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961.
Sebastian Sewerin Marco Taubert Henning Vollmann Virginia Conde Arno Villringer Patrick Ragert 《BMC neuroscience》2011,12(1):1-5
Background
The aberrant pyramidal tract (APT) refers to the collateral pathway of the pyramidal tract (PT) through the medial lemniscus in the midbrain and pons. Using diffusion tensor tractography (DTT), we investigated the characteristics of the APT in comparison with the PT in the normal human brain.Results
In thirty-four (18.3%, right hemisphere: 20, left hemisphere: 14) of the 186 hemispheres, the APTs separated from the PT at the upper midbrain level, descended through the medial lemniscus from the midbrain to the pons, and then rejoined with the PT at the upper medulla. Nine (26.5%) of the 34 APTs were found to originate from the primary somatosensory cortex without a primary motor cortex origin. Values of fractional anisotropy (FA) and tract volume of the APT were lower than those of the PT (P < 0.05); however, no difference in mean diffusivity (MD) value was observed (P > 0.05).Conclusion
We found that the APT has different characteristics, including less directionality, fewer neural fibers, and less origin from the primary motor cortex than the PT. 相似文献962.
Meier B Greiser S Haase J Herrmannsdörfer T Wolff-Fabris F Wosnitza J 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,210(1):1-6
Nuclear Magnetic Resonance (NMR) experiments in pulsed high magnetic fields up to 62T at the Dresden High Magnetic Field Laboratory (Hochfeld-Magnetlabor Dresden) are reported. The time dependence of the magnetic field is investigated by observing various free induction decays (FIDs) in the vicinity of the maximum of the field pulse. By analyzing each FID's phase and its evolution with time the magnetic field's time dependence can be determined with high precision. Assuming a quadratic or cubic dependence on time near the field maximum its confidence is found to be better than ± 0.03ppm at low fields and ± 0.8ppm near 62T. In turn, the thus obtained time dependence of the field can be used to demodulate and phase-correct all FIDs so that they appear phase-locked to each other. As a consequence signal averaging is possible. The increase in signal-to-noise ratio is found to be close to that expected theoretically. This shows that the intrinsic time dependence of the pulsed fields can be removed so that the NMR signals appear to be taken at rather stable static field. This opens up the possibility of performing precise shift measurements and signal averaging also of unknown, weak signals if a reference signal is measured during the same field pulse with a double-resonance probe. 相似文献
963.
K.B. Jose J. Cyriac J. T. Moolayil V.S. Sebastian M. George 《Journal of Physical Organic Chemistry》2011,24(8):714-719
We have studied the kinetics and elucidated the mechanism by DFT calculation of the reaction between ethanolamine (EOA) and 1‐fluoro‐2,4‐dinitrobenzene (DNFB) in acetonitrile and toluene. To determine the contribution of the nitro group, the activation energy of the reaction between ethanolamine and 1‐fluoro‐2‐nitrobenzene (MNFB) vs. DNFB was determined in acetonitrile and calculated by DFT method. Kinetic measurements reveal that the reaction is faster in acetonitrile than in toluene. The reaction follows overall second‐order kinetics: first order with respect to both EOA and DNFB which is similar to the results reported for reaction between other primary amines and 1‐substituted‐2,4‐dinitrobenzenes. The calculations by using DFT methods reveal that the mechanism of the reaction involves the formation and decomposition of a Meisenheimer complex (MC). DFT calculations also reveal that the activation energy of the reaction is highest in vacuum and decreases with increasing polarity of the solvent reaching a minimum in acetonitrile. In addition, activation energies obtained by both DFT calculations and experiments show that the reactivity of MNFB is less than that of DNFB showing the effect of the 4‐nitro group. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
964.
In this paper we propose a method to construct more general fuzzy sets using ordinary fuzzy sets as building blocks. We introduce
the concept of multi-fuzzy sets in terms of ordered sequences of membership functions. The family of operations T, S, M of multi-fuzzy sets are introduced by coordinate wise t-norms, s-norms and aggregation operations. We define the notion of coordinate wise conjugation of multifuzzy sets, a method for obtaining
Atanassov’s intuitionistic fuzzy operations from multi-fuzzy sets. We show that various binary operations in Atanassov’s intuitionistic
fuzzy sets are equivalent to some operations in multi-fuzzy sets like M operations, 2-conjugates of the T and S operations. It is concluded that multi-fuzzy set theory is an extension of Zadeh’s fuzzy set theory, Atanassov’s intuitionsitic
fuzzy set theory and L-fuzzy set theory. 相似文献
965.
Enhanced switching law for synchronized switch damping on inductor with bimodal excitation 总被引:1,自引:0,他引:1
Marcus Neubauer Xu Han Sebastian M. Schwarzendahl 《Journal of sound and vibration》2011,330(12):2707-2720
Piezoelectric shunt damping is an emerging field of research. In recent years, a multitude of different electrical circuits have been developed aiming to increase the damping performance and robustness. Synchronized switch damping on inductor (SSDI) is a semi-active control technique that utilizes a passive inductance to build-up a voltage on the piezoceramics that is synchronized with the mechanical vibration. For a single mode excitation the voltage inversion should occur at the moments of maximum deformation, but for multimodal vibrations such a switching law may not be optimal.In this paper a novel switching law for bimodal vibrations is presented using a modal observer. An enhanced voltage build-up is generated by utilizing the vibration energy of the second mode. The amplification of dissipated energy is calculated in an analytical way using normalized parameters, yielding a general result which includes the influence of the frequency and amplitude ratio of the excitation signal. Measurements on a clamped beam test rig are conducted in order to validate the proposed method. An increase of nearly 350 percent in energy dissipation compared to the classical SSDI has been achieved. Furthermore, the increase in energy dissipation is higher than for a previously suggested, comparable switching law. 相似文献
966.
967.
Marcin Magdziarz Sebastian Orzeł Aleksander Weron 《Journal of statistical physics》2011,145(1):187-203
The earliest model of stock prices based on Brownian diffusion is the Bachelier model. In this paper we propose an extension
of the Bachelier model, which reflects the subdiffusive nature of the underlying asset dynamics. The subdiffusive property
is manifested by the random (infinitely divisible) periods of time, during which the asset price does not change. We introduce
a subdiffusive arithmetic Brownian motion as a model of stock prices with such characteristics. The structure of this process
agrees with two-stage scenario underlying the anomalous diffusion mechanism, in which trapping random events are superimposed
on the Langevin dynamics. We find the corresponding fractional Fokker-Planck equation governing the probability density function
of the introduced process. We construct the corresponding martingale measure and show that the model is incomplete. We derive
the formulas for European put and call option prices. We describe explicit algorithms and present some Monte-Carlo simulations
for the particular cases of α-stable and tempered α-stable distributions of waiting times. 相似文献
968.
We have experimentally studied few-body impurity systems consisting of a single fermionic atom and a small bosonic field on the sites of an optical lattice. Quantum phase revival spectroscopy has allowed us to accurately measure the absolute strength of Bose-Fermi interactions as a function of the interspecies scattering length. Furthermore, we observe the modification of Bose-Bose interactions that is induced by the interacting fermion. Because of an interference between Bose-Bose and Bose-Fermi phase dynamics, we can infer the mean fermionic filling of the mixture and quantify its increase (decrease) when the lattice is loaded with attractive (repulsive) interspecies interactions. 相似文献
969.
We establish a theory that traces light amplification in an active double-fishnet metamaterial back to its microscopic origins. Based on ab initio calculations of the light and plasmon fields we extract energy rates and conversion efficiencies associated with gain and loss channels directly from Poynting's theorem. We find that for the negative refractive index mode both radiative loss and gain outweigh resistive loss by more than a factor of 2, opening a broad window of steady-state amplification (free of instabilities) accessible even when a gain reduction close to the metal is taken into account. 相似文献
970.
Marvin Cummings Sebastian Gliga Boris Lukanov Eric I. Altman Matthias Bode Enrique V. Barrera 《Surface science》2011,605(1-2):72-80
Here, the interactions of C60 at the surface of pseudomorphic Ni/Cu(100) and Co/Ru(0001) thin films and its effect on film growth and morphology were determined using in-situ scanning tunneling microscopy (STM) and Auger electron spectroscopy (AES). The novel development of C60-metallic based nanosystems, such as C60 molecular junction transistors, hinges on our ability to understand the factors governing structural stability in these nanosystems and the nature of the bond interactions at the C60–metal interface. In this study, C60 deposited onto the Ni(100) film surface is observed to be fairly immobile and uniformly distributed across the Ni surface. On the Co(0001) film surface however, C60 mobility is observed to be severely limited in some regions and highly mobile in others dependent upon Co film surface reconstruction, resulting in a non-uniform distribution of C60 across the Co film surface. Despite the presence of C60 on the Ni surface, there is no obvious influence of the C60 on further Ni film growth. In contrast, during Co film growth, islands only nucleate and grow from step edges or locally around C60 molecules. The strength of the Co–C60 bond interaction appears stronger than the Co–Co bond on Co film terrace. Generally, the Ni and Co films both continue epitaxial film growth in the presence of molecular C60. AES results indicate the C60 molecules maintain their chemical integrity during growth. 相似文献