全文获取类型
收费全文 | 558140篇 |
免费 | 20987篇 |
国内免费 | 10936篇 |
专业分类
化学 | 303278篇 |
晶体学 | 8075篇 |
力学 | 27321篇 |
综合类 | 577篇 |
数学 | 73572篇 |
物理学 | 177240篇 |
出版年
2022年 | 4278篇 |
2021年 | 5417篇 |
2020年 | 6453篇 |
2019年 | 6234篇 |
2018年 | 14417篇 |
2017年 | 14948篇 |
2016年 | 13506篇 |
2015年 | 8665篇 |
2014年 | 10649篇 |
2013年 | 22202篇 |
2012年 | 23236篇 |
2011年 | 33547篇 |
2010年 | 21795篇 |
2009年 | 21497篇 |
2008年 | 28446篇 |
2007年 | 30891篇 |
2006年 | 17834篇 |
2005年 | 21592篇 |
2004年 | 16781篇 |
2003年 | 14917篇 |
2002年 | 12756篇 |
2001年 | 13134篇 |
2000年 | 10444篇 |
1999年 | 8382篇 |
1998年 | 6952篇 |
1997年 | 6909篇 |
1996年 | 7023篇 |
1995年 | 6198篇 |
1994年 | 5993篇 |
1993年 | 5612篇 |
1992年 | 6141篇 |
1991年 | 6052篇 |
1990年 | 5690篇 |
1989年 | 5539篇 |
1988年 | 5299篇 |
1987年 | 5224篇 |
1986年 | 5032篇 |
1985年 | 6530篇 |
1984年 | 6523篇 |
1983年 | 5446篇 |
1982年 | 5810篇 |
1981年 | 5493篇 |
1980年 | 5215篇 |
1979年 | 5514篇 |
1978年 | 5900篇 |
1977年 | 5698篇 |
1976年 | 5685篇 |
1975年 | 5292篇 |
1974年 | 5378篇 |
1973年 | 5475篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
941.
942.
N. V. Vysotina A. S. Naumov N. N. Rozanov R. L. Sabirov V. E. Semenov V. A. Smirnov T. V. Starchikova S. V. Fedorov S. A. Chizhov V. E. Yashin 《Optics and Spectroscopy》2004,97(3):411-415
The final stage of self-focusing of 500-ps pulses of a neodymium laser in silicate and phosphate glasses and in the nonlinear liquids perfluorooctane, benzene, and toluene is studied theoretically and experimentally. The formation of spatial solitons, which are stable due to the nonlinearity saturation, is demonstrated. It is found that the intensity of the nonlinearity saturation is close to that of the threshold breakdown for glasses and the role of stimulated Raman scattering is significant for liquids. 相似文献
943.
A self-consistent, completely quantum calculation of the structure of the inner crust of neutron stars is carried out in the Wigner-Seitz approximation with a realistic phenomenological nuclear energy functional, where pair correlations of neutrons and protons are included in the explicit form. It has been shown that the superfluidity of neutrons and protons affects the structure of the ground state of the crust. 相似文献
944.
The kinetics of formation and relaxation of transient holographic gratings recorded in a system of saturable three-level centers is studied. Distortions in the shape of the profile of recorded and decaying structures of population and of the refractive index are taken into account. The analysis of the time dependences of diffraction efficiencies of different orders is performed for phase (thermal) and amplitude (concentration) gratings. 相似文献
945.
Aiqing Zhang Xiangdan Li Changwoon Nah Keejun Hwang Myong‐Hoon Lee 《Journal of polymer science. Part A, Polymer chemistry》2003,41(1):22-29
A soluble aromatic polyimide was chloromethylated via a reaction with chloromethyl methyl ether in the presence of tin(IV) chloride to produce a new starting material for the modification of aromatic polyimides. The chemical structure of the resulting polymer was confirmed by 1H NMR and Fourier transform infrared spectroscopy. The maximum number of chloromethyl groups per repeat unit was 1.81. The chloromethylated polyimide was stable up to 250 °C and soluble in both chloroform and tetrahydrofuran. So that its utilization for further modification could be demonstrated, cinnamic acid was reacted with the formed polyimide, and it produced a new photosensitive polyimide with a cinnamoyl side chain. The photosensitivity of the resulting polyimide was investigated with ultraviolet spectroscopic methods. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 22–29, 2003 相似文献
946.
947.
948.
B. Ya. Balagurov 《Technical Physics》2003,48(8):945-951
A sequential scheme for calculating the polarizability of a pair of parallel cylinders with an arbitrary (but fairly symmetric) form is suggested. An infinite set of algebraic equations is derived for coefficients involved in an expression for the potential. The numerical solution of this set makes it possible to find the polarizability with any degree of accuracy. This method is unrelated to the cylinder shape. The electrostatic properties of the cylinders are described in terms of the multipolar polarizability matrix. 相似文献
949.
K. K. Turgunov B. Tashkhodzhaev L. V. Molchanov Kh. M. Shakhidoyatov 《Journal of Structural Chemistry》2004,45(5):912-916
The structure of bis-(2,3-pentamethylene-3,4-dihydro-4-oxoquinazolinium) tetrachlorocuprate (II) sesquihydrate, (C13H15N2O)2[CuCl4]·1.5H2O, was determined by single crystal X-ray diffraction. In contrast to the previously studied analogs, the compound contains crystallization water molecules.Original Russian Text Copyright © 2004 by K. K. Turgunov, B. Tashkhodzhaev, L. V. Molchanov, and Kh. M. Shakhidoyatov__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 955–959, September–October, 2004. 相似文献
950.