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81.
Antonella Cristiano Alba Marcellan Bert J. Keestra Paul Steeman Costantino Creton 《Journal of Polymer Science.Polymer Physics》2011,49(5):355-367
Fracture properties of model elastomeric networks of polyurethane have been investigated with a double‐edge notch geometry. The networks were synthesized from monodisperse end‐functionalized polypropylene glycol precursors and a trifunctional isocyanate. All reagents were carefully purified and nearly defect‐free ideal networks were prepared at a stoichiometry very close to the theoretical one. Three networks were prepared: an unentangled network of short chains (Mn = 4 kg mol?1), an entangled network of longer chains (Mn = 8 kg mol?1) and a bimodal network with 8 kg mol?1 and 1 kg mol?1 chains. The presence of entanglements was found to increase significantly the toughness of the rubber, in particular at room temperature, relative to the bimodal networks and to the short chains network. Fracture experiments were carried out at different strain rates and temperatures and showed for all three networks a marked decrease in fracture toughness with increasing temperature and decreasing strain rate which mirrored reasonably well the rate and temperature dependence of tan δ, the dissipative factor. However the proportionality factor between tan δ, and GIC was very material dependent and the shift factors obtained for the master curves of the viscoelastic properties could not be used to build fracture energy master curves. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010 相似文献
82.
Rasmus Fonseca Glennie Helles Pawel Winter 《Journal of Mathematical Modelling and Algorithms》2011,10(4):357-369
One reason why ab initio protein structure predictors do not perform very well is their inability to reliably identify long-range
interactions between amino acids. To achieve reliable long-range interactions, all potential pairings of β-strands (β-topologies) of a given protein are enumerated, including the native β-topology. Two very different β-topology scoring methods from the literature are then used to rank all potential β-topologies. This has not previously been attempted for any scoring method. The main result of this paper is a justification
that one of the scoring methods, in particular, consistently top-ranks native β-topologies. Since the number of potential β-topologies grows exponentially with the number of β-strands, it is unrealistic to expect that all potential β-topologies can be enumerated for large proteins. The second result of this paper is an enumeration scheme of a subset of β-topologies. It is shown that native-consistent β-topologies often are among the top-ranked β-topologies of this subset. The presence of the native or native-consistent β-topologies in the subset of enumerated potential β-topologies relies heavily on the correct identification of β-strands. The third contribution of this paper is a method to deal with the inaccuracies of secondary structure predictors
when enumerating potential β-topologies. The results reported in this paper are highly relevant for ab initio protein structure prediction methods based
on decoy generation. They indicate that decoy generation can be heavily constrained using top-ranked β-topologies as they are very likely to contain native or native-consistent β-topologies. 相似文献
83.
Brandon J. O'Neill David H. K. Jackson Dr. Anthony J. Crisci Carrie A. Farberow Fengyuan Shi Dr. Ana C. Alba‐Rubio Dr. Junling Lu Dr. Paul J. Dietrich Dr. Xiangkui Gu Dr. Christopher L. Marshall Prof. Peter C. Stair Dr. Jeffrey W. Elam Dr. Jeffrey T. Miller Prof. Fabio H. Ribeiro Prof. Paul M. Voyles Prof. Jeffrey Greeley Prof. Manos Mavrikakis Prof. Susannah L. Scott Prof. Thomas F. Kuech Prof. James A. Dumesic 《Angewandte Chemie (International ed. in English)》2013,52(51):13824-13824
84.
85.
Stefan Eibl Andrew Fitch Michela Brunelli Alexander Dominic Evans Philip Pattison Marie Plazanet Mark Robert Johnson Christiane Alba‐Simionesco Helmut Schober 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(6):o278-o280
The title compound, C10H18, a decalin stereoisomer, crystallizes with Z′ = 0.5 in the space group P21/n. The trans‐decalin molecule is located on an inversion centre with both rings in a chair conformation, making for a quasi‐flat overall shape. Despite the absence of hydrogen bonds, it crystallizes easily. In this work the unknown crystal structure of trans‐decalin has been solved and refined using X‐ray powder diffraction data. 相似文献
86.
C. M. Da Fonseca 《Annali di Matematica Pura ed Applicata》2008,187(2):251-261
A different approach is given to recent results due mainly to R. C. Johnson and A. Leal Duarte on the multiplicities of eigenvalues
of a Hermitian matrix whose graph is a tree. The techniques developed are based on some results of matching polynomials and
used a work by O. L. Heilmann and E. H. Lieb on an apparently unrelated topic.
相似文献
87.
C.M. da Fonseca 《Discrete Mathematics》2009,309(8):2519-757
Given partitions R and S with the same weight, the Robinson-Schensted-Knuth correspondence establishes a bijection between the class A(R,S) of (0, 1)-matrices with row sum R and column sum S and pairs of Young tableaux of conjugate shapes λ and λ∗, with S?λ?R∗. An algorithm for constructing a matrix in A(R,S) whose insertion tableau has a prescribed shape λ, with S?λ?R∗, is provided. We generalize some recent constructions due to R. Brualdi for the extremal cases λ=S and λ=R∗. 相似文献
88.
José R. Fonseca Michael I. Friswell John E. Mottershead Arthur W. Lees 《Journal of sound and vibration》2005,288(3):587-599
To incorporate uncertainty in structural analysis, a knowledge of the uncertainty in the model parameters is required. This paper describes efficient techniques to identify and quantify variability in the parameters from experimental data by maximising the likelihood of the measurements, using the well-established Monte Carlo or perturbation methods for the likelihood computation. These techniques are validated numerically and experimentally on a cantilever beam with a point mass at an uncertain location. Results show that sufficient accuracy is attainable without a prohibitive computational effort. The perturbation approach requires less computation but is less accurate when the response is a highly nonlinear function of the parameters. 相似文献
89.
90.
Luigi Ambrosio Irene Fonseca Paolo Marcellini Luc Tartar 《Archive for Rational Mechanics and Analysis》1999,149(1):23-47
. Existence of minimizers for a volume-constrained energy $ E(u) := \int_{\Omega} W(\nabla u)\, dx Existence of minimizers for a volume-constrained energy E(u) : = òW W(?u) dx E(u) := \int_{\Omega} W(\nabla u)\, dx where LN({u = zi}) = ai, i = 1, ?, P, {\cal L}^N(\{u = z_i\}) = \alpha_i, i = 1, \ldots, P, is proved for the case in which ziz_i are extremal points of a compact, convex set in \Bbb Rd\Bbb R^d and under suitable assumptions on a class of quasiconvex energy densities W. Optimality properties are studied in the scalar-valued problem where d=1d=1, P=2P=2, W(x)=|x|2W(\xi)=|\xi|^2, and the &-limit as the sum of the measures of the 2 phases tends to \L(W)\L(\Omega) is identified. Minimizers are fully characterized when N=1N=1, and candidates for solutions are studied for the circle and the square in the plane. 相似文献