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941.
The 15NMR chemical shifts were measured of a number of N-substituted formamides and acetamides at the natural abundance level. The ratios of the cis and trans isomers for several N-alkylformamides were also determined. Substituent effects on the 15N chemical shifts of formamides are compared with those of some other nitrogen-containing compounds. There is a consistent pattern of behavior of the one bond spin–spin coupling constants [1J(15NH)] wherein the trans isomers of N-alkylformamides are larger than those of the cis isomers. 相似文献
942.
943.
Masayuki Yoshikawa Yoshiharu Ikeda Hiroshi Kayakiri Kohei Takenaka Isao Kitagawa 《Tetrahedron letters》1982,23(45):4717-4720
By use of a decarboxylation reaction with lead tetraacetate and a deacetoxylation reaction with sodium borohydride as key-reactions, paromamine ( and tri-N-benzyloxycarbonylparomamine () were synthesized from D-glucosamine. 相似文献
944.
We present solutions of seven graph equations involving the line graph, complement and n-th power operations. One such equation generalizes a result of M. Aigner. In addition, some comments are made about graphs satisfying . 相似文献
945.
Hiroshi Narushima 《Journal of Combinatorial Theory, Series A》1974,17(2):196-203
We introduce an enumeration theorem under lattice action. Let L be a finite semilattice and Ω be a nonempty set. Let be a map satisfying f(x ? y) ? f(x) ∩ f(y), where ? and (Ω) mean “join” and the power set of Ω, respectively. Then , where C is the set of all chains in L and l(c) denotes the length of a chain c. Also the theorem can be dualized. Furthermore, we describe two applications of the theorem to a Boolean lattice of sets and a partition lattice of a set. 相似文献
946.
947.
948.
Takasuke Matsuo Yoshio Kume Hiroshi Suga SyûzÔ Seki 《Journal of Physics and Chemistry of Solids》1976,37(5):499-506
The heat capacities of copper(II) formate tetrahydrate and tetradeuterate have been measured from 12 to 300 K with an adiabatic calorimeter. They have sigmoidal temperature dependence except near the antiferroelectric-paraelectric transition temperatures, 235.78 ± 0.05 K and 245.64 ± 0.05 K, respectively. The corresponding enthalpy changes are 836.0 ± 1.0 J mol?1 and 936.9 ± 0.5 J mor?1. The entropy changes are 3.546 ± 0.005 JK?1mol?1 and 3.814 ± 0.002 JK?1 mol?1. The heat capacities are larger in the high temperature phase than in the low temperature phase, the difference amounting to 5.74 JK?1 mol?1 and 7.15 JK?1 mol?1 for the hydrate and the deuterate, respectively. The heat capacity anomaly is compared with those in tin(II) chloride dihydrate and potassium hexacyanoferrate trihydrate and discussed in relation to the structure of the hydrogen bond networks in these substances. The discussion is extended to include possible properties of the hydrogen bond frameworks in ices Ih and II. 相似文献
949.
950.
The equations of motion of a test particle moving near the center of a massive rotating ring are derived up to the post-post-Newtonian order of approximation, by using the metric tensor for many body system which is Minkowskian at spatial infinity. Logarithmic divergences due to self-interaction of the ring appear in the equations of motion. These divergences can be removed by the procedure which is similar to the renormalization method in particle physics. In the equations of motion there appears a force directing to the rotation axis and depending on the angular velocity of the ring. This force vanishes when the magnitude of the gravitational constant times the mass of the ring divided by the radius of the ring is about one tenth of the square of the velocity of light. Under this condition it is shown that the relative magnitude of the Coriolis force to the centrifugal force in the equations of motion agrees with the expected one from the equations of motion in a rotating reference frame. 相似文献