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801.
802.
803.
Noriyuki Tsuboniwa Seijiro Matsubara Yoshitomi Morizawa Koichiro Oshima Hitosi Nozaki 《Tetrahedron letters》1984,25(24):2569-2572
Treatment of α-halo carbonyl compounds with title Sn-Al or Pb-Al reagents provides enolates which react with aldehydes or ketones to give β-hydroxy carbonyl compounds effectively. 相似文献
804.
We develop hydrodynamics in a new geometrical gravitational theory, calledO
4 gravity, which we recently proposed. According to this formulation, matter is not necessarily conserved. The nonconservation of matter might have been considerable in an early era of cosmological evolution. 相似文献
805.
806.
YeBing Xing XiaoHong Zhou YuHu Zhang YingXiang Guo Long Ma XiangGuo Lei WenTao Guo M. Oshima Y. Toh M. Koizumi A. Osa Y. Hatsukawa FuRong Xu M. Sugawara 《中国科学G辑(英文版)》2008,51(8):1053-1071
High-spin states in 187Pt were studied via the 173Yb(18O, 4n) reaction. Rotational bands based on the νi13/2, ν7/2−[503], νi2
13/2νj, ν3/2−[512] and ν1/2−[521] configurations were observed, and interpreted within the framework of the cranked shell model. The TRS calculations
show that the νi13/2 band has an appreciable negative γ deformation, and the negative-parity bands tend to have a near prolate shape with small positive γ values. Experimental values of B(M1)/B(E2) ratios have been extracted and compared with theoretical values from the semi-classical D?nau and Frauendof approach,
strongly suggesting a low frequency πh9/2 alignment in the ν7/2−[503] band.
Supported by the National Natural Science Foundation of China (Grant Nos. 10475097 and 10505025) and the Chinese Academy of
Sciences 相似文献
807.
Kokubo K Nakajima Yi Iijima K Yamaguchi H Kawamoto T Oshima T 《The Journal of organic chemistry》2000,65(11):3371-3378
Irradiation of various meta- and para-substituted homobenzoquinones with ethyl vinyl ether gave the [2 + 2] photoadducts, tricyclic diones, regio- and endo-selectively and in good yields. The tricyclic skeleton has an anti-form built by the addition of ethyl vinyl ether from the less hindered side of homoquinones. All of the CH(3), Cl, Br, and CH(3)O substituents at the reacting C=C double bond afforded head-to-head (HH) addition predominantly. In the case of CH(3), Cl, and Br, the ethoxy group was oriented in the endo-position, while the CH(3)O substituent led to a 1/5 mixture with the exo-isomer. It was also found that the Br-substituted [2 + 2] adducts undergo a facile skeletal rearrangement, being converted into dihydro-o-benzoquinone monomethide derivatives for para-substitution and dihydrobenzofuran derivatives for meta-substitution, probably under the influence of the in situ generated HBr. Intramolecular [2 + 2] photocycloaddition of an alkenylhomobenzoquinone afforded a tetracyclic dione. 相似文献
808.
Let P be a matrix whose entries are homogeneous polynomials in n variables of degree one over an algebraically closed field. We show that the maximal minors, say m-minors, of P generate the linear space of homogeneous polynomials of degree m if P has the maximal rank m at every point of the affine n-space except the origin. 相似文献
809.
We have studied the ground state of a fullerene-based magnet, the alpha;{'}-phase tetra-kis-(dimethylamino)-ethylene-C60 (alpha'-TDAE-C(60)), by electron spin resonance and magnetic torque measurements. Below T(N) = 7 K, nonparamagnetic field dependent resonances with a finite excitation gap (1.7 GHz) are observed along the a axis. Strong enhancement in their intensity as temperature is decreased is inconsistent with excitation from a singlet state, which had been proposed for the alpha'-phase ground state. Below T(N), nonquadratic field dependence of the magnetic torque signal is also observed in contrast to quadratic field dependence in the paramagnetic phase. The angle-dependent torque signals below T(N) indicate the existence of an anisotropy of the bulk magnetization. From both experiments, we propose an antiferromagnetic ground state driven by the cooperative orientational ordering of C(60) in the alpha'-TDAE-C(60). 相似文献
810.
A new fluorescent ionophore for Mg2+, 4′-(1-naphthaleneacetamido)benzo-15-crown-5 (1), was synthesized, and its complexation behavior in acetonitrile was investigated by means of UV and fluorescence spectrometry. In the absence of a metal ion, the naphthalene moiety showed quite weak fluorescence emission (fluorescence ‘Off’ state). On the other hand, after the addition of Mg2+, fluorescence emission from the naphthalene moiety increased (fluorescence ‘On’ state). 相似文献