高性能混凝土及其掺合料的性能机理探讨

本文在比较高强混凝土和高性能混凝土的性能、优点和存在的问题的基础上主要讨论了改善混凝土性能的掺合料的类型及其性能机理。     

Predictors of foster parents' satisfaction and intent to continue to foster

OBJECTIVE: The United States General Accounting Office (United States General Accounting Office [USGAO], 1989) report on out-of-home care affirmed that the foster care system is in crisis. To shed light on some factors that influence retention, the study reported here asked "What factors influence the satisfaction of foster parents?" and "What factors influence the intent of licensed foster parents to continue to foster?" METHOD: A sample of 539 foster parents in eight urban counties in a large Midwestern state completed questionnaires aimed at addressing these questions. RESULTS: Some of the factors exerting the strongest influence on satisfaction were: feeling competent to handle the children who were placed; wanting to take in children who needed loving parents; no regrets about investment in foster children; foster mother's age; and agency social worker providing information and showing approval for a job well done. An example of factors exerting influence on intent to continue to foster include overall satisfaction, readiness to phone the social worker, number of foster boys in the home, being treated like one needed help oneself, and agency affiliation (private). CONCLUSIONS: Efforts to increase the supply of foster homes through recruitment is not enough. The support, training, and professional regard given to parents after they have begun the fostering task is of greater need. Based on analysis of the findings, implications for practice, programming, and policy are offered.     

教你活得更好

这是一个十分感人的古老故事,许多年来,这个故事曾激励了无数的美国人从无到有,从贫穷到富有,因此被美国传媒一再颂扬为“能影响人的精神的经典之作”。     

东西合"笔","东"写"西"说(下)

Comments on “Tea”&“Questions”:Different Countries,DifferentCultures,Different Customs 对文章《“茶”和“问题”:不同的国度,不同的文化,不同的习俗》的点评     

捕月亮的网

我做了一张捕月亮的网, 今晚,我就要(带着它)出去探险; 我要边跑边高高甩出我的网, 让它套住那颗发光的大球。所以,明天如果你发现天上没有了月亮,你就知道     

调查和评估职业教育机构的现代手段

一、对学校的调查和评估一些西方国家为了评价学校和教育机构的实际水平，往往采取规范化、系统化的调查方法。用这种方法对学校进行评价，要靠客观的调查标准，要查明学校的现状，而不是考虑学校以前的荣誉或以前的贡献。评估时首先需要有明确的目标要能够处理应用的指标。在这种指标的基础上，通过系统化的调查和评价，我们才能获知职教机构的个别弱点和优势。调查的结果使我们能够评价课程的针对性以及整个教学和培训过程的效果。评估的结果对教育机构能发挥反馈作用，提供指导和启发，使学校优化教学过程、修改课程和教学计划、培养具…     

密度估计量在混合条件下的L_1收敛性

我们考虑取值在R~d上的随机变量的一般核密度估计量,并证明在混合的假设下,此估计①在L_1中全收敛的充分必要条件与i·i·d 情形的一样。     

浅谈地理信息系统在水文工作中的应用

科学技术的发展日新月异，以计算机为代表的信息化技术在现代社会进步中扮演着非常重要的角色。     

英国中学科学教育新动向

中学生在化学课上都会学到卤元素,包括元素氟在内。氟是化学性质很活跃的一种元素,化学教师津津乐道的是氟的强氧化作用,可是学生想知道氟化物在饮用水里的作用,这种强氧化物还会对牙齿有好处,学生感到很奇怪。其实氟和氟化物     

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.