逐步距离判别分析在甲状腺滤泡性腺瘤与滤泡性腺癌的判定中的运用

在认定甲状腺滤泡性腺瘤与滤泡性腺癌的细胞核形态指标存在显著差异的条件下,对两类样本通过逐步判别分析筛选出鉴别能力较强的少数几个指标,并运用距离判别分析建立了甲状腺滤泡性腺瘤与滤泡性腺癌的判别函数,为临床病理诊断提供辅助诊断方法.     

线性回归模型中自变无选择的逐步回归方法及其相合性研究

线性回归模型的建立,一个很重要的过程就是自变元的选择,它直接决定着模型的优劣。本文给出了“宜取回归方程”的逐步回归方法,在一组适当的条件下,证明了这种方法的强相合性。     

Modification and Electrochemical Properties of Poly(phenylazomethine) Derivatives

Summary: Oligo(phenylazomethine)s (OPAs) and aniline-capped OPAs (OPA's) are used as model compounds of polyphenylazomethine (PPA), and their fundamental properties and their modification methods are investigated. Cyclic voltammograms of bis(diphenylmethyleneamino)benzene (OPA2′) showed irreversible redox response in the presence of trifluoroacetic acid. A selective synthesis of oligophenanthridine was achieved through the photocyclization of OPA2′ in concentrated sulfuric acid. Stepwise complexation behavior in dendritic poly(phenylazomethine)s (DPAs) was supported by the shell-selective reduction of the imines. Using the shell-selective reduction method and the terminal-modification method of the DPAs, the core and terminals of DPAs were functionalized by ferrocene units, respectively.     

影响系统主因素综合筛选技术研究

系统影响因素过多不仅会增加系统建模难度,而且会增加系统模型的不确定性和数据收集工作量,因此提出一种影响系统的主因素综合筛选技术.技术将综合灰色关联度、普通相关技术、逐步回归方法、DEMATEL法以及系统动力学等方法的优点和缺点,通过彼此互补和相互融合技术,使得该技术能够有效地筛选出影响系统的主因素.通过在筛选影响船舶柴油机寿命周期费用主因素的应用,和其他方法的比较和分析,验证了本技术的可行性、有效性和先进性.     

某型飞机燃料油消耗模型的建立及诊断

为确定某型飞机的燃料油消耗量同其它因素之间的相关关系,借助SPSS统计分析软件,运用逐步回归分析方法,对某场站近三年燃料油消耗的实际数据进行研究.首先,运用逐步回归分析的方法,分别挑选出影响飞机在起飞滑跑、空中飞行及降落滑跑等三个阶段燃油消耗量的变量,并建立对应的回归模型.然后,对回归模型作统计诊断,检验模型的有效性及可能存在的异常点.最后,根据回归分析及统计诊断的结果,得出结论.     

Evidence for the Reversible Stepwise Polarographic Reduction of Pyrazine from Strong Acid Media

Abstract

The direct and alternating current polarography of pyrazine has been re-examined. Evidence shows that the aromatic 1,4-diazine is reduced stepwise from strong acid, and the added resolving power afforded by the a.c. technique indicates that such a mechanism may prevail up to pH 4.5. Controlled potential electrolysis of pyrazine at pH 1 produced an intense violet color whose spectral characteristics and time instability suggest the presence of an acid-stabilized radical.     

Theoretical model of acoustic emission under mechanical loading of rocks in the maximum compaction region

A theoretical model of changes in acoustic emission activity in a geomaterial under continuous or stepwise mechanical loading is justified. Based on this model, the experimentally found laws of emission in the region of the maximum compaction of rock samples with different rates of mechanical loading of these samples are analyzed. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 4, pp. 145–152, July–August, 2006.     

Self‐Assembly versus Stepwise Synthesis: Heterometal–Organic Frameworks Based on Metalloligands with Tunable Luminescence Properties

A new family of heterometal–organic frameworks has been prepared by two synthesis strategies, in which IFMC‐26 and IFMC‐27 are constructed by self‐assembly and IFMC‐28 is obtained by stepwise synthesis based on the metalloligand (IFMC=Institute of Functional Material Chemistry). IFMC‐26 is a (3,6)‐connected net and IFMC‐27 is a (4,8)‐connected 3D framework. The metalloligands {Ni(H₄L)}(NO₃)₂ are connected by binuclear lanthanide clusters giving rise to a 2D sheet structure in IFMC‐28 . Notably, IFMC‐26‐Eu _x Tb _y and IFMC‐28‐Eu _x Tb _y have been obtained by changing the molar ratios of raw materials. Owing to the porosity of IFMC‐26 , Tb³⁺@IFMC‐26‐Eu and Eu³⁺@IFMC‐26‐Tb are obtained by postencapsulating Tb^III and Eu^III ions into the pores, respectively. Tunable luminescence in metal–organic frameworks is achieved by the two kinds of doping methods. In particular, the quantum yields of heterometal–organic frameworks are apparently enhanced by postencapsulation of Ln^III ions.     

土壤重金属砷的高光谱估算模型

砷是严重危害人体的重金属之一。利用高光谱技术进行土壤重金属砷含量的估测具有很大的应用潜力,但受区域和土壤背景的影响,估算模型适用性和精度都会有很大的差异。针对石家庄市地表水源地保护区土壤砷含量的高光谱估算,在水源地保护区的主要采矿地和冶炼企业进行了土壤实地采样和实验室重金属分析,对土壤样本的原始光谱反射率采用Savitzky-Golay 7点平滑处理,进行一阶微分（FD）、二阶微分（SD）、倒数（RT）、倒数一阶微分（RTFD）、倒数二阶微分（RTSD）、倒数对数（AT）、倒数对数一阶微分（ATFD）、倒数对数二阶微分（ATSD）、连续统去除（CR）9种光谱变换后,再对重金属砷实测含量与经光谱变换后的光谱指标进行相关分析,并提取各光谱指标的最大敏感波段。运用多元线性逐步回归（MLSR）、单光谱变换指标偏最小二乘回归（U-PLSR）和多光谱变换指标偏最小二乘回归（M-PLSR）方法构建土壤重金属砷含量估算模型,最后通过相关系数r、均方根误差（root mean square error, RMSE）和统计值F来比对建模效果。结果表明：研究区部分土壤样本重金属砷含量已经出现了轻度污染,大部分样本处于污染的临界状态;经连续统去除变换后的光谱特征与砷的相关性最大,一阶微分与砷含量存在最大负相关性;相较于多元线性逐步回归和单光谱变换指标偏最小二乘回归,采取多光谱变换指标偏最小二乘回归方法土壤重金属砷含量模型估算值与实测值最为接近,建模R2达到0.852,RMSE和F值分别达到0.147和32.384,多光谱变换指标建模集成效果显著。因此研究结果可以为石家庄水源地保护区主要采矿地和冶炼企业重金属砷污染高光谱快速监测提供科学依据。     

Graphene‐Like Covalent Organic Framework with a Wide Band Gap Synthesized On Surface via Stepwise Reactions

Developing graphene‐like two‐dimensional materials naturally possessing a band gap has sparked enormous interest. Thanks to the inherent wide band gap and high mobility in the 2D plane, covalent organic frameworks containing triazine rings (t‐COFs) hold great promise in this regard, whilst the synthesis of single‐layer t‐COFs remains highly challenging. Herein, we present the fabrication of a well‐defined graphene‐like t‐COF on Au(111). Instead of single/multiple‐step single‐type reactions commonly applied for on‐surface synthesis, distinct stepwise on‐surface reactions, including alkynyl cyclotrimerization, C?O bond cleavage, and C?H bond activation, are triggered on demand, leading to product evolution in a controlled step‐by‐step manner. Aside from the precise control in sophisticated on‐surface synthesis, this work proposes a single‐atomic‐layer organic semiconductor with a wide band gap of 3.41 eV.