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Date: 13-1-2022
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Date: 2-1-2020
1306
Date: 11-8-2018
2055
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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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أمين عام أوبك: النفط الخام والغاز الطبيعي "هبة من الله"
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قسم شؤون المعارف ينظم دورة عن آليات عمل الفهارس الفنية للموسوعات والكتب لملاكاته
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