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991.
Simplicity of C*-algebras associated to higher-rank graphs 总被引:1,自引:0,他引:1
We prove that if is a row-finite k-graph with no sources, thenthe associated C*-algebra is simple if and only if is cofinaland satisfies Kumjian and Pask's aperiodicity condition, knownas Condition (A). We prove that the aperiodicity condition isequivalent to a suitably modified version of Robertson and Steger'soriginal nonperiodicity condition (H3), which in particularinvolves only finite paths. We also characterise both cofinalityand aperiodicity of in terms of ideals in C*(). 相似文献
992.
Masters SL Grassie DA Robertson HE Hölbling M Hassler K 《Chemical communications (Cambridge, England)》2007,(25):2618-2620
The vapour produced upon mild heating of hexa-tert-butyldisilane (superdisilane) has been studied by gas electron diffraction and ab initio molecular orbital calculations; the disilane is not observed in the vapour, and the observed radical structure is not the lowest energy structure predicted ab initio. 相似文献
993.
Leitch AA Brusso JL Cvrkalj K Reed RW Robertson CM Dube PA Oakley RT 《Chemical communications (Cambridge, England)》2007,(32):3368-3370
A pair of isostructural bis-selenathiazolyl and bis-diselenazolyl radical conductors display weak (spin-canted) ferromagnetism with Tc values of 18 K and 27 K respectively. 相似文献
994.
Ir-catalyzed (20 °C) or thermal (70 °C) dehydrocoupling of the linear diborazane MeNH(2)-BH(2)-NHMe-BH(3) led to the formation of poly- or oligoaminoboranes [MeNH-BH(2)](x) (x = 3 to >1000) via an initial redistribution process that forms MeNH(2)·BH(3) and also transient MeNH═BH(2), which exists in the predominantly metal-bound and free forms, respectively. Studies of analogous chemistry led to the discovery of metal-free hydrogenation of the B═N bond in the "model" aminoborane iPr(2)N═BH(2) to give iPr(2)NH·BH(3) upon treatment with the diborazane Me(3)N-BH(2)-NHMe-BH(3) or amine-boranes RR'NH·BH(3) (R, R' = H or Me). 相似文献
995.
An efficient synthesis of NP25302 is presented that relies on 5-endo-dig N-cyclization to establish the bicyclic core and Curtius rearrangement to install the N-acyl vinylogous urea functionality. 相似文献
996.
Kennedy AR Mulvey RE O'Hara CT Robertson GM Robertson SD 《Angewandte Chemie (International ed. in English)》2011,50(36):8375-8378
Molecular salt cellars: The addition of substoichiometric quantities of lithium halides to the lithium hexamethyldisilazide was studied. Surprisingly, a novel class of mixed amido-halide macrocyclic complexes, namely metal anionic crowns (MACs) was revealed (see picture: Li?pink, N?yellow, Cl?green, Si?orange, C?black). 相似文献
997.
998.
M. E. Coleman M. D. Glascock J. D. Robertson 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(3):935-941
A new instrumental epithermal neutron activation analysis procedure to quantitatively determine titanium, barium, and bromine
in obsidian with improved sensitivity has been developed. The advantage of epithermal activation for Ti, Ba, and Br is demonstrated
with multiple geological standards and the ability to determine arsenic in obsidian is demonstrated. The results for titanium
are compared to previous electron-microprobe results for Kenyan obsidian. 相似文献
999.
Sarah L. Masters Iain D. Mackie Derek A. Wann Heather E. Robertson David W. H. Rankin Simon Parsons 《Structural chemistry》2011,22(2):279-285
The molecular structures of 1-Br-4-F-C6H4 and 1-Cl-4-F-C6H4 have been studied in the gas phase using gas electron diffraction (GED) and ab initio methods. The structure of 1-Cl,4-F-C6H4 in the crystalline phase has also been studied, but whilst the gaseous structures were found to possess C
2v symmetry, the solid-state structure was found to be quite distorted, with three molecules in the asymmetric unit. These fragments
only possess C
s symmetry in the plane of the molecules, as opposed to the C
2v symmetry observed in the gas phase. The bonding motifs within the solid-state structure are very unusual and unexpected,
with quite different C–F bond lengths for the three moieties, and are a result of weak hydrogen-halogen interactions within
the structure. 相似文献
1000.
Current phase-shift cavity ring-down spectroscopy (PS-CRDS) experiments make use of equations originally developed for fluorescence studies. As these equations fail to take the length of the optical cavity and the superposition of reflecting beams into account, they lose validity as the length of the cavity increases. A new set of equations, based solely on the principles of PS-CRDS, is developed for determining the ring-down time from either the phase shift or the intensity of the waveform exiting the cavity. It is shown that the PS-CRDS equations reduce to those developed for fluorescence study for short cavities. The new equations provide a more accurate method in determining the characteristic ring-down time and phase shift for long cavities, especially fiber optic cavities, which is promising in on-site chemical sensing. 相似文献