全文获取类型
收费全文 | 355364篇 |
免费 | 2283篇 |
国内免费 | 881篇 |
专业分类
化学 | 158499篇 |
晶体学 | 5433篇 |
力学 | 19713篇 |
综合类 | 11篇 |
数学 | 69018篇 |
物理学 | 105854篇 |
出版年
2020年 | 1729篇 |
2019年 | 1925篇 |
2018年 | 18728篇 |
2017年 | 19329篇 |
2016年 | 12061篇 |
2015年 | 3686篇 |
2014年 | 3934篇 |
2013年 | 9478篇 |
2012年 | 13361篇 |
2011年 | 27622篇 |
2010年 | 16719篇 |
2009年 | 17162篇 |
2008年 | 22146篇 |
2007年 | 27064篇 |
2006年 | 7067篇 |
2005年 | 13692篇 |
2004年 | 10056篇 |
2003年 | 9945篇 |
2002年 | 7068篇 |
2001年 | 6502篇 |
2000年 | 5172篇 |
1999年 | 3693篇 |
1998年 | 2960篇 |
1997年 | 2848篇 |
1996年 | 2882篇 |
1995年 | 2622篇 |
1994年 | 2473篇 |
1993年 | 2312篇 |
1992年 | 2934篇 |
1991年 | 2844篇 |
1990年 | 2779篇 |
1989年 | 2810篇 |
1988年 | 2844篇 |
1987年 | 2845篇 |
1986年 | 2711篇 |
1985年 | 3426篇 |
1984年 | 3443篇 |
1983年 | 2730篇 |
1982年 | 2830篇 |
1981年 | 2882篇 |
1980年 | 2657篇 |
1979年 | 3006篇 |
1978年 | 3002篇 |
1977年 | 3029篇 |
1976年 | 2887篇 |
1975年 | 2616篇 |
1974年 | 2565篇 |
1973年 | 2566篇 |
1972年 | 1755篇 |
1968年 | 1808篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
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
83.
84.
X-ray diffraction patterns of nanocrystalline Fe-Cu-Nb-Si-B (FINEMET) alloys reveal that bcc α-Fe/α-FeSi crystallites with
the average grain size of 20(5) nm are dispersed in amorphous matrix. Enhanced electron—electron interaction (EEI) and quantum
interference (QI) effects as well as electron-magnon (and/or electron-spin fluctuation) scattering turn out to be the main
mechanisms that govern the temperature dependence of resistivity. Of all the inelastic scattering processes, inelastic electron-phonon
scattering is the most effective mechanism to destroy phase coherence of electron wave functions. The diffusion constant,
density of states at the Fermi level and the inelastic scattering time have been estimated, for the first time, for the alloys
in question
Article presented at the International Symposium on Advances in Superconductivity and Magnetism: Materials, Mechanisms and
Devices, ASMM2D-2001, 25–28 September 2001, Mangalore, India. 相似文献
85.
86.
I. V. Denisova O. A. Ladyzhenskaya G. A. Seregin N. N. Uraltseva E. V. Frolova 《Journal of Mathematical Sciences》2005,130(4):4775-4779
Bibliography: 42 titles.__________Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 306, 2003, pp. 7–15. 相似文献
87.
88.
V. V. Kozlov 《Functional Analysis and Its Applications》2005,39(4):271-283
We discuss the symplectic geometry of linear Hamiltonian systems with nondegenerate Hamiltonians. These systems can be reduced to linear second-order differential equations characteristic of linear oscillation theory. This reduction is related to the problem on the signatures of restrictions of quadratic forms to Lagrangian planes. We study vortex symplectic planes invariant with respect to linear Hamiltonian systems. These planes are determined by the solutions of quadratic matrix equations of a special form. New conditions for gyroscopic stabilization are found. 相似文献
89.
Dimitar I. Pushkarov 《Central European Journal of Physics》2004,2(3):420-455
Basic ideas and results which characterize quantum diffusion of defects in quantum crystals like solid helium as a new phenomenon
are presented. Quantum effects in such media lead to a delocalization of point defects (vacancies, impurities etc.) and they
turn into quasiparticles of a new type—defectons, which are characterized not by their position in the crystal lattice but
by their quasimomentum and dispersion law. Defecton-defecton and defecton-phonon scattering are considered and an interpolation
formula for the diffusion coefficient valid in all interesting temperature and concentration regions is presented. A comparison
with the experimental data is made. Some alternative points of view are discussed in detail and the inconsistency of the Kisvarsanyi-Sullivan
theory is shown. 相似文献
90.
The rate constants k1 for the reaction of CF3CF2CF2CF2CF2CHF2 with OH radicals were determined by using both absolute and relative rate methods. The absolute rate constants were measured at 250–430 K using the flash photolysis–laser‐induced fluorescence (FP‐LIF) technique and the laser photolysis–laser‐induced fluorescence (LP‐LIF) technique to monitor the OH radical concentration. The relative rate constants were measured at 253–328 K in an 11.5‐dm3 reaction chamber with either CHF2Cl or CH2FCF3 as a reference compound. OH radicals were produced by UV photolysis of an O3–H2O–He mixture at an initial pressure of 200 Torr. Ozone was continuously introduced into the reaction chamber during the UV irradiation. The k1 (298 K) values determined by the absolute method were (1.69 ± 0.07) × 10?15 cm3 molecule?1 s?1 (FP‐LIF method) and (1.72 ± 0.07) × 10?15 cm3 molecule?1 s?1 (LP‐LIF method), whereas the K1 (298 K) values determined by the relative method were (1.87 ± 0.11) × 10?15 cm3 molecule?1 s?1 (CHF2Cl reference) and (2.12 ± 0.11) × 10?15 cm3 molecule?1 s?1 (CH2FCF3 reference). These data are in agreement with each other within the estimated experimental uncertainties. The Arrhenius rate constant determined from the kinetic data was K1 = (4.71 ± 0.94) × 10?13 exp[?(1630 ± 80)/T] cm3 molecule?1 s?1. Using kinetic data for the reaction of tropospheric CH3CCl3 with OH radicals [k1 (272 K) = 6.0 × 10?15 cm3 molecule?1 s?1, tropospheric lifetime of CH3CCl3 = 6.0 years], we estimated the tropospheric lifetime of CF3CF2CF2CF2CF2CHF2 through reaction with OH radicals to be 31 years. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 36: 26–33, 2004 相似文献