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1.
Silver was introduced into medieval glass by an ancient painting process using different clay minerals (ochre, illitic, montmorillonitic, and kaolinitic clays). The colorimetric properties, studied by UV-Vis spectroscopy, were dependent on the clay mineral as a result of different concentration of Ag ions diffused into the glass surface. TEM results showed the well known formation of silver nanoclusters which give the yellow coloration of the glass. The obtained results showed that clay properties such as specific surface area, pore volume and iron concentration (Fe2O3), are important factors that affect the yellow coloration. It is also observed that Fe2O3 acts as an oxidant agent for silver atoms providing the Ag2O formation. This oxide cannot diffuse into the glass structure and avoid the ion-exchanged process. After Ag ion diffusion some structural changes occur in the glass as it has been shown by Raman spectroscopy. It is observed that the diffusion process leads to depolymerization of the glass network as it is determined by analyzing the Qn components of Raman spectra. Two Raman bands at 148 and 244 cm−1 assigned to Ag-O bonds can be associated to the presence of Ag2O on the glass painted surface. 相似文献
2.
F. Zontone F. D'Acapito G. Faraci A.R. Pennisi 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(4):501-505
We report on the formation and detection of a compressed fluid phase of Xe clusters in as- implanted Si, at room temperature.
The simultaneous structural characterization of the Xe clusters and of the Si matrix was performed by X-ray diffraction at
grazing incidence coupled with two-dimensional detection; in both cases, the nearest-neighbor distance and the coordination
were obtained. In order to investigate the early stage of the atomic inclusion and the cluster segregation, the average compression
and size of Xe fluid clusters within the amorphous Si matrix were explained within the simple Hard Sphere model.
Received 4 September 2000 and Received in final form 13 December 2000 相似文献
3.
M. Dubiel S. Brunsch W. Seifert H. Hofmeister G.L. Tan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):229-232
Ag particles of 3.9 and 5.1 nm mean size in silicate glasses were produced by ion exchange and subsequent annealing at 480
and 600 °C. These thermal treatments may induce stresses in matrix and particles in addition to the well known effect of surface atoms
because of the thermal expansion mismatch of both materials. Structural characterisation of the particles by high-resolution
electron microscopy revealed a size-dependent lattice dilatation quite opposite to the so far observed lattice contraction
of similar metal/glass composites. This result, confirmed by X-ray absorption spectroscopy at the Ag K-edge, is discussed
in terms of an Ag-Ag bond length increase near the particle surface. The temperature-dependent EXAFS spectra (10-300 K) indicate
an increased thermal expansion coefficient of the particles with an increased mean particle size calculated on the basis of
an anharmonic Einstein model. With that the bond length increase can be explained. The results can be interpreted by a combination
of both the particle size effects and the influence of the surrounding matrix.
Received 30 November 2000 相似文献
4.
A sensitive total-scattering measurement setup for the DUV spectral range is presented, which allows precise determination
of both forward and backward scatter losses from optical components for excimer lasers with a sensitivity below 10 ppm for
248 nm and 50 ppm for 193 nm.
Scattering from several different coated and uncoated DUV optical surfaces was monitored. For uncoated samples, the backward
scatter losses are in good agreement with the predictions of scalar scattering theory, indicating that in this case scattering
is mainly determined by surface effects. Although forward and backward scatter losses are of the same order of magnitude for
uncoated samples, they differ by up to two orders of magnitude for high-reflection- and by one order of magnitude for anti-reflection-coated
samples. The experimental data demonstrate that the anti-reflection coatings suffer from substantial losses due to forward
scattering, whereas backward scattering is the predominant loss channel for high-reflection coatings. In addition, the strong
influence of defects and impurities on the total scattering is demonstrated.
Received: 5 June 2000 / Accepted: 6 June 2000 / Published online: 13 September 2000 相似文献
5.
Picosecond laser-induced radiative emission from flames injected with aromatic substances has been measured spectrally and
temporally resolved. The measurements were performed in various seeded regions and for different stoichiometric ratios of
the surrounding gas. The wavelength of the excitation radiation was 266 nm.
Changes in the lifetime and the spectral composition of the emission were observed with changes in the equivalence ratio and
the position in the flame. Considerable agreement with previously reported cell measurements was obtained for those regions
close to the injection zone. Temperatures were determined from spectrally and temporally resolved measurements. The comparison
with elastic scattering gave reasonable results at low seeding rates for naphthalene, and is hoped to be improved even further
in future experiments by increasing the time resolution and the signal-to-noise ratio of the measurements. Downstream and
towards the surrounding gas, the lifetimes increased and the spectral profiles shifted and broadened towards the red. This
effect increased when the equivalence ratio for the surrounding gas decreased and the oxygen concentration increased.
The study was also directed towards characterizing features in the emission that could be indicative of a transition from
the seeded aromatic substance to the formation of soot. An indicator for molecular or particle growth was the composition
of the spectral emission in terms of UV, blue and green–yellow bands and the ratio between elastic-scattering signal and total
emission signal. Spatially resolved measurements across the seeding region using a gated intensified CCD camera allowed a
closer study of the molecular-growth region from the parent aromatic substance seeded to the soot formed. The fluorescence
properties of dimers and their cyclodehydrogenated compounds and polymers containing aryl units are also discussed.
Received: 11 July 2000 / Revised version: 30 October 2000 / Published online: 21 February 2001 相似文献
6.
W. Koban J. D. Koch R. K. Hanson C. Schulz 《Applied physics. B, Lasers and optics》2005,80(6):777-784
Gas-phase oxygen quenching of toluene laser-induced fluorescence (LIF) is studied between 300 and 650 K in a nitrogen/oxygen bath gas of 1-bar total pressure with oxygen partial pressures up to 400 mbar. With increasing vibrational excitation of the laser-excited toluene, intramolecular decay becomes faster, resulting in a decreasing relative strength of collisional quenching by oxygen. Additionally, Stern–Volmer plots are found to be non-linear for temperatures above 500 K in the case of 266-nm excitation and at all temperatures for 248-nm excitation. This is attributed to the onset of internal conversion from specific vibrational levels. A photophysical model is developed that describes the experimental data and predicts toluene LIF signal strengths for higher oxygen partial pressures. One important result for practical application is that oxygen quenching is not the dominant de-excitation process for engine-related temperature and pressure conditions, and thus application of the popular fuel–air ratio LIF (FARLIF) concept leads to erroneous signal interpretation.This revised version was published online in August 2005 with a corrected cover date. 相似文献
7.
J. Laverdière S. Jandl A. A. Mukhin V. Yu. Ivanov 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,54(1):67-72
We have studied RMnO3 manganites (R = Pr, Sm, Eu, Tb, Y) Raman excitations in the 200–2800 cm-1 range as a function of temperature. Combinations of phonon energies are observed up to the fourth order, indicating the presence
of electron-phonon coupling. In comparison to Γ-point phonon combinations, double phonon excitations appear to be blue shifted
in large size rare earth ion compounds. The phonon combination intensities decrease rapidly with their increasing order, confirming
other studies which conclude that the electron-phonon coupling is not as strong as supposed in the localized limit. Moreover,
different intensity order dependences are observed between the phonon combination and the so-called Jahn-Teller mode. These
effects are better described in the orbiton-phonon coupling scheme. 相似文献
8.
F. F. Gong F. X. Gong F. Y. Gong 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,49(3):267-268
Open dynamic behaviour of financial markets with internal
interactions between agents and with external “fields” from other systems
are investigated using the approach of Grossman and Stiglitz for inefficient
markets, and Keynes for interference of the market using physics of finance
(referred to hereafter as phynance). The simulation results indicate that
the NYSE data analyzed in Plerou, V. et al., Nature 421, 130 (2003) can be fitted
by an equation of order parameter Φ and local deviation R of type:
-(R+0.03) Φ+ 0.6 Φ3 + 0.02 = 0, which is shown to be in
remarkable agreement with Plerou's data. 相似文献
9.
K. Lochmann A. Anikeenko A. Elsner N. Medvedev D. Stoyan 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(1):67-76
The performance of various structure characteristics in
the task of indicating structural peculiarities in packings of
hard spheres is investigated. Various characteristics based on
Voronoi polyhedra, spherical harmonics, and Delaunay simplices are
considered together with the pair correlation function and the
mean number of r-close triples. They are applied to a set of
hard sphere packings of density φ from 0.62 to 0.72. It turns
out that all used structure characteristics are able to indicate
changes of order from non-crystalline to crystalline packings.
However, not all of them are sensitive enough to indicate
different stages of structure transformation under densification.
The characteristics based on Delaunay simplices turn out to be the
most sensitive for this purpose.
For the models considered three principal structure classes are
found: packings of densities lower than the known critical value
0.64 showing a non-crystalline behavior; packings with
considerable crystalline regions for φ up to 0.66–0.67;
rather complete crystals although with numerous defects for φ
above 0.67. 相似文献
10.
Y.F. Lu W.D. Song B.W. Ang M.H. Hong D.S.H. Chan T.S. Low 《Applied Physics A: Materials Science & Processing》1997,65(1):9-13
Received: 13 November 1996/Accepted: 30 January 1997 相似文献