一株蓝麻黄内生细菌的分离鉴定和抑菌活性研究

为筛选具有拮抗活性的植物内生菌,以新疆有毒植物蓝麻黄(E.glauca)为材料,采用研磨法和琼脂扩散法从中分离并筛选出一株对多种植物致病菌具有较强抗性的内生细菌XJEG-GB-13。对其生物学特性进行初步研究,研究表明,最适生长温度为37℃,最适生长pH 值为6.0。根据其形态特征、生理生化检测、16S rDNA 测序,将其鉴定为枯草芽孢杆菌的一个亚种Bacillus subtilis subsp. subtilis。XJEG-GB-13 的获得可为进一步研究高效拮抗菌的拮抗机制提供实验材料。     

机械加工技术在汽车制造维修中的有效应用

在现代社会,汽车已经成为普通家庭必备的代步工具,随着汽车数量的提升,汽车制造与维修技术也需要紧随市场需求不断提升。在汽车制造维修中,机械加工技术十分关键,该技术的应用能够有效提升汽车制造及维修质量,提高工作效率,同时还为人们出行提供了安全与便利。本文首先阐述了机械加工技术在汽车制造维修中的重要作用,全面分析了机械加工技术在汽车制造和汽车维修中的具体应用,以期为相关从业者提高理论借鉴,进一步提升我国机械加工技术,使之能够在汽车制造维修中发挥更大作用。     

基于类别分布差异和特征熵的维吾尔语文本特征选择

文本特征选择是在文本自动分类中最重要的一个环节。为了更好地解决维吾尔文文本分类中特征空间的高维性和文档表示向量的稀疏性问题, 提出一种基于特征的类别分布差异和信息熵的维吾尔文文本特征选择方法。该方法不仅要考虑特征在类别间的分布情况, 而且也要考虑特征在类别内的分布情况。采用本方法对维吾尔文文本语料进行了分类实验, 并与一些传统的特征选择方法进行了比较。从结果来看, 本方法在所选特征数更少的情况下, 达到了比其他方法更高的分类MacroF1值853%, 比传统的IG和CHI等方法在MacroF1值上分别高出了43%和61%。     

Itkis-Reyzin前向安全签名方案的一种改进

前向安全数字签名方案无法保证数字签名的后向安全性.本文对Itkis-Reyzin的前向安全数字签名方案进行了改进,将单向散列链嵌入到该方案的签名中,使该方案具有后向安全检测功能.改进后的方案不仅具有数字签名的前向安全性而且同样具有后向安全性,攻击者即使在第i时段入侵系统,也无法伪造以前或以后时段的签名.     

Synthesis of two novel acenaphthyl-quinoxaline based low-band gap polymers and its electrochromic properties

Dispersion stability and electrokinetic properties of TiO₂ nanoparticles, dispersed in aqueous solution of polyallylamine hydrochloride (PAAm.HCl) and polyvinyl alcohol (PVA) blends was examined. The electrophoresis method was employed to study electrokinetic properties of nanodispersion by varying pH and temperature with an emphasis on dispersion stability. The measurements were performed over a wide range of pH from 2–12 and temperature from 25–65 °C and the isoelectric points (IEPs) of nanodispersions were determined. The concentration of TiO₂ was varied from 2–12 wt%. The dispersions were found to be quite stable (no sedimentation) over a period of two months. The zeta potential of nanodispersions decreases as the pH increases. When temperature increases, a more distinct decrease in the zeta potential was observed. Such behavior may be due to the changes occurring in the linear dimension of adsorbing macromolecules with increasing temperature. As temperatures increases, the adsorption of polymers causes a decrease in the diffuse layer charge, which leads to a decrease in zeta potential. Also, the increase in ionic strength leads to a compression of the diffuse layer and reduction in the zeta potential. The conductivity of nanodispersions increases for all pH and temperatures studied.     

Spring mechanics of {{alpha}}-helical polypeptide

To design protein- and polymer-based micro-machineries, it isimportant to understand the mechanical properties of basic structuralelements such as the     

Construction of a protease-deficient strain set for the fission yeast Schizosaccharomyces pombe, useful for effective production of protease-sensitive heterologous proteins

One of the major problems hindering effective production and purification of heterologous proteins from the fission yeast Schizosaccharomyces pombe is proteolytic degradation of the recombinant gene products by host-specific proteases. As an initial solution to this problem, we constructed a protease-deficient disruptant set by respective disruption of 52 Sz. pombe protease genes. Functional screening of the resultant set was performed by observing secretory production of a proteolytically sensitive model protein, human growth hormone (hGH). The results indicated that some of the resultant disruptants were effective in reducing hGH degradation, as observed during the hGH expression procedure and mainly as a result of unknown serine- and/or cysteine-type proteases in the culture medium. These findings also demonstrated that construction of a protease-deficient strain set is not only useful for practical application in protein production, but also for functional screening, specification and modification of proteases in Sz. pombe, where further investigations of proteolytic processes and improvement through multiple gene manipulations are required.     

The gap-filling sequence on the left arm of chromosome 2 in fission yeast Schizosaccharomyces pombe

We report a gap-filling sequence between SPBPB21E7.09 (in contig c1348) and SPBPB10D8.01 (in contig pB10D8) on the left arm of chromosome 2 in the fission yeast, Schizosaccharomyces pombe. The sequence was determined from a BAC clone overlapping SPBPB21E7.01c (eno102) (in contig c1348) and SPBC1683.07 (mal1) (in contig pB10D8). The gap-filling sequence is 17,881 bp in length and contains five putative open reading frames, which were systematically named as SPBC460.01c, SPBC460.02c, SPBC460.03, SPBC460.04c and SPBC460.05. Their deduced amino acid sequences respectively include protein motifs corresponding to amino acid permease, glutathione S-transferase C-terminal domain, taurine catabolism dioxygenase TauD TfdA family and major facilitator superfamily, whereas their functions are unknown.     

维吾尔语词切分方法初探

维语词的词干-词附加成分切分、音节切分的规律对维吾尔语自然语言处理方面提供更多方便。本文提出了以“词=词根+附加成分”结构。维语附加成分种类繁多,连接形式各式各样,在句子中起着非常重要的作用,同时有相当的规律性。本文提出了维语中可能出现的基本语音规律的处理方法,如:语音同化、音节切分、语音和谐规律处理。本文对维文词的词法和语音法结构进行了归纳,提出了维语词切分的一些规律和实现方法。以新疆高校学报为语料来测试,对规则词准确率达到95%。     

自耦变压器零序电流方向纵联保护

高压大容量自耦变压器在高、中压侧常配有零序电流差动保护,以提高对接地故障的灵敏性,但其受电流互感器饱和影响较大,不易整定．据此提出一种自耦变压器零序电流方向纵联保护原理,通过比较自耦变高、中压侧零序电流和中性点零序电流相位实现保护判别,该原理能够灵敏地反应变压器的匝地和匝间故障,受电流互感器饱和影响小．仿真和动模试验数据验证了该方法的可行性．