全文获取类型
收费全文 | 317230篇 |
免费 | 7735篇 |
国内免费 | 5379篇 |
专业分类
化学 | 166240篇 |
晶体学 | 5069篇 |
力学 | 15722篇 |
综合类 | 323篇 |
数学 | 36574篇 |
物理学 | 106416篇 |
出版年
2021年 | 3375篇 |
2020年 | 3890篇 |
2019年 | 4295篇 |
2018年 | 5231篇 |
2017年 | 5067篇 |
2016年 | 6967篇 |
2015年 | 4554篇 |
2014年 | 7071篇 |
2013年 | 14460篇 |
2012年 | 12097篇 |
2011年 | 14197篇 |
2010年 | 10465篇 |
2009年 | 10375篇 |
2008年 | 12658篇 |
2007年 | 12406篇 |
2006年 | 11596篇 |
2005年 | 10426篇 |
2004年 | 9514篇 |
2003年 | 8455篇 |
2002年 | 8538篇 |
2001年 | 9310篇 |
2000年 | 7113篇 |
1999年 | 5653篇 |
1998年 | 4910篇 |
1997年 | 4625篇 |
1996年 | 4420篇 |
1995年 | 3974篇 |
1994年 | 3971篇 |
1993年 | 3991篇 |
1992年 | 4083篇 |
1991年 | 4285篇 |
1990年 | 4025篇 |
1989年 | 3905篇 |
1988年 | 3791篇 |
1987年 | 3718篇 |
1986年 | 3523篇 |
1985年 | 4566篇 |
1984年 | 4746篇 |
1983年 | 3850篇 |
1982年 | 4063篇 |
1981年 | 3905篇 |
1980年 | 3773篇 |
1979年 | 3981篇 |
1978年 | 4085篇 |
1977年 | 3989篇 |
1976年 | 4183篇 |
1975年 | 3785篇 |
1974年 | 3810篇 |
1973年 | 3870篇 |
1972年 | 2850篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
991.
孟昭英院士是著名物理学家、我国电子学开拓者,在清华大学物理系历史上是积极倡导“理工会通”教育思想的杰出大师,曾为我国培养了许多高级科技人才,有的成了我国某学科学术带头人,有的是佩戴上“两弹、一星”国家勋章的科学家.孟昭英先生一生辉煌、半生坎坷,但是即使在蒙受奇冤的年代,仍然以国家和民族大业为重,不懈努力.改革开放后,更是老骥伏枥,惮精竭虑地为清华大学物理系的重振作出了卓越贡献.值此孟昭英先生诞辰100周年之际,挥泪命笔写下此文。 相似文献
992.
Yu. D. Perfiliev V. S. Rusakov L. A. Kulikov A. A. Kamnev K. Alkhatib 《Hyperfine Interactions》2006,167(1-3):881-885
To explain line broadening in emission Mössbauer spectra as compared to the corresponding absorber measurements, the model of trapped electrons has been proposed. Auger electrons (emitted, e.g. after electron capture by 57Co or after the converted isomeric transition of 119mSn), as well as secondary electrons, may be trapped in the proximity to the nucleogenic ion. Electrons captured by lattice traps at different distances from the daughter ion induce an asymmetric distribution of quadrupole splitting in the resulting emission spectra, as shown in a few examples. This model is supported by estimates of quadrupole splitting values which may be caused by such trapped electrons located at specified distances from the nucleogenic atom. 相似文献
993.
Rare earths exhibit complex magnetic phase diagrams resulting from the competition between various contributions to the magnetic
energy: exchange, anisotropy and magnetostriction. The epitaxy of a rare-earth film on a substrate induces (i) a clamping
to the substrate and (ii) pseudomorphic strains. Both these effects are shown to lead to modifications of the magnetic properties
in (0 0 1)Dy, (0 0 1)Tb and (1 1 0)Eu films. In Dy and Tb films, spectacular variations of the Curie temperature have been
evidenced. Additionally, Tb films exhibit a new large wavelength magnetic modulation. In Eu films, one of the helical magnetic
domains disappears at low temperature whereas the propagation vectors of the other helices are tilted. The link between structural
and magnetic properties is underlined via magnetoelastic models. Moreover, molecular beam epitaxy permits the growth of Sm
in a metastable dhcp phase. The magnetic structure of dhcp Sm has been elucidated for the first time. In this review, neutron
scattering is shown to be a powerful technique to reveal the magnetic structures of rare-earth films. 相似文献
994.
We analyze the spectra of pions and protons in heavy-ion collisions at relativistic energies from 2 A GeV to 65+65 A GeV by
using a jet-implemented hadron-string cascade model. In this energy region, hadron transverse mass spectra first show softening
until SPS energies, and re-hardening may emerge at RHIC energies. Since hadronic matter is expected to show only softening
at higher energy densities, this re-hardening of spectra can be interpreted as a good signature of the quark-gluon plasma
formation 相似文献
995.
N. P. Landsman 《Communications in Mathematical Physics》1989,125(4):643-660
Bounds for large-mass behaviour in renormalized perturbation expansions at zero temperature, which were previously obtained by Manoukian and Caswell-Kennedy in momentum space, are rederived in the parametric representation. A very simple unified proof of the BPHZ theorem and the decoupling theorem is also given. A new technique for asymptotic analysis, based on a generalized Kontorovich-Lebedev integral transform, is introduced. This method is applied to find the leading high-temperature behaviour of perturbative field theories in the imaginary-time formalism. We prove that diagrams containing nonstatic modes, which at high temperature behave like particles with a large mass, are suppressed relative to purely static diagrams. This rigorously proves a limited form of dimensional reduction at infinite temperature. 相似文献
996.
997.
998.
999.
Eliza P. de Jager 《Topology and its Applications》2007,154(10):2117-2126
We show that the infimum of any family of proximally symmetric quasi-uniformities is proximally symmetric, while the supremum of two proximally symmetric quasi-uniformities need not be proximally symmetric. On the other hand, the supremum of any family of transitive quasi-uniformities is transitive, while there are transitive quasi-uniformities whose infimum with their conjugate quasi-uniformity is not transitive. Moreover we present two examples that show that neither the supremum topology nor the infimum topology of two transitive topologies need be transitive. Finally, we prove that several operations one can perform on and between quasi-uniformities preserve the property of having a complement. 相似文献
1000.