无限长掺杂Zn棱柱型硅纳米管的理论研究     

李英 《商洛学院学报》2011,25(4)

运用密度泛函方法在(U)B3LYP/LanL2DZ水平上研究了无限长四棱柱、五棱柱和六棱柱型掺杂锌的硅纳米管的几何结构、电荷布局、能级和电偶极矩。计算结果表明,无限长四、六棱柱型Zn-Si纳米管的最低能结构均保持着基本的管状结构,五棱柱型的则畸变严重。五棱柱和六棱柱型Zn-Si纳米管的最低能结构的电子自旋多重态都为五重态,而四棱柱的为单重态。五棱柱型Zn-Si纳米管是这三种纳米管中热力学稳定性最强的。四、六棱柱型Zn-Si纳米管中电子从硅原子转向Zn原子,Zn原子充当电荷的受体,出现了电子反转现象。五棱柱型Zn-Si纳米管电子的转移方向比较复杂,Zn原子的位置不同,充当不同的电荷角色。两边的Zn原子是电荷的施体,而中间的则充当了电荷的受体。无限长掺杂Zn的五棱柱型硅纳米管的HOMO-LUMO能隙比较大,它的化学稳定性比较强。这三种纳米管呈半导体型。虽然这三种纳米管是极性的,但是五棱柱型的极性很弱。  相似文献   

Abdominal Obesity Associated with Elevated Serum Butyrylcholinesterase Activity,Insulin Resistance and Reduced High Density Lipoprotein-Cholesterol Levels     

Surapon Tangvarasittichai  Suthap Pongthaisong  Suwadee Meemark  Orathai Tangvarasittichai 《Indian journal of clinical biochemistry : IJCB》2015,30(3):275-280

Abdominal obesity (AO) has a strong correlation with cardiovascular disease and has been linked to Alzheimer’s disease and type 2 diabetes. We investigated the association between AO and elevated serum butyrylcholinesterase (BChE) activity, insulin resistance and the serum lipid profile, including triglyceride (TG), HDL-cholesterol (HDL-C) and LDL-cholesterol (LDL-C) levels in AO and non-AO women subjects. A total of 500 AO subjects (age 49.1 ± 10.5 years), and 142 non-AO women subjects (age 49.9 ± 11.9 years) were enrolled for the general biochemistry tests, serum BChE, fasting insulin and homeostasis model assessment of insulin resistance (HOMA-IR). Body mass index, waist circumference, Blood pressure (BP), plasma glucose (Glu), triglyceride (TG), BChE, insulin, HOMA-IR were significantly higher and HDL-C levels were significantly lower in AO subjects (p < 0.05). Waist circumference was significantly correlated with BP, Glu, TG, BChE, insulin and HOMA-IR in AO subjects. Multiple logistic regression demonstrated that AO was associated with elevated BChE, HOMA-IR, hypertension and reduced HDL-C after adjusting for these variables. AO is associated with elevated BChE, insulin resistance, HT and reduced HDL-C. These may predict the development of type 2 diabetes mellitus and may be associated with cognitive disorder in the future, both are mediated through insulin resistance.  相似文献   

基于社会网络分析的微信朋友圈实证研究——以华中农业大学信息1003班为例     

付永升  邬凯伟 《情报探索》2015,(1):21-25

基于华中农业大学信息1003班30位同学问卷调查所得的数据,利用社会网络分析方法和UCINET软件,对信息1003班成员的微信朋友圈进行了中心性分析和凝聚子群分析,同时计算了整体网络密度。结果表明:班长、团支书或人缘好的同学在微信朋友圈的信息传播中拥有较高的"权利",即能够在较大程度上控制信息的流动;室友或有共同兴趣爱好的人很容易形成小团体;信息1003班成员通过微信朋友圈联系紧密。  相似文献   

用密度梯度离心法富集源于小鼠胚胎干细胞的运动神经元样细胞前体     

StephanieRichardsonMilazi  BenjaminRixBrooks  Jean-LucMougeot 《河北北方学院学报(医学版)》2011,(1)

目的:我们的目标是从源于胚胎体(EBs)的小鼠胚胎干细胞(mESCs)中分离运动神经元样细胞前体(MNLCPs),以用于发展针对运动神经元疾病的药物筛选试验和移植疗法.天然Shh蛋白(或Shh通路激动剂)和维甲酸诱导的胚胎体中,MNLCPs和未分化细胞的含量是不确定的.如果不把未分化的细胞从细胞培养中充分去除,其可能会干涉药物筛选试验或在移植后增生.我们开发了一种以密度梯度离心法为基础的富集MNLCPs的方法.方法:我们用Wichterle等人2008年改进的方法,将mESCs( HBG3:eGFP:HB9)扩大和分化.通过化学和酶学的无研磨处理,含有绿色荧光蛋白的MNLCPs和未分化细胞的胚胎体被小心轻轻地离解成单细胞.利用OptiprepTM8％～20％逐步梯度离心技术将MNLCPs回收.拥有绿色荧光蛋白的MNLCPs的含量由流式细胞仪检测.结果:我们的结果表明,在胚胎体形成前,mESCs在明胶包被的培养板上生长,其分化为MNLCPs的能力减少.比较mESCs在明胶,明胶与PMEFs,及PMEFs包被的培养板上的生长发现,mESCs在PMEFs包被的培养板上产生含绿色荧光蛋白的MNLCPs的得率为(54.1±11.0)％(x-±s;n=12),在明胶包被的培养板上的得率为(2.8±1.1)％(x-±s;n=9).用密度梯度离心法获得的含绿色荧光蛋白的MNLCPs的平均含量为(87.7±5.5)％(x-±s;n=3).结论:我们的数据表明,不使用细胞分选器,无研磨解离和密度梯度离心法也能用于富集具有高存活率的MNLCPs.有必要对MNLCPs在体外、体内和表型上进行进一步的生理学意义(如神经轴突的生长及形成神经肌肉接头的能力)上的鉴定.  相似文献   

An efficient method of addressing ectopic beats: new insight into data preprocessing of heart rate variability analysis     

Wen F  He FT 《Journal of Zhejiang University. Science. B》2011,12(12):976-982

Heart rate variability (HRV) analysis is affected by ectopic beats. An efficient method was proposed to deal with the ectopic beats. The method was based on trend correlation of the heart timing signal. Predictor of R-R interval (RRI) value at ectopic beat time was constructed by the weight calculation and the slope estimation of preceding normal RRI. The type of ectopic beat was detected and replaced by the predictor of RRI. The performance of the simulated signal after ectopic correction was tested by the standard value using power spectrum density (PSD) estimation, whereas the results of clinical data with ectopic beats were compared with the adjacent ectopic-free data. The result showed the frequency indexes after ectopy corrected had less error than other methods with the test of simulated signal and clinical data. It indicated our method could improve the PSD estimation in HRV analysis. The method had advantages of high accuracy and real time properties to recover the sinus node modulation.  相似文献   

黄山风景区浮溪河水域淡水藻类种群结构调查     

刘恒霞  黄静  许柱  王慧忠 《滁州学院学报》2011,13(2):38-42

通过对黄山风景区浮溪河水域藻类植物的采集、室内显微镜检分类方法对该水域的淡水藻类资源进行调查研究。镜检过程中在所有样品中共记录到藻类植物112种(其中包括变种和变型),隶属5门42属。根据该水域藻类植物种群结构分析,知该水域中藻类植物群落属硅藻-蓝藻-绿藻-黄藻型。其中,硅藻在种类及数量上均占优势,有20属68种,占60.7%;蓝藻门,有11属21种,占18.7%;绿藻门,有9属16种,占14.3%;黄藻门1属4种,占3.6%;裸藻门,有2属3种,占2.7%。通过调查得知在沿河流自上而下采集的四个样品中,藻类的种类数以及植物体数量呈递增趋势。  相似文献   

水库淹没处理实施规划阶段农村移民身份认定问题探讨     

袁静  龙世红 《长江工程职业技术学院学报》2011,28(3):42-44

随着我国经济改革的发展,部分农村人口暂时脱离了农村土地以进城务工、经商等方式赖以生存,但在农村仍保留有户口、原承包土地或房屋等等,情况较复杂。本文对在丹江口水库大坝加高工程建设征地实施过程中,这部分移民身份认定问题进行探讨,供其他水利水电工程建设征地移民搬迁实施时参考。  相似文献   

Evidence-based digital literacy class for older,low-income African-American adults     

Hyunjin Seo  Joseph Erba  Darcey Altschwager  Mugur Geana 《Journal of Applied Communication Research》2019,47(2):130-152

Based on our community engagement project involving 47 older, low-income African-American adults from a senior community center, this study analyzes how an underserved population acquires knowledge and skills related to digital technologies. We discuss the conceptualization, implementation, and evaluation of a weekly, four-month long computer class for members of the senior community center. Our mixed-method research shows the importance of taking into account both the multidimensional nature of adult learning and the social and cultural contexts in which learning occurs when working with underserved adult populations. Findings from our formative and evaluative research offer insights into changes in the computer class participants’ attitudes toward and perspectives on key digital literacy issues including security and privacy online and online information verification. Scholarly and policy implications are discussed in the context of digital competency and adult learning for marginalized populations.  相似文献   

行人最大速度对行人流影响的研究     

刘祥树  陆安山 《钦州学院学报》2011,26(3):43-47

应用改进的格子气模型(即将行人的最大速度扩展到大于1)研究行人的最大速度对过道中单向和双向行人流的影响。模拟结果显示:最大速度为5时所对应基本图的临界密度跟实验值比较符合,说明该扩展是必要的;在一定范围内随着行人最大速度的增大道路的整体通行能力增强同时临界密度减小;双向行人流的时空斑图显示行人最大速度的增大加快了拥堵的形成过程(即缩短了行人从局部拥堵演化为完全拥堵的时间)。  相似文献   

新疆人口受教育程度与经济发展的灰色关联分析     

郭涛 《喀什师范学院学报》2015,(1)

人口受教育程度与经济发展有着密切的关系,立足新疆人口受教育程度和社会经济发展现状,构建了人口受教育程度与经济发展相互作用的灰色关联模型,揭示了新疆人口受教育程度与经济发展的相互关系：人口受教育程度的提高有利于劳动生产率和经济效益的提高,经济水平的提高为教育的发展提供可靠的物质保障。因此,政府应该高度重视教育的改革和发展,最大限度地发挥教育在区域经济发展中作用。  相似文献