نتایج جستجو برای: 3 or n
تعداد نتایج: 5141904 فیلتر نتایج به سال:
the space now known as complete erdos space ec was introduced by paul erdos in 1940 as the closed subspace of the hilbert space ?2 consisting of all vectors such that every coordinate is in the convergent sequence {0} ? { 1 n : n ? n}. in a solution to a problem posed by lex g. oversteegen we present simple and useful topological characterizations of ec. as an application we determine the ...
In the title compound, C(21)H(33)FN(3)O(2)P, the P atom has a distorted tetra-hedral environment and the N atoms display geometries consistent with a model of sp(2) hybridization (with bond-angle sums for the tertiary N atoms of 357.8 and 358.7°). The phosphoryl and carbonyl groups are anti with respect to each other. In the crystal, inversion dimers linked by pairs of N-H⋯O hydrogen bonds gene...
N, N΄-3, 4-di(methylamino)-1, 2, 5-oxadiazole (1f) was prepared by dehydration of N, N΄-3, 4-di(methylamino)glyoxime (2f) in aqueous potassium hydroxid at 170-180 ˚C. Under similar conditions N, N΄-3, 4-di(benzylamino)-1, 2, 5-oxadiazole (1c) and N, N΄-3, 4-di(isopropylamino)...
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