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991.
Derek H.R. Barton Michel Bénéchie Françoise Khuong-Huu Pierre Potier Victor Reyna-Pinedo 《Tetrahedron letters》1982,23(6):651-654
Two approaches to the partial synthesis of C1–C5 of a bis-nor maytansinoid have been investigated starting on the one hand with (S)-(?)-malic acid and on the other, with D-(+)-ribonolactone. 相似文献
992.
The interpolation method for calculation of the density of states g(ν) of Gilat and Raubenheimer has been extended to monoclinic crystals. Numerical results are given for Cl2 at 118 K and Br2 at 130 and 250 K. 相似文献
993.
François Fricker 《Commentarii Mathematici Helvetici》1968,43(1):402-416
Ohne Zusammenfassung 相似文献
994.
995.
996.
François Dunlop Jacques Magnen Vincent Rivasseau Philippe Roche 《Journal of statistical physics》1992,66(1-2):71-98
We prove that in a two-dimensional Gaussian SOS model with a small attractive potential the height of the interface remains bounded no matter how small the potential is; this is in sharp contrast with the free situation in which the interface height diverges logarithmically in the thermodynamic limit. 相似文献
997.
The isotropic-liquid crystalline transition of concentrated DNA solutions is investigated using freeze-fracture electron microscopy in order to understand the first steps of the DNA condensation process. Between the isotropic liquid and the cholesteric mesophase, we report the existence of double twist DNA bundles and describe their long range ordering into 3D networks. This organization corresponds to the formation of 'blue phases' already observed in thermotropic liquid crystals, but never reported in lyotropic systems. In addition, the size of the DNA molecule, about ten times that of most thermotropic materials, allows here the molecular resolution imaging of blue phase structures. Since such structures recall chromatin organization of some Procaryotes and lower Eucaryotes, we suspect that they may be widespread and of potential interest in the regulation of chromatin functions. 相似文献
998.
999.
Hüseyi̇in Koçak 《Journal of Differential Equations》1984,51(3):359-407
Equivalence classes of time independent, linear, real Hamiltonian systems can be identified, up to canonical transformations, with the orbits of the adjoint action of the real symplectic group on its Lie algebra. A new set of representatives, also called normal forms, for these orbits is given. Versal deformations of systems in normal form are constructed. Applications of versal deformations to the study of bifurcations of linear systems with small codimension are indicated. 相似文献
1000.
A. Celler Ch. Briançon J.S. Dionisio A. Lefebvre Ch. Vieu J. Żylicz R. Kulessa C. Mittag J. Fernandez-Niello Ch. Lauterbach H. Puchta F. Riess 《Nuclear Physics A》1985,432(2):421-435
Yrast states in the nucleus 220Ra were studied by means of the 208Pb(14C, 2n) reaction at 61 and 64 MeV. A staggering sequence of levels of positive and negative parity has been observed up to spin and parity Iπ = 16+ (18 +) and from Iπ = 5? to Iπ = 17?, respectively. These states are connected by strong E1 transitions competing with the stretched E2 transitions, the ratio being ~ 10 ?6 fm?2. The ratio of the excitation energy of the 4+ state to that of the 2+ state is close to the vibrational limit. The moment of inertia associated with the negative-parity yrast states is slightly increasing with the rotational frequency ω. It is considerably higher than that of the positive-parity states at lower spins, the difference decreasing monotonically with increasing ω. The data are discussed with reference to the octupole vibrational picture as well as to the results of recent models predicting reflection-asymmetric shapes in the Ra-Th region. 相似文献