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991.
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994.
L. Wang H. P. Dai H. Dong Y. Y. Cao Y. X. Sun 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(3):335-342
This paper considers the problem of controlling
weighted complex dynamical networks by applying adaptive control
to a fraction of network nodes. We investigate the local and
global synchronization of the controlled dynamical network through
the construction of a master stability function and a Lyapunov
function. Analytical results show that a certain number of nodes
can be controlled by using adaptive pinning to ensure the
synchronization of the entire network. We present numerical
simulations to verify the effectiveness of the proposed scheme. In
comparison with feedback pinning, the proposed pinning control
scheme is robust when tested by noise, different weighting and
coupling structures, and time delays. 相似文献
995.
X. M. Wen L. V. Dao P. Hannaford S. Mokkapati H. H. Tan C. Jagadish 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,62(1):65-70
We investigate the electron dynamics of p-type modulation doped and undoped
InGaAs/GaAs quantum dots using up-conversion photoluminescence at low
temperature and room temperature. The rise time of the p-doped sample is
significantly shorter than that of the undoped at low temperature. With
increasing to room temperature the undoped sample exhibits a decreased rise
time whilst that of the doped sample does not change. A relaxation mechanism
of electron-hole scattering is proposed in which the doped quantum dots
exhibit an enhanced and temperature independent relaxation due to excess
built-in holes in the valence band of the quantum dots. In contrast, the
rise time of the undoped quantum dots decreases significantly at room
temperature due to the large availability of holes in the ground state of
the valence band. Furthermore, modulation p-doping results in a shorter
lifetime due to the presence of excess defects. 相似文献
996.
An explicit thermoelastic model is developed to describe
the photothermal deformation of a coated sample excited by a cw modulated
laser beam with a top-hat profile. The surface displacement obtained with
this explicit model is compared to that obtained by an approximate model
developed by Reichling and Gr?nbeck (J. Appl. Phys. 75, 1914 (1994)).
Both thermoelastic models are then applied in a Fresnel diffraction based
surface thermal lens (STL) theory. Numerical calculations are performed to
investigate the differences between the explicit and approximate models in
both surface displacement and STL signal. The simulation results show that
the approximate model over-estimates the surface displacement and the
corresponding STL signal amplitude. A decrease in the thermal diffusion
length reduces the differences between the results obtained with the two
thermoelastic models. 相似文献
997.
J. S. Wang Y. Cheng Q. J. Huang X. J. Liu S. Y. Zhang 《The European physical journal. Special topics》2008,153(1):155-158
The three-dimensional (3D) temperature field of
laser-induced transient thermal grating (TTG) for two-layered structures
such as diamond/substrate is obtained by the finite element method (FEM).
The numerical results indicate that the thickness of the diamond film has a
significant influence on the temperature field. On the other hand, we
further find that variation of the substrate significantly affects on the
temperature distribution in the diamond film, which has been ascribed to the
various thermal conductivities of the substrates. 相似文献
998.
I. Abt A. Caldwell K. Kröninger J. Liu X. Liu B. Majorovits 《The European Physical Journal C - Particles and Fields》2008,54(3):425-433
Procedures developed to separate single- and multiple-site events in germanium detector are tested with specially selected
event samples provided by an 18-fold segmented prototype germanium detector for phase II of the germanium detector array,
GERDA. The single Compton scattering, i.e. single-site, events are tagged by coincidently detecting the scattered photon with
a second detector positioned at a defined angle. A neural network is trained to separate such events from events which come
from multi-site dominated samples. Identification efficiencies of ≈80% are achieved for both single- and multi-site events.
PACS 23.40.-s; 14.60Pq; 29.40.-n 相似文献
999.
Performance of gain-switched all-solid-state quasi-continuous-wave tunable Ti:sapphire laser system
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We have made a gain-switched all-solid-state quasi-continuous-wave (QCW) tunable Ti:sapphire laser system, which is pumped by a 532 nm intracavity frequency-doubled Nd:YAG laser. Based on the theory of gain-switching and the study on the influencing factors of the output pulse width, an effective method for obtaining high power and narrow pulse width output is proposed. Through deliberately designing the pump source and the resonator of the Ti:sapphire laser, when the repetition rate is 6 kHz and the length of the cavity is 220 mm, at an incident pump power of 22 W, the tunable Ti:sapphire laser from 700 to 950nm can be achieved. It has a maximum average output power of 5.6W at 800nm and the pulse width of 13.2 ns, giving an optical conversion efficiency of 25.5% from the 532 mn pump laser to the Ti:sapphire laser. 相似文献
1000.
The inflow conditions for spatial direct numerical simulation (SDNS) of turbulent boundary layers should reflect the characteristics
of upstream turbulence, which is a puzzle. In this paper a new method is suggested, in which the flow field obtained by using
temporal direct numerical simulation (TDNS) for fully developed turbulent flow (only flow field for a single moment is sufficient)
can be used as the inflow of SDNS with a proper transformation. The calculation results confirm that this method is feasible
and effective. It is also found that, under a proper time-space transformation, all statistics of the fully developed turbulence
obtained by both temporal mode and spatial mode DNS are in excellent agreement with each other, not only qualitatively, but
also quantitatively. The normal-wise distributions of mean flow profile, turbulent Mach number and the root mean square (RMS)
of the fluctuations of various variables, as well as the Reynolds stresses of the fully developed turbulence obtained by using
SDNS, bear similarity in nature.
Supported by the National Natural Science Foundation of China (Grant No. 90205021), the China Postdoctoral Science Foundation
(Grant No. 20060400707), and the Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No.
200328), and partially supported by Liu-Hui Center of Applied Mathematics, Nankai University and Tianjin University 相似文献