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61.
The application of peptides in chiral separations using techniques such as capillary electrophoresis (CE), electrokinetic capillary chromatography (EKC) and liquid chromatography is the focus of this review. Methods for finding peptide selectors using combinatorial library approaches are discussed, as well as recent advances in the use of peptides as general chiral selectors for electrophoresis and liquid chromatography. One example shows the effectiveness of polymeric dipeptide surfactants as general chiral selectors for electrophoresis. Another example shows the versatility of oligoproline chiral stationary phases, exhibiting resolution for a number of racemic analytes comparable to other well-established chiral stationary phases. 相似文献
62.
Additional Magnetic Examinations of Ti3?xMxO5-Phases (M = Al3+, Fe2+, Mn2+, Mg2+) with a Contribution about CrTi2O5 Ti3?xMxO5 was prepared with M = Al3+, Fe2+, Mn2+, and Mg2+. Die magnetic properties of this phases were examinated by the Faraday method in respect to the temperature. The well known magnetic effect of Ti3O5 near 450 K is shifted to lower degrees if Ti is replaced by Al, Fe, Mn, or Mg. Compared to Ti3?xVxO5 and Ti3?xCrxO5 the stability of the low temperature-form of Ti3O5 is much more reduced in Ti3?xMxO5 (M = Al, Fe, Mn, Mg). The crystal structure investigation of CrTi2O5 explained the anomalous behaviour of the Cr3+ and V3+ doped Ti3O5. 相似文献
63.
Andersson K Ketteler G Bluhm H Yamamoto S Ogasawara H Pettersson LG Salmeron M Nilsson A 《Journal of the American Chemical Society》2008,130(9):2793-2797
Autocatalytic dissociation of water on the Cu(110) metal surface is demonstrated on the basis of X-ray photoelectron spectroscopy studies carried out in situ under near ambient conditions of water vapor pressure (1 Torr) and temperature (275-520 K). The autocatalytic reaction is explained as the result of the strong hydrogen-bond in the H2O-OH complex of the dissociated final state, which lowers the water dissociation barrier according to the Br?nsted-Evans-Polanyi relations. A simple chemical bonding picture is presented which predicts autocatalytic water dissociation to be a general phenomenon on metal surfaces. 相似文献
64.
F. Razmara B. Behjati N. Aftandilians Th. Bluhm 《Journal of heterocyclic chemistry》1979,16(8):1641-1641
The photolysis of 1H-benzotriazole in the presence of benzene produces two products, namely 2-aminobiphenyl and 1-anilinobenzotriazole isolated as 2-acetylaminobiphenyl and 1-(N- acetylanilino)benzotriazole, respectively, upon chromatography on Kieselgel 60. 相似文献
65.
After complexation with copper(II) ions, Schiff bases 1a-d may undergo an oxidative ring closure using atmospheric oxygen to give a number of imidazo[1,5-a]pyridines 2, an imidazo[1,5-a]imidazole 3, and an imidazo[5,1-a]isochinoline 4. This ligand oxidation can be performed with catalytic amounts of copper ions in the reaction. A catalytic cycle for the copper-catalyzed oxidative heterocyclization will be presented together with isolated copper complexes of Schiff bases 1a,b and intermediates 5 and 8 that were found by X-ray structure analyses which confirm this reaction scheme. 相似文献
66.
67.
Willneff EA Braun S Rosenthal D Bluhm H Hävecker M Kleimenov E Knop-Gericke A Schlögl R Schroeder SL 《Journal of the American Chemical Society》2006,128(37):12052-12053
The electronic structure of a highly active Au/TiO2 powder catalyst was probed in situ by synchrotron X-ray photoelectron spectroscopy (XPS) in the 10-1 mbar range. The electronic structure of the Au component was found to respond sensitively to changes in temperature and indicated the absence of bulklike metallic Au under the conditions of highest catalytic activity. Concurrent modification of interfacial sites adjacent to Au on the TiO2 support was not evident from the Ti photoemission, but may have been below the detection limit of XPS. 相似文献
68.
69.
M. Hvecker A. Knop-Gericke H. Bluhm E. Kleimenov R. W. Mayer M. Fait R. Schlgl 《Applied Surface Science》2004,230(1-4):272-282
The surface of an activated vanadium phosphorus oxide (VPO) catalyst was investigated by means of in situ X-ray absorption spectroscopy in the total electron yield mode. We observed significant changes of the V L3-near edge X-ray absorption fine structure (NEXAFS) when the material was transferred from room temperature to working conditions at 400 °C in the reaction atmosphere. We studied the same VPO material under different gas compositions comprising the reaction mixture of n-butane and oxygen, pure oxygen and vacuum to elucidate the influence of the gas–surface interaction and the effect of the temperature. The results of this extensive study indicate a dynamic response of the catalyst surface to the applied conditions. 相似文献
70.