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Date: 13-8-2018
2274
Date: 7-8-2019
1498
Date: 7-8-2019
1781
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A very important characteristic of three-bond proton-proton couplings,H−C−C−H, is the way that they depend on the conformation at the C−C bond. Typical values for several particular conformations are
For protons in groups such as ethyl groups, in which rotation is rapid and the favored conformations are staggered (but none of the staggered conformations is preferred over the others), average proton-proton splittings are observed. The average for CH3CH2− splittings is about 7Hz, which corresponds to [2×4.5(gauche)÷12(trans)]/3.
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"عادة ليلية" قد تكون المفتاح للوقاية من الخرف
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ممتص الصدمات: طريقة عمله وأهميته وأبرز علامات تلفه
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المجمع العلمي للقرآن الكريم يقيم جلسة حوارية لطلبة جامعة الكوفة
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