نتایج جستجو برای: surface roughness and erosion type and severity p 005 therefore

تعداد نتایج: 17281764  

2013
Meire Coelho Ferreira Maria Letícia Ramos-Jorge Alberto Carlos Botazzo Delbem Ricardo de Sousa Vieirac

The aim of the present study was to investigate the abrasive effect of CaCO3 and SiO2-based fluoride-free experimental toothpastes on eroded human permanent dental enamel and evaluate the effectiveness of waiting periods between acid exposure and tooth brushing. Twelve volunteers wore palatal appliances containing human enamel blocks for two periods of five days each. The appliances were immers...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه ارومیه - پژوهشکده ادبیات 1393

testing plays a vital role in any language teaching program. it allows teachers and stakeholders, including program administrators, parents, admissions officers and prospective employers to be assured that the learners are progressing according to an accepted standard (douglas, 2010). the problems currently facing language testers have both practical and theoretical implications but the first i...

پایان نامه :دانشگاه تربیت معلم - تهران - دانشکده ادبیات و علوم انسانی 1391

efl/esl textbooks have been regarded as essential language teaching materials with which the learners spend about 70 up to 90 percent of their class time. the important role they play and their vast use make them not only influential in learning the language but also in shaping values and attitudes. put it another way, textbooks socialize learners using their contents (i.e. texts, illustrations...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علامه طباطبایی 1389

armenias geopolitics and its historical experience have had a determining impact on the character of its foreign policy .present-day armenia is a small, landlocked country with _11,620 square miles area armenias landlocked nature makes it dependent on the benevolence of its neighbors for access to the outside world a fact that gives it a sense of isolation and vulnerability. as it was indic...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علامه طباطبایی 1390

insurers have in the past few decades faced longevity risks - the risk that annuitants survive more than expected - and therefore need a new approach to manage this new risk. in this dissertation we survey methods that hedge longevity risks. these methods use securitization to manage risk, so using modern financial and insurance pricing models, especially wang transform and actuarial concepts, ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تبریز 1390

the present research study attempted to find out the extent to which two pre-task activities of “glossary of unknown vocabulary items” and “content related support” assisted efl language learners with their performance on listening comprehension questions across two different proficiency levels (low and high). data for this study were obtained from a total of 120 language learners, female and m...

J. Joudaki M. Emadi M. Safari,

Lubricant and coolant can improve surface roughness in machining. In addition of ecological harms, thermal shock of coolant or lubricant may affect the surface integrity especially on surface residual stresses and micro-crack nucleation. Dry machining is ecologically desirable and it is considered as a necessity for manufacturing enterprises in the recent years. 55Cr3 steel grade is steel with ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه صنعتی اصفهان - دانشکده شیمی 1389

in this project, some new polyaspartimides, (pas)s, have been synthesized form michael addition reaction between new synthetic bismaleimide (bmi) and some aromatic diamines. a characteristic property of this polyaspartimides is a pendent carboxylic group, which introduced to these polymers from new bismaleimide. bismaleimides (bmi) is one of the interesting compounds, which can be self-polymeri...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه مازندران - دانشکده علوم انسانی و اجتماعی 1388

abstract the present study was conducted to examine the effect of proficiency on students interaction while carrying out the grammar-based task(s) in collaboration. in particular, the study examines whether the level of proficiency affects the learners’ focus of attention to grammatical and lexical features. the study takes a further step and examines whether there is any difference in the use...

پایان نامه :0 1374

in fact this study is concerned with the relationship between the variation in thematice structure and the comprehension of spoken language. so the study focused on the following questions: 1. is there any relationship between thematic structure and the comprehension of spoken language? 2. which of the themes would have greated thematic force and be easier for the subjects to comprehend? accord...

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