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961.
962.
Terminal acetylenes can be converted in excellent yields into Mannich bases by reacting them with gem-aminoethers instead of formaldehyde and a secondary amine. This provides a possibility of preparing cyclic aminoacetylenes from w-acetylenic secondary amines, via the derived gem-aminoethers, using high dilution technique. 相似文献
963.
J.C. Steckmeyer F. Lefebvres C. Le Brun J.F. Lecolley M. lHaridon A. Osmont J.P. Patry 《Nuclear Physics A》1984,427(2):357-396
The angular momentum transferred to fragment spins has been studied in the damped nuclear reactions Ar+Bi at 255 MeV and 295 MeV and Ni+Pb at 435 MeV from measurement of the angular distribution of the fission fragments of the heavy-recoil nucleus in coincidence with the projectile-like fragment. The heavy-fragment spin is strongly aligned along the normal to the reaction plane and the rigid-rotation limit of the dinuclear system is attained. The dealignment mechanisms produce spin components mainly located in a plane approximately perpendicular to the heavy-recoil lab direction. They are well described by a dynamical model based on the nucleon exchange between the two ions during the collision. The spin-component fluctuations reach high values. In the heavy-recoil direction, these fluctuations are increasing with the total kinetic energy loss and the charge transfer from the projectile to the target. The spin values extracted from both the angular distributions and the fission probabilities are seen to be compatible. 相似文献
964.
Abstract-o-Acylaminobenzylidenephosphoranes lead to indoles in good yield by an intramolecular Wittig reaction with the amide carbonyl group. Mechanistic aspects are discussed. A general method is described for the synthesis of indoles from o-nitrobenzyl bromides and o-aminobenzyl alcohols. 相似文献
965.
设m是正整数,f(X,Y)=a0Xn+a1X(n-1)Y+...+anYn∈Z[X,Y]是Q上不可约化的叫n(n≥3)次齐次多项式。本文证明了:当gcd(m,a0)=1,n≥400且m≥10(35)时,方程|f(x,y)|=m,x,y∈z,gcd(x,y)=1,至多有6nv(m)组解(x,y),其中v(m)是同余式F(z)=f(z,1)≡0(modm)的解数。特别是当gcd(m,DF)=1时,该方程至多有6n(ω(m)+1)组解(x,y),其中DF是多项式F的判别式,ω(m)是m的不同素因数的个数. 相似文献
966.
The vibration-rotation spectrum of methyl isocyanide (CH3NC) has been recorded with the aid of a high-resolution Fourier transform spectrometer in the region 1370 to 1560 cm−1 containing the perpendicular band of the fundamental vibration ν6 (species E), the weaker parallel band of the ν3 (A1) fundamental, and the perpendicular combination band ν7 + ν8 (E) enhanced by Fermi resonance with ν6. Sixteen hundred seventy well-resolved lines were assigned to 15 subbands of ν6, 6 subbands of ν3, and 3 subbands of ν−7 + ν−8. A strong x, y-Coriolis resonance between ν3 and ν6 and Fermi resonance between ν±6 and the E component ν7 + ν8, as well as between ν3 and the A1,2 components ν±7 + ν8, greatly affects the spectrum. Additional weaker anharmonic interaction of ν6 with the ν4 + 2ν28 combination and higher-order rotational interactions connecting the various states were also detected in the spectrum. All of these interactions have been incorporated into a 9 × 9 Hamiltonian matrix used for modeling the upper states of the observed transitions. A set of spectroscopic constants is reported for the upper states of the bands ν3, ν6, and ν7 + ν8 and for ν4 + 2ν28 which reproduces the observed lines with an overall standard deviation of 0.0012 cm−1. 相似文献
967.
968.
Jean-Francois Le Borgne 《Journal of organometallic chemistry》1976,122(2):129-137
The condensation of metallated aldimines, prepared from activated lithium dialkylamides, with different dihalogenoalkenes gives aldehydes with a halogenovinylic group. Acidic hydrolysis of these aldehydes leads directly to cyclopentenones. When treated with an excess of activated amide, halogenovinylic aldimines give γ-acetylenic aldehydes. 相似文献
969.
970.
The electronic structure of PbMo6S8 has been investigated using the so-called EHT-tight-binding method. An idealized cubic and an experimental distorted geometry are used, with standard atomic orbital parameters and diagonal H-matrix elements. A full band structure is presented in the idealized case. In both cases, the density of state curves computed using an integration over the Brillouin zone are also presented. The results show the importance of the twisting angle on the electronic structure near the Fermi level. 相似文献