假如小行星撞地球

我儿子相信UFO,好奇百慕大的神秘,也想见识一下尼斯湖的水怪。最近他又在考虑小行星碰撞地球的问题。他问我。我说,别听那些吃饱了没事干的家伙瞎蒙,这是不可能的。儿子说,作为一种假设总是可以的吧?为此,他提出了一个方案。要么把小行星炸了,要么改变地球运行轨道,可不可以?你     

FLOSSWorld全球调查结果显示服务器更多使用开源软件

FLOSSWorld调查的主体由5部分构成,包括:个人(Private sector)、政府(Government sector)、开源社区参与者(Open Source participants community)、高校管理者(Heigher Education Institutes——Administrators)、高校信息部门主管(Heigher Education Institute——ITManagers)     

Synthetic and biological studies on a cyclopolypeptide of plant origin

Objective: A natural cyclic peptide previously isolated from Citrus medica was synthesized by coupling oftetrapep-tide units Boc-Leu-Pro-Trp-Leu-Ome and Boc-Ile-Ala-Ala-Gly-Ome after proper deprotection at carboxyl and amino terminals followed by cyclization of linear octapeptide segment.Methods: Solution phase technique was adopted for the synthesis of cyclooctapeptide--sarcodactylamide.Required tetrapeptide units were prepared by coupling of Boc-protected dipeptides viz.Boc-Leu-Pro-OH and Boc-Ile-Ala-OH with respective dipeptide methyl esters Trp-Leu-Ome and Ala-Gly-Ome.Cyclization of linear octapeptide unit was done by p-nitrophenyl ester method.The structure of synthesized cyclopolypeptide was elucidated by FTIR,1H NMR,13C NMR,FABMS spectral data and elemental analysis.The newly synthesized peptide was evaluated for dif-ferent pharmacological activities including antimicrobial,anthelmintic and cytotoxic activities.Results: Synthesis of sarcodac-tylamide was accomplished with >78% yield utilizing dicyclohexylcarbodiimide (DCC) as coupling agent.Newly synthesized peptide possessed potent cytotoxic activity against Dalton's lymphoma ascites (DLA) and Ehrlich's ascites carcinoma (EAC) cell lines,in addition to moderate anthelmintic activity against earthworms Megascoplex konkanensis,Pontoscotex corethruses and Eudrilus sp.Moreover,cyclopolypeptide displayed good antimicrobial activity against pathogenic fungi Candida albicans and Gram-negative bacteria Pseudomonas aeruginosa,in comparison to standard drugs griseofulvin and ciprofloxacin.Conclusion: Solution phase technique employing DCC and triethylamine (TEA) as base proved to be effective for the synthesis of natural cyclooctapeptide.N-methyl morpholine (NMM) was found to be a better base for the cyclization of linear octapeptide unit in comparison to TEA and pyridine.     

Developmental links of very early phonological and language skills to second grade reading outcomes: strong to accuracy but only minor to fluency

The authors examined second grade reading accuracy and fluency and their associations via letter knowledge to phonological and language predictors assessed at 3.5, 4.5, and 5.5 years in children in the Jyv?skyl? Longitudinal Study of Dyslexia. Structural equation modeling showed that a developmentally highly stable factor (early phonological and language processing [EPLP]) behind key dyslexia predictors (i.e., phonological awareness, short-term memory, rapid naming, vocabulary, and pseudoword repetition) could already be identified at 3.5 years. EPLP was significantly associated with reading and spelling accuracy and by age with letter knowledge. However, EPLP had only a minor link with reading fluency, which was additionally explained by early letter knowledge. The results show that reading accuracy is well predicted by early phonological and language skills. Variation in fluent reading skills is not well explained by early skills, suggesting factors other than phonological core skills. Future research is suggested to explore the factors behind the development of fast and accurate decoding skills.     

基于国家教育标准的地理教材

为进一步增强美国地理教育。我们要做的许多事情之一就是改进教材的质量。其中最主要的三个方面的任务是:(1)开发优良的教材,(2)利用教师联盟的在职培训网络和职前教育计划培训教师使用这种新教材,(3)通过提供强有力的课程指导,特别是将教材与师资培训和基于国家     

心理学视野中的青少年暴力行为研究

青少年时期是生理心理发育的关键时期，也是心理冲突和情绪、行为问题的高发阶段，暴力行为便是其中较为突出的问题之一。暴力行为是青少年对生活事件的一种应激方式，也是对父母不良监控方式和冷淡亲子关系的一种不合理反应，它易受不良同伴关系的影响。对待青少年暴力行为，一方面必须正确认识它，分清偶然性行为和经常性行为，另一方面必须采取积极的预防和干预措施，如丰富青少年的文化生活，转移和缓解各种暴力行为的力量来源；营造良好的教育环境，创建和谐健康的家庭、社会环境。     

Deafness, language skills, and rehearsal: a model for the development of a memory strategy

We review a series of studies that evaluate the role of developing language skills as a prerequisite to spontaneous rehearsal use in deaf populations. We propose a theoretical model that summarizes the contribution of language skills by highlighting the interrelations among age, language proficiency, and automatized language skills. In an initial test of the model, an index of deaf children's language experience was found to be an almost complete mediator of strategy use. Increasing language proficiency, therefore, was implicated as a critical variable in predicting children's spontaneous rehearsal use, minimizing any direct contribution from age per se. In a more direct assessment of the link between general language proficiency and rehearsal use, pragmatic language skills (as measured by the Language Proficiency Profile: LPP-I) were found to be a nearly complete mediator of rehearsal use, with the remaining contributions of age and language experience being nonsignificant. Language proficiency, therefore, was identified as a strong and necessary prerequisite for rehearsal to be used spontaneously as a memory strategy. The additional hypothesis that the automatization of these general language skills, measured by a rapid automatized naming task (RAN), contributes to spontaneous rehearsal was also evaluated. Automatized language emerged as a partial mediator of the language proficiency → rehearsal use relation but additional language-processing variables were implicated. We discuss these findings as they relate to issues around the nature of language proficiency and the identification of those automatized language skills involved in rehearsal.     

对未来公民的数学素质的探讨

在由“应试教育”向“素质教育”转轨的今天,从数学教育的目的出发,探讨数学素质问题无疑是极有价值的。本文试就未来公民的数学素质这一层次,谈几点认识和浅见。 (一) 数学是什么?尽管说法不一,但革命导师恩格斯的概括是较为妥贴的,即数学是关于现实世界的空间形式和数量关系的科学。从这一提法出发,名著《数学的内容方法和意义》把数学的特点概括为:高度的抽象性、逻辑的严谨性和应用的广泛性,时至今日,随着以计算机为标志的现代计算工具的出现,数学再象当年恩格斯那样仅用一句话来描述恐怕太显浅薄了,这主要体现在这样三方面:一是数学具有了作为科学的方法论属性;二是数学是关于客观世界的模式的科学;三是数学是关于客观世界的数学化过程。有鉴于此,对数学特征的“三性”似乎也应该重新认识。首先,数学的抽象性应从它的形式化来理解。诚如苏联数学家辛钦所说:“一切数学学科的决定性特点总是某种形式化的方法。”而这种形式的东西,正是布尔巴基学派所称的“结构”。其次,数学的严谨性离不开数学思维,而数学思维的本质在于生动活泼的策略创造,     

高职人才培养目标定位的新思考

大众化高等教育背景下,单一的精英型技能人才目标不仅不切实际,也不能满足学生多样化成才需要,应将高职人才培养目标定位为人力资源开发。在技术日新月异的新时代,高职应适当拓宽人才培养基础,加强学生的通识能力培养,并树立大市场观念,不仅考虑行业企业用人单位的需要,还应考虑学生的需要,摒弃单一的技术理性思维,激发学生自我成才动机,培养学生的创造性。随着企业生产组织方式的变迁,高职人才培养目标应作出相应调整。