全文获取类型
收费全文 | 132201篇 |
免费 | 1524篇 |
国内免费 | 825篇 |
专业分类
化学 | 49348篇 |
晶体学 | 2070篇 |
力学 | 8792篇 |
综合类 | 52篇 |
数学 | 27877篇 |
物理学 | 46411篇 |
出版年
2023年 | 230篇 |
2022年 | 396篇 |
2021年 | 435篇 |
2020年 | 431篇 |
2019年 | 420篇 |
2018年 | 10077篇 |
2017年 | 11009篇 |
2016年 | 5132篇 |
2015年 | 1520篇 |
2014年 | 906篇 |
2013年 | 1459篇 |
2012年 | 6363篇 |
2011年 | 15524篇 |
2010年 | 9140篇 |
2009年 | 9258篇 |
2008年 | 13094篇 |
2007年 | 16930篇 |
2006年 | 1635篇 |
2005年 | 8741篇 |
2004年 | 4778篇 |
2003年 | 4479篇 |
2002年 | 2272篇 |
2001年 | 1267篇 |
2000年 | 1121篇 |
1999年 | 700篇 |
1998年 | 520篇 |
1997年 | 471篇 |
1996年 | 560篇 |
1995年 | 460篇 |
1994年 | 422篇 |
1993年 | 335篇 |
1992年 | 329篇 |
1991年 | 306篇 |
1990年 | 290篇 |
1989年 | 242篇 |
1988年 | 240篇 |
1987年 | 214篇 |
1986年 | 191篇 |
1985年 | 206篇 |
1984年 | 194篇 |
1983年 | 147篇 |
1982年 | 145篇 |
1981年 | 140篇 |
1980年 | 121篇 |
1979年 | 139篇 |
1978年 | 151篇 |
1976年 | 105篇 |
1975年 | 90篇 |
1973年 | 119篇 |
1968年 | 112篇 |
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
101.
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
102.
103.
X Y Liu C J Li 《Science in China. Series B, Chemistry, life sciences & earth sciences》1989,32(10):1215-1223
To further evaluate the causality between endogenous pyrogen (EP)-induced fever and cyclic adenosine-3',5'-monophosphate (cyclic AMP) level, the effects of sodium salicylate (SS) on the febrile response and increased levels of cyclic AMP in both cerebrospinal fluid (c.s.f.) and plasma during EP-induced fever in rabbits were observed. The results suggest that cyclic AMP is probably involved in the central mediation of EP-induced fever and that increased concentration of cyclic AMP in c.s.f. associated with EP-induced fever is not the result of temperature elevation but appears to be caused by the increased synthesis in the central nervous system. In addition it is confirmed that blood is impossibly a contributory source of increased cyclic AMP in c.s.f. during EP fever, and that SS may act subsequent to the increase in cyclic AMP. 相似文献
104.
P.A. Grillet 《Acta Mathematica Hungarica》2005,106(4):301-315
Summary Three weak variants of compactness which lie strictly between compactness and quasicompactness, are introduced. Their basic properties are studied. The interplay with mapping and their direct and inverse preservation under mappings are investigated. In the process three decompositions of compactness are observed. 相似文献
105.
106.
Comprehensive studies of X-ray diffraction, oxygen content, superconductivity and Mössbauer effect have been made on FexCu1−xBa2YCu2O7+y superconductors (0.00≤x≤0.70) synthesized by ambient (AM) and high pressure (HP). Results indicate that all the HP-samples have tetragonal structure, smaller lattice parameter c and unit-cell volume than the AM-samples. The studies of oxygen content, and Mössbauer spectroscopy indicate that the HP-samples have higher oxygen content, carrier concentration and average valence of Fe than the AM-samples. Moreover, for the HP-samples more Fe atoms located in CuOx chains have fivefold-oxygen coordination. These are important reasons for the enhancement of Tc in the HP-samples. 相似文献
107.
A mixed problem is considered for a system of partial differential equations modeling the process of adsorption dynamics. An existence and uniqueness theorem is proved for this problem, and the solution properties are investigated. The inverse problem is posed, involving the determination of the system coefficient given additional information about the solution. A uniqueness theorem is proved for the solution of the inverse problem.__________Translated from Prikladnaya Matematika i Informatika, No. 16, pp. 5 – 14, 2004. 相似文献
108.
109.
In this paper we obtain a number of Maharam-type slice integral representations, with respect to scalar measures, for positive
projections in Dedekind complete vector lattices and f-algebras.
AMS Classification: 47B65, 46A40, 06F25 相似文献
110.
Within the framework of a piecewise homogeneous body model, with the use of three-dimensional geometrically nonlinear exact equations of elasticity theory, a method for determining the stress—strain state in unidirectional fibrous composites with locally curved fibers is developed for the case where the interaction between the fibers is neglected. All the investigations are carried out for an infinite elastic body containing a single locally curved fiber. Numerical results illustrating the effect of geometrical nonlinearity on the distribution of the self-balanced normal and shear stresses acting on the interface and arising as a result of local curving of the fiber are presented.__________Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 41, No. 4, pp. 433–448, July–August, 2005. 相似文献