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991.
This paper analyzes a generic class of two-node queueing systems. A first queue is fed by an on–off Markov fluid source; the
input of a second queue is a function of the state of the Markov fluid source as well, but now also of the first queue being
empty or not. This model covers the classical two-node tandem queue and the two-class priority queue as special cases. Relying
predominantly on probabilistic argumentation, the steady-state buffer content of both queues is determined (in terms of its
Laplace transform). Interpreting the buffer content of the second queue in terms of busy periods of the first queue, the (exact)
tail asymptotics of the distribution of the second queue are found. Two regimes can be distinguished: a first in which the
state of the first queue (that is, being empty or not) hardly plays a role, and a second in which it explicitly does. This
dichotomy can be understood by using large-deviations heuristics.
This work has been carried out partly in the Dutch BSIK/BRICKS project. 相似文献
992.
Arnas Tamaevi
ius Elena Tamaevi
it Tatjana Pyragien Gytis Mykolaitis Skaidra Bumelien 《Communications in Nonlinear Science & Numerical Simulation》2009,14(12):4273-4279
An improvement of the recently described resonant chaos control method is suggested. Negative feedback loop containing a notch-rejection filter, tuned to the main harmonic of the unstable periodic orbit, is supplemented with a set of notch filters tuned to the higher harmonics. The extended method is applied to an electrical circuit representing the Duffing–Holmes type non-autonomous two-well chaotic oscillator. Stabilization of the period-1 orbit is achieved with very small control force. The residual control signal is about 1% compared to the main variable. Mathematical model based on a two-well piecewise parabolic potential is presented and numerical simulation is performed. Numerical results are confirmed by hardware experiments. 相似文献
993.
Elena Cordero Stevan Pilipović Luigi Rodino Nenad Teofanov 《Mediterranean Journal of Mathematics》2005,2(4):381-394
We study localization operators within the framework of ultradistributions. More precisely, given a symbol a and two windows φ1, φ2, we investigate the multilinear mapping from
to the localization operator
Results are formulated in terms of modulation spaces with weights which may have exponential growth. We give sufficient and
necessary conditions for
a to be bounded or to belong to a Schatten class. As an application, we study symbols defined by ultra-distributions with
compact support, that give trace class localization operators. 相似文献
994.
Elena Cordero Karlheinz Grö chenig 《Proceedings of the American Mathematical Society》2005,133(12):3573-3579
We study time-frequency localization operators of the form , where is the symbol of the operator and are the analysis and synthesis windows, respectively. It is shown in an earlier paper by the authors that a sufficient condition for , the Schatten class of order , is that belongs to the modulation space and the window functions to the modulation space . Here we prove a partial converse: if for every pair of window functions with a uniform norm estimate, then the corresponding symbol must belong to the modulation space . In this sense, modulation spaces are optimal for the study of localization operators. The main ingredients in our proofs are frame theory and Gabor frames. For and , we recapture earlier results, which were obtained by different methods.
995.
Hayashi Nakao; Kaikina Elena I.; Naumkin Pavel I. 《Journal London Mathematical Society》2005,72(3):663-688
The Cauchy problem is studied for the nonlinear equations withfractional power of the negative Laplacian
where (0,2), with critical = /n and sub-critical (0,/n)powers of the nonlinearity. Let u0 L1,a L C, u0(x) 0 in Rn, = . The case of not small initial data is of interest. It is proved that the Cauchy problemhas a unique global solution u C([0,); L L1,a C) and the largetime asymptotics are obtained. 相似文献
996.
A new method of constructing numerical schemes on the base of a variational principle for models including convection-diffusion operators is proposed. An original element is the use of analytical solutions of local adjoint problems formulated for the operators of convection-diffusion within the framework of the splitting technique. This results in numerical schemes which are absolutely stable, monotonic, transportive, and differentiable with respect to the state functions and parameters of the model. Artificial numerical diffusion is avoided due to the analytical solutions. The variational technique provides strong consistency between the numerical schemes of the main and adjoint problems. A theoretical study of the new class of schemes is given. The quality of the numerical approximations is demonstrated by an example of the non-linear Burgers equation. These new schemes enhance our variational methodology of environmental modelling. As one of the environmental applications, an inverse problem of risk assessment for Lake Baikal is presented. 相似文献
997.
Marco Andreatta Elena Chierici Gianluca Occhetta 《Central European Journal of Mathematics》2004,2(2):272-293
Let X be a Fano variety of dimension n, pseudoindex i
X
and Picard number ρX. A generalization of a conjecture of Mukai says that ρX(i
X
−1)≤n. We prove that the conjecture holds for a variety X of pseudoindex i
X
≥n+3/3 if X admits an unsplit covering family of rational curves; we also prove that this condition is satisfied if ρX> and either X has a fiber type extremal contraction or has not small extremal contractions. Finally we prove that the conjecture holds
if X has dimension five. 相似文献
998.
We characterize the relation between the geometrical properties of Weyl manifolds and the algebraic properties of the Weyl
algebras (§1) and the deformation algebras associated to two conformal Weyl connections (§2). The last section is devoted
to the study of the Weyl-Lyra algebras associated to a conformal Weyl connection and a conformal semisymmetric connection. 相似文献
999.
This paper addresses the problem of determining stowage plans for containers in a ship, that is the so-called master bay plan problem (MBPP). 相似文献
1000.
Elena Cherkaev 《PAMM》2007,7(1):1042001-1042002
The paper formulates inverse homogenization problem as a problem of recovery of Markov function using diagonal Padé approximants. Inverse homogenization or de-homogenization problem is a problem of deriving information about the micro-geometry of composite material from its effective properties. The approach is based on reconstruction of the spectral measure in the analytic Stieltjes representation of the effective tensor of two-component composite. This representation relates the n-point correlation functions of the microstructure to the moments of the spectral measure, which contains all information about the microgeometry. The problem of identification of the spectral function from effective measurements in an interval of frequency has a unique solution. The problem is formulated as an optimization problem which results in diagonal Padé approximation and exact formulas for the moments of the measure. The reconstructed spectral function can be used to evaluate geometric parameters of the structure and to compute other effective parameters of the same composite; this gives solution to the problem of coupling of different effective properties of a two-component composite material with random microstructure. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献