微米铜粉在润滑脂中摩擦学性能的考察

通过四球试验,考察了微米铜粉在润滑脂中的摩擦学行为和抗磨性。试验结果表明：在适当百分含量范围内和载荷条件下,润滑脂中加入铜粉可以提高脂的抗磨性。对钢球磨斑表面形貌分析,添加微米铜粉的润滑脂的磨斑表面要比基础脂的磨斑表面光洁许多。     

悲喜交集的生命之歌——评迟子建的《逝川》

在短篇小说《逝川》中,迟子建写了一条河,一个人,一种鱼。这条河,无疑是一条生命之河,一条时间之河,在这条河边,主人公吉喜经历了充满生机却又不乏辛酸的人生。吉喜与泪鱼的对照,显示出吉喜强韧的生命力。这条河流淌着的,是一曲悲喜交集的生命之歌。     

Evaluation and application of an efficient plant DNA extraction protocol for laboratory and field testing

Nucleic acids in plant tissue lysates can be captured quickly by a cellulose filter paper and prepared for amplification after a quick purification.In this study,a published filter paper strip method was modified by sticking the filter paper on a polyvinyl chloride resin(PVC)sheet.This modified method is named EZ-D,for EASY DNA extraction.Compared with the original cetyl trimethylammonium bromide(CTAB)method,DNA extracted by EZ-D is more efficient in polymerase chain reaction(PCR)amplification due to the more stable performance of the EZ-D stick.The EZ-D method is also faster,easier,and cheaper.PCR analyses showed that DNA extracted from several types of plant tissues by EZ-D was appropriate for specific identification of biological samples.A regular PCR reaction can detect the EZ-D-extracted DNA template at concentration as low as 0.1 ng/μL.Evaluation of the EZ-D showed that DNA extracts could be successfully amplified by PCR reaction for DNA fragments up to 3000 bp in length and up to 80%in GC content.EZ-D was successfully used for DNA extraction from a variety of plant species and plant tissues.Moreover,when EZ-D was combined with the loop-mediated isothermal amplification(LAMP)method,DNA identification of biological samples could be achieved without the need for specialized equipment.As an optimized DNA purification method,EZ-D shows great advantages in application and can be used widely in laboratories where equipment is limited and rapid results are required.     

一类交换半群在求解二元二次不定方程中的应用

建立了一类新的交换半群,对《一个交换半群的元素的表示形式》、《一个交换半群的推广与应用》两文中半群的元素表示形式和结果进行了推广与加强.并且利用其结果得到了几类二元二次不定方程的整数解表达式.     

AgxZn1-x和AgxAl1-x双相合金超导体的超导态参数

A well-known pseudopotential is used to investigate the superconducting state parameters (SSP), viz., electron-phonon coupling strength, Coulomb pseudopotential, transition temperature, isotope effect exponent and effective interaction strength for AgxZn1-x and AgxAl1-x binary alloys theoretically for the first time. We have incorporated here five different types of the local field correction functions to show the effect of exchange and correlation on the aforesaid properties. Very strong influence of various exchange and correlation functions is concluded from the present study. Comparison with others such experimental values is encouraging, which confirms applicability of the model potential in explaining the superconducting state parameters of binary mixture.     

应用Base64编码在SOAP中传输文件

从SOAP协议的概念出发,探讨了SOAP消息的结构．介绍了Base64编码技术的定义、规则．阐述了应用Base64编码技术在SOAP消息中传输二进制文件的方法．     

熔盐法合成无机粉体材料

熔盐法是一种制备无机粉体材料的新方法．本文简要说明了熔盐合成法的原理和特点,从合成颗粒状氧化物粉体、片状氧化物、针棒状氧化物等方面综述了该方法的研究进展,并概述了熔盐合成法尚存在的问题。     

A Mixture IRTree Model for Extreme Response Style: Accounting for Response Process Uncertainty

This paper presents a mixture item response tree (IRTree) model for extreme response style. Unlike traditional applications of single IRTree models, a mixture approach provides a way of representing the mixture of respondents following different underlying response processes (between individuals), as well as the uncertainty present at the individual level (within an individual). Simulation analyses reveal the potential of the mixture approach in identifying subgroups of respondents exhibiting response behavior reflective of different underlying response processes. Application to real data from the Students Like Learning Mathematics (SLM) scale of Trends in International Mathematics and Science Study (TIMSS) 2015 demonstrates the superior comparative fit of the mixture representation, as well as the consequences of applying the mixture on the estimation of content and response style traits. We argue that methodology applied to investigate response styles should attend to the inherent uncertainty of response style influence due to the likely influence of both response styles and the content trait on the selection of extreme response categories.     

Testing Measurement Invariance Across Unobserved Groups: The Role of Covariates in Factor Mixture Modeling

Factor mixture modeling (FMM) has been increasingly used to investigate unobserved population heterogeneity. This study examined the issue of covariate effects with FMM in the context of measurement invariance testing. Specifically, the impact of excluding and misspecifying covariate effects on measurement invariance testing and class enumeration was investigated via Monte Carlo simulations. Data were generated based on FMM models with (1) a zero covariate effect, (2) a covariate effect on the latent class variable, and (3) covariate effects on both the latent class variable and the factor. For each population model, different analysis models that excluded or misspecified covariate effects were fitted. Results highlighted the importance of including proper covariates in measurement invariance testing and evidenced the utility of a model comparison approach in searching for the correct specification of covariate effects and the level of measurement invariance. This approach was demonstrated using an empirical data set. Implications for methodological and applied research are discussed.     

二值图像的四边形区域压缩算法研究

从二值图像的区域特征出发，提出了基于四叉树的二值图像四边形区域压缩算法，该算法的思想是将二值图像用四叉树进行四分区域划分，在同一个区域中如果像素值相同则可用一个元素表示，否则继续划分，该算法的优点体现在如下两个方面：1．采用二进制移位的思想提高了MD码的生成效率。2．采用基于对数模型的方法进行区域像素压缩。该算法的内存开销小，运行速度高于其它相关方法。