منابع مشابه
Vitamin C as a green and efficient catalyst in synthesis of quinoxaline derivatives at room temperature
A simple, highly efficient and green procedure for the condensation of o-phenylenediamines with 1, 2-dicarbonyl compounds in the presence of vitamin C, as an inexpensive organocatalyst, is described. Using this method, variety of quinoxaline derivatives with different electron releasing and electron withdrawing substituents, are produced in high to excellent yields at room temperature in ethano...
متن کاملVitamin C as a green and efficient catalyst in synthesis of quinoxaline derivatives at room temperature
A simple, highly efficient and green procedure for the condensation of o-phenylenediamines with 1, 2-dicarbonyl compounds in the presence of vitamin C, as an inexpensive organocatalyst, is described. Using this method, variety of quinoxaline derivatives with different electron releasing and electron withdrawing substituents, are produced in high to excellent yields at room temperature in ethano...
متن کاملeffect of oral presentation on development of l2 learners grammar
this experimental study has been conducted to test the effect of oral presentation on the development of l2 learners grammar. but this oral presentation is not merely a deductive instruction of grammatical points, in this presentation two hypotheses of krashen (input and low filter hypotheses), stevicks viewpoints on grammar explanation and correction and widdowsons opinion on limited use of l1...
15 صفحه اولdevelopment of feminist poetics in adrienne rich
اشعار ریچ، به عنوان اشعاری که همیشه در حال تغییر و دگرگونی هستند، تجسمی از رشد و دگرگونیِ انسان هستد. پایان نامه ی حاضر، با تمرکز بر روی مراحل سیر شعری ریچ از تغییری در دنیا به عکس هایی فوری از یک عروس، سپس به شیرجه به درون کشتی شکسته و در نهایت به صبری عجیب مرا تا اینجا آورده، به بررسی این مراحل در قالب نظر شوالتر در رابطه با سه مرحله ی پیشرفت ادبی زنان یعنی مرحله ی زنانه، زن گرا و زن محور می پ...
15 صفحه اولBenefits of combinations of vitamin A, C and E derivatives in the stability of cosmetic formulations.
Chemically stable ester derivatives of vitamins A, C and E have become a focus of interest for their role in the satisfactory results in skin aging treatments. Accordingly, the aim of this study was to evaluate the physical and chemical stability of a cosmetic formulation containing 1% retinyl palmitate, ascorbyl tetraisopalmitate and tocopheryl acetate, alone or in combination. In the studies ...
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ژورنال
عنوان ژورنال: Journal of Society of Cosmetic Chemists of Japan
سال: 1996
ISSN: 1884-4146,0387-5253
DOI: 10.5107/sccj.29.382