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تبیین پاسخ به پرسش از چرایی یک پدیده یا رویداد است ، همان گونه کهتوصیف پاسخ به پرسش از چگونگی آن است . الگوهای اصلی در تبیین علمی دوالگویِ قیاسی -قانون وار و استقرائی -آماری بوده اند. الگوهای دیگری نیز به عنوانمکمل یا جانشین این دو الگو معرفی شده اند که در بهترین حالت بهبود یافته ویا اصلاح شدۀ آن دو به شمار می آیند. جدانگری توضیح در علوم طبیعی براساس تبیین و علوم انسانی بر اساس فهم در هم نهاده ا...
introduction: obtaining top academic position among countries of the middle east and having advanced knowledge and ability to produce knowledge are among the most important goals set in iran’s twenty-year vision. present study aimed to determine impact factor of specialized and technical journals of iran and to compare with selected countries and provide appropriate recommendation. methods: in ...
Ab initio calculations at HF/6-31G* level of theory for geometry optimization and MP2/6-31G*//HF/6-31G* for a single point total energy calculation are reported for the importantenergy-minimum conformations and transition-state geometries of 1, 3-diazacyclohepta-1, 2-diene (2) and 1, 3-diazacycloocta-1, 2-diene (3). The C2 symmetric twist-chair (2-TC)conformation of 2 is calculated to be 7.4 kJ...
on the eve of 14th year of publication of “negin iran: a quarterly for studies of iran-iraq war” and after the release of an index for the first 28 issues of the quarterly published in 29th issue, the journal executive editor decided to release another index for the numbers of 1-50 in the new release of the quarterly to be used by the related researchers and those interested in this field of st...
endothelial dysfunction is thought to be a central pathogenic feature in preeclampsia on the basis of elevated adhesion molecules. soluble forms of these molecules can be detected in plasma, and their concentrations are thought to reflect the degree of activation of a particular cell type. the aim of the present study was to compare the levels of soluble vascular cell adhesion molecule-1 (svcam...
a facile and efficient method for the preparation of 1, 1-diacetates of aldehydes is improved.p2o5/sio2 catalyzed 1, 1-diacetates formation from aldehydes in dry media. advantages of this methodare the use of an inexpensive and selective catalyst with high yields in simple operation and shortreaction time under solvent-free conditions.
five new 1-hydroxy-2-(1-alkyloxymethyl)-9,10-anthraquinones (9a-e) have been prepared. selective nitration of 2-methyl-9,10-anthraquinone, reduction to the corresponding amine, diazotization and treatment by sulfuric acid solution afforded the 1-hydroxy-2-methyl-9,10-anthraquinone in good yield as the key intermediate. reaction with dimethylsulphate/k2co3 and subsequent monobromination with nbs...
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