全文获取类型
收费全文 | 4813篇 |
免费 | 248篇 |
国内免费 | 220篇 |
专业分类
化学 | 1058篇 |
晶体学 | 52篇 |
力学 | 158篇 |
综合类 | 17篇 |
数学 | 2255篇 |
物理学 | 1741篇 |
出版年
2023年 | 40篇 |
2022年 | 65篇 |
2021年 | 95篇 |
2020年 | 123篇 |
2019年 | 116篇 |
2018年 | 102篇 |
2017年 | 60篇 |
2016年 | 82篇 |
2015年 | 103篇 |
2014年 | 150篇 |
2013年 | 463篇 |
2012年 | 158篇 |
2011年 | 194篇 |
2010年 | 166篇 |
2009年 | 256篇 |
2008年 | 298篇 |
2007年 | 327篇 |
2006年 | 244篇 |
2005年 | 160篇 |
2004年 | 133篇 |
2003年 | 156篇 |
2002年 | 202篇 |
2001年 | 165篇 |
2000年 | 188篇 |
1999年 | 168篇 |
1998年 | 153篇 |
1997年 | 72篇 |
1996年 | 60篇 |
1995年 | 62篇 |
1994年 | 66篇 |
1993年 | 47篇 |
1992年 | 52篇 |
1991年 | 47篇 |
1990年 | 43篇 |
1989年 | 46篇 |
1988年 | 32篇 |
1987年 | 53篇 |
1986年 | 27篇 |
1985年 | 57篇 |
1984年 | 39篇 |
1983年 | 26篇 |
1982年 | 36篇 |
1981年 | 11篇 |
1980年 | 18篇 |
1979年 | 24篇 |
1978年 | 14篇 |
1977年 | 21篇 |
1976年 | 16篇 |
1974年 | 11篇 |
1973年 | 10篇 |
排序方式: 共有5281条查询结果,搜索用时 15 毫秒
101.
S.?Terranova D.?M.?Zhou A.?BonaseraEmail author 《The European Physical Journal A - Hadrons and Nuclei》2005,26(3):333-337
We show that large fluctuations of D-mesons kinetic-energy (or momentum) distributions might be a signature of a phase transition to the Quark-Gluon Plasma (QGP).
In particular, a jump in the variance of the momenta or kinetic energy, as a function of a control parameter (temperature
or Fermi energy at finite baryon densities) might be a signature for a first-order phase transition to the QGP. This behavior
is completely consistent with the order parameter defined for a system of interacting quarks both at zero temperature (and
finite baryon densities) or at finite temperatures which shows a jump in correspondence with a first-order phase transition
to the QGP. The J/Ψ displays exactly the same behavior of the order parameter and of the variance of the D-mesons. We discuss implications for relativistic heavy-ion collisions within the framework of a transport model and possible
hints for experimental search. 相似文献
102.
The surfaces of three kinds of copolymerized polyimide films were irradiated by ultraviolet (UV) light. The chemical composition changes of the films after irradiation were investigated by X-ray photoelectron spectroscopy (XPS), while their topographical changes were studied by atomic force microscopy (AFM). Besides, the surface topographical variation induced changes in friction behavior were recorded on a DF·PM unidirectional friction and wear test rig in a ball on block contact configuration. It was found that photodegradation took place, which induced the chain scission of the polyimide molecules and formation of low molecular weight oxidized material (LMWOM). Due to different photostability of the three kinds of polyimide, different chemical composition changes and forms of “LMWOM” were observed. Also, different friction behavior variations of the three kinds of polyimide films were recorded. It is thought that the polyimide film of PI (PPA + PMDA) with rod-like structures might have stronger photo-resistance, whose form of “LMWOM” was “nodules” and whose friction coefficient increased at 2 h of irradiation possibly due to cross-linking. In the case of PI (OPA + PMDA) and PI (MPA + PMDA) films, they mainly underwent photodegradation, which might soften the surfaces and increased the friction coefficients with increasing irradiation time. 相似文献
103.
U. K.?Sapaev J.?KutznerEmail author K.?Finsterbusch 《Optical and Quantum Electronics》2005,37(6):515-527
Type-II frequency doubling of short Gaussian laser pulses is studied theoretically. The situation is analysed when the group velocity mismatch and the walk-off angle of the interacting waves limit the frequency conversion efficiency. It is shown that with collinear ‘o’ and ‘e’ polarized fundamental waves a temporal and spatial separation of the fundamental beams is necessary to compensate for both effects. Results of the presented model are discussed for KDP crystals. 相似文献
104.
D. Khalil A. Makhoute A. Maquet G. Rahali M. Zitane 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):287-295
The dynamics of laser-assisted elastic collisions in
helium is studied using the second-order Born approximation.
Detailed calculations of the scattering amplitudes are performed
by using the Sturmian basis expansion. Differential cross sections
for elastic scattering with the net absorption/emission of up to
two photons are calculated for collision energies of 5 eV, 10 eV,
and 20 eV. We discuss the influence of the low-energy electrons on
the differential cross section (DCS) as a function of the
scattering angle for selected choices of the laser frequency and
the number of photons exchanged between the external field and
electron-helium system. 相似文献
105.
Most of the recent literature dealing with the modeling of financial assets assumes that the underlying dynamics of equity prices follow a jump process or a Lévy process. This is done to incorporate rare or extreme events not captured by Gaussian models. Of those financial models proposed, the most interesting include the CGMY, KoBoL and FMLS. All of these capture some of the most important characteristics of the dynamics of stock prices. In this article we show that for these particular Lévy processes, the prices of financial derivatives, such as European-style options, satisfy a fractional partial differential equation (FPDE). As an application, we use numerical techniques to price exotic options, in particular barrier options, by solving the corresponding FPDEs derived. 相似文献
106.
We study a quantum chain of oscillators with nonlinear quartic interactions, under the “narrow packet” approximation. We analyse the dynamics of quantum corrections and the conditions at which the quantum solution for average complex amplitude converges to the corresponding classical unstable solution which describes the four-wave decay processes of phonons. We develop an asymptotic theory by using a small quasiclassical parameter, and determine the characteristic time scale for which the evolution of decay processes is essentially specified by quantum effects.
AMS Subject classification: Primary: 35F10 Secondary: 35Q40, 35B40 相似文献
107.
108.
L. Pietronero F. Sylos Labini 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(1-2):285-289
Models of structure formation in the universe postulate that matter
distributions observed today in galaxy catalogs arise, through a
complex non-linear dynamics, by gravitational evolution from a very
uniform initial state. Dark matter plays the central role of providing
the primordial density seeds which will govern the dynamics of
structure formation. We critically examine the role of cosmological
dark matter by considering three different and related issues: Basic
statistical properties of theoretical initial density fields, several
elements of the gravitational many-body dynamics and key correlation
features of the observed galaxy distributions are discussed, stressing
some useful analogies with known systems in modern statistical
physics. 相似文献
109.
H. Wabnitz Y. Mairesse L. J. Frasinski M. Stankiewicz W. Boutu P. Breger P. Johnsson H. Merdji P. Monchicourt P. Salières K. Varjú M. Vitteau B. Carré 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(2):305-311
We investigate the carrier-envelope phase dependence of the total ionization yield for single and double ionization of xenon.
We compare our results to theoretical calculations and to the phase dependent asymmetry in photoelectron emission. We observe
that the phase dependence of the photoion yields, regardless if single or double ionization, is at least 2-3 orders of magnitude
below the photoelectron emission signal. We conclude that total photoionization yields are only very weakly dependent on the
carrier envelope phase, and that they are not a useful means for measurement of the phase. It seems possible that the broad
bandwidth of few-cycle pulses facilitates multiphoton ionization, which leads to a randomization of strong field ionization
phase dependencies. Besides, we observe that the spatial asymmetry in photoelectron emission appears to be useful as an indicator
for the laser pulse duration in the few cycle regime. 相似文献
110.
Intermediate processes and critical phenomena: Theory, method and progress of fractional operators and their applications to modern mechanics 总被引:1,自引:0,他引:1
From point of view of physics, especially of mechanics, we briefly introduce fractional operators (with emphasis on fractional
calculus and fractional differential equations) used for describing intermediate processes and critical phenomena in physics
and mechanics, their progress in theory and methods and their applications to modern mechanics. Some authors’ researches in
this area in recent years are included. Finally, prospects and evaluation for this subject are made. 相似文献