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تعداد نتایج: 21187904 فیلتر نتایج به سال:
section{introduction} the concept of {sl cartan geometry} appeared at the beginning of the twentieth century, when {e}lie cartan was working on the so-called {sl equivalence problem}, the aim of which is to determine whether two given geometric structures can be mapped bijectively onto each other by some diffeomorphism. this problem can be considered in many different contexts, such as ...
This study concerns about quantum chemical modeling behavior of 02 on Cr (100)surface by using density functional theory (DFT) by LANL2DZ and 6 — 31G* basissets, we presented the results of our first principles electronic structure calculationson the 02 molecules and their interface with Cr (100) surface. The chromium metalhas the body-centered cubic structure, and chromium cluster has five Cr ...
in this thesis, a new optically active poly(amide-imide) (pai) was synthesized by the indirect polycondensation reaction of the l-phenylalanine based diacid chloride and 4,4?-diaminodiphenylether in the presence of triethylamine in n-methyl-2-pyrrolidone. the formation of pai was confirmed by ftir, 1h nmr and elemental analysis. in next step, the surface of titanium dioxide (tio2) nanoparticles...
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...
الملخّص الحنین إلی الوطن، کان من الموضوعات الأساسیّه منذ أزمنه قدیمه فی الأدب العربی. فی العصور الماضیه کان یبین الشعراء تذکاراتهم الجیّده، و الحنین إلی الحبیبه ، و القبیله، و الأطلال و الدمن بتحسّر فی أشعارهم. توجد نماذج منها فی أشعار إمرء القیس و عنتره و... . راج هذا النوع من الحنین فی أشعار الشعراء فی العصر الأموی و العباسی کثیراً بسبب الفتوحات و الهجره. نحن شاهدنا آثاراَ کثیره کـ«الحنین إلی الأو...
به طور کلی در فرآیندهای مارکوف ارگودیک دو بعدی یافتن فرم بسته توزیع ایستا، تنها برای حالات خیلی خاص امکان پذیر است. با توجه به این مشکل و نیز با توجه به اهمیت توزیع ایستا، بررسی و مطالعه رفتار مجانبی توزیع ایستای این فرآیندها مورد توجه قرار گرفته است. زنجیر قدم زدن تصادفی دو بعدی که در برخی متون به آن، فرآیند qbd دو طرفه نیز می گویند، یکی از این فرآیندها است. یک فرآیند qbd زمان گسسته یک زنجیر م...
thermal decomposition of two coal samples obtained from top seam sibi (tss) and sore range quetta (srq) coal fields in their raw and acid washed forms were carried out in an open type tubular pyrolyzer coupled to a gas chromatograph with fid. elemental analyses were carried out with scanning electron microscope-energy dispersive x-rays (sem-edx) analyzer. effect of inherent mineral contents on ...
the ability to speak two languages in the world is a remarkable achievement. there is a good reason to believe that bilingualism is the norm for the majority of people in the world because 70% of the earth’s population are supposed to be bilingual or multilingual. various investigations have shown that the native language impacts foreign word recognition, and this influence is adapted by the de...
Considering the increase in number of offshore oil production projects and for better understanding of plume dynamics in accidental underwater oil blowouts, a series of laboratory experiments in a square cross section open top basin were carried out to investigate the effect of changes in seawater stratification and water column stability on plume dynamics and peeling height. Accordingly the o...
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