烧结温度对La1.2Sr1.8Mn2O7结构和磁性的影响

采用溶胶-凝胶法在不同的烧结温度下制备了La1.2Sr1.8Mn2O7多晶样品.磁性测量表明,1 200℃热处理的样品存在3个磁转变温度,且在116 K～365 K温区范围内磁化强度显著高于1 400℃热处理的样品;同时,1 400℃热处理的样品,在整个温区只存在2个磁有序转变温度,并且呈现出类自旋玻璃态.结合这2个样品的结构分析发现,较高温度处理更有利于双层钙钛矿结构的形成.     

Effect of microcystin-LR on protein phosphatase 2A and its function in human amniotic epithelial cells

Due to their toxicity, the increased distribution of microcystins (MCs) has become an important worldwide problem. MCs have been recognized as inhibitors of protein phosphatase 2A (PP2A) through their binding to the PP2A catalytic subunit. However, the exact mechanism of MC toxicity has not been elucidated, especially concerning the cellular response and its autoregulation. To further dissect the role of PP2A in MC-induced toxicity, the present study was undertaken to determine the response of PP2A in human amniotic epithelial (FL) cells treated with microcystin-LR (MCLR), one of the MC congeners. The results show that a low-dose treatment of MCLR in FL cells for 6 h induced an increase in PP2A activity, and a high-dose treatment of MCLR for 24 h decreased the activity of PP2A, as expected. The increased mRNA and protein levels of the PP2A C subunit may explain the increased activity of PP2A. Furthermore, MCLR altered microtubule post-translational modifications through PP2A. These results further clarify the underlying mechanism how MCLR affects PP2A and may be helpful for elucidating the complex toxicity of MCLR.     

食品中亚硫酸盐使用及检测方法的研究进展

亚硫酸盐是一类在食品中广泛使用却常被忽视的添加剂,不恰当的使用会对人体造成一定的损伤.笔者综述了食品中亚硫酸盐的使用及检验方法,并讨论了各种检测方法的优缺点.旨在对食品生产过程中亚硫酸盐的使用及检测起到一定的指导作用.     

Comparison of different techniques for time-frequency analysis of internal combustion engine vibration signals

In this study, we report an analysis of cylinder head vibration signals at a steady engine speed using short-time Fourier transform (STFT). Three popular time-frequency analysis techniques, i.e., STFT, analytic wavelet transform (AWT) and S transform (ST), have been examined. AWT and ST are often applied in engine signal analyses. In particular, an AWT expression in terms of the quality factor Q and an analytical relationship between ST and AWT have been derived. The time-frequency resolution of a Gaussian function windowed STFT was studied via numerical simulation. Based on the simulation, the empirical limits for the lowest distinguishable frequency as well as the time and frequency resolutions were determined. These can provide insights for window width selection, spectrogram interpretation and artifact identification. Gaussian function windowed STFTs were applied to some cylinder head vibration signals. The spectrograms of the same signals from ST and AWT were also determined for comparison. The results indicate that the uniform resolution feature of STFT is not necessarily a disadvantage for time-frequency analysis of vibration signals when the engine is in stationary state because it can more accurately localize the frequency components excited by transient excitations without much loss of time resolution.     

高职教育实践教学体系要素构建研究

文章探讨了高职教育实践教学体系的特征,构建高职实践教学体系的原则,阐述了高职实践教学体系的构成要素,构建实践教学体系应注意的几个环节。     

Exploring the cosmopolitanism in China: examining mosheng ren (“the stranger”) communication through Momo

This paper discusses a phenomenon that has become popular in mainland China in recent years, “mosheng ren communication,” focusing specifically on an application known as Momo, a social discovery and dating platform that is widely used in China. It first outlines the context of post-Mao China, which has produced urbanism, individualization, and a sexual revolution. Thereafter, it turns to the theories of the stranger and cosmopolitanism, which are used to analyze mosheng ren communication. This paper adopts cultural discourse analysis as the analytical procedure to present the findings of online and offline interviews conducted in both Beijing and Shanghai to examine how Momo users in urban metropolises make use of this app in order to analyze the cultural radiants in their communication practices. Based on the data obtained, this paper analyzes mosheng ren communication in the Chinese context and describes how Momo is designed to facilitate it. Momo users can enter into sexual relations based on the use of authentic photos on their profiles; alternatively, they can communicate anonymously. They are also “in-between” traditional Chinese values and new values. Momo users contribute a Chinese form of cosmopolitanism through cultivation of insensitivity to mosheng ren, while their engagement in mosheng ren communication implies that the members of are more open to others.     

新入职教师课堂教学方法的选择与运用

对即将从事教育工作的新入职教师而言,在学校课堂教学中不仅要考虑指导学生获得直接的知识经验,更要考虑教导他们以最简单、最便捷的途径和方法,有效地获取更多的间接知识经验,这就有一个如何选择与运用课堂教学方法的问题。为此,在选择教学方法时首先要遵循目标性原则、效率性原则和以学定教原则,还要关注到应用每种方法的制约条件,这样才能有效地提高教学质量。     

公民社会视角下大学生政治参与的特点与引导

公民社会为学生政治参与提供广阔的平台,大学生政治参与为公民社会提供重要的人才支持。当前,公民社会呼唤大学生政治意识、公民意识的形成和完善。在公民社会的背景下,学生政治参与途径与方式日益多样化,对其特点进行归纳分析并寻求相关引导性对策具有现实必要性。     

《论语》：一个传播社会学文本

在传播社会学的视野里,《论语》既是春秋时期贵族政治兴起和礼制复兴的产物,又是城邦制民主政治兴起后,“士”阶层文化消费、伦理教育思想与文化传播社会科学的征候。作品中诸多审美范式和哲学对话方式被春秋时期及后世传媒文化频繁援引,作为一种新型“哲学咨询”式知识传媒形态,它被发现或未被阐释的传播社会学知识俨然成为春秋社会的“转述者”。     

环境工程专业模型嵌入式实验教学改革与实践

为保障新建本科院校高级应用型人才的培养质量,针对环境工程实验教学中普遍存在的问题,构建了模型嵌入式实验教学体系。以重庆文理学院环境工程专业为例,介绍了模型嵌入式实验教学体系的特点和运行过程,提出并实施了该教学体系的几点保障措施,取得了一定的实践教学成效。