نتایج جستجو برای: heavy metals due to their non biodegradability properties and can accumulate in living tissues

تعداد نتایج: 22824906  

ژورنال: ایمنی زیستی 2020

The sustainability and non-biodegradability of heavy metals, on the one hand, and the increasing environmental pollution caused by industrial wastewater on the other hand have increased the attention to heavy metal remediation. Cyanobacteria are one of the most important agents of heavy metals removal in drought and aquatic environments. Their ability to remove metals is related to various mech...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تبریز - دانشکده ادبیات و زبانهای خارجی 1392

abstract while task-based instruction is considered as the most effective way to learn a language in the related literature, it is oversimplified on various grounds. different variables may affect how students are engaged with not only the language but also with the task itself. the present study was conducted to investigate language and task related engagement on the basis of the task typolog...

پایان نامه :دانشگاه تربیت معلم - تهران - دانشکده ادبیات 1390

this study is an outlook of iranians religious practices and customs in eras such as nasser one. it attempts to answer the main question, "religious practices and ceremonies in the society during naseri ruling" and other subsidiary questions with scientific and historical theories. iran was a traditional and religious community . people abided by their religious practices and duties within reli...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس 1389

abstract: country’s fiber optic network, as one of the most important communication infrastructures, is of high importance; therefore, ensuring security of the network and its data is essential. no remarkable research has been done on assessing security of the country’s fiber optic network. besides, according to an official statistics released by ertebatat zirsakht company, unwanted disconnec...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه پیام نور - دانشگاه پیام نور استان تهران - دانشکده ادبیات و علوم انسانی 1393

as far as bandura’s (1977) conceptualization of the sense of self-efficacy is concerned, it is argued to be context- and even task-specific, compared to other concepts like self-esteem (brown, 2000); therefore, upon the previous research studies, related theories and definitions, and the ideas and views obtained from the interviews conducted with the scholars, the current research study aimed a...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه مازندران - دانشکده علوم انسانی 1390

iv abstract this study examined the linguistic behaviors of two iranian efl teachers each of them teaching learners of two similar proficiency levels, a beginner level and an intermediate level, to investigate the relationship between the learners proficiency levels and the amounts and purposes for l1 use by the two teachers. the study was carried out to investigate whether there were differe...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه فردوسی مشهد - دانشکده ادبیات و علوم انسانی 1393

abstract: the present study is an attempt to find out cultural exophoric references in iranian high-school elt textbooks and touch stone series to compare the frequency of occurrence of such references in these books. the purpose is to find out which of the series of the books under investigation impose a greater referential burden on efl learners as far as their reading comprehension of the ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت دبیر شهید رجایی - دانشکده علوم انسانی و پایه 1390

the present study aimed at investigating the relationship between iranian efl teachers’ classroom management orientations and their teaching styles. additionally, the difference between male and female teachers’ teaching styles and classroom management orientations and their relationship with experience and age were explored. three hundred efl teachers filled in attitudes and beliefs on classro...

پایان نامه :دانشگاه تربیت معلم - تهران - دانشکده زیست شناسی 1391

بررسی تآثیر کورکومین بر بیان آکواپورین5 در سلول های سرطانی روده بزرگ انسان(ht-29) سرطان روده بزرگ جزو بیماری های خطرناک بوده و از نظر شیوع سومین سرطان شایع و دومین علت مرگ ومیر ناشی از سرطان در جهان محسوب می شود. خطرابتلا به این سرطان تحت تاثیر دو عامل محیطی وفاکتورهای ژنتیکی می باشد. آکواپورین ها، پروتئین های کانال آبی بوده که نقش مهمی را در انتقال آب در بافتهای اندوتلیالی و اپی تلیالی بر عهد...

Journal: :محیط زیست طبیعی 0
مریم زارع دانشجوی کارشناسی ارشد، گروه محیط زیست، دانشکده منابع طبیعی دانشگاه تهران، ایران امیرحسین حمیدیان استادیار گروه محیط زیست، دانشکده منابع طبیعی دانشگاه تهران، ایران هادی پورباقر استادیار گروه شیلات، دانشکده منابع طبیعی دانشگاه تهران، ایران سهراب اشرفی استادیار گروه محیط زیست، دانشکده منابع طبیعی دانشگاه تهران، ایران لیلا وزیری دانشجوی کارشناسی، گروه محیط زیست، دانشکده منابع طبیعی دانشگاه تهران، ایران

industrial activities lead to an increase in heavy metal burden in rivers. sediment and algae (spirogyra sp.) samples were collected from the shoor river to investigate their heavy metal concentrations. dry and ashed samples of algae and sediment were digested using concentrated nitric acid. heavy metals (as, fe, zn and cr) concentration measured using an icp-oes instrument (perkinelmer, usa). ...

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