全文获取类型
收费全文 | 303820篇 |
免费 | 3338篇 |
国内免费 | 999篇 |
专业分类
化学 | 158891篇 |
晶体学 | 3871篇 |
力学 | 13518篇 |
综合类 | 10篇 |
数学 | 33458篇 |
物理学 | 98409篇 |
出版年
2020年 | 2369篇 |
2019年 | 2538篇 |
2018年 | 3234篇 |
2017年 | 3084篇 |
2016年 | 4863篇 |
2015年 | 3162篇 |
2014年 | 4737篇 |
2013年 | 13165篇 |
2012年 | 10032篇 |
2011年 | 12307篇 |
2010年 | 8278篇 |
2009年 | 7992篇 |
2008年 | 11113篇 |
2007年 | 11257篇 |
2006年 | 10947篇 |
2005年 | 10030篇 |
2004年 | 9190篇 |
2003年 | 8192篇 |
2002年 | 7974篇 |
2001年 | 9075篇 |
2000年 | 7036篇 |
1999年 | 5519篇 |
1998年 | 4542篇 |
1997年 | 4449篇 |
1996年 | 3902篇 |
1995年 | 3950篇 |
1994年 | 3612篇 |
1993年 | 3494篇 |
1992年 | 3989篇 |
1991年 | 3907篇 |
1990年 | 3827篇 |
1989年 | 3641篇 |
1988年 | 3705篇 |
1987年 | 3704篇 |
1986年 | 3457篇 |
1985年 | 4662篇 |
1984年 | 4980篇 |
1983年 | 4125篇 |
1982年 | 4509篇 |
1981年 | 4329篇 |
1980年 | 4239篇 |
1979年 | 4368篇 |
1978年 | 4537篇 |
1977年 | 4490篇 |
1976年 | 4577篇 |
1975年 | 4316篇 |
1974年 | 4178篇 |
1973年 | 4472篇 |
1972年 | 2825篇 |
1967年 | 2177篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Werner WinterGünther W.H Höhne 《Thermochimica Acta》2003,403(1):43-53
A method for measuring heat capacities of small samples using a chip-calorimeter and a heat pulse technique is described. The theoretical background to calculate the heat transport properties and the heat capacity of the sample from the pulse response function is given. Problems and potentials of the method are discussed. An example is given. 相似文献
992.
D. H. Beck 《Progress in Particle and Nuclear Physics》2003,50(2):248-449
A brief review of the structure of the nucleon as determined through parity-violating electron scattering is presented. The relationship between the electromagnetic and neutral weak currents is developed in a pedagogical introduction. Recent results and present measurements are discussed. 相似文献
993.
L. V. Giurgiu M. N. Grecu X. Filip O. Raita Al. Darabont D. Gavre J. Blasco 《Applied magnetic resonance》2003,24(3-4):351-360
We report an electron paramagnetic resonance (EPR) investigation of the spin dynamics in the paramagnetic regime of the colossal magnetoresistive manganites La2/3Ca1/3Mn1?x Me x O3 (Me=Al, In;x≤0.05). The temperature dependences of the EPR linewidth and integral intensity have been analyzed in terms of the bottleneck spin relaxation and small-polaron hopping models. The exchange coupling integral between Mn3+ and Mn4+ ions and the polaron activation energy decrease with increasing doping level. A discussion is given concerning the factors which could explain the observed changes. 相似文献
994.
995.
996.
A formulation of an implicit characteristic-flux-averaging method for the unsteady Euler equations with real gas effects is presented. Incorporation of a real gas into a general equation of state is achieved by considering the pressure as a function of density and specific internal energy. The Ricmann solver as well as the flux-split algorithm are modified by introducing the pressure derivatives with respect to density and internal energy. Expressions for calculating the values of the flow variables for a real gas at the cell faces are derived. The Jacobian matrices and the eigenvectors are defined for a general equation of state. The solution of the system of equations is obtained by using a mesh-sequencing method for acceleration of the convergence. Finally, a test case for a simple form of equation of state displays the differences from the corresponding solution for an ideal gas. 相似文献
997.
998.
999.
E. S. Moskalenko M. Larsson K. F. Karlsson P. O. Holtz B. Monemar W. V. Schoenfeld P. M. Petroff 《Physics of the Solid State》2007,49(10):1995-1998
We report on low-temperature microphotoluminescence (μ-PL) measurements of InAs/GaAs quantum dots (QDs) exposed to a lateral
external electric field. It is demonstrated that the QDs’ PL signal could be increased severalfold by altering the external
and/or the internal electric field, which could be changed by an additional infrared laser. A model which accounts for a substantially
faster lateral transport of the photoexcited carriers achieved in an external electric field is employed to explain the observed
effects. The results obtained suggest that the lateral electric fields play a major role for the dot luminescence intensity
measured in our experiment—a finding which could be used to tailor the properties of QD-based optoelectronic applications.
The text was submitted by the authors in English. 相似文献
1000.
A. D. Krisch 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):417-423
There will be a review of the history of polarized proton beams, and a discussion of the unexpected and still unexplained
large transverse spin effects found in several high-energy proton-proton spin experiments at the ZGS, AGS and Fermilab. Next,
there will be a discussion of present and possible future experiments on the violent elastic collisions of polarized protons
at IHEP-Protvino's 70GeV U-70 accelerator in Russia and the new high-intensity 50GeV J-PARC facility being built at Tokai
in Japan. 相似文献