料,但处理气氛明显影响着铝热反应的程度及产物的形貌,在埋炭条件下处理后的产物中氮化钛含量、晶粒大小、晶格常数明显低于流动氮气氛下处理产物中上述各项值;热力学计算发现埋炭条件下铝除参与铝热还原反应外,还与炭粉床中氧发生反应,使参与铝热反应的金属铝不足,造成产物中有剩余的金红石存在。     

遗传学教学的改革与实践

遗传学是农科院校的一门核心基础课，也是生物科学的重要基础学科，近年来遗传学及其相关学科的研究进展很快，为使遗传学课程教学适库这一形势，获得良好的教学效果，就必须加强遗传学课程的改革，加强实践环节。文章从遗樗学教学大纲修订、多媒体辅助对教学改革及自主性实验教学改革等方面对我们在遗传学教学改革的一些做法和成效进行了介绍和分析，以期进一步促进我们遗传学教学水平的提高。