全文获取类型
收费全文 | 23020篇 |
免费 | 822篇 |
国内免费 | 1066篇 |
专业分类
化学 | 1130篇 |
晶体学 | 83篇 |
力学 | 1133篇 |
综合类 | 13篇 |
数学 | 18320篇 |
物理学 | 4229篇 |
出版年
2023年 | 151篇 |
2022年 | 331篇 |
2021年 | 448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 | 219篇 |
1994年 | 198篇 |
1993年 | 230篇 |
1992年 | 217篇 |
1991年 | 220篇 |
1990年 | 202篇 |
1989年 | 168篇 |
1988年 | 124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 125 毫秒
991.
We obtain sufficient conditions for the continuity of the general nonlinear superposition operator (generalized Nemytskii operator) acting from the space
of differentiable functions on a bounded domain
to the Lebesgue space
. The values of operators on a function
are locally determined by the values of both the function
itself and all of its partial derivatives up to order
inclusive. In certain particular cases, the sufficient conditions obtained are proved to be necessary as well. The results are illustrated by several examples, and an application to the theory of Sobolev spaces is also given. 相似文献
992.
For a system of functional differential equations of the neutral type with nonlinear deviations of an argument dependent on an unknown function, we establish sufficient conditions for the existence of a solution continuously differentiable and bounded for t and study its properties. 相似文献
993.
In this paper, we establish lower bounds for n-term approximations in the metric of L
2(I
2
) of characteristic functions of plane convex subsets of the square I
2
with respect to arbitrary orthogonal systems. It is shown that, as n, these bounds cannot decrease more rapidly than
. 相似文献
994.
995.
In terms of Berezin symbols, we give several criteria for operators to belong to the Schatten--von Neumann classes
. In particular, for functions of model operators, we give a complete answer to a question posed by Nordgren and Rosenthal. 相似文献
996.
Oscillation and nonoscillation criteria for the higher order self-adjoint differential equation (-1)n(talphay(n))(n)+q(t)y = 0 (*) are established. In these criteria, equation (*) is viewed as a perturbation of the conditionally oscillatory equation (-1)n(talphay(n))(n) - µ,t2n-y = 0, where
n, is the critical constant in conditional oscillation. Some open problems in the theory of conditionally oscillatory, even order, self-adjoint equations are also discussed. 相似文献
997.
For I
G
(J
PC)=1−(1−+) exotic waves in the reactions ρπ → ρπ, ρπ → ηπ, ρπ → η′π, and ρπ →
and in allied reactions, a model is constructed that satisfies the conditions of unitarity and analyticity and which employs,
as an input, an “anomalous” nondiagonal VPPP interaction relating the ρπ, ηπ, η′π, and
channels. The possibility of obtaining, within this simple field-theoretical model, a resonance behavior of the I
G(J
PC)=1−(1−+) amplitudes corresponding to the {10} −
and {8} representations of the SU(3) group and their mixing is demonstrated explicitly in the mass range 1.3–1.6 GeV, where data of present-day experiments
suggest a rich exoticism.
__________
Translated from Yadernaya Fizika, Vol. 65, No. 3, 2002, pp. 579–588.
Original Russian Text Copyright ? 2002 by Achasov, Shestakov. 相似文献
998.
A. I. Pavlov 《Mathematical Notes》1999,66(4):442-450
The main result of the paper is as follows.Theorem. Suppose that G(z) is an entire function satisfying the following conditions: 1) the Taylor coefficients of the function
G(z) are nonnegative: 2) for some fixed C>0 and A>0 and for |z|>R0, the following inequality holds:
Further, suppose that for some fixed α>0 the deviation DN of the sequence xn={αn}, n=1, 2, ..., as N→∞ has the estimate DN=0(lnB N/N). Then if the function G(z) is not an identical constant and the inequality B+1<A holds, then the power series
converging in the disk |z|<1 cannot be analytically continued to the region |z|>1 across any arc of the circle |z|=1.
Translated fromMatematicheskie Zametki, Vol. 66, No. 4, pp. 540–550, October, 1999. 相似文献
999.
V. V. Kurta 《Mathematical Notes》1999,65(4):462-469
The main result of the paper is the nonexistence of integer positive solutions in wide classes of quasilinear elliptic equations
whose model examples are equations of the form {
}, where α>1 andq are some fixed real numbers.
Translated fromMatematicheskie Zametki, Vol. 65, No. 4, pp. 552–561, April, 1999. 相似文献
1000.
In this paper the authors develop a new approach to the problemof propagation of smallness for harmonic functionsin arbitrary domains, in Rn (n 2). The main result of thispaper is a certain logarithmic-convexity relation for the L2-normsof harmonic functions. As a consequence, new kinds of uniquenessresults for harmonic functions are obtained. The method worksalso for analytic functions in C, with Lp-norms (p > 0).1991 Mathematics Subject Classification 31B05. 相似文献