谷氨酸及其衍生物在304不锈钢表面的自组装膜

采用电化学阻抗谱、极化曲线、量子化学和分子动力学,研究了谷氨酸、焦谷氨酰胺、焦谷氨酸三种自组装膜在0.5 mol/L硫酸溶液中对304不锈钢的缓蚀性能.结果表明,三种缓蚀剂均为阴极型缓蚀剂,对不锈钢具有较好的缓蚀作用;在0.02 mol/L的浓度下,随着组装时间的延长,自组装膜对不锈钢的缓蚀效率也相应增强.它们的缓蚀能力与理论EHOMO越高、能量间隙△E越低.自组装分子成键能力越强、缓蚀效率越高相一致.三种缓蚀剂分子中的氮原子、氧原子可以与铁原子形成化学键,发生化学吸附.缓蚀能力依次为:焦谷氨酸＞焦谷氨酰胺＞谷氨酸.     

手机壳塑料模具紫铜电极高速铣削加工

对手机壳塑料模具紫铜电极的结构和功能进行了研究,分析了电极高速加工的工作过程、工艺路线、装夹方式、刀具选用和切削用量,介绍了紫铜电极高速加工编程的具体步骤,重点阐述了如何选取高速加工工艺参数。实践结果表明,整个加工过程清晰、刀具和切削参数选用合理。     

Synthesis and characterization of La（OH）_3 nanopowders from hydrolysis of lanthanum carbide

The lanthanum carbide alloy was induction melted in vacuum induction melting furnace from lanthanum and graphite with the mass ratio of 89:11. Lanthanum hydroxide (La(OH)3) nanopowders were prepared by a simple hydrolysis of lanthanum carbide at room temperature under normal atmospheric pressure without any surfactant. X-ray diffraction (XRD) showed that the nanoparticles were with a hex-agonal structure. The effect factors such as reaction time,reaction temperature and the mass ratio of lanthanum carbide p...     

Androgen synthesis in a songbird: a study of cyp17 (17alpha-hydroxylase/C17,20-lyase) activity in the zebra finch

Extracellular nucleotides, e.g., ATP, ADP, and UTP, are important signaling molecules which elicit various physiological responses in different tissues. Their degradation is catalyzed by ectonucleotidases which are located on cell surfaces. Most tissues have a mixed population of ectonucleotidases. In this report, the ATP and ADP hydrolyzing ectonucleotidases of chicken gizzard smooth muscle and liver plasma membranes were studied. The two membranes exhibited marked differences in the ratio of ATPase/ADPase activities, activation by divalent cations, thermal stability, responses to detergents and cross-linking agents, and sensitivity to several enzyme inhibitors. The ATPase activity of chicken gizzard membranes is (i) labile to heat and detergents; (ii) activated by concanavalin A and disuccinimidyl suberate, both cross-linking agents; (iii) inhibited by mercurials; and (iv) insensitive to high concentrations of azide, a known inhibitor of ecto-ATP diphosphohydrolases (ecto-ATP/Dase). In contrast, the liver membrane ATPase and ADPase activities are more stable to treatment by heat and detergents and insensitive to cross-linking agents and mercurials, but are inhibited by azide. A low ADP hydrolase activity in the gizzard membranes could be distinguished from both the gizzard ATPase and the liver ATPase/ADPase. This ADP hydrolase, which is markedly stimulated by NBD-Cl, accounts for most of the ADP hydrolysis activity in gizzard membranes. It is concluded that the major ectonucleotidase in the gizzard membranes is an ecto-ATPase whereas that in the liver membranes is an ecto-ATP/Dase. That both membranes contain a mixed population of the ecto-ATPase and ecto-ATP/Dase, but in different proportions, is further demonstrated by immunochemical characterization. The different composition of ectonucleotidases in the two membranes is expected to have an important effect on the regulation of hydrolysis of extracellular ATP as well as the concentration of extracellular adenine nucleotides in the gizzard and liver tissues.     

Development of Debris-free Laser Plasma Sources for EUV Lithography in CIOMP

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｌａｓｅｒ - ｐｒｏｄｕｃｅｄｐｌａｓｍａ (ＬＰＰ)ｉｓａｎａｔｔｒａｃ ｔｉｖｅｔａｂｌｅｔｏｐＥＵＶｓｏｕｒｃｅｆｏｒａｐｐｌｉｃａｔｉｏｎｉｎＥＵＶｌｉｔｈｏｇｒａｐｈｙｄｕｅｔｏｉｔｓｓｍａｌｌｓｉｚｅ ,ｈｉｇｈｐｅａｋｐｏｗｅｒａｎｄｓｐａｔｉａｌｓｔａｂｉｌｉｔｙ .Ｈｏｗｅｖｅｒ,ｔｈｅｃｏｎｖｅｎｔｉｏｎａｌＬＰＰｓｏｕｒｃｅｗｉｔｈｍｅｔａｌｔａｒｇｅｔｈａｓａｓｅｒｉｏｕｓｄｉｓａｄ ｖａｎｔａｇｅｏｆｅｊｅｃｔｉｎｇｈｉｇｈ -ｔｅｍｐｅｒａｔｕｒｅａ…     

改进ORB算法在图像匹配中的应用

在计算机视觉领域，图像匹配是一个核心问题。为了提高图像特征点匹配算法的准确度，增强算法的抗干扰能力，针对ORB（oriented FAST and rotated BRIEF）算法的不足，提出一种改进的图像特征点匹配算法。该算法通过设置自适应阈值来进行特征点检测，并在算法粗匹配结果的基础上剔除不符合图像几何特性的部分外点。最后，利用仿射不变性约束筛选出精确匹配点。实验表明，该方法可有效提高算法匹配质量且执行时间短，对于不同模糊度和曝光度的图像匹配均具有很好的鲁棒性。     

一次大到暴雪过程的流型配置及诊断分析

利用常规气象观测资料和NCEP再分析资料,对2012年4月11日出现在宁夏境内的大到暴雪过程进行了流型配置、物理量诊断,并结合卫星和雷达综合分析.结果表明,这次持续性大到暴雪天气过程的出现是在有利环流背景下,400 hPa以下偏西、偏南、东北3支急流或气流强盛,且随高度顺转,是这次大到暴雪过程流型配置的主要特征.大到暴雪的产生需要一定的动力条件.高空辐散、低层辐合的散度场配置,强而深厚的上升气流,对降雪区上空的上升运动非常有利,是降雪天气维持和发展的重要因素.大到暴雪的落区与散度场,水汽通量散度场和垂直速度场高低层的辐散、辐合强度,湿层的厚度及上升运动的强度成正比.通过单站剖面图分析,进一步证实了风的垂直切变是降水维持的一个重要特征.     

应用型本科院校机械专业人才培养模式的探索

随着机械制造业的快速发展,机械类应用型人才的需求越来越大,作为地方型本科院校的机械专业,需调整其人才培养模式和培养方案,以满足市场需求,为地方经济发展服务,为此机电工程系制定了相应的培养目标和培养方案。通过十年的本科教育探索和不断完善,毕业生就业单位的良好反应证明此方案的正确性和可行性。     

铝熔体用稀土熔剂的使用效果及分析

针对我国在铝加工业存在能耗大，环境污染严重和含氢、含杂量高的问题，研究了一种新型溶剂JDN－I。结果发现，该熔剂个有多种功能：覆盖隔热作用，既可保护铝合金免潮湿大气的污染，又能细化晶粒，又可使共晶硅变质；铝熔体的含氢、含杂量降低到极低的水平，确保铝熔体的纯净化；细化变质作用，既可细化晶粒，又可使共晶硅变质；使用简便，不污染环境，在这种熔剂的作用，可使A356铝合金的流动性大大提高，并使抗拉强度度提高7．25％，伸长率提高85．58％。     

P91大管氩电联焊工艺试验

P91马氏体钢在大型火力发电厂中得到广泛的应用。针对φ460mm×47.5mm的P91马氏体厚壁大径管接头在全位置状态下焊接进行了工艺性试验。确定了焊接工艺参数和焊后热处理温度,对接头进行了拉伸、弯曲、冲击等性能试验,观察了接头的微观金相组织。结果表明:焊接接头抗拉强度与弯曲试验结果合格,焊接接头所有区域的组织基本为回火马氏体状态,综合机械性能均能够满足国家标准DL/T868-2004和JB/T 8129-2002等规范要求,同时分析了焊接接头各区组织不同的形成原因。