全文获取类型
收费全文 | 508486篇 |
免费 | 5212篇 |
国内免费 | 1608篇 |
专业分类
化学 | 256014篇 |
晶体学 | 7188篇 |
力学 | 25089篇 |
综合类 | 13篇 |
数学 | 80057篇 |
物理学 | 146945篇 |
出版年
2021年 | 3805篇 |
2020年 | 4217篇 |
2019年 | 4562篇 |
2018年 | 15608篇 |
2017年 | 15335篇 |
2016年 | 14552篇 |
2015年 | 6351篇 |
2014年 | 8822篇 |
2013年 | 20463篇 |
2012年 | 19105篇 |
2011年 | 28961篇 |
2010年 | 18696篇 |
2009年 | 18957篇 |
2008年 | 23756篇 |
2007年 | 25526篇 |
2006年 | 16493篇 |
2005年 | 15766篇 |
2004年 | 14944篇 |
2003年 | 13749篇 |
2002年 | 12665篇 |
2001年 | 13632篇 |
2000年 | 10333篇 |
1999年 | 8040篇 |
1998年 | 6727篇 |
1997年 | 6435篇 |
1996年 | 6264篇 |
1995年 | 5587篇 |
1994年 | 5465篇 |
1993年 | 5288篇 |
1992年 | 5880篇 |
1991年 | 5989篇 |
1990年 | 5714篇 |
1989年 | 5525篇 |
1988年 | 5547篇 |
1987年 | 5431篇 |
1986年 | 5143篇 |
1985年 | 6607篇 |
1984年 | 6737篇 |
1983年 | 5339篇 |
1982年 | 5430篇 |
1981年 | 5406篇 |
1980年 | 5002篇 |
1979年 | 5389篇 |
1978年 | 5528篇 |
1977年 | 5406篇 |
1976年 | 5344篇 |
1975年 | 4930篇 |
1974年 | 4897篇 |
1973年 | 4904篇 |
1972年 | 3472篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
O. Kortner M.P. Locher V.E. Markushin P. Weber O. Wigger 《The European Physical Journal C - Particles and Fields》2002,25(3):353-360
We study correlations in the exclusive reaction at rest with complete reconstruction of the kinematics for each event. The inclusive distribution is fairly flat at small
invariant mass of the pion pair while a small enhancement in the double differential distribution is observed for small invariant
masses of both pion pairs. Dynamical models with resonances in the final state are shown to be consistent with the data while
the stochastic HBT mechanism is not supported by the present findings.
Received: 26 February 2002 / Revised version: 22 July 2002 / Published online: 30 August 2002 相似文献
122.
G. Tiana M.H. Jensen K. Sneppen 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(1):135-140
A feedback mechanism that involves the proteins p53 and mdm2, induces cell death as a controlled response to severe DNA damage.
A minimal model for this mechanism demonstrates that the response may be dynamic and connected with the time needed to translate
the mdm2 protein. The response takes place if the dissociation constant k between p53 and mdm2 varies from its normal value. Although it is widely believed that it is an increase in k that triggers the response, we show that the experimental behaviour is better described by a decrease in the dissociation
constant. The response is quite robust upon changes in the parameters of the system, as required by any control mechanism,
except for few weak points, which could be connected with the onset of cancer.
Received 8 May 2002 / Received in final form 9 July 2002 Published online 17 September 2002 相似文献
123.
Z. V. Golubenko A. S. Kamzin L. P. Ol’khovik M. M. Khvorov Z. I. Sizova V. P. Shabatin 《Physics of the Solid State》2002,44(9):1698-1702
Magnetization and remagnetization processes in a close-packed nanodispersed barium hexaferrite powder sample in the magnetically stable state were analyzed. Reversibility effects were discussed in terms of interparticle interaction. Judging from the magnetization curve and the parameters characterizing remagnetization irreversibility, the sample under study is a model system of small Stoner-Wohlfarth particles. 相似文献
124.
An analysis of events in the tunneling junction shows that the interaction of one-electron processes in a many-electron system may be a source of scale-invariant low-frequency fluctuations of conductivity (the interaction consists in that the quantum probability of an electron transition depends on fast random changes in the environment in the course of the transition, including the changes caused by analogous transitions). The theory relates flicker fluctuations in the tunneling conductivity to the discrete character of the spectrum of electron states and explains the nonlinearity of the noise-current characteristic observed in nanocomposites. 相似文献
125.
M.V. Kossov 《The European Physical Journal A - Hadrons and Nuclei》2002,14(3):377-392
Photonuclear interaction cross-sections from the GEANT4 database are approximated for all nuclei and all energies (from the
hadron production threshold to about 40 TeV). The approximation methods in the giant-dipole resonance region, nucleon resonance
region, and high-energy region are improved with respect to existing approximations. As an application of the approximation
for photonuclear cross-sections, an improved method of calculating electronuclear cross-sections is developed. The interaction
cross-section of virtual photons with nuclei at high Q2 are approximated and a simple algorithm for describing the electronuclear reactions, including high-Q2 scattering, is proposed.
Received: 22 February 2002 / Accepted: 6 May 2002 相似文献
126.
Using elementary graded automorphisms of polytopal algebras (essentially the coordinate rings of projective toric varieties)
polyhedral versions of the group of elementary matrices and the Steinberg and Milnor groups are defined. They coincide with
the usual K-theoretic groups in the special case when the polytope is a unit simplex and can be thought of as compact/polytopal substitutes
for the tame automorphism groups of polynomial algebras. Relative to the classical case, many new aspects have to be taken
into account. We describe these groups explicitly when the underlying polytope is 2-dimensional. Already this low-dimensional
case provides interesting classes of groups.
Received: 13 December 2001 / Revised version: 24 June 2002
The second author was supported by the Deutsche Forschungsgemeinschaft, INTAS grant 99-00817 and TMR grant ERB FMRX CT-97-0107
Mathematics Subject Classification (2000): 14L27, 14M25, 19C09, 52B20 相似文献
127.
王巨平 《中国科学A辑(英文版)》2002,45(7):827-835
This paper verifies the singularity conjecture for Jacobi forms with higher degree in some typical cases, and gives constructions
for the Jacobi cusp forms whose Fourier coefficients can be expressed by some kind of Rankin-typeL-series. 相似文献
128.
A.R. DegheidyM.T. Attia M. Sallah 《Journal of Quantitative Spectroscopy & Radiative Transfer》2002,74(3):285-297
The time-independent radiative transfer problem in a scattering and absorbing planar random medium with general boundary conditions and internal energy source is considered. The medium is assumed to consist of two randomly mixed immiscible fluids, with the mixing statistics described as a two-state homogeneous Markov process. The problem is solved in terms of the solution of the corresponding free-source problem with simple boundary conditions which is solved using Pomraning-Eddington approximation in the deterministic case. A formalism, developed to treat radiative transfer in statistical mixtures, is used to obtain the ensemble-averaged solution. The average partial heat fluxes are calculated in terms of the albedoes of the source-free problem. Results are obtained for isotropic and anisotropic scattering for specular and diffused reflecting boundaries. 相似文献
129.
It is explicitly shown that if phase transition occurs at the core of a newborn neutron star with moderately strong magnetic
field strength, which populates only the electron’s Landau levels, then in the β -equilibrium condition, the quark core is
energetically much more unstable than the neutron matter of identical physical condition. 相似文献
130.