Unperturbed dimensions of atactic poly（dibenzyl itaconate）s

The unperturbed dimension and temperature character of poly(dibenzyl itaconate)s (PDBzI) are studied by a revised rotational isomeric state (RIS) method. The improved formulas of the mean-square radius of gyration, deduced by the pseudo-stereochemical equilibrium approach, may be used to investigate the configurational-conformational properties of atactic polymers with large side groups [poly(itaconates) for instance]. The calculated results showed that poly(itaconates) have larger dimension of the molecule than other vinyl polymers. Comparison of the dimension between considering and without considering side groups showed that the effect of large side groups on the unperturbed dimension for short-chain polymers is more obvious than that of long-chain polymers and, if the dimension of side groups increases, the effect also increases. The dimension differences of PDBzI between short-chain and long-chain polymers are investigated by the relation of characteristic ratios and temperature coefficients with temperature. Moreover, the dependence between the temperature coefficients and the tacticity of chains shows that the temperature characters of the isotactic, syndiotactic and atactic PDBzI chains have remarkable difference.     

校园网中VLAN的设计与实现

本从分析传统的校园网中逻辑子网之间的通信入手，介绍了在邢台职业技术学院校园网中采用了三层交换机中划分VLAN的办法，来解决子网之间的通信和安全以及广播风暴等问题。     

美国师范教育发展历史给我们的启示

美国的师范教育经历了师范学校、师范学院及综合大学教育院（系）的三个阶段,这种演变蕴藏着一些规律。我国师范教育历史悠久,自创建以来,为不同层次的学校提供所需师资,培育了大批人才。然而我国师范教育却也存在很多问题,面临重大挑战。美国师范教育的发展历史对我国师范教育的改革有一定的启示作用。     

可能与不能:社会分层对职业教育发展影响的一个悖论

社会分层对职业教育发展的影响已成为职业教育理论研究的一个焦点.社会阶层表现的是社会资源分配的不平衡状态.社会分层理论昭示:现代社会个人阶层的获得越来越依赖个人职业的获得.在我国当今阶层状态下,现代职业变迁使我国职业教育发展成为可能,但接受职业教育的阶层所拥有资源的现状却使职业教育发展往往不能.     

高校改制过程中校园精神的塑造

塑造良好的校园精神 ,是校园文化建设的核心 ,对高校的健康发展起着非常重要的作用。校园精神的作用是无形的 ,它直接影响到师生、学校 ,甚至人才的素质。因此 ,在认识到它的重要性的同时 ,需要全体师生共同努力 ,塑造一个良好的校园氛围。     

"十一五"期间我国职业教育改革与发展面临的主要问题(下)

(接上期) (三)职业学校办学条件较差 1.职业学校固定资产总值水平偏低.2002年全国各类学校固定资产总值为8769.05亿元,其中高等学校固定资产总值为2379.35亿元,占27.13%;普通中学为2783.44亿元,占31.74%;小学为2374.38亿元,占27.08%.而中、初等职业学校(包括中专、技工学校、职业中学)固定资产总值为820.15亿元,仅占合计的9.35%,远低于其他几类教育.一般来说,职业学校要为学生提供实习实训设备,固定资产总值水平应该高于普通中学.目前职业学校生均固定资产投资不足,最重要的正是反映在学生实习实训设备不足方面,直接影响了学生职业技能水平的提高.     

浅谈软件蓝领与高等技术教育

本通过对印度和日本软件产业的分析，对照我国软件产业的现状，初步探讨了软件开发工程化的具体内容和实现途径，以及与之相配套的人力结构和人才的知识结构、能力结构，并对职业技术学院培养的人才规格，能力结构及实现方法提出了一些见解。     

RNAi的革命

通过实验手段向细胞内导入长的双链RNA或者转基因可以产生一些短片段的双链RNA,这些短片段的双链RNA可以通过促使特定基因的mRNA降解来高效、特异地阻断体内特定基因的表达,使细胞出现特定基因缺失的表型,称为RNA干扰(RNA interference,RNAi)。SiRNA(small interference RNA)就是这种短片段双链RNA分子,能够以序列同源互补的mRNA为靶目标,降解特定的mRNA。基本上所有的生物体内也都存在一种内源的小分子RNA,为单链RNA,由基因组转录生成,但是不编码蛋白质,它们的功能在于调节mRNA的翻译,称为miRNA,是由具有发夹结构的前体剪切产生的。RNAi的发现具有划时代的意义,它不仅揭示了细胞内基因沉默的机制,而且有望成为后基因组时代基因功能分析的有力工具,极大地促进了人类揭示生命奥秘的进程。     

用Excel绘制物理图像

介绍了用Excel软件绘制物理图像的方法。     

Risk factors for infant maltreatment: a population-based study

CONTEXT: Of the approximately 900,000 children who were determined to be victims of abuse or neglect by US child protective services in 2002, the birth-to-3 age group had the highest rate of victimization (1.6%) and children younger than 1 accounted for the largest percentage of victims (9.6%). OBJECTIVE: To identify perinatal and sociodemographic risk factors associated with maltreatment of infants up to 1 year of age. DESIGN AND SETTING: Observational cohort study. PARTICIPANTS: 189,055 children born in 1996 in Florida. MAIN OUTCOME MEASURE: Infant maltreatment, defined as a verified report of abuse, neglect, or threatened harm that occurred between day 3 of life and 1 year. RESULTS: 1,602 children (.85%) of the 1996 birth cohort had verified instances of maltreatment by age 1. Of 15 perinatal and sociodemographic variables studied, 11 were found to be significantly related to infant maltreatment. Five factors had adjusted relative risks (RR) of two or greater: Mother smoked during pregnancy (RR 2.8); more than two siblings (RR 2.7); Medicaid beneficiary (RR 2.1); unmarried marital status (RR 2.0); low birth weight infant (RR 2.0). Infants who had four of these five risk factors had a maltreatment rate seven times higher than the population average. CONCLUSIONS: Data on nearly all risk factors found to be significantly associated with infant maltreatment are available on the birth certificate. Such information can be incorporated into a population-based risk-assessment tool that could identify subpopulations at highest risk for infant maltreatment. Because resources are limited, these groups should be given priority for enrollment in child abuse prevention programs.