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421.
Lorenzo Bertini Emilio N. M. Cirillo Enzo Olivieri 《Journal of statistical physics》2007,126(4-5):987-1006
We consider a two-dimensional Ising model with random i.i.d. nearest-neighbor ferromagnetic couplings and no external magnetic
field. We show that, if the probability of supercritical couplings is small enough, the system admits a convergent cluster
expansion with probability one. The associated polymers are defined on a sequence of increasing scales; in particular the
convergence of the above expansion is compatible with the infinite differentiability of the free energy but does not imply
its analyticity. The basic tools in the proof are a general theory of graded cluster expansions and a stochastic domination
of the disorder.
MSC2000. Primary 82B44, 60K35. 相似文献
422.
Renormalization-Group Transformations Under Strong Mixing Conditions: Gibbsianness and Convergence of Renormalized Interactions 总被引:2,自引:0,他引:2
Bertini Lorenzo Cirillo Emilio N. M. Olivieri Enzo 《Journal of statistical physics》1999,97(5-6):831-915
In this paper we study a renormalization-group map: the block averaging transformation applied to Gibbs measures relative to a class of finite-range lattice gases, when suitable strong mixing conditions are satisfied. Using a block decimation procedure, cluster expansion, and detailed comparison between statistical ensembles, we are able to prove Gibbsianness and convergence to a trivial (i.e., Gaussian and product) fixed point. Our results apply to the 2D standard Ising model at any temperature above the critical one and arbitrary magnetic field. 相似文献
423.
424.
For a graph matrix M, the Hoffman limit value H(M) is the limit (if it exists) of the largest eigenvalue (or, M-index, for short) of M(Hn), where the graph Hn is obtained by attaching a pendant edge to the cycle Cn-1 of length n-1. In spectral graph theory, M is usually either the adjacency matrix A or the Laplacian matrix L or the signless Laplacian matrix Q. The exact values of H(A) and H(L) were first determined by Hoffman and Guo, respectively. Since Hn is bipartite for odd n, we have H(Q)=H(L). All graphs whose A-index is not greater than H(A) were completely described in the literature. In the present paper, we determine all graphs whose Q-index does not exceed H(Q). The results obtained are determinant to describe all graphs whose L-index is not greater then H(L). This is done precisely in Wang et al. (in press) [21]. 相似文献
425.
426.
Laura Alessandrini Silvana Casati Roberta Ottria Enzo Santaniello 《Journal of carbohydrate chemistry》2013,32(5):332-344
Starting from D‐ribose, differently protected 1‐C‐methyl‐D‐ribofuranoses have been prepared as intermediates for the synthesis of variously modified 1′‐C‐methyl‐ribonucleosides, a class of compounds potentially endowed with interesting biological activity. 相似文献
427.
E. Kraleva M. L. Saladino R. Matassa E. Caponetti S. Enzo A. Spojakina 《Journal of Structural Chemistry》2011,52(2):330-339
Pure titania, zirconia, and mixed oxides (3–37 mol.% of ZrO2) are prepared using the sol-gel method and calcined at different temperatures. The calcined samples are characterized by
Raman spectroscopy, X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen
adsorption porosimetry. Measurements reveal a thermal stability of the titania anatase phase that slightly increases in the
presence of 3–13 mol.% of zirconia. Practically, the titania anatase-rutile phase transformation is hindered during the temperature
increase above 700°C. The mixed oxide with 37 mol.% of ZrO2 treated at 550°C shows a new single amorphous phase with a surface area of the nanoparticles double with respect to the other
crystalline samples and the formed srilankite structure (at 700°C). The anatase phase is not observed in the sample containing
37 mol.% of ZrO2. The treatment at 700°C causes the formation of the srilankite (Ti0.63Zr0.37Ox) phase. 相似文献
428.
Enantiomerically pure (R)- and (S)-1-benzoyloxypropane-2,3-diol have been prepared from (S)-(+)-2,2-dimethyl-1,3-dioxolane-4-methanol and used as reference compounds to correct the reported stereochemical outcome of the Candida antarctica lipase (CAL)-catalyzed benzoylation of glycerol. 相似文献
429.
A branching process of particles moving at finite velocity over the geodesic lines of the hyperbolic space (Poincaré half-plane
and Poincaré disk) is examined. Each particle can split into two particles only once at Poisson spaced times and deviates
orthogonally when splitted. At time t, after N(t) Poisson events, there are N(t)+1 particles moving along different geodesic lines. We are able to obtain the exact expression of the mean hyperbolic distance
of the center of mass of the cloud of particles. We derive such mean hyperbolic distance from two different and independent
ways and we study the behavior of the relevant expression as t increases and for different values of the parameters c (hyperbolic velocity of motion) and λ (rate of reproduction). The mean hyperbolic distance of each moving particle is also examined and a useful representation,
as the distance of a randomly stopped particle moving over the main geodesic line, is presented. 相似文献
430.
We introduce loop ranking, a new ranking measure based on the detection of closed paths, which can be computed in an efficient way. We analyze it with respect to several ranking measures which have been proposed in the past, and are widely used to capture the relative importance of the vertices in complex networks. We argue that loop ranking is a very appropriate measure to quantify the role of both vertices and edges in the network traffic. 相似文献