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1.
A. I. Meyers A. H. Reine J. C. Sircar K. B. Rao S. Singh H. Weidmann M. Fitzpatrick 《Journal of heterocyclic chemistry》1968,5(2):151-159
The cyclization of enamines derived from β-aminoesters and β-aminonitriles into bi- and tricyclic enaminoketones ( 6,9,13 and 24 ) has been investigated. The enamines derived from aminonitriles cyclize smoothly with magnesium perchlorate in benzene or toluene, whereas the enamines derived from aminoesters cyclize spontaneously during their formation. The scope and limitation of this process is discussed. 相似文献
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Resonance Raman spectra (RRS) of Co(II) and Co(III)5,10,15,20tetrakis(4Nmethylpyridinium)porphyrin ((CoII(TmpyP4), and CoIII(TMPyP4)) in aqueous solutions at different pH as well as in organic solvents (methanol, ethanol, DMSO, DMF) are obtained. The increased sensitivity of the oscillation frequencies 2, 4, 8, and 6 — the markers of the oxidation state of a metal — to the nature of an axial ligand has been revealed. For CoIII(TmpyP4), the shifts of the indicated frequencies in extracoordination have turned out to be twofold larger than those for CoII(TmpyP4). The spectral effects observed are related to different electron influence of the extraligands on the system of the porphyrin ring. In the case of Co(III)porphyrin, interaction of the d
orbitals of the metal and the e
g
*orbitals of the macrocycle is more efficient since its ionic radius is smaller than for the Co(II)complex. For CoIII(TmpyP4), a linear correlation between the oscillation frequencies 2, 4, 8, and 6 and the experimental Gutmann parameters characterizing the electronacceptor properties of solvents is found. 相似文献
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Latvian Institute of Organic Synthesis, Riga. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1701–1702, December, 1995. Original article submitted September 28. 1995. 相似文献
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Ek M Borgstr?m MT Karlsson LS Hetherington CJ Wallenberg LR 《Microscopy and microanalysis》2011,17(5):752-758
The twin interface structure in twinning superlattice InP nanowires with zincblende structure has been investigated using electron exit wavefunction restoration from focal series images recorded on an aberration-corrected transmission electron microscope. By comparing the exit wavefunction phase with simulations from model structures, it was possible to determine the twin structure to be the ortho type with preserved In-P bonding order across the interface. The bending of the thin nanowires away from the intended 110 axis could be estimated locally from the calculated diffraction pattern, and this parameter was successfully taken into account in the simulations. 相似文献
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D.A. Bell J.A. Buchanan M.M. Calkin J.M. Clement W.H. Dragoset M. Furić K.A. Johns J.D. Lesikar H.E. Miettinen T.A. Mulera G.S. Mutchler G.C. Phillips J.B. Roberts S.E. Turpin 《Physics letters. [Part B]》1980,94(3):310-314
We have measured the asymmetry parameter A and the spin correlation parameter Ann in pp elastic scattering, using the Argonne ZGS polarized proton beam and a polarized proton target. Angular distributions of A and Ann for |t| ? 0.2 (GeV/c)2wereobtainedateightmomentabetween 1.10 and 2if2.75 GeV/c. We find significant structure in both the energy and t-dependence of Ann at these energies. At plab ≈ 1.34 GeV/cAnn reaches a very large value of about 0.8–0.9 near θcm = 90°. 相似文献
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Maxime Jarret Victor Turpin Aurlien Tap Jean‐Franois Gallard Cyrille Kouklovsky Erwan Poupon Guillaume Vincent Laurent Evanno 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(29):9966-9970
Reported is the enantioselective total syntheses of mavacuran alkaloids, (+)‐taberdivarine H, (+)‐16‐hydroxymethyl‐pleiocarpamine, and (+)‐16‐epi‐pleiocarpamine, and their postulated biosynthetic precursor 16‐formyl‐pleiocarpamine. This family of monoterpene indole alkaloids is a target of choice since some of its members are subunits of intricate bisindole alkaloids such as bipleiophylline. Inspired by the biosynthetic hypothesis, an oxidative coupling approach from the geissoschizine framework to form the N1?C16 bond was explored. Quaternization of the aliphatic nitrogen center was key to achieving the oxidative coupling induced by KHMDS/I2 as it masks the nucleophilicity of the aliphatic nitrogen center and locks in the required cis conformation. 相似文献