بررسی تنوع ژنتیکی ژنوتیپ‏های بومی پیاز ایرانی در مقایسه با انواع خارجی چکیده: برنامه های اصلاحی گیاهان بر اساس تنوع و انتخاب صفات برتر کمی و کیفی صورت می گیرد. لذا، ارزیابی تنوع ژنتیکی، اولین مرحله در برنامه های اصلاحی است. در این راستا، استفاده از روش های جدید مطالعه‏ی تنوع ژنتیکی ضروری به نظر می رسد. در این بررسی تعیین تنوع ژنتیکی سیزده ژنوتیپ پیاز ایرانی در مقایسه با دو ژنوتیپ خارجی با است...

attempts have been made to study the thermodynamic behavior of 1,3 butadiene purification columns with the aim of retrofitting those columns to more energy efficient separation schemes. 1,3 butadiene is purified in two columns in series through being separated from methyl acetylene and 1,2 butadiene in the first and second column respectively. comparisons have been made among different therm...

the aim of this study has been to find answers for the following questions: 1. what is the effect of immediate correction on students pronunciation errors? 2. what would be the effect of teaching the more rgular patterns of english pronunciation? 3. is there any significant difference between the two methods of dealing with pronuciation errore, i. e., correction and the teaching of the regular ...

this study investigated the effects of planning on second-language written production with regard to task type. the participants were 75 iranian learners of english as a foreign language attending a private foreign language institution. they were asked to complete two different types of writing tasks (expository writing task and argumentative writing task) in different planned conditions (indiv...

since the 1960s the age effects on learning both first and second language have been explored by many linguists and applied linguists (e.g lennerberg, 1967; schachter, 1996; long, 1990) and the existence of critical period for language acquisition was found to be a common ground of all these studies. in spite of some common findings, some issues about the impacts of age on acquiring a second or...

a large number of single research studies on the effects of strategy-based instruction (sbi) in teaching english as a foreign or second language has been conducted so far. however, the lack of a comprehensive meta-analysis targeting the effectiveness of english language sbi is observed. moreover, the findings of experimental studies regarding the context of the english language, proficiency lev...

the ability of composing a coherent and extended piece of writing in second language is considered as a fundamental factor to convey information and ideas of learners through the academic issues. although learners may achieve a perfect academic writing skill through assigning the l2 tasks in content based instruction, but demonstration of their abilities may be related to their ability in l1 es...