全文获取类型
收费全文 | 14890篇 |
免费 | 398篇 |
国内免费 | 12篇 |
专业分类
化学 | 7613篇 |
晶体学 | 128篇 |
力学 | 365篇 |
综合类 | 1篇 |
数学 | 3365篇 |
物理学 | 3828篇 |
出版年
2021年 | 134篇 |
2020年 | 187篇 |
2019年 | 180篇 |
2018年 | 307篇 |
2017年 | 302篇 |
2016年 | 545篇 |
2015年 | 461篇 |
2014年 | 518篇 |
2013年 | 1093篇 |
2012年 | 747篇 |
2011年 | 970篇 |
2010年 | 569篇 |
2009年 | 504篇 |
2008年 | 662篇 |
2007年 | 619篇 |
2006年 | 515篇 |
2005年 | 353篇 |
2004年 | 364篇 |
2003年 | 310篇 |
2002年 | 308篇 |
2001年 | 229篇 |
2000年 | 225篇 |
1999年 | 179篇 |
1998年 | 163篇 |
1997年 | 152篇 |
1996年 | 147篇 |
1995年 | 136篇 |
1994年 | 125篇 |
1993年 | 123篇 |
1992年 | 143篇 |
1991年 | 118篇 |
1990年 | 138篇 |
1989年 | 124篇 |
1988年 | 126篇 |
1987年 | 114篇 |
1986年 | 109篇 |
1985年 | 160篇 |
1984年 | 172篇 |
1983年 | 144篇 |
1982年 | 146篇 |
1981年 | 139篇 |
1980年 | 137篇 |
1979年 | 146篇 |
1978年 | 161篇 |
1977年 | 128篇 |
1976年 | 150篇 |
1975年 | 133篇 |
1974年 | 143篇 |
1973年 | 115篇 |
1968年 | 92篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
83.
Classification of conformally flat n-dimensional pseudo-Riemannian spaces via Plebanski's method is discussed. It is based on embedding these spaces into a flat (n + 2)-dimensional space and on finding their minimal isometry groups which are subgroups of the conformal group. In particular, the case n = 4 is given in full detail and compared with incomplete results known in the literature. The found conformally flat spacetimes are identified with the associated solutions of the Einstein equations and with the spacetimes used in various cosmological considerations. 相似文献
84.
85.
Marijana ?aković Zora Popović 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(11):m507-m509
In the title compound, [Ni(N3)2(C6H6N2O)2], the NiII atom lies on an inversion centre. The distorted octahedral nickel(II) coordination environment contains two planar trans-related N,O-chelating picolinamide ligands in one plane and two monodentate azide ligands perpendicular to this plane. Molecules are linked into a three-dimensional framework by N—H...N hydrogen bonds. 相似文献
86.
87.
M. Mijatović G. Ivanovski B. Veljanoski K. Trenčevski 《Zeitschrift für Physik A Hadrons and Nuclei》1993,345(1):65-77
We have investigated the scattering and bound states of a nonrelativistic spin-1/2 particle in the system ofN magnetic barriers (or magnetic wells) andN magnetic delta functions. We have studied three types of problems: tunnelling with spin, band structure and change of polarization during transmission and reflection. 相似文献
88.
M. Kveder R. Rakoš M. Gavella V. Lipovac G. Pifat S. Pečar M. Schara 《Applied magnetic resonance》2004,27(1-2):77-86
The perturbation of the physical state of cell membranes triggered by an external oxidative stimulus has been studied with sperm cells which were chosen as a model system. Electron paramagnetic resonance (EPR) spectroscopy was applied and three different nitroxides bearing a paramagnetic group on the 5th, 7th and 13th carbon of the stearic acid acyl chain were used to probe different regions of the membrane. The theoretical simulations of the experimental spectra indicate distinct domains in the intact cell plasma membrane where local steric constraints impose different degrees of motional averaging experienced by the reporter group. Upon the external oxidative stimulus the spectral changes were proportional to the accumulated oxidation products and were detected only for the reporter group residing close to the lipid-water interface. The EPR spectra reveal that the motion of the reporter group has slowed down in the oxidized cells and that the oxidatively modified membrane shows up as a more rigid structure as compared with the native state. The results also indicate that the oxidation-induced spectral changes are supressed in the presence of gangliosides. 相似文献
89.
90.
Dragan DJURCIC Aleksandar TORGASEV 《数学学报(英文版)》2006,22(3):689-692
In this paper, we prove some properties of the Seneta sequences and functions, and in particular we prove a representation theorem in the Karamata sense for the sequences from the Seneta class SOc. 相似文献