Accurate localization and excision of genomic islands in four strains of <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> and <Emphasis Type="Italic">Pseudomonas fluorescens</Emphasis>

Mobile genomic islands (GIs) can be excised from the chromosome, then form a circular intermediate and be reintegrated into the chromosome by the GI internal integrase. Some mobile GIs can also be transferred into a new receptor cell by transformation, conjugation, or transduction. The action sites of the integrase are usually flanked direct repeats (DRs) of the GIs. Accurate localization of the flanking sequences is a precondition for determining the mobility of the GI. Mobile GIs are generally associated with transfer RNAs (tRNAs). Based on the correlation between flanking sequences and tRNA sequences, the flanking sequences of 11 putative mobile GIs in Pseudomonas aeruginosa PAO1, P. aeruginosa PA14, P. fluorescens Pf-5 and P. fluorescens Pf0-1 were identified. Among the 11 GIs, Pf0-1GI-1 is responsible for benzoate degradation. PAO1GI-1, Pf5GI-2, Pf5GI-3, and Pf5GI-4 were confirmed experimentally to be excised from a chromosome to form a circular intermediate. The action sites of the integrases are these GIs direct repeats. Due to distinct DRs, cutting sites for the internal integrase of PAO1GI-1, Pf5GI-2, Pf5GI-3 and Pf5GI-4 were determined outside the T-loop of the tRNA^Gly gene, outside the anticodon loop of the tRNA^Ser gene and tRNA^Lys gene, and at the asymmetric 3′-end of the tRNA^Leu gene, respectively. PAO1GI-1 and other mobile GIs may be transferred into many different strains that belong to different phyla because of the clear flanking sequences. This study describes basic information about the action sites of the integrases, assesses the mobility of GIs, and can help design and transfer mobile GIs to candidate strains.     

浅议如何提高煤炭运销企业员工的科学素质

目前,煤炭运销企业面临国内诸多新形势、新任务、新挑战,受到不确定因素的影响,企业科学发展着力需求一批有知识、懂业务、能力强、素质高的职工队伍,在企业建设中能够充分发挥群体作用,以便适应当前市场经济变幻莫测、企业形势此起彼伏的需求,亟待解决的是创建学习型企业,提高职工队伍素质,培养造就一支过硬的团队是煤炭运销企业又好又快科学发展的必要途径,也是建立健全现代化煤炭运销企业的基础保证。     

基于MALAB的车牌定位算法研究

利用Matlab工具实现车牌定位算法研究。利用灰度修正，滤波和图像增强等预处理方法。较好地消除了图像的噪音，提高了图像质量。通过对车牌特征的研究，利用边缘检测和扫描方法实现车牌定位。     

库容有限且有批量折扣的不允许缺货存贮模型

Ｗｉｌｓｏｎ公式隐含着用户仓库容量足够大，单价与订购批量无关的假设，这一假设往往与实际情况相悖。为此，本文提出了仓库容量有限且有批量折扣条件下不允许缺货存贮模型，并通过实例说明了模型的应用。     

化工物性数据库CPPDB在IBM-PC/XT机上的实现

讨论了文题实现方法,介绍了该数据库的总体结构。CPPDB利用dBASE Ⅲ支持建库,数据独立性高,修改、扩充方便。CPPDB存储了468种物质的29种物性数据,具有较强的物性估算和图形输出功能。     

生成测试数据的结构归纳法

提出了生成测试数据的结构归纳法,并举例说明如何运用结构归纳法产生程序的测试数据,以利于程序员有规则地产生测试数据。它对提高测试效率,改善软件产品的可靠性有促进作用。     

N,N’—二羧甲基,N,N’—二(2,2,6,6—四甲基—1—氧基哌啶—4—氧酰甲基)乙二胺的合成

本文报道了以丙酮和EDTA为原料合成N,N'—二羧甲基,N,N'—二(2,2,6,6—四甲基—1—氧基哌啶—4—氧酰甲基)乙二胺的方法。该方法具有产率高、操作简便、易于提纯等优点。     

染料激光器宽带双折射调谐器设计

双折射调谐器是用于染料激光器的调谐,调谐器的光轴与其表面的夹角 E,直接影响调谐器的调节灵敏度.分析指出:对石英晶体,将 E 角设计在最灵敏区域30°—35°,可在调谐调节角度不超过±20°的条件下,将调谐器的波长覆盖从可见光区延伸至红外区.     

复合延迟片研究

调整两波片快轴之间的夹角,可得到一种复合延迟),能用来代替1/4和1/2波片使用。     

混凝土内时损伤本构模型

应用内时理论和损伤力学建立了混凝土内时损伤本构模型。该模型的特点是：混凝土的弹塑性特性由内时理论描述，而微裂缝由损伤力学来描述。前者使本构模型摆脱了一般弹塑性模型中的屈服面的概念，从而简化了非线性计算过程；后者使微裂缝引起的软化、休积膨胀等效应都可由损伤变量来考虑，从而既反映了混凝土的本质特性，又使模型的参数和基本方程大大减少。应用本文建议的本构模型于各种实例分析中，所得计算结果与试验结果符合较好。