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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
Robert K. Boeckman David M. Blum Edward V. Arnold Jon Clardy 《Tetrahedron letters》1979,20(48):4609-4612
The complete structure of the unique tricyclic sesterterpene gascardic acid is proposed based on a single crystal x-ray diffraction analysis of the dicyclohexylammonium salt. 相似文献
994.
Roy Nilsson Ralf Nyholm Anders Berndtsson Jan Hedman Carl Nordling 《Journal of Electron Spectroscopy and Related Phenomena》1976,9(4):337-353
A new source for producing YMξ radiation in an ESCA spectrometer is described. The system makes use of continuous evaporation of yttrium on a rotating anode. It is demonstrated that this scheme allows YMξ-excited electron spectra to be recorded without gradual loss of resolution and intensity due to anode oxidation. Electron spectra of Ar, Hg and N2 excited by YMξ radiation are studied. Relative photoelectric cross-sections of the 5d, 5d and 6s orbitals in Hg and the four valence orbitals in N2 are measured. The valence electron shake-up spectrum of N2 is discussed. 相似文献
995.
996.
A separation and detection scheme is presented for the determination of the antitumor drugs adriamycin and daunorubicin in human urine. Separation is accompished by reversed-phase high-performance liquid chromatography and the drugs are detected down to the low picograms level by laser excited fluoresence using a unique fiber optic based flow-cell. Excellent detector selectivity and linearity are reported, and some of the factors influencing the performance of the detector are discussed. Possible extension of the procedure to other biologically important determinations are mentioned. 相似文献
997.
The Self Consistent Modified Extended Hückel molecular orbital method had been applied to several square planar complexes of platinum (II). Calculations including both the limited 5d, 6s, 6p and extended 5s, 5p, 5d, 6s, 6p starting bases for platinum were made. It is shown that in PtCl
4
2–
both the nuclear quadrupole moment and minimum total energy vs. bond distance are calculated to be in good agreement with experiment, only with the extended platinum AO basis.Specific inclusion of relativistic parameters via a pseudo-relativistic approximation are shown to have a significant effect on the energy molecular energy levels, however no meaningful rationalization can be made without the simultaneous inclusion of ligand field parameters as well.Supported in part by a grant made available through the Cancer Association of Greater New Orleans. Use of the facilities of the Computer Research Center of the University of New Orleans is gratefully acknowledged. 相似文献
998.
Edward J. Spanier Frank E. Caropreso 《Journal of polymer science. Part A, Polymer chemistry》1969,7(9):2679-2687
The polymerization of benzyl chloride in the presence of various group II metal salts has been investigated. The extent of reaction and the relative activities of various salts were determined by measurement of the evolved HCl as a function of time. Formation, in situ, of an active catalyst is proposed. 相似文献
999.
Selected ortho-disubstituted pyridines and thiopenes react with Michael acceptors to give functionalized quinolines or benzo[b]thiopenes, respectively. 相似文献
1000.
Edward B. Manoukian 《International Journal of Theoretical Physics》1983,22(4):315-321
The decoupling theorem of quantum field theory with massive particles is proved in Minkowski space when all the masses of the theory are led to go to infinity. The theorem establishes the vanishing property, in the distributional sense, of (absolutely convergent) Feynman amplitudes in a model independent way with subtractions performed at the origin. This extends previous efforts dealing with the proof of the theorem in the Euclidean region. 相似文献