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81.
82.
Abstract: The peroxidative metabolism of N -methylcarbazole emits light independently of the presence of oxygen. It is likely that two chemiexcited transients are formed by electron transfer to the activated peroxidase, the cation radical by one electron transfer and a cation biradical by two electron transfer consistent with the failure to observe horseradish peroxidase-II in the steady state of the reaction. In the spectral range investigated (390–700 nm) the observed emission (570–700 nm) is ascribed to the biradical, as the latter is equivalent to an excited state of the postulated iminium cation.
While lipoxygenase has no effect upon N -methylcarbazole, it markedly enhances the emission if peroxidase is present. This effect requires oxygen and is ascribed to an excited product formed by lipoxygenase acting upon an intermediate hydroperoxide of the aerobic process promoted by peroxidase.
Our results are of importance on two counts. First they extend to N -rnethylcarbazole the formation of excited species in the peroxidative metabolism of important xenobiotics. Second, the mechanistic information they provide supports the scheme of metabolism postulated by Kedderis et al. (1986, J. Biol. Chem. 261, 15910–15914). 相似文献
While lipoxygenase has no effect upon N -methylcarbazole, it markedly enhances the emission if peroxidase is present. This effect requires oxygen and is ascribed to an excited product formed by lipoxygenase acting upon an intermediate hydroperoxide of the aerobic process promoted by peroxidase.
Our results are of importance on two counts. First they extend to N -rnethylcarbazole the formation of excited species in the peroxidative metabolism of important xenobiotics. Second, the mechanistic information they provide supports the scheme of metabolism postulated by Kedderis et al. (1986, J. Biol. Chem. 261, 15910–15914). 相似文献
83.
B. V. Costa N. P. Silva A. S. T. Pires 《Zeitschrift für Physik B Condensed Matter》1988,71(4):491-493
In this paper we study the thermodynamic properties of the Ising model on a linear chain in which the sites are generated according to the Fibonacci sequence. We calculate the partition function, the specific heat and the q-dependent magnetic susceptibility. 相似文献
84.
Marcia M. Meier Luiz A. Kanis Joo C. de Lima Alfredo T. N. Pires Valdir Soldi 《先进技术聚合物》2004,15(10):593-600
The influence of the plasticizer content and film preparation procedure on the morphology, density, thermal and mechanical properties of cellulose acetate (CA) films plasticized with poly‐(caprolactone triol) (PCL‐T), were studied. Differential scanning calorimetry (DSC), thermal mechanical analysis (TMA), scanning electron microscopy (SEM), wide‐angle X‐ray diffraction (WAXD) and infrared spectroscopy (FT‐IR) techniques were used. The films were prepared by dry‐casting CA and CA/PCL‐T in acetone or acetone/water solutions, which produced transparent and opaque films, respectively. In contrast to the transparent films, which were dense, the opaque films presented a porous morphology. However, the presence of PCL‐T reduced the opaque film porosity, increasing, in consequence, its bulk density. The TMA results revealed that PCL‐T reduced the glass transition temperature more significantly in the transparent than in opaque films. Only the transparent CA/PCL‐T films presented a melting temperature, that reduced with higher concentrations of PCL‐T, suggesting a higher ordering (crystallinity) when the films were prepared in the absence of water, as observed from WAXD curves. The mechanical properties also showed that the transparent films were more soft and tough than the opaque films. In summary, PCL‐T was a good plasticizer agent for CA films due to the presence of hydrogen bonds between the components (FT‐IR spectra). The presence of water in the dry casting process has a significant effect mainly on film morphology and mechanical properties. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
85.
S. L. Menezes M. E. Gouvêa A. S. T. Pires 《Zeitschrift für Physik B Condensed Matter》1991,82(3):375-381
The out-of-plane dynamical correlation functionsS
zz
(q, ) for two-dimensional easy-plane ferro- and antiferromagnets are calculated using a diagrammatic expansion for the temperature dependent Green function. Vortex-magnon interference effects on the multimagnon and vortex contribution toS
zz
(q, ) are also analised, in a classical context, for ferromagnets. Our calculations show that we cannot expect multimagnon processes to contribute to a central peak (=0) that has been observed in these systems for temperaturesT>T
c
, whereT
c
is the temperature at which a topological phase transition is predicted to occur. However, vortex-magnon interactions considerably reduce the intensity of the vortex induced central peak. 相似文献
86.
87.
Phase change effects on the total organic yield have been studied in crystalline chlorobenzene derivatives activated by radiative neutron capture. Irradiation of the compounds in benzene solution decreased the organic yield considerably while these values remained unchanged when 11 benzene + DMSO or 11 benzene + acetonitrile solvent mixtures were used, the 11 benzene + THF solvent gave the lowest yield in all the cases. Heat treatment to the neutron activated solids enhanced the organic yield only in the case of 2-amino 5-chlorobenzophenone by 7%. 相似文献
88.
The characterization of the hydrophobic-hydrophilic properties of different types of microporous materials, namely activated carbons, pillared clays and zeolites, was made by the determination of water adsorption isotherms. The data were analysed by the Dubinin and Astakhov (D-A) equation. The use of the E parameter of the D-A equation as a measure of the hydrophobic-hydrophilic character is proposed. When the information obtained from the E parameter is compared with the information that can be obtained from other parameters used in the literature to characterize the hydrophobicity of materials, it is found that the former is more sensitive and is more directly related with the shape of the adsorption isotherms which, ultimately, is the more direct manifestation of the hydrophobic-hydrophilic properties of a given material. 相似文献
89.
90.