肼还原法制备镍纳米粒子及其机理

在乙二醇中用肼作还原剂还原Ni2 制备镍纳米粒子。用X射线衍射仪测定出产物的相结构,用扫描电子显微镜观察产物的微观结构。根据反应现象和产物的相结构,研究温度、pH值调节剂种类和pH值对镍纳米粒子形成的影响,并推断其形成机理。研究结果表明,用肼作还原剂还原Ni2 制备纳米Ni的最佳反应温度为60℃,用NaOH作pH值调节剂调pH值到10～11得到的镍纳米粒子为体心立方结构,平均粒径为25nm。在Ni纳米粒子的形成过程中,NaOH不仅起到调节pH值的作用,还起催化作用。     

电镀Zn-Fe-SiO2复合材料的性能研究

镀锌与Zn-Fe合金广泛用于钢铁零件的防护,但是仍存在钝化液毒性大、环境污染严重、耐蚀性低、氢脆高等不足。本文采用无氰电镀技术制备了Zn-Fe-SiO2复合材料,并测试了Zn-Fe-SiO2复合材料的耐蚀性、孔隙率和氢脆性等综合性能,同时与电镀Zn及Zn-Fe合金进行了对比。实验结果表明:电镀Zn-Fe-SiO2复合材料的耐蚀性及其它综合性能均优于镀锌与Zn-Fe合金,无需钝化处理,环境友好,应用前景广阔。     

一种基于智能Agent的用户个性化信息检索系统模型

针对当前信息检索工具缺乏对知识的理解和处理能力,提出了一种基于智能Agent的用户个性化信息检索系统模型,通过多个Agent的协调工作为用户提供个性化服务。描述了该模型的系统结构及各功能模块的实现方法,分析了系统模型的工作流程,部分解决了信息检索中的文档相关性计算、搜索引擎的调度算法、数据库的构建等技术问题。     

基于组态王的智能仪表液位控制系统的设计与实现

介绍了基于组态王的智能仪表液位控制系统组成和控制算法。叙述了组态王监控界面设计和组态王与智能仪表的通讯。该系统可实现数据采集、动态数据显示和现场设备的实时监控,调试和运行。应用表明,该系统工艺流程显示直观,人机界面友好,易于操作。系统运行稳定,维护成本低,对于相关的工程应用具有一定的价值。     

中国企业国际化经营与国际市场进入方式

中国企业国际化经营表现出自身多目标特点。在获得技术、占领市场、获取资源、实现企业总体战略、实现全球战略等多目标约束条件下,针对直接出口、合同进入、独资进入、跨国并购等国际市场进入方式对不同目标的效果值以及各目标之间的相互关联性,运用目标关联分析方法对各种方案优化决策,结果发现,我国企业国际化经营的国际市场进入方式,应首选“独资进入”和“跨国并购”方式。     

基于Kalman滤波与多特征模糊聚类的图像融合

为了减低图像的噪声，保留有用的信息，获得更为可靠的融合图像，将Kalman滤波引入图像融合中，提出基于Kalman滤波与多特征模糊聚类的图像融合算法．该方法结合滤波和多特征优点，实验结果表明了该方法的有效性．     

高校教学服务部门日常经费分配模型

依据教育经济学原理，遵循兼顾平衡、持续发展、工种特性之原则，综合运用层次分析法、当量法及平滑法等计量方法，得到了教学服务部门日常经费分配模型．     

西门子WinCC及S7-400的应用

本文叙述了利用S7-400可编程控制器组建PROFIBUS现场总线的基本过程,并讨论通过PROFIBUS实现S7-400与工控组态软件WinCC之间通讯的方法。     

Convergence of Recursive Identification for ARMAX Process with Increasing Variances

The autoregressive moving average exogenous (ARMAX) model is commonly adopted for describing linear stochastic systems driven by colored noise. The model is a finite mixture with the ARMA component and external inputs. In this paper we focus on a parameter estimate of the ARMAX model. Classical modeling methods are usually based on the assumption that the driven noise in the moving average (MA) part has bounded variances, while in the model considered here the variances of noise may increase by a power of log n. The plant parameters are identified by the recursive stochastic gradient algorithm. The diminishing excitation technique and some results of martingale difference theory are adopted in order to prove the convergence of the identification. Finally, some simulations are given to show the reliability of the theoretical results.     

Inhibitory Kinetics of p-Substituted Benzaldehydes on Polyphenol Oxidase from the Fifth Instar of Pieris Rapae L.

Polyphenol oxidase (PPO) is the enzyme responsible for enzymatic browning during the growth of insects. It is also involved in defense reactions and is related with immunities in insects. PPO, a metalloenzyme oxidase, catalyzes the oxidation of ο-diphenol to ο-quinone. The present paper de- scribes the effects of benzaldehyde and its p-substituted derivatives on the activity of PPO from the fifth instar of Pieris rapae L. PPO from the fifth instar of Pieris rapae L. was purified using ammonium sulfate fractionation and chromatography on Sephadex G-100. The enzyme kinetics was characterized using L-3,4-dihydroxyphenylalanine (L-DOPA) as substrate. The results show that benzaldehyde, p- hydroxybenzaldehyde, p-chlorobenzaldehyde, and p-cyanobenzaldehyde can inhibit the PPO activity for the oxidation of L-DOPA. The inhibitor concentration leading to 50% activity lost, IC50, was esti- mated to be 5.90, 5.62, 2.83, and 2.91 mmol/L for the four tested inhibitors, respectively. Kinetic analy- ses show that the inhibitory effects of these compounds are reversible. Benzaldehyde, p- hydroxybenzaldehyde, and p-chlorobenzaldehyde are noncompetitive inhibitors while p-cyano- benzaldehyde is a mixed-type inhibitor. The inhibition constants were determined for all four inhibitors. p-chlorobenzaldehyde and p-cyanobenzaldehyde were more potent inhibitors than the other com- pounds. These results provide a basis for developing PPO inhibition-based pesticides.