初等行变换在线性代数中的应用

初等变换在线性代数中是一个核心概念,很多内容都与之相关,大致包含这几个方面的内容:矩阵或向量组的秩、矩阵的逆、解矩阵方程、解线性方程组等.初等变换分两类:初等行变换和初等列变换.很多学生弄不清什么时候用行变换,什么时候用列变换,什么时候可以一起用.其实很多列变换也可用行变换代替.     

公众对北京市中小学教师的满意度调查

以北京市2234名中小学生家长为样本,研究考察了公众对中小学教师满意度的总体状况及不同背景的公众对教师的满意度。结果表明:(1)从整体上看,公众对北京市中小学教师的满意度比较高,对教师的满意度由高到低依次为师生关系、教育教学与学生课外学习;(2)教育质量越好的学校,公众对教师的满意度越高,但在不同学段表现出差异;(3)公众的受教育程度越高,其对教师教育教学的满意度越低,但因学生的学习成绩不同而表现出差异。对于学习成绩中游及以上的学生家长,接受过高等教育的家长对教育教学的满意度明显低于中等教育程度及以下的家长,成绩差的学生家长对教师的满意度在受教育程度上的差异不明显。     

智能路灯的设计与研究

该智能路灯控制系统分为系统控制部分、恒流源部分、液晶显示部分、传感器控制部分、负载（路灯）部分、外围辅助部分。全系统以单片机控制部分为主题,利用液晶显示部分分别显示路灯的点亮时间和关闭时间以及计时显示;系统由AT89C51进行精密控制,通过时间设定、环境光强弱的变化、物体的运动方向自动控制,电路工作时稳流电源将电流保持恒定不变。     

提高计算机英语学习能力的探索

传统的计算机英语教学存在许多问题,针对这些问题分别在教学方向、教学内容和教学方式三个方面进行了讨论并提出了教学改革建议.     

和谐校园呼唤活力社团——对高校学生社团建设的思考

高校学生社团的存在和发展是高校校园文化活跃与和谐的重要载体.对于新形势下高校的改革和发展的新要求,以及构建社会主义和谐社会的新体系,如何通过会员的活力来带动社团的活力,是目前高校学生社团建设应该做好的一篇大文章.高校社团组织应以"充满活力"为切入点,以"充满活力"为生存和发展的动力,紧紧抓住当今这个与学校发展共同发展的机遇,在为构建和谐校园献力量的同时,融入社会,融入校园,提升服务水平和自身作用地位.     

主变噪音异常及案例分析

从噪音产生机理、谐波电流的影响、直流电流的影响等对主变压器噪音异常现象进行了分析。直流入侵时会产生直流偏磁现象,随着直流分量的增大,励磁电流畸变越来越严重,并出现严重的半周饱和,从而对变压器产生严重危害。通过分析,确认驿南府变电站主变压器异常噪音为直流电流的影响,为解决这些问题,提出了串联电阻、串联高压电容器等解决的方案。实践证明了这些方案的有效性。     

从叙述时空看哈代小说人物的"漂泊"

哈代小说中人物居无定所,心灵也一直游离在反抗与顺从之间,是"漂泊"中的小人物.哈代巧妙地运用时间和空间,使人物的"漂泊"带有普遍性和永恒性,从而增强了人物漂泊的悲剧性.因此,从叙述时空的角度来解读哈代小说中人物的"漂泊",可以更加深刻地理解哈代小说.     

Development of a large-scale isolation chamber system for the safe and humane care of medium-sized laboratory animals harboring infectious diseases

The close phylogenetic relationship between humans and non-human primates makes non-human primates an irreplaceable model for the study of human infectious diseases. In this study, we describe the development of a large-scale automatic multi-functional isolation chamber for use with medium-sized laboratory animals carrying infectious diseases. The isolation chamber, including the transfer chain, disinfection chain, negative air pressure isolation system, animal welfare system, and the automated system, is designed to meet all biological safety standards. To create an internal chamber environment that is completely isolated from the exterior, variable frequency drive blowers are used in the air-intake and air-exhaust system, precisely controlling the filtered air flow and providing an air-barrier protection. A double door transfer port is used to transfer material between the interior of the isolation chamber and the outside. A peracetic acid sterilizer and its associated pipeline allow for complete disinfection of the isolation chamber. All of the isolation chamber parameters can be automatically controlled by a programmable computerized menu, allowing for work with different animals in different-sized cages depending on the research project. The large-scale multi-functional isolation chamber provides a useful and safe system for working with infectious medium-sized laboratory animals in high-level bio-safety laboratories.     

Effect of high glucose levels on the calcification of vascular smooth muscle cells by inducing osteoblastic differentiation and intracellular calcium deposition via BMP-2/Cbfα-1 pathway

In this paper,we investigate the effect and the possible mechanism of high glucose levels on the calcification of human aortic smooth muscle cells (HASMCs).HASMCs were divided into four groups: normal glucose group (NG),osmolality control group (OC),high glucose group (HG,HASMCs culture medium containing 30 mmol/L glucose),and high glucose plus recombinant human Noggin protein (bone morphogenetic protein-2 (BMP-2) antagonist) group (HN).The mRNA levels and the protein expressions of BMP-2 and core binding factor alpha-1 (Cbfα-1) were measured by real-time quantitative polymerase chain reaction (PCR) and Western blot.After induced by 10 mmol/L β-glycerol phosphoric acid,cells were harvested for assessments of alkaline phosphatase (ALP) activities at Days 1,2,and 3,and intracellular calcium contents at Days 7 and 14,respectively.High glucose levels increased the mRNA levels and the protein expressions of BMP-2 and Cbfα-1 (P0.05).The expression of Cbfα-1 was partially blocked by Noggin protein (P0.05),while BMP-2 was not (P0.05).After being induced by β-glycerol phosphoric acid,high glucose levels increased the ALP activity [(48.63±1.03) vs.(41.42±2.28) U/mg protein,Day 3;P0.05] and the intracellular calcium content [(2.76±0.09) vs.(1.75±0.07) μmol/mg protein,Day 14;P0.05] in a time-dependent manner when compared with the NG group,while the ALP activity could not be blocked by Noggin protein [(48.63±1.03) vs.(47.37±0.97) U/mg protein,Day 3;P0.05].These results show that high glucose levels can evoke the calcification of HASMCs by inducing osteoblastic trans-differentiation and intracellular calcium deposition via the BMP-2/Cbfα-1 pathway,which can be partially blocked by Noggin protein.     

提高外语专业本科生中文水平的意义与方法

对外语学习中"母语作用"的研究一直是外语教学研究的一个重要内容。中文学习对外语专业本科生来说既能补益外语学习,又能增强就业竞争力。针对目前外语专业本科生普遍下降的中文水平问题,建议通过精选学习内容、课内外结合、浏览报刊、品读汉-外译作和更新教学方法和教学手法等方法,以提高其中文水平。