1,4-双(4''''-溴苯酰基)苯的合成工艺改进

以对苯二甲酰氯和溴苯为原料,无水氯化铝粉末为催化剂,合成了1,4-双(4'-溴苯酰基)苯,其结构经1H NMR,IR和DSC表征.     

Bayesian networks applied to credit scoring

Email: kchang{at}gmu.eduEmail: RobertFung{at}Fairlsaac.comEmail: alan.lucas{at}hotmail.com^¶Email: BobOliver{at}Fairlsaac.com^||Email: NShikaloff{at}Fairlsaac.com The objectives of this paper are to apply the theory and numericalalgorithms of Bayesian networks to risk scoring, and comparethe results with traditional methods for computing scores andposterior predictions of performance variables. Model identification,inference, and prediction of random variables using Bayesiannetworks have been successfully applied in a number of areas,including medical diagnosis, equipment failure, informationretrieval, rare-event prediction, and pattern recognition. Theability to graphically represent conditional dependencies andindependencies among random variables may also be useful incredit scoring. Although several papers have already appearedin the literature which use graphical models for model identification,as far as we know there have been no explicit experimental resultsthat compare a traditionally computed risk score with predictionsbased on Bayesian learning algorithms. In this paper, we examine a database of credit-card applicantsand attempt to ‘learn’ the graphical structure ofthe characteristics or variables that make up the database.We identify representative Bayesian networks in a developmentsample as well as the associated Markov blankets and cliquestructures within the Markov blanket. Once we obtain the structureof the underlying conditional independencies, we are able toestimate the probabilities of each node conditional on its directpredecessor node(s). We then calculate the posterior probabilitiesand scores of a performance variable for the development sample.Finally, we calculate the receiver operating characteristic(ROC) curves and relative profitability of scorecards basedon these identifications. The results of the different modelsand methods are compared with both development and validationsamples. Finally, we report on a statistical entropy calculationthat measures the degree to which cliques identified in theBayesian network are independent of one another.     

超高速转镜式扫描相机的时间分辨率测量

分析了影响转镜扫描相机时间分辨率的各种因素,给出了极限时间分辨率和基于相机动态摄影分辨率计算的时间分辨率的理论计算公式和结果。结合国内普遍使用的SJZ-15型转镜扫描相机,用自研设备动态像质检查仪和100ps超短脉冲激光照明两种测试方法,计算出了该相机钢转镜和铍转镜在不同转速下的实测时间分辨率值,并对数据进行了分析、比对和讨论。实测数据表明：钢转镜的转速为12×104 r/min,其最高时间分辨率约为8ns;铍转镜的实用最高转速为30×104 r/min,其最高时间分辨率约为4ns。     

一种准确量热敏电阻温度特性的方法

热敏电阻具有显著的内热效应,是测量热敏电阻温度特性的一个难点。本文介绍一种考虑内热效应,准确测量热敏电阻温度特性的方法,可作为大学物理的一个研究型的实验课题。     

生物质合成气一步法合成二甲醚的在线分析系统

建立了一套由生物质合成气一步法制取二甲醚的在线分析系统.针对生物质合成气一步法合成二甲醚特征,采用两台分别装有TCD和FID检测器的色谱仪分析反应产物.利用原料气中N2作为内标物,来确定TCD上检测到的永久性气体组分浓度;通过CH4作内标物,来确定FID上检测到的有机物组分浓度.TCD和FID之间通过CH4来关联,从而确定反应产物中主要组分的浓度.该系统在压力3 MPa,温度250℃,空速(流速与催化剂体积的比值)分别为1 000、2 000、3 000 h-1的条件下用C306和HZSM-5催化剂进行评价测试,发现系统分析效果好,重复性高,并且反应前后主产物碳平衡到达90%以上.     

对正丁氧基-N,N-二(2-巯乙基)苯胺的合成

以对乙酰氨基苯酚为原料,经4步反应合成了新化合物——对正丁氧基-N,N-（2-巯乙基）苯胺,其结构经^1H NMR和元素分析确证。     

四氯化锡诱导的Prins环化法高选择性地合成四氢吡喃衍生物合成四氢吡喃衍生物

本文通过预先将醛和四氯化锡进行配位形成高活性的醛中间体,同时采用滴加高烯丙醇的方法高收率和高选择性地合成了2,4,6-三取代四氢吡喃.     

F-T合成校正综合动力学模型

考虑了烯烃、醇与酸的再吸附及其非本征效应(烯烃、醇与酸在催化剂孔道中的扩散作用、物理吸附及溶解度效应)对产物分布的影响,推导了基于详细反应机理的亚甲基插入的烷基机理F-T合成校正综合动力学模型.利用文献数据对动力学模型进行了回归,获得了与文献报道结果相一致的动力学参数.由校正动力学模型计算的烷烃、烯烃、醇与酸产物分布及烯烃比、醇烃比及酸烃比与实验数据较好地吻合.动力学计算结果表明,在铁锰催化剂上,烷烃、烯烃、醇与酸生成的反应是平行竞争反应,烯烃、醇与酸在催化剂表面的再吸附及二次反应导致产物分布偏离了ASF分布.动力学研究还表明,相同碳数的醇与酸产物在催化剂表面上再吸附及二次反应的机会比相同碳数的烯烃大.通过比较相同碳数的烯烃、醇与酸的分子体积及沸点,指出了在铁锰催化剂上,低碳数的烯烃、醇与酸的再吸附及二次反应对产物分布影响的非本征效应中,烯烃、醇与酸的扩散阻力不是主导效应.     

凝胶渗透色谱和气相色谱-质谱法测定动物食品中27种有机氯和15种拟除虫菊酯类农药残留量

有机氯农药虽已被世界各国禁止使用,但由于其化学性质稳定和难以降解,在环境中仍然存在有机氯农药残留,并通过食物链的富集作用,造成对食物的污染.