全文获取类型
收费全文 | 182328篇 |
免费 | 16788篇 |
国内免费 | 12829篇 |
专业分类
化学 | 111175篇 |
晶体学 | 2167篇 |
力学 | 11238篇 |
综合类 | 977篇 |
数学 | 22199篇 |
物理学 | 64189篇 |
出版年
2023年 | 2242篇 |
2022年 | 4301篇 |
2021年 | 4904篇 |
2020年 | 5168篇 |
2019年 | 5242篇 |
2018年 | 5422篇 |
2017年 | 5198篇 |
2016年 | 6954篇 |
2015年 | 5942篇 |
2014年 | 7688篇 |
2013年 | 10567篇 |
2012年 | 11895篇 |
2011年 | 12452篇 |
2010年 | 9066篇 |
2009年 | 8982篇 |
2008年 | 9539篇 |
2007年 | 8777篇 |
2006年 | 8122篇 |
2005年 | 7036篇 |
2004年 | 5940篇 |
2003年 | 5030篇 |
2002年 | 4937篇 |
2001年 | 4361篇 |
2000年 | 3702篇 |
1999年 | 3468篇 |
1998年 | 3142篇 |
1997年 | 2815篇 |
1996年 | 2864篇 |
1995年 | 2414篇 |
1994年 | 2438篇 |
1993年 | 2160篇 |
1992年 | 2016篇 |
1991年 | 1954篇 |
1990年 | 1776篇 |
1989年 | 1618篇 |
1988年 | 1362篇 |
1987年 | 1341篇 |
1986年 | 1255篇 |
1985年 | 1293篇 |
1984年 | 1165篇 |
1983年 | 1037篇 |
1982年 | 973篇 |
1981年 | 838篇 |
1979年 | 868篇 |
1978年 | 874篇 |
1977年 | 864篇 |
1976年 | 973篇 |
1975年 | 873篇 |
1974年 | 898篇 |
1973年 | 910篇 |
排序方式: 共有10000条查询结果,搜索用时 18 毫秒
991.
A procedure for calculating the efficiency at which electrons are captured into axial channeling with a realistic axis potential is discussed. That region in the space of the electron's total transverse energy E and angular momentum L (integrals of motion) which corresponds to stable bound states of the electron with an atomic row is found. The temperature dependence of the capture coefficient is analyzed. As the crystal temperature is increased, the capture coefficient decreases, to a particularly noticeable extent for beams making a small angle with the crystallographic axis and for crystals having a high atomic number z.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 69–74, May, 1988. 相似文献
992.
M. A. Il'in P. Yu. Karasev N. A. Denisova A. V. Rezvov S. V. Tyurina 《Russian Physics Journal》1988,31(1):19-24
On the basis of numerical calculations and experimental studies we analyze the possibilities of measuring the electrophysical parameters of indium phosphide by means of infrared reflection spectra at wavelengths ranging from 5 to 200 m. We demonstrate that contactless nondestructive measurements of the electron density in the range 1016–1020 cm–3 can be made with a relative error not exceeding 15%, and of mobility with a relative error not exceeding 25%. A nomogram method is presented for rapid conversion of data from infrared reflection spectra into the parameters being measured.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 22–27, January, 1988. 相似文献
993.
S. Yu. Orevkov 《Mathematical Notes》1990,47(1):82-88
Translated from Matematicheskie Zametki, Vol. 47, No. 1, pp. 127–136, January, 1990. 相似文献
994.
Yu. A. Aminov 《Journal of Mathematical Sciences》1990,48(1):1-5
In this article we prove that the principal direction fields are holonomic and use them to introduce curvilinear coordinates on an immersed region in terms of which the linear element of Lobachevskií space is written in the form
where
The fundamental system of equations is established for an immersion ofn-dimensional Lobachevskií space into 2n-dimensional Euclidean space withn principal direction fields for the functions
i and, and a way of constructing an arbitrary local analytic immersion is shown.Translated from Ukrainskií Geometricheskií Sbornik, No. 28, pp. 3–8, 1985. 相似文献
995.
The complete convergence theorem implies that starting from any initial distribution the one dimensional contact process converges to a limit ast. In this paper we give a necessary and sufficient condition on the initial distribution for the convergence to occur with exponential rapidity.This work was discussed while the authors were visiting the Nankai Mathematics Institute in Tianjin.Partially supported by the National Science Foundation, the Army Research Office through the Mathematical Sciences Institute at Cornell University, and a Guggenheim fellowship.Research supported by the National Science Foundation of China. 相似文献
996.
997.
998.
999.
1000.
Yu. P. Goncharov 《Letters in Mathematical Physics》1990,19(1):73-81
The possibility is discussed of generalizing the Polyakov approach to strings on membranes and the connection of such a generalization with Thurston's classification of three-dimensional geometries. The important ingredients for computing a membrane path integral are the determinants of scalar Laplacians acting in real line bundles over three-dimensional closed manifolds. In the closed bosonic membrane case, such determinants are evaluated for a class of closed 3-manifolds of the H
3/ form with a discrete subgroup of isometries of the three-dimensional Lobachevsky space H
3 and they are expressed in terms of the Selberg zeta function. Some further possible implications of the results obtained are also discussed. 相似文献