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41.
Ben J. Morris 《Random Structures and Algorithms》2002,21(2):135-146
We study the problem of sampling contingency tables (nonnegative integer matrices with specified row and column sums) uniformly at random. We give an algorithm which runs in polynomial time provided that the row sums ri and the column sums cj satisfy ri = Ω(n3/2m log m), and cj = Ω(m3/2n log n). This algorithm is based on a reduction to continuous sampling from a convex set. The same approach was taken by Dyer, Kannan, and Mount in previous work. However, the algorithm we present is simpler and has weaker requirements on the row and column sums. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 21: 135–146, 2002 相似文献
42.
This paper is concerned with the spectral analysis of a one-velocity transport operator with Maxwell boundary condition in
L
1-space. After a detailed spectral analysis it is shown that the associated Cauchy problem is governed by a C
0-semigroup. Next, we discuss the irreducibility of the transport semigroup. In particular, we show that the transport semigroup
is irreducible. Finally, a spectral decomposition of the solutions into an asymptotic term and a transient one which will
be estimated for smooth initial data is given. 相似文献
43.
A new concept of orthogonality in real normed linear spaces is introduced. Typical properties of orthogonality (homogeneity, symmetry, additivity, ...) and relations between this orthogonality and other known orthogonalities (Birkhoff, Boussouis, Unitary-Boussouis and Diminnie) are studied. In particular, some characterizations of inner product spaces are obtained. 相似文献
44.
Deformed classical mechanics and gravity is discussed. Infinitesimally deformed quantum field theory is reviewed. Infinitesimally deformed Bose-Einstein distribution is derived. Infinitesimally deformed thermofield dynamics is constructed and applied to a scalar field and string theories.On leave of absence from: Mathematics Department, Faculty of Science, Mansoura University, Mansoura, Egypt 相似文献
45.
M.I.Gil' 《Annals of Differential Equations》2004,20(2):145-154
The nonlocal initial problem for nonlinear nonautonomous evolution equati-ons in a Banach space is considered. It is assumed that the nonlinearities havethe local Lipschitz properties. The existence and uniqueness of mild solutionsare proved. Applications to integro-differential equations are discussed.The main tool in the paper is the normalizing mapping (the generalizednorm). 相似文献
46.
47.
Ben Morris 《Probability Theory and Related Fields》2003,125(2):259-265
We show that a.s. all of the connected components of the Wired Spanning Forest are recurrent, proving a conjecture of Benjamini,
Lyons, Peres and Schramm. Our analysis relies on a simple martingale involving the effective conductance between the endpoints
of an edge in a uniform spanning tree. We believe that this martingale is of independent interest and will find further applications
in the study of uniform spanning trees and forests.
Received: 20 April 2001 / Revised version: 23 July 2002 / Published online: 14 November 相似文献
48.
Ahmed Jalal Uddin Yutaka Ohkoshi Yasuo Gotoh Masanobu Nagura Tetsuya Hara 《Journal of Polymer Science.Polymer Physics》2003,41(22):2878-2891
The effect of moisture on the mechanical relaxation processes of semiaromatic semicrystalline polyamides synthesized by a long‐chain aliphatic diamine and terephthalic acid was investigated by dynamic viscoelastic analysis (DVA) and differential scanning calorimetry (DSC). Moreover, the implication of moisture with the amorphous and crystalline domains was also examined by temperature‐dependent wide‐angle X‐ray diffraction and Fourier transform infrared spectra. The characteristics of the relaxations such as α, β, γ, and the pronounced peak shoulder appeared at 25–100 °C in DVA tan δ curves were found to be strongly susceptible to the presence of moisture. With moisture evaporation, the peak shoulder of 25–100 °C and the β‐relaxation disappeared. The former is anticipated to originate from to the side group motion of hydrogen‐bonded water, whereas the later one is from the motions of the amide–water complex units. With the disappearance of the β‐relaxation, the γ‐relaxation appeared simultaneously in much lower temperatures and ultimately coupled with the δ‐relaxation. The γ‐relaxation is attributed to be associated with the molecular motion of the amide group and δ‐relaxation with for the motion of the methylene units. The existence of two types of water was identified in the polymer, namely, tightly bound and loosely bound. The tightly bound water is believed to be directly connected by hydrogen bonding with the strong polar groups and the loosely bound water weakly links with those connected water making hydrogen bridges. The moisture acts as a plasticizer in the polymer matrix, which causes quite a large depression in its glass transition temperature (Tg). WAXD and FTIR studies corroborated the existence of water solely in amorphous regions, i.e., no rapport of water with the crystalline parts. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2878–2891, 2003 相似文献
49.
50.
Ahmed I. Zayed 《Journal of Fourier Analysis and Applications》1995,2(3):303-314
In this article a generalized sampling theorem using an arbitrary sequence of sampling points is derived. The sampling theorem
is a Kramer-type sampling theorem, but unlike Kramer's theorem the sampling points are not necessarily eigenvalues of some
boundary value problems. The theorem is then used to characterize a class of entire functions that can be reconstructed from
their sample values at the points tn = an + b if n = 0, 1, 2, ... and tn = an + c if n = 0, -1, -2, ..., where a, b, c are arbitrary constants. The reconstruction formula is derived explicitly in
the form of a sampling series expansion. When a = 1, b = 0 = c, the famous Whittaker-Shannon-Kotel'nikov sampling theorem
is obtained as a special case. 相似文献