全文获取类型
收费全文 | 14252篇 |
免费 | 2261篇 |
国内免费 | 1582篇 |
专业分类
化学 | 6263篇 |
晶体学 | 98篇 |
力学 | 3067篇 |
综合类 | 71篇 |
数学 | 1914篇 |
物理学 | 6682篇 |
出版年
2024年 | 42篇 |
2023年 | 214篇 |
2022年 | 609篇 |
2021年 | 570篇 |
2020年 | 592篇 |
2019年 | 553篇 |
2018年 | 456篇 |
2017年 | 510篇 |
2016年 | 703篇 |
2015年 | 620篇 |
2014年 | 776篇 |
2013年 | 1347篇 |
2012年 | 801篇 |
2011年 | 879篇 |
2010年 | 754篇 |
2009年 | 881篇 |
2008年 | 922篇 |
2007年 | 938篇 |
2006年 | 851篇 |
2005年 | 661篇 |
2004年 | 538篇 |
2003年 | 488篇 |
2002年 | 461篇 |
2001年 | 385篇 |
2000年 | 397篇 |
1999年 | 333篇 |
1998年 | 318篇 |
1997年 | 219篇 |
1996年 | 198篇 |
1995年 | 172篇 |
1994年 | 163篇 |
1993年 | 121篇 |
1992年 | 94篇 |
1991年 | 86篇 |
1990年 | 63篇 |
1989年 | 58篇 |
1988年 | 44篇 |
1987年 | 49篇 |
1986年 | 31篇 |
1985年 | 33篇 |
1984年 | 28篇 |
1983年 | 17篇 |
1982年 | 27篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 15篇 |
1978年 | 9篇 |
1976年 | 10篇 |
1971年 | 9篇 |
1957年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
In order to understand the rise of runaway solutions in the radiation reaction problem a mechanical model is used. An alternative
demonstration of Daboul’s theorem, through Hurwitz’s criterion, is given. The origin of runaway solutions in electrodynamics
is discussed. They arise when the particle has a negative mechanical mass or when approximations are used in the equation
of motion. In the 1-dimensional mechanical model an exact and linear equation of motion for the particle is obtained, the
corresponding exact solution is again runaway when the mechanical mass is negative. The exact solution is not runaway when
the mechanical mass is positive. However, the use of approximations leads to an equation of motion which has runaway solutions.
It is exhibited that the use of approximations in the 3-dimensional mechanical model is completely necessary because the general
equation of motion for the particle is non-linear. The analysis of this case proceeds in a very similar way to the one carried
out in electrodynamics. This means that the number of dimensions also plays an important role in the analysis. 相似文献
992.
M. Porfiri E. M. Bollt D. J. Stilwell 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(4):481-486
Opinion compromise models can give insight into how groups of individuals may either come to form
consensus or clusters of opinion groups, corresponding to parties. We consider models where randomly
selected individuals interact pairwise. If the opinions of the interacting agents are not within a certain confidence
threshold, the agents retain their own point of view. Otherwise, they constructively dialogue and smooth their
opinions. Persuasible agents are inclined to compromise with interacting individuals. Stubborn individuals slightly
modify their opinion during the interaction. Collective states for persuasible societies include extremist minorities,
which instead decline in stubborn societies. We derive a mean field approximation for the compromise model in stubborn
populations. Bifurcation and clustering analysis of this model compares favorably with Monte Carlo analysis found in
the literature. 相似文献
993.
S. J. Brodsky 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):638-644
The AdS/CFT correspondence between conformal field theory and string states in an extended space-time has provided new insights
into not only hadron spectra, but also their light-front wave functions. We show that there is an exact correspondence between
the fifth-dimensional coordinate of anti-de Sitter space z and a specific impact variable ζ which measures the separation of the constituents within the hadron in ordinary space-time. This connection allows one to
predict the form of the light-front wave functions of mesons and baryons, the fundamental entities which encode hadron properties
and scattering amplitudes. A new relativistic Schr?dinger light-front equation is found which reproduces the results obtained
using the fifth-dimensional theory. Since they are complete and orthonormal, the AdS/CFT model wave functions can be used
as an initial ansatz for a variational treatment or as a basis for the diagonalization of the light-front QCD Hamiltonian.
A number of applications of light-front wave functions are also discussed. 相似文献
994.
995.
In 2005, Zhang presented a Grubin-like inlet zone analysis to the isothermal line contact elastohydrodynamic lubrication under relatively heavy loads when the hydrodynamic film thickness in the Hertzian zone approaches zero and the EHL fluid is Newtonian [Zhang, Y.B. A justification of the load-carrying capacity of elastohydrodynamic lubrication film based on the Newtonian fluid model. Industrial Lubrication and Tribology, 2005, Vol. 57, pp. 224–232]. His results showed that in this EHL, when the rolling speed is lower than the characteristic rolling speed (Uch =) 0.0372W1.50/G, the Hertzian zone is in physical adsorbed layer boundary lubrication while the inlet zone is in conventional hydrodynamic lubrication. This mode of EHL represents a mode of mixed EHL with mixed contact regimes, where hydrodynamic films with different rheological behaviors occur in different areas of the contact. The present paper presents an analysis to this mode of mixed EHL by using the Grubin type method when the contact adhering layer in the inlet zone is neglected. Pressures, film thicknesses and load partition in the contact are obtained from this analysis. It is also found that the formula for the characteristic rolling speed Uch = 0.0372W1.50/G obtained by Zhang [Zhang, Y.B. A justification of the load-carrying capacity of elastohydrodynamic lubrication film based on the Newtonian fluid model. Industrial Lubrication and Tribology, 2005, Vol. 57, pp. 224–232] may be valid for the dimensionless load W > 1.0E−7, while it may be invalid for the dimensionless load W < 1.0E−8. In part II [Zhang, Y.B. Analytical solution to a mode of mixed elastohydrodynamic lubrication with mixed contact regimes: Part II. Considering the contact adhering layer effect in the inlet zone. Journal of Molecular Liquids, 2006, Vol. 117. (doi:10.1016/j.molliq.2006.04.007)] will be presented an analysis to other two modes of mixed EHL with mixed contact regimes for relatively heavy loads, low rolling speeds and Newtonian fluids, where the conventional hydrodynamic lubrication, physical adsorbed layer boundary lubrication and oxidized chemical layer boundary lubrication can simultaneously occur in the inlet zone while the oxidized chemical layer boundary lubrication or the fresh metal-oxidized chemical boundary layer dry contact occur in the Hertzian zone, considering the contact adhering layer effect in the inlet zone. 相似文献
996.
Beniamino Cappelletti Montano Antonio De Nicola 《Journal of Geometry and Physics》2007,57(12):2509-2520
We present a compared analysis of some properties of 3-Sasakian and 3-cosymplectic manifolds. We construct a canonical connection on an almost 3-contact metric manifold which generalises the Tanaka–Webster connection of a contact metric manifold and we use this connection to show that a 3-Sasakian manifold does not admit any Darboux-like coordinate system. Moreover, we prove that any 3-cosymplectic manifold is Ricci-flat and admits a Darboux coordinate system if and only if it is flat. 相似文献
997.
The damage spreading of the Ising model on three kinds of networks is studied with Glauber dynamics. One of the networks is
generated by evolving the hexagonal lattice with the star-triangle transformation. Another kind of network is constructed
by connecting the midpoints of the edges of the topological hexagonal lattice. With the evolution of these structures, damage
spreading transition temperature increases and a general explanation for this phenomenon is presented from the view of the
network. The relationship between the transition temperature and the network measure-clustering coefficient is set up and
it is shown that the increase of damage spreading transition temperature is the result of more and more clustering of the
network. We construct the third kind of network-random graphs with Poisson degree distributions by changing the average degree
of the network. We show that the increase in the average degree is equivalent to the clustering of nodes and this leads to
the increase in damage spreading transition temperature.
相似文献
998.
S. Ansumali S. Arcidiacono S. S. Chikatamarla N. I. Prasianakis A. N. Gorban I. V. Karlin 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(2):135-139
A general lattice Boltzmann method for simulation of
fluids with tailored transport coefficients is presented. It is
based on the recently introduced quasi-equilibrium kinetic models,
and a general lattice Boltzmann implementation is developed.
Lattice Boltzmann models for isothermal binary mixtures with a
given Schmidt number, and for a weakly compressible flow with a
given Prandtl number are derived and validated. 相似文献
999.
L. Wu S. Zhu Y. Ni 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):349-354
Combination of two basic types of synchronization, anticipatory
synchronization and lagged synchronization, is investigated
numerically between two coupled semiconductor lasers. It is found
that lagged synchronization produced by a backward coupling with a
suitable delay can combine with the originally hidden anticipatory
synchronization and produce a type of synchronization overcoming the
original lagged synchronization produced by a forward coupling. We
study the combination synchronization phenomenon when the delay of
the backward coupling is different from that of the original
anticipatory synchronization. Our results suggest that the
synchronization combination phenomenon might allow an interpretation
of an experimental observation by Sivaprakasam et al. [Phys.
Rev. Lett. 87, 154101 (2001)] that the anticipating time is
irrespective of the external-cavity round trip time, which to date remains to be understood. 相似文献
1000.
Non-Fellerian particle systems are characterized by nonlocal interactions, somewhat analogous to non-Gibbsian distributions.
They exhibit new phenomena that are unseen in standard interacting particle systems. We consider freezing transitions in one-dimensional
non-Fellerian processes which are built from the abelian sandpile additions to which in one case, spin flips are added, and
in another case, so called anti-sandpile subtractions. In the first case and as a function of the sandpile addition rate,
there is a sharp transition from a non-trivial invariant measure to the trivial invariant measure of the sandpile process.
For the combination sandpile plus anti-sandpile, there is a sharp transition from one frozen state to the other anti-state. 相似文献