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1.
A simple scheme is developed for treatment of vertical bed topography in shallow water flows. The effect of the vertical step on flows is modelled with the shallow water equations including local energy loss terms. The bed elevation is denoted with zb‐ for the left and zb+ for the right values at each grid point, hence exactly representing a discontinuity in the bed topography. The surface gradient method (SGM) is generalized to reconstruct water depths at cell interfaces involving a vertical step so that the fluxes at the cell interfaces can accurately be calculated with a Riemann solver. The scheme is verified by predicting a surge crossing a step, a tidal flow over a step and dam‐break flows on wet/dry beds. The results have shown good agreements compared with analytical solutions and available experimental data. The scheme is efficient, robust, and may be used for practical flow calculations. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
2.
W.T. Ingram 《Topology and its Applications》2006,153(10):1530-1539
3.
Bozlee BJ Misra AK Sharma SK Ingram M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(10):2342-2348
In the present study, we investigated remote laser-induced fluorescence (LIF), at a distance of 4.8 m, of a variety of natural minerals and rocks, and Hawaiian Ti (Cordyline terminalis) plant leaves. These minerals included calcite cleavage, calcite onex and calcite travertine, gypsum, fluorapatite, Dover flint and chalk, chalcedony and nephelene syenite, and rubies containing rock. Pulsed laser excitation of the samples at 355 and 266 nm often resulted in strong fluorescence. The LIF bands in the violet-blue region at approximately 413 and approximately 437 nm were observed only in the spectrum of calcite cleavage. The green LIF bands with band maxima in the narrow range of approximately 501-504 nm were observed in the spectra of all the minerals with the exception of the nephelene syenite and ruby rocks. The LIF red bands were observed in the range approximately 685-711 nm in all samples. Excitation with 532 nm wavelength laser gave broad but relatively low fluorescence background in the low-frequency region of the Raman spectra of these minerals. One microsecond signal gating was effective in removing nearly all background fluorescence (with peak at approximately 610 nm) from calcite cleavage Raman spectra, indicating that the fluorescence was probably from long-lifetime inorganic phosphorescence. 相似文献
4.
Radiation damaged fluorite single crystals iso-thermally annealed showed an oscillating structure of the intensity of a diffracted neutron beam. This is in accord with previous report on crystalline cobaltic compound examined for reconstitution of parent complex ions from recoil hot atoms and for annealing of radiation damage by neutron diffraction. The oscillation phenomenon already found by radiochemical means in various solids irrespectively of their chemical constitution combined by a pure physical method as the neutron diffraction, greatly supports a hypothesis of a spatial temporal oscillatory diffusion of defects in isothermal annealing of radiation damaged crystalline lattice. 相似文献
5.
6.
K. Funke R. D. Banhatti D. Laughman M. Mutke M. D. Ingram 《The European physical journal. Special topics》2008,161(1):65-78
Complementary ways for studying the motion of mobile ions
in materials with disordered structures are obtained by varying
pressure, tempe- rature and frequency. New results are presented based
on a combination of experimental work and modelling. Pressure-dependent measurements on alkali borate glasses show there
is a remarkable difference between the activation volumes for
conduction and diffusion, with ΔVσ< ΔVD,
implying that the Haven ratio decreases with increasing pressure. We
propose a mechanism that is characterised by a directionally
positive correlation between successive hops of different ions into
a moving vacant site. The effect of increasing pressure is to
increase the degree of directional correlation and thus to make the
conduction pathways increasingly linear in aspect. In sodium
borate glasses with much lower sodium content, a maximum has been
observed when ionic conductivity is plotted versus temperature at
fixed frequency. This feature is identified as being of the nearly
constant loss (NCL) type, caused by localised flip-flop movements of
interacting charges in the B2O3 network. In crystalline
γ-RbAg4I5, a related localised effect has also been
found, in this case caused by activated hops of silver ions confined
within structural “pockets”. Finally, the frequency dependence
of the ionic conductivity is reviewed in fragile ionic melts.
Fragility is interpreted here as a consequence of the shape of the
local ionic potentials, which unlike in glass do not reflect the
pre-existence of empty cation sites for successive ions to hop into.
This difference in short-range, short-time behaviour leads directly
to the emergence of non-Arrhenius dc conductivity and fluidity
behaviours in molten salts. We are thus able to establish a
common phenomenological and theoretical approach to ion transport in
a wide range of systems, largely based on broadband conductivity
spectroscopy. 相似文献
7.
A study of the pyrolytic behavior of the butanol isomers has been made in order to establish a basis for their identification from the thermolysis pattern of each butanol. The identity of the volatile products was established by gas chromatographic analysis. Each isomer was found to decompose via degradation reactions characteristic of the structural arrangement of each alcohol molecule for which mechanisms are proposed. 相似文献
8.
The results of an investigation into the nature of the carbon reduction process in the Unterzaucher method for the microdetermination of oxygen are reported and discussed. The reaction between carbon dioxide and carbon is discussed, and its relation to the specific surface area, which contrary to belief has been found not to contribute to the efficiency of the reaction. It is shown that carbon-oxygen complexes give rise to errors in the results, and that an intermediate, SiO(OH), formed on the inner surface of the silica pyrolysis tube might be a precursor to the formation of carbon monoxide as a source of blank error and of the apparent oxygen content of pure hydrocarbons. 相似文献
9.
The Dirichlet integral provides a formula for the volume over the k-dimensional simplex ω={x1,…,xk: xi?0, i=1,…,k, s?∑k1xi?T}. This integral was extended by Liouville. The present paper provides a matrix analog where now the region becomes , where now each Vi is a p×p symmetric matrix and A?B means that A?B is positive semidefinite. 相似文献
10.
In this paper, we report on the preparation of lead zirconate films for the first time using atomic layer deposition in an attempt to investigate some of the film properties and also to evaluate possible use of the precursor combination to prepare more complex lead titanate zirconate. In the depositions tetraphenyl lead (Ph4Pb) was used as the lead and zirconium 2,2,6,6-tetramethyl-3,5-heptadionato (Zr(thd)4) as the zirconium precursor, while ozone was used as the oxygen source. Film growth, stoichiometry and quality were studied using different pulsing ratios at deposition temperatures of 275 and 300 °C. According to X-ray diffraction, the crystalline perovskite phase was observed when films deposited on SrTiO3(1 0 0) were annealed at 600 °C. Surface roughness was reduced for lead deficient films as well as in annealed samples. 相似文献