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351.
We report on the first experimental observation of modulation instability and spontaneous pattern formation with incoherent white light emitted from an incandescent lamp in self-defocusing photorefractive LiNbO3:Fe crystal. Experimental results show that the modulation instability of white light in self-defocusing medium is related to the input intensity, illumination time and the direction of the crystalline c-axis with respect to that of the lamp filament. At the illumination time t = 0 and the steady-state of MI, we give the spatial distribution of the optical Fourier power spectrum experimentally and the corresponding Fourier transformation of the output intensity numerically, and observe the emergence of the high frequency component along the c-axis. 相似文献
352.
In this paper, we present the (1 + 1)-dimensional inhomogeneous nonlinear Schrödinger (NLS) equation, which describes propagation of optical waves in nonlinear optical systems exhibiting spatial inhomogeneity, inhomogeneous nonlinearity and gain or loss at the same time. Exact multi-soliton solutions are presented by the simple Darboux transformation based on the Lax Pair, and the exact one- and two-soliton solutions in explicit forms are also generated. As two examples, we consider two nonlinear optical systems. In the systems, based on the exact solutions, a series of interesting properties of optical waves are displayed. 相似文献
353.
Zhiyong Xu 《Optics Communications》2008,281(22):5605-5609
We address surface soliton complexes formed at the edge of annular guiding structures containing several concentric rings. Such soliton complexes feature a π-phase difference between neighboring spots. It is shown that the multipole-mode solitons can rotate steadily upon propagation, and the existence domain is strongly affected by the rotation frequency. The rotation may enhance the stabilization of surface multipole-mode solitons. 相似文献
354.
By considering the effect of background light and diffusion, the self-deflection process of partially spatially incoherent (PSIC) beams and photovoltaic (PV) solitons in open-circuit PV photorefractive crystals has been investigated by employing numerical method and the perturbation technique, respectively. The results from the two approaches are in good agreement: the center of PSIC PV solitons moves on a parabolic trajectory, which is similar to those of coherent solitons. In addition, we also discuss that the dependence of self-deflection effect on the coherent parameter θ0 and find it is slight relative to θ0 for quasi-soliton but decreases monotonously with θ0 for PSIC beam. 相似文献
355.
I. Sankowska Ch. Droste E. Grodner T. Morek J. Srebrny A. A. Pasternak J. Kownacki P. Napiorkowski S. G. Rohoziński M. Kowalczyk M. Kisieliński R. Kaczarowski E. Ruchowska 《The European Physical Journal A - Hadrons and Nuclei》2008,37(2):169-175
Lifetimes of the yrast levels with spins I π = 23/2? to 39/2? in 129La produced via the 120Sn(14N, 5n) reaction at a beam energy of 77MeV have been measured by the Doppler shift attenuation method. The properties of the studied levels belonging to the πh11/2 band were compared with the theoretical predictions obtained in the framework of the core quasi-particle coupling model. It is suggested that the rigid-rotor model used to describe the cores is too simplified as the even-even nuclei from the A ~ 130 region are susceptible to shape deformation. Reasonable agreement was obtained with the phenomenological cores based on the experimental data of 128Ba. 相似文献
356.
M. Taki A. Mussot A. Kudlinski E. Louvergneaux M. Kolobov M. Douay 《Physics letters. A》2010,374(4):691-695
We theoretically and numerically evidence that optical rare and strong temporal events generated in fiber supercontinua originate from convective modulational instabilities. This convective nature is induced by higher-order terms (odd-order dispersion and stimulated Raman scattering) that break the time reversal symmetry of the nonlinear Schrödinger equation. We demonstrate (i) analytically that the third-order dispersion term alone turns the system to be convectively unstable and (ii) numerically that the sign of the curvature of the tail of the probability density function changes (in logarithmic scale) when the third-order dispersion term is added. This latter feature results in more powerful rare events. If, in addition, stimulated Raman scattering is taken into account, both the convective instabilities and the power of extreme events are further enhanced giving rise to a probability density function with a more pronounced curvature. 相似文献
357.
This paper presents experimental evidence that orthogonally crossed dark soliton stripes form quasi-two-dimensional spatial
solitons with a soliton constant equal to that of singly charged optical vortices. Besides the pairs of oppositely charged
optical vortex solitons, the snake instability of the dark formation at moderate saturation is found to lead to generation
of steering mixed edge–screw phase dislocations with zero total topological charges.
Received: 26 October 1998 / Revised version: 19 January 1999 / Published online: 12 May 1999 相似文献
358.
J. Mrázek M. Honusek A. Špalek J. Bielčík J. Slívová J. Adam A.A. Pasternak 《The European Physical Journal A - Hadrons and Nuclei》1999,5(4):399-408
The results of in-beam investigations of excited states of 99Ru using the 98Mo(α,3n) reaction are presented. Angular distributions of γ–rays and γ–γ coincidences have been measured. Excited states have
been identified up to an energy of E = 5603 keV and spin of Iπ= 31/2−. Mean lifetimes τ have been determined using the DSA method for eleven levels. Aligned angular momenta are discussed and
the probable (νh
11/2) origin of a backbending at frequency about 0.5 MeV was confirmed. The possible role of (νd
5/2) alignment at frequencies above 0.5 MeV was pointed out.
Received: 13 January 1999 / Revised version: 26 March 1999 相似文献
359.
This study focused on the preparation and evaluation of several new fluorene‐based dimethacrylates, as possible intermediates to formulate improved dental composites. As the first step towards modification of the composite formulation, the new monomers and unfilled resin matrix were prepared. The formulated and visible light‐cured materials were found to be more hydrophobic, along with having higher wet (water saturated) glass transition temperatures (Tg) than the commonly used matrix resins based on 2,2‐bis(4(2‐hydroxy‐3‐methacryloxy‐propyloxy))‐phenylpropane (Bis GMA). In addition, the new matrix resins exhibited greater compressive strength, along with greater resistant to creep and fracture. Finally, the results suggested a correlation may exist between creep and the homologous temperature (T/Tg) of the light‐cured neat resins, where the T/Tg may be used to compare the mechanical properties of different materials at various temperature. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
360.
Sorin O. Manolache Klinsmann A. Gutierrez Charles D. Hall 《Macromolecular Symposia》2010,296(1):493-504
Summary : Cold plasma as source for charged particles was used to induce nanotopographies on homopolymeric surfaces (nylon 12, PMMA, PMA, etc.). Hydrogen and helium plasmas were successfully used for surface nanoengineering of polymers using inductively coupled or atmospheric pressure non-equilibrium barrier discharge reactors. AFM analyses reveal the presence of nanotopographies on the treated surfaces. Physical factors control the process below the Tg and chemical factors dominate the process above Tg. Pyrolysis GC/MS analyses have been performed in order to obtain more information about the plasma processes. Cold plasma chemical processes, including charges effects are discussed as tools that open-up new ways for nanoengineering of the polymers' surfaces with specific functionalities and / or topography. Future nanomanufacturing techniques can generate anti-scratch, superhydrophobic or superhydrophilic properties on surface of every day use polymeric products by simple and convenient plasma enhanced processes. 相似文献