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21.
The adsorption of a metal monolayer on a foreign substrate generates a change in the surface stress. We calculate this change for a number of substrate/adsorbate systems using the embedded-atom method. The results are compared with those obtained from a continuum model. A cycle, in which the stretching of a substrate/adsorbate system is decomposed into several steps, helps in understanding the numerical results. 相似文献
22.
Hugo Leiva 《Journal of Mathematical Analysis and Applications》2003,280(1):1-8
In this paper we prove that the controllability for evolution equations in Banach spaces is not destroyed, if we perturb the equation by “small” unbounded linear operator. This is done by employing a perturbation principle from linear operator theory and a characterization of surjective operators in Banach spaces. Finally, we apply these to a control system governed by partial integro-differential equations. 相似文献
23.
M. Mariscal E. Leiva K. Pötting W. Schmickler 《Applied Physics A: Materials Science & Processing》2007,87(3):385-389
Polycrystalline higher manganese silicide (MnSi1.73) films with addition of chromium were prepared on thermally oxidized silicon substrates by magnetron sputtering. A cap layer
of chromium disilicide was used as the doping source. Both the Seebeck coefficient and the resistivity were strongly dependent
on the amount of chromium added to the film. When the thickness ratio of chromium disilicide to manganese silicide increased
from 2.4% to 9.8%, the Seebeck coefficient at room temperature decreased from 121 to 100 μV/K. However, the temperature at
which the maximum value of the Seebeck coefficient occurred increased from 343 to 633 K. When the thickness ratio was about
2.4%, the resistivity increased to 33×10-3 Ω cm. Otherwise, the resistivity decreased from 13×10-3 to 5.2×10-3 Ω cm by increasing the thickness ratio. As a result, the thermoelectric power factor increased greatly at high temperatures.
Several activation energies (0.021–0.383 eV) were observed from the curves of the logarithm of resistivity versus reciprocal
temperature.
PACS 72.20.Pa; 72.80.Ga; 72.15.Jf; 73.50.Lw; 73.61.Le 相似文献
24.
Dimedes Brcenas Hugo Leiva Ambrosio Tineo Moya 《Journal of Mathematical Analysis and Applications》2006,320(2):691-702
We study the notion of dual quasisemigroups of bounded linear operators as a generalization of that for strongly continuous semigroup and prove some properties similar to the dual of a semigroup, among other things we prove that for reflexive Banach spaces the dual quasisemigroup is strongly continuous on (0,+∞). This allows us to extend some recent criteria of controllability to a general class of evolution equations in reflexive Banach spaces. 相似文献
25.
Molecular dynamic simulations in combination with energy minimizations are used in order to understand the basis of the novel experiments reported recently by Haiss et al. (W. Haiss, C. Wang, I. Grace, A.S. Batsanov, D.J. Schiffrin, S.J. Higgins, M.R. Bryce, C.J. Lambert, R.J. Nichols, Nature Mater. 5 (2006) 995). Our model suggests that single-molecule junctions produced by the trapping method can be reached when the STM tip – substrate surface separation is smaller than 8 Å. Additionally, our model predicts that the effect of the electric field on the attachment/detachment process can be neglected. 相似文献
26.
27.
In this article a technique to achieve synchronization in spatially extended systems is introduced. The basic idea behind this method is to map a system of partial differential equations (PDEs) into a high-dimensional space where the representation of this PDE is an ordinary differential equation. By using semi-group theory, we are able to find conditions that ensure the synchronization of two systems of non-identical reaction–diffusion equations with a master–slave coupling. 相似文献
28.
Carlos Leiva 《Pramana》2010,74(2):169-175
The harmonic oscillator in Snyder space is investigated in its classical and quantum versions. The classical trajectory is
obtained and the semiclassical quantization from the phase space trajectories is discussed. An effective cut-off to high frequencies
is found. The quantum version is developed and an equivalent usual harmonic oscillator is obtained through an effective mass
and an effective frequency introduced in the model. This modified parameters give us a modified energy spectrum also. 相似文献
29.
Solid solutions of the end members Fe2WO6, Cr2WO6, and Rh2WO6 have been prepared and their crystallographic and magnetic properties studied. All solid solutions crystallize with the trirutile structure, and their magnetic behavior is characterized by the existence of antiferromagnetic interactions and effective molar Curie constants corresponding to those expected from contributions of the spinonly moments of high-spin Fe3+, Cr3+, and diamagnetic low-spin Rh3+ ions. Fe2WO6 crystallizes with the tri-α-PbO2 structure and is antiferromagnetic and conducting. The random rutile Rh2WO6 is conducting, and the difference between its magnetic and electric properties and those of the inverse trirutile Cr2WO6 are discussed in terms of possible interactions between Cr3+(3d) or Rh3+(4d) orbitals and W6+(5d) orbitals. 相似文献
30.
Laura C. Leiva Nelly L. Jorge Jorge M. Romero Lzaro F. R. Cafferata Manuel E. Gmez Vara 《国际化学动力学杂志》2004,36(5):302-307
The thermal decomposition reaction of acetone cyclic diperoxide (3,3,6,6‐tetramethyl‐1,2,4,5‐tetroxane, ACDP), in the temperature range of 130.0–166.0°C and initial concentrations range of 0.4–3.1 × 10?2 mol kg?1 has been studied in methyl t‐butyl ether solution. The thermolysis follows first‐order kinetic laws up to at least ca 60% ACDP conversion. Under the experimental conditions, the activation parameters of the initial step of the reaction (ΔH# = 33.6 ± 1.1 kcal mol?1; ΔS# = ?4.1 ± 0.7 cal mol?1 K?1; ΔG# = 35.0 ± 1.1 kcal mol?1) and acetone, as the only organic product, support a stepwise reaction mechanism with the homolytic rupture of one of its peroxidic bond. Also, participation of solvent molecules in the reaction is postulated given an intermediate diradical, which further decomposes by C? O bond ruptures, yielding a stoichiometric amount of acetone (2 mol per mole of ACDP decomposed). The results are compared with those obtained for the above diperoxide thermolysis in other solvents. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 302–307, 2004 相似文献