全文获取类型
收费全文 | 551900篇 |
免费 | 3683篇 |
国内免费 | 926篇 |
专业分类
化学 | 258308篇 |
晶体学 | 8280篇 |
力学 | 30846篇 |
综合类 | 11篇 |
数学 | 84393篇 |
物理学 | 174671篇 |
出版年
2020年 | 4680篇 |
2019年 | 5465篇 |
2018年 | 12721篇 |
2017年 | 13162篇 |
2016年 | 13050篇 |
2015年 | 5772篇 |
2014年 | 9736篇 |
2013年 | 20318篇 |
2012年 | 18564篇 |
2011年 | 26352篇 |
2010年 | 18875篇 |
2009年 | 18977篇 |
2008年 | 24310篇 |
2007年 | 26377篇 |
2006年 | 16668篇 |
2005年 | 17681篇 |
2004年 | 15353篇 |
2003年 | 14674篇 |
2002年 | 13749篇 |
2001年 | 13177篇 |
2000年 | 10613篇 |
1999年 | 7872篇 |
1998年 | 7203篇 |
1997年 | 7072篇 |
1996年 | 6707篇 |
1995年 | 6020篇 |
1994年 | 6171篇 |
1993年 | 5895篇 |
1992年 | 6297篇 |
1991年 | 6615篇 |
1990年 | 6496篇 |
1989年 | 6409篇 |
1988年 | 6285篇 |
1987年 | 6246篇 |
1986年 | 5800篇 |
1985年 | 7328篇 |
1984年 | 7760篇 |
1983年 | 6587篇 |
1982年 | 6822篇 |
1981年 | 6523篇 |
1980年 | 6319篇 |
1979年 | 6684篇 |
1978年 | 7044篇 |
1977年 | 6973篇 |
1976年 | 7193篇 |
1975年 | 6659篇 |
1974年 | 6560篇 |
1973年 | 6866篇 |
1972年 | 5279篇 |
1971年 | 4585篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
162.
The capability of gated saturable absorbers for single-pulse selection is studied theoretically using the classical space-time-dependent rate-equation model. The dynamics of operation is followed experimentally by the well-known pump—probe technique. Comparing the theoretical and experimental results, it is found that gated saturable absorbers can efficiently be used for pulse forming and pulse selection of pulses longer than picosecond. 相似文献
163.
V. A. Nebol'sin B. M. Darinskii E. E. Popova A. A. Shchetinin 《Russian Physics Journal》1995,38(10):1023-1026
An estimate of the factors which influence the rate of growth of filamentary silicon crystals in a standard chloride system using a quartz reactor with hot walls is given. It is shown that a diffusion form of crystallization is observed under the conditions investigated.Voronezh State Technical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 22–26, October, 1995. 相似文献
164.
V. I. Storozhev 《Journal of Mathematical Sciences》1995,77(6):3514-3518
On the basis of the method of successive approximations in formal series we construct systems of particular solutions of the
equations of planar and flexural harmonic vibrations of thin rectilinear anisotropic plates with a plane of symmetry of elastic
properties parallel to the faces. The solutions constructed are classified as special sk-functions of generalized complex
variables.
Translated fromTeoreticheskaya i Prikladnaya Mekhanika No. 24, 1993, pp. 54–61. 相似文献
165.
F. G. Vagizov 《Hyperfine Interactions》1995,95(1):85-95
We present the results of an experimental investigation of a RF splitting of57Fe hyperfine lines in the regime of NMR and Mössbauer double resonance. The experiments have been performed as a function of RF field intensity and static magnetic field magnitude. The intensity of the RF components and the separation between them are extremely sensitive to the frequency and amplitude of the RF magnetic field. The RF splitting of hyperfine lines is inversely proportional to the strength of the static magnetic field. 相似文献
166.
The characterization of the clusters formed on alkaline hydrolysis of [PdCl4]2– was performed using17O,23Na,35Cl,133Cs NMR and UV spectroscopy. The chemical composition of the clusters was found to be [Pd(OH)2]
n
·nNaCl. No mononuclear oxo- or hydroxocomplexes were detected. The spatial structure of the clusters is stabilized by alkali metal cations.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 675–679, April, 1993. 相似文献
167.
We consider tilde-geometries (orT-geometries), which are geometries belonging to diagrams of the following shape: Here the rightmost edge stands for the famous triple cover of the classical generalized quadrangle related to the group Sp4(2). The automorphism group of the cover is the nonsplit extension 3·Sp4(2) – 3 ·S
6. Five examples of flag-transitiveT-geometries were known. These are rank 3 geometries related to the groupsM
24 (the Mathieu group),He (the Held group) and and 37·Sp6(2) (a nonsplit extension); a rank 4 geometry related to the Conway groupCo
1 and a rank 5 geometry related to the Fischer-Griess Monster groupF
1. In the present paper we construct an infinite family of flag-transitiveT-geometries and prove that all the new geometries are simply connected. The automorphism group of the rankn geometry in the family is a nonsplit extension of a 3-group by the symplectic group Sp2n
(2). The rank of the 3-group is equal to the number of 2-dimensional subspaces in ann-dimensional vector space over GF(2). 相似文献
168.
The electrical conductivity of hydrosols of ultradispersed diamonds was studied. The electromembrane method for cleaning and concentrating of ultradispersed diamonds in hydrosols was considered. The influence exerted by the concentration of the dispersed phase on the electrical characteristics of the cleaning process was analyzed. A mathematical relation making it possible to evaluate the output characteristics of the process and to determine the geometrical characteristics of the apparatus was proposed. 相似文献
169.
A. E. Dorokhov 《Czechoslovak Journal of Physics》2002,52(3):C79-C90
Nonperturbative nolocal structure of QCD vacuum is well described by instanton model. Specific helicity and flavor structure of zero modes of quarks, in instanton field allows simultaneously to explain some important features of low-and high-energy hadron phenomemology. The basic characteristics of hadron spectrum, partonic sum rules, heavyquark potential etc within the instanton liquid model are briefly discussed. 相似文献
170.
The radiation emitted by charged, scalar particles in a Schwarzschild field with maximal acceleration corrections is calculated classically and in the tree approximation of quantum field theory. In both instances the particles emit radiation that has characteristics similar to those of gamma-ray bursters. 相似文献