全文获取类型
收费全文 | 23144篇 |
免费 | 822篇 |
国内免费 | 1066篇 |
专业分类
化学 | 1166篇 |
晶体学 | 84篇 |
力学 | 1137篇 |
综合类 | 13篇 |
数学 | 18330篇 |
物理学 | 4302篇 |
出版年
2023年 | 151篇 |
2022年 | 332篇 |
2021年 | 453篇 |
2020年 | 630篇 |
2019年 | 454篇 |
2018年 | 696篇 |
2017年 | 790篇 |
2016年 | 654篇 |
2015年 | 703篇 |
2014年 | 943篇 |
2013年 | 1408篇 |
2012年 | 1198篇 |
2011年 | 1153篇 |
2010年 | 1188篇 |
2009年 | 1219篇 |
2008年 | 1181篇 |
2007年 | 1136篇 |
2006年 | 1146篇 |
2005年 | 820篇 |
2004年 | 694篇 |
2003年 | 686篇 |
2002年 | 746篇 |
2001年 | 792篇 |
2000年 | 496篇 |
1999年 | 498篇 |
1998年 | 457篇 |
1997年 | 299篇 |
1996年 | 224篇 |
1995年 | 259篇 |
1994年 | 210篇 |
1993年 | 242篇 |
1992年 | 227篇 |
1991年 | 230篇 |
1990年 | 215篇 |
1989年 | 184篇 |
1988年 | 128篇 |
1987年 | 112篇 |
1986年 | 123篇 |
1985年 | 145篇 |
1984年 | 120篇 |
1983年 | 119篇 |
1982年 | 126篇 |
1981年 | 114篇 |
1979年 | 105篇 |
1978年 | 100篇 |
1975年 | 98篇 |
1974年 | 129篇 |
1973年 | 119篇 |
1972年 | 100篇 |
1968年 | 94篇 |
排序方式: 共有10000条查询结果,搜索用时 19 毫秒
131.
《Physica A》2006,362(1):105-110
We examine the Galilean invariance of standard lattice Boltzmann methods for two-phase fluids. We show that the known Galilean invariant term that is cubic in the velocities, and is usually neglected, is a major source of Galilean invariance violations. We show that incorporating a correction term can improve the Galilean invariance of the method by up to two orders of magnitude for large velocities. We found that this is true in particular for methods in which the interactions are incorporated through a forcing term. Methods in which interactions are incorporated through a non-ideal pressure tensor only benefit for large velocities. 相似文献
132.
B. Bojarski 《Proceedings of the Steklov Institute of Mathematics》2006,255(1):65-81
We prove that a function f is in the Sobolev class W
loc
m,p
(ℝ
n
) or W
m,p
(Q) for some cube Q ⊂ ℝ
n
if and only if the formal (m − 1)-Taylor remainder R
m−1
f(x,y) of f satisfies the pointwise inequality |R
m−1
f(x,y)| ≤ |x − y|
m
[a(x) + a(y)] for some a ε L
p
(Q) outside a set N ⊂ Q of null Lebesgue measure. This is analogous to H. Whitney’s Taylor remainder condition characterizing the traces of smooth
functions on closed subsets of ℝ
n
.
Dedicated to S.M. Nikol’skiĭ on the occasion of his 100th birthday
The main results and ideas of this paper were presented in the plenary lecture of the author at the International Conference
and Workshop Function Spaces, Approximation Theory and Nonlinear Analysis dedicated to the centennial of Sergei Mikhailovich Nikol’skii, Moscow, May 24–28, 2005. 相似文献
133.
S. F. Karpenko 《Ukrainian Mathematical Journal》1989,41(4):487-492
Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 41, No. 4, pp. 559–565, April, 1989. 相似文献
134.
A nonclassical problem is considered for the transport equation with coefficients depending on the energy of radiation. The task is to find the discontinuity surfaces for the coefficients of the equation from measurements of the radiation flux leaving the medium. For this tomography problem, an optimization problem is stated and numerically analyzed. The latter consists in determining the radiation energy that ensures the best reconstruction of the unknown medium. A simplified optimization problem is solved analytically. 相似文献
135.
The problem of reducing polynomial matrices to canonical form by using semiscalar equivalent transformations is studied. This problem is wild as a whole. However, it is tame in some special cases. In the paper, classes of polynomial matrices are singled out for which canonical forms with respect to semiscalar equivalence are indicated. We use this tool to construct a canonical form for the families of coefficients corresponding to the polynomial matrices. This form enables one to solve the classification problem for families of numerical matrices up to similarity. 相似文献
136.
Mathematical Notes - It is shown in this paper that ${h\left( r \right)}$ is a smoothly varying function of order ? if and only if the function $\rho \left( r \right) = \left( {\ln h\left(... 相似文献
137.
本文得到关于全纯扩充的BHW定理的一个全新的证明,同时也对BHW定 理做出了更一般的推广,并且给出了推广后的BHW定理的两种不同的证明方法. 相似文献
138.
A. D. Zamanov 《Mechanics of Composite Materials》2005,41(1):49-54
The possibility of using the finite-element method for investigating two-dimensional problems on natural vibrations in the mechanics of composite materials with curved structures is considered. With the example of a hinge-supported strip made of a composite material with a locally curved structure, the influence of geometrical and mechanical parameters of the strip on its eigenfrequencies is examined. It is established that the presence of local curving in the structure of strip material decreases the magnitude of eigenfrequencies.Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 1, pp. 71–78, January–February, 2005. 相似文献
139.
Promarz Tamrazov 《Comptes Rendus Mathematique》2005,341(7):405-408
We give a complete solution to the extremal problem posed by N.G. Tchebotaröv in the mid 1920s, and we establish explicit parametric formulae for the extremals. To cite this article: P. Tamrazov, C. R. Acad. Sci. Paris, Ser. I 341 (2005). 相似文献
140.
In this paper, by the use of a fixed point theorem, many new necessary and sufficient conditions for the existence of positive solutions in C[0,1]∩C1[0,1]∩C2(0,1) or C[0,1]∩C2(0,1) are presented for singular superlinear and sublinear second-order boundary value problems. Singularities at t=0, t=1 will be discussed. 相似文献