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131.
A.B. Shvartsburg L. Stenflo P.K. Shukla 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(1):71-74
The dynamics of large localized repulsive clouds is examined by means of exact non-stationary solutions of the one-dimensional
Thomas-Fermi model. The nonlinear flattening of the cloud peak, the wave breakdown at the cloud peripheries, and the condensate
velocity distributions are thus described. Our solutions, which can contain an arbitrary amount of free parameters, show the
nonlinear evolution of an arbitrary initial wave form. A unique procedure for analyzing these solutions is presented. The
difference between our breakdown matter wave solutions and the well known Riemann shock waves is stressed.
Received 22 March 2002 Published online 9 July 2002 相似文献
132.
Nicholas I. M. Gould 《Mathematical Programming》1985,32(1):90-99
We present practical conditions under which the existence and uniqueness of a finite solution to a given equality quadratic program may be examined. Different sets of conditions allow this examination to take place when null-space, range-space or Lagrangian methods are used to find stationary points for the quadratic program.This research supported in part by the Natural Sciences and Engineering Research Council, Canada. 相似文献
133.
Ch. Dorschfeldt N. N. Tarkhanov 《Transactions of the American Mathematical Society》1999,351(2):581-594
Let be an elliptic system with real analytic coefficients on an open set and let be a fundamental solution of Given a locally connected closed set we fix some massive measure on . Here, a non-negative measure is called massive, if the conditions and imply that We prove that, if is a solution of the equation in then for each relatively compact open subset of and every there exist a solution of the equation in and a sequence () in satisfying such that for This complements an earlier result of the second author on representation of solutions outside a compact subset of
134.
135.
The procedure samples the efficient set by computing the nondominated criterion vector that is closest to an ideal criterion
vector according to a randomly weighted Tchebycheff metric. Using ‘filtering’ techniques, maximally dispersed representatives
of smaller and smaller subsets of the set of nondominated criterion vectors are presented at each iteration. The procedure
has the advantage that it can converge to non-extreme final solutions. Especially suitable for multiple objective linear programming,
the procedure is also applicable to integer and nonlinear multiple objective programs. 相似文献
136.
Bound states in the continuum (BIC) are shown to exist
in a single-level Fano-Anderson model with a colored interaction
between the discrete state and a structured tight-binding
continuum, which may describe mesoscopic electron or photon
transport in a semi-infinite one-dimensional lattice. The
existence of BIC is explained in the lattice realization as a
boundary effect induced by lattice truncation. 相似文献
137.
Distribution of eigenfrequencies for vibrating plates 总被引:2,自引:0,他引:2
P. Bertelsen C. Ellegaard E. Hugues 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,15(1):87-96
Acoustic spectra of free plates with a chaotic billiard shape have been measured, and all resonance frequencies in the range
0-500 kHz have been identified. The spectral fluctuations are analyzed and compared to predictions of the Gaussian Orthogonal
Ensemble (GOE) of random matrices. The best agreement is found with a superposition of two independent GOE spectra with equal
density which indicates that two types of eigenmodes contribute to the same extent. To explain and predict these results a
detailed theoretical analysis is carried out below the first cut-off frequency where only flexural and in-plane vibrations
are possible. Using three-dimensional plate dispersion relations and two-dimensional models for flexural and in-plane vibrations
we obtained two first terms of the asymptotic expansion of the counting function of these eigenmodes. The contribution of
edge modes is also discussed. The results are in a very good agreement with the experimentally measured number of modes. The
analysis shows that the two types of modes have almost equal level density in the measured frequency interval, and this explains
the observed spectral statistics. For a plate with broken symmetry in the up-down direction (where flexural and in-plane modes
are strongly coupled) experimentally observed spectral fluctuations correspond to a single GOE spectrum. Above the first cut-off
frequency a greater complexity of the spectral fluctuations is expected since a larger number of types of modes will contribute
to the spectrum.
Received 5 January 1999 and Received in final form 5 September 1999 相似文献
138.
We consider a linear model of a rotating Timoshenko beam, which is clamped at one end to a disk the other being free. The motion of the beam is controlled by the angular acceleration of the disk. We study the minimization problem of mean square deviation of the Timoshenko beam from a given position. For the minimization problem of the first mode we prove that optimal control is the chattering control, i.e., it has an infinite number of switches in a finite time interval. We construct a suboptimal control with a finite number of switches. To cite this article: M.I. Zelikin, L.A. Manita, C. R. Mecanique 334 (2006). 相似文献
139.
A second-order Godunov-type scheme for the Euler equations in conservation form is derived. The method is based on the ENO formulation proposed by Harten et al. The fundamental difference lies in the use of a two-step scheme to compute the time evolution. The scheme is TVD in the linear scalar case, and gives oscillation-free solutions when dealing with nonlinear hyperbolic systems. The admissible time step is twice that of classical Godunovtype schemes. This feature makes it computationally cheaper than one-step schemes, while requiring the same computer storage.
Sommario Viene data una nuova estensione al secondo ordine del metodo di Godunov per la soluzione delle equazioni di Eulero in forma conservativa. Il metodo é basato sulla formulazione ENO proposta da Harten et al. La differenza fondamentale consiste nel calcolo dell'evoluzione temporale, ottenuta mediante uno schema a due passi. Questo consente l'uso di un passo di integrazione nel tempo doppio rispetto agli altri schemi alla Godunov ad un solo passo. Il metodo proposto risulta quindi piú efficiente e puó inoltre essere implementato senza alcun aumento dell'occupazione di memoria. Viene dimostrato che lo schema é TVD nel caso lineare, e che fornisce soluzioni prive di oscillazioni spurie nel caso di sistemi non-lineari.相似文献
140.
The temperature‐composition phase equilibria of the Hg0.8Cd0.2Te‐HgI2 system were investigated between about 100 and 800 °C using Debye‐Scherrer powder X‐ray diffraction techniques, differential thermal analysis, differential scanning calorimetry, and thermochemical and structural calculations. This system is a pseudobinary temperature‐ composition plane in the HgTe‐CdTe‐HgI2 pseudoternary phase diagram. Measurable solid solutions of HgI2 in Hg0.8Cd0.2Te with the cubic zinc blende‐type structure exist between about 290 and 700 °C, with a maximum solubility of 4.9 ± 0.3 mole‐% HgI2 at 363 ± 3 °C. Further addition of HgI2 to HgI2‐saturated Hg0.8Cd0.2Te yields the formation of CdI2, which reduces the mole fraction (x) of CdTe in the Hg1—xCdxTe host lattice. After sufficient HgI2 is added, the host lattice is depleted in CdTe and forms Hg3Te2I2 in addition to CdI2. Phase fields containing the ternary compound Hg3TeI4, which we first observed in the HgTe‐HgI2 system, also exist in the present system. Quaternary analogs of the known ternary compounds Hg3Te2I2 and Hg3TeI4, i.e., Hg3—yCdyTe2I2 and Hg3—yCdyTeI4, were not observed under present experimental conditions. 相似文献