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991.
Dennis Kretschmann Dirk Schlingemann Reinhard F. Werner 《Journal of Functional Analysis》2008,255(8):1889-1904
We show a continuity theorem for Stinespring's dilation: two completely positive maps between arbitrary C∗-algebras are close in cb-norm if and only if we can find corresponding dilations that are close in operator norm. The proof establishes the equivalence of the cb-norm distance and the Bures distance for completely positive maps. We briefly discuss applications to quantum information theory. 相似文献
992.
Manuel Bächtold 《Foundations of Physics》2008,38(9):843-868
The aim of this paper is to show that quantum mechanics can be interpreted according to a pragmatist approach. The latter
consists, first, in giving a pragmatic definition to each term used in microphysics, second, in making explicit the functions
any theory must fulfil so as to ensure the success of the research activity in microphysics, and third, in showing that quantum
mechanics is the only theory which fulfils exactly these functions.
This work received financial support from the European Union (Marie Curie Actions). 相似文献
993.
Motivated by the far-infrared transmission experiments of Demel et al., we have investigated the magnetoplasmon excitations in an array of quantum dots within the Thomas–Fermi–Dirac–von Weizsäcker (TFDW) approximation. Detailed calculations of the magnetic dispersion and power absorption from a uniform radiation field unambiguously demonstrates that the noncircular symmetry of the individual dots is responsible for the anticrossing behaviour observed in the experiments. The interdot Coulomb interaction is unimportant at the interdot separation of the samples studied. 相似文献
994.
S. K. Jung S. W. Hwang D. Ahn J. H. Park Yong Kim E. K. Kim 《Physica E: Low-dimensional Systems and Nanostructures》2000,7(3-4)
We report on the fabrication and the characterization of quantum dot transistors incorporating a single self-assembled quantum dot. The current–voltage characteristics exhibit clear staircase structures at room temperature. They are attributed to electron tunneling through the quantized energy levels of a single quantum dot. 相似文献
995.
M. Roncadelli 《Il Nuovo Cimento D》1989,11(1-2):73-99
Summary We present in a rather pedagogical way a new formulation of quantum mechanics. Our starting point is the path integral representation
of the quantum-mechanical propagator analytically continued to imaginary timeW(X″, s″|X′, s′). We view the set of random paths contributing toW(X″, s″|X′, s′) as the manifold of solutions of a Langevin equation with a Gaussian white noise. We thus obtainW(X″, s″|X′, s′) as the noise-average of a suitable functional of the solution of the Langevin equation. The standard quantum-mechanical propagator
is finally recovered by analytically continuingW(X″, s″|X′, s′) back to real time. The present approach allows for a straightforward application of standard methods of classical stochastic
processes to quantum-mechanical problems and offers a new promising way to perform computer simulations of quantum-dynamical
systems.
To speed up publication, the author has agreed not to receive proofs which have been supervised by the Scientific Committee. 相似文献
996.
Band structure parameters such as the conduction band edge, the valence band edge and the quasi‐particle gap of diffusing CdSe quantum dots (Q‐dots) of various sizes were determined using cyclic voltammetry. These parameters are strongly dependent on the size of the Q‐dots. The results obtained from voltammetric measurements are compared to spectroscopic and theoretical data. The fit obtained to the reported calculations based on the semi‐empirical pseudopotential method (SEPM)—especially in the strong size‐confinement region, is the best reported so far, according to our knowledge. For the smallest CdSe Q‐dots, the difference between the quasi‐particle gap and the optical band gap gives the electron–hole Coulombic interaction energy (Je1,h1). Interband states seen in the photoluminescence spectra were verified with cyclic voltammetry measurements. 相似文献
997.
Derivatives of N-pyrrolobenzene with a para-donor and a para-acceptor substituent on the benzene ring are compared. It is shown that by a suitable increase of the donor strength of the pyrrolo group, CT fluorescence can be achieved even for donor–donor-substituted benzenes. The ICT emission for sterically hindered compounds is more forbidden than that of unhindered phenyl pyrroles. This suggests conformational effects which induce a narrower twist angle distribution around a perpendicular minimum in the excited state. 相似文献
998.
A. Polimeni A. Patan M. Henini L. Eaves P. C. Main G. Hill 《Physica E: Low-dimensional Systems and Nanostructures》2000,7(3-4)
The optical properties of InAs/AlyGa1−yAs self-assembled quantum dots are studied as a function of temperature from 10 K to room temperature. The temperature dependence of carrier hopping between dots is discussed in terms of the depth of the dot confinement potential and the dispersion in dot size and composition. We show that carrier hopping between dots influences both the electrical and optical properties of laser devices having dots as active medium. 相似文献
999.
Adrián A. Budini 《Journal of statistical physics》2008,131(1):51-78
Non-Markovian Lindblad rate equations arise from alternative microscopic interactions such as quantum systems coupled to composite
reservoirs, where extra degrees of freedom mediate the interaction between the system and a Markovian reservoir, as well as
from systems coupled to complex structured reservoirs whose action can be well approximated by a direct sum of Markovian sub-reservoirs
(Budini in Phys. Rev. A 74:053815 [2006]). The purpose of this paper is two fold. First, for both kinds of interactions we find general expressions for the system
operator correlations written in terms of the Lindblad rate propagator. Secondly, we find the conditions under which a quantum
regression hypothesis is valid. We show that a non-Markovian quantum regression theorem can only be granted in a stationary
regime, being a necessary condition the fulfillment of a detailed balance condition. This result is independent of the underlying
microscopic interaction, providing a criterion for the validity of the regression hypothesis in non-Markovian Lindblad-like
master equations. As an example, we study the correlations of a two-level system coupled to different kind of reservoirs. 相似文献
1000.
Quantum chemical methods are becoming ever more prevalent for assessing surface interactions of different molecules using cluster models and semi-empirical, ab initio Hartree–Fock and density functional theory (DFT) studies considering the standard potential energy surfaces. Examination of the efficacy of some pyridine derivatives to counter aluminium corrosion in hydrochloric acid using ab initio and semi-empirical quantum chemical deductions and its comparison with the available experimental data forms the basis of this research. It is believed that the inhibition efficiency has lucid correlation with the total energy of inhibitor molecules and highest occupied molecular orbital energy levels calculated by DFT study methods and thus the adsorption energy for the pyridine on Al1, Al5, Al14, Al18 and Al26 clusters are determined to assess the convergence of the results with respect to size of the cluster. Subsequently, Al26 is used for the inhibitor/aluminium cluster interface investigations. Results highlight the reaction between pyridine molecules and appropriately active sites such as corners and steps or kinks and screw dislocations towards which pyridine molecules are attracted as is evident from a three times rise in adsorption energy from (−35) to (−107) kJ mol−1. Therefore, inhibition mechanism is primarily associated with local properties. Interactions take place between the surface defect and the nitrogen group of the pyridine molecule however, the possibility of ion pair formation between protonated pyridine and chloride ion and its influence on the general adsorption of pyridine on aluminium is also examined. The interaction energies of pyridine and aluminium cluster with the natural bond orbital are also reported. 相似文献