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关键词： GLUTAMIC acid   PEROXIDASE   MUTAGENESIS  

摘要： Site-directed mutagenesis has been used to investigate the role of glutamic acid 183 in chloroperoxidase catalysis. Based on the x-ray crystallographic structure of chloroperoxidase, Glu-183 is postulated to function on distal side of the heme prosthetic group as an acid-base catalyst in facilitating the reaction between the peroxidase and hydrogen peroxide with the formation of Compound I. In contrast, the other members of the heme peroxidase family use a histidine residue in this role. Plasmids have now been constructed in which the codon for Glu-183 is replaced with a histidine codon. The mutant recombinant gene has been expressed in Aspergillus niger. An analysis of the produced mutant gene shows that the substitution of Glu-183 with a His residue is detrimental to the chlorination and dismutation activity of chloroperoxidase. The activity is reduced by 85 and 50% of wild type activity, respectively. However, quite unexpectedly, the epoxidation activity of the mutant enzyme is significantly enhanced similar to2.5-fold. These results show that Glu-183 is important but not essential for the chlorination activity of chloroperoxidase. It is possible that the increased epoxidation of the mutant enzyme is based on an increase in the hydrophobicity of the active site.

关键词： 进厂检验   质量管理   企业管理   预防作用   龙谊麦业公司   面粉加工企业  

摘要： 在科学技术飞速发展的今天,现代化大生产中的科学管理方法和手段也在不断地完善,尤其是质量问题,愈加明显地被摆在企业管理的首要地位.

关键词： 农村   经济合同   合同签订   发包方   承包方   承包经营   数量   质量   收益分配  

关键词： 工程施工   施工监理   质量控制   工程验收  

摘要： 就施工阶段监理质量控制的手段之一——“平行检验”在监理实践中所起的作用及“平行检验”的具体操作,从依据、定义、认识和执行等方面进行探讨。其目的是为了让监理人员在监理工作中将质量控制做得有度,并为建设工程项目的预验收及质量评估和最终的竣工验收提供依据。

关键词： 港口航道   测绘产品   质量检验   航道测量   质量管理  

摘要： 针对港口航道测绘产品本身的特点 ,应用质量管理的理论 ,分析。

关键词： 劳动合同   书面形式   法律效力   诺成性合同   意思自治   订约主体   合同成立要件   合同生效要件  

摘要： 劳动合同的本质特性决定书面形式与劳动合同的法律效力并无必然的联系。无论是从立法宗旨或是从司法实践经验来看,劳动法对劳动合同书面形式的要求,其根本目的应当是基于保护处于弱势地位的劳动者的合法权益,作为证明劳动关系存在及合同具有真实内容的证据。因此,有必要对我国有关劳动合同的形式的法律规定做出修改和完善。

关键词： Hyaluronic-acid   Articular-cartilage   Temperature-dependence   N-isopropylacrylamide   Engineered cartilage   Polymer scaffolds   Hydrogels   Peptide   Repair   Surfaces  

摘要： The adhesion between artificial extracellular matrixes (ECMs), or scaffolds, and native tissue is an often overlooked component of the tissue engineering design process. Therefore, we developed an axisymmetric adhesion test method to examine the interfacial interactions between hydrogel scaffolds and a model of the articular cartilage ECK Semi-interpenetrating polymer networks (semi-IPNs), consisting of poly(N-isopropylacrylamide-co-acrylic acid) [P(NIPAAm-co-AAc)] hydrogels and physically entangled linear P(AAc) chains grafted with peptides that bind to hyaluronic acid (HA), were synthesized, and the adhesion between the P(NIPAAm-co-AAc)-based semi-IPNs and hemispherical glass lenses (plain or HA-grafted) was examined as a function of temperature, contact time, and semi-IPN type. The adhesion between the semi-IPNs and the lenses significantly increased with increasing contact time and significantly decreased with increasing temperature, independent of the. P(NIPAAm-co-AAc)-based matrix type. Furthermore, when using a 5-min contact time at 22 degreesC, the peptide-modified P(NIPAAm-co-AAc)-based semi-IPNs demonstrated significantly greater adhesion to the HA-grafted lenses, compared to that exhibited between nonfunctionalized P(NIPAAm-co-AAc)-based semi-IPNs and HA-grafted lenses. The method developed is useful for examining the interfacial interactions between biologically modified polymer scaffolds and models of the native ECM and may aid in improving the integration between synthetic polymers and native tissues.

关键词： 合同   形式   合同效力   合同法  

摘要： 本文通过合同形式的不同分类 ,阐述了合同形式的基本原则 ,进一步揭示了合同形式与合同效力之间的相互关系 。

关键词： 笔迹检验   文字布局特征   信件检验工作   票据检验  

摘要： 文字布局特征是指字迹书写在承受载体上的安排形式和分布特点,虽然各种文件制作均有一定的规范要求,但是,由于书写人的文化素养、个人爱好、职业、社会经历等主、客观条件各异,加之一些规范要求的宽容性,在书写过程中就形成了区别于他人而独有的习惯特点.笔迹检验中常用的布局特征主要有:标题安排、分段空格、字行的方向和形态、字间与行间的间隔、字行与格线的关系、字行与页边的关系、字位的偏正、页码安排、标点符号的安排、信封三款安排、程式语安排、数字在格中的安排以及字间组合等.文字布局特征是书写习惯的组成部分,同单字个性特征一样,一经形成动力定型就难以改变,具有较强的稳定性、特殊性、自身同一性.在一般情况下,作案人利用文字作案时,往往只注意对字迹笔画进行有意识的伪装,而忽视或根本意识不到对布局特征的改变.

关键词： 货币政策   非对称性   GRACH模型  

摘要： 货币政策的非对称性主要是指货币政策在经济周期的不同阶段具有不同的作用效果.文章利用描述实际GDP增长率波动成分的各种GARCH模型检验发现,在我国经济运行当中,紧缩性货币政策对于经济的减速作用大于扩张性货币政策对于经济的加速作用.因此,应该在经济收缩阶段实行稳健性货币政策来规避金融风险和防范通货膨胀,采用积极财政政策刺激投资需求和消费需求,以保持经济的快速稳定增长.