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41.
A polemic arose recently about the applicability of the t-expansion method to the calculation of the ground state energy E0 of the Rabi model. For specific choices of the trial function and very large number of involved connected moments, the t-expansion results are rather poor and exhibit considerable oscillations. In this Letter, we formulate the t-expansion method for trial functions containing two free parameters which capture two exactly solvable limits of the Rabi Hamiltonian. At each order of the t-series, E0 is assumed to be stationary with respect to the free parameters. A high accuracy of E0 estimates is achieved for small numbers (5 or 6) of involved connected moments, the relative error being smaller than 10−4 (0.01%) within the whole parameter space of the Rabi Hamiltonian. A special symmetrization of the trial function enables us to calculate also the first excited energy E1, with the relative error smaller than 10−2 (1%). 相似文献
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We show that every plane graph with maximum face size four in which all faces of size four are vertex‐disjoint is cyclically 5‐colorable. This answers a question of Albertson whether graphs drawn in the plane with all crossings independent are 5‐colorable. © 2009 Wiley Periodicals, Inc. J Graph Theory 64: 184–205, 2010 相似文献
45.
Costas Iliopoulos M. Sohel Rahman Michal Voráček Ladislav Vagner 《Journal of Discrete Algorithms》2010,8(2):117-130
In this paper, we present linear-time algorithms for the construction two novel types of finite automata and show how they can be used to efficiently solve the Longest Common Subsequence (LCS), Shortest Common Supersequence (SCS) and Constrained Longest Common Subsequence (CLCS) problems for degenerate strings. 相似文献
46.
Solutions of the perfluoro anion-exchange membrane TosHex® in a solvent mixture composed of methanol + isopropanol + water (1:1:1) were prepared and applied in coating glassy carbon electrodes. The evaporated films were used to accumulate the Fe(CN)
6 redox couple on the electrode surface. The magnitude of the electrochemical response of the loaded films is comparable with that for Nafion® incorporated cationic redox species. The multicharged Fe(CN)
6 couple accumulated in Tosflex® film causes an ion cross-linking of the polymeric backbone, thus decreasing ion transport in the film substantially. 相似文献
47.
We propose a criterion giving a sufficient condition for quantum states of a harmonic oscillator not to be expressible as a convex mixture of Gaussian states. This nontrivial property is inherent to, e.g., a single-photon state and the criterion thus allows one to reveal a signature of the state even in quantum states with a positive Wigner function. The criterion relies on directly measurable photon number probabilities and enables detection of this manifestation of a single-photon state in quantum states produced by solid-state single-photon sources in a weak coupling regime. 相似文献
48.
Ladislav Ceniga 《Acta Mechanica Sinica》2010,26(1):101-106
The paper deals with analytical models of the elastic energy gradient Wsq representing an energy barrier. The energy barrier is a surface integral of the elastic energy density Wq. The elastic energy density is induced by thermal stresses acting in an isotropic spherical particle (q = p) with the radius R and in a cubic cell of an isotropic matrix (q = m). The spherical particle and the matrix are components of a multi-particle-matrix system representing a model system applicable to a real two-component material of a precipitation-matrix type. The multi-particle-matrix system thus consists of periodically distributed isotropic spherical particles and an isotropic infinite matrix. The infinite matrix is imaginarily divided into identical cubic cells with a central spherical particle in each of the cubic cells. The dimension d of the cubic cell then corresponds to an inter-particle distance. The parameters R, d along with the particle volume fraction v = v(R, d) as a function of R, d represent micro- structural characteristics of a real two-component material. The thermal stresses are investigated within the cubic cell, and accordingly are functions of the microstructural charac- teristics. The thermal stresses originate during a cooling pro- cess as a consequence of the difference am - ap in thermal expansion coefficients between the matrix and the particle, am and ap, respectively. The energy barrier Wsq is used for the determination of the thermal-stress induced strengthening aq. The strengthening represents resistance against com- pressive or tensile mechanical loading for am - ap 〉 0 or am - ap 〈 0. respectively. 相似文献
49.
Libuse Trnkova Ladislav Novotny Nuria Serrano Katerina Klosova Petra Polaskova 《Electroanalysis》2010,22(16):1873-1880
Elimination voltammetry with linear scan (EVLS) in connection with renewed mini‐ drop mercury electrodes provides valuable information about the character and kinetics of processes at electrode/electrolyte interfaces. Based on the experiment related to the hydrogen evolution, it is presented that the EVLS is more sensitive than other voltammetric methods. Using miniaturized mercury electrodes, the EVLS is capable of detecting the effect of spherical diffusion associated with both the scan rates and the size of an electrode drop. 相似文献
50.
Anamika Mishra Karel Matou? Kumud B. Mishra Ladislav Nedbal 《Journal of fluorescence》2009,19(5):905-913
Automatic discrimination of plant species is required for precision farming and for advanced environmental protection. For
this task, reflected sunlight has already been tested whereas fluorescence emission has been only scarcely considered. Here,
we investigated the discriminative potential of chlorophyll fluorescence imaging in a case study using three closely related
plant species of the family Lamiaceae. We compared discriminative potential of eight classifiers and four feature selection methods to identify the fluorescence
parameters that can yield the highest contrast between the species. Three plant species: Ocimum basilicum, Origanum majorana and Origanum vulgare were grown separately as well as in pots where all three species were mixed. First, eight statistical classifiers were applied
and tested in simulated species discrimination. The performance of the Quadratic Discriminant Classifier was found to be the
most efficient. This classifier was further applied in combination with four different methods of feature selection. The Sequential
Forward Floating Selection was found as the most efficient method for selecting the best performing subset of fluorescence
images. The ability of the combinatorial statistical techniques for discriminating the species was also compared to the resolving
power of conventional fluorescence parameters and found to be more efficient. 相似文献