全文获取类型
收费全文 | 7199篇 |
免费 | 361篇 |
国内免费 | 55篇 |
专业分类
化学 | 332篇 |
晶体学 | 4篇 |
力学 | 69篇 |
综合类 | 5篇 |
数学 | 5982篇 |
物理学 | 1223篇 |
出版年
2023年 | 15篇 |
2022年 | 20篇 |
2021年 | 19篇 |
2020年 | 31篇 |
2019年 | 131篇 |
2018年 | 133篇 |
2017年 | 89篇 |
2016年 | 83篇 |
2015年 | 79篇 |
2014年 | 173篇 |
2013年 | 386篇 |
2012年 | 192篇 |
2011年 | 259篇 |
2010年 | 177篇 |
2009年 | 403篇 |
2008年 | 529篇 |
2007年 | 591篇 |
2006年 | 442篇 |
2005年 | 311篇 |
2004年 | 289篇 |
2003年 | 204篇 |
2002年 | 128篇 |
2001年 | 134篇 |
2000年 | 130篇 |
1999年 | 135篇 |
1998年 | 142篇 |
1997年 | 101篇 |
1996年 | 166篇 |
1995年 | 164篇 |
1994年 | 161篇 |
1993年 | 148篇 |
1992年 | 133篇 |
1991年 | 67篇 |
1990年 | 98篇 |
1989年 | 91篇 |
1988年 | 94篇 |
1987年 | 131篇 |
1986年 | 103篇 |
1985年 | 131篇 |
1984年 | 81篇 |
1983年 | 66篇 |
1982年 | 122篇 |
1981年 | 112篇 |
1980年 | 96篇 |
1979年 | 49篇 |
1978年 | 88篇 |
1977年 | 87篇 |
1976年 | 82篇 |
1975年 | 9篇 |
1974年 | 5篇 |
排序方式: 共有7615条查询结果,搜索用时 890 毫秒
41.
The present paper deals with the study of a Durrmeyer-type integral modification of certain modified Baskakov operators. Here
we study simultaneous approximation properties for these operators by using the iterative combinations. We obtain an asymptotic
formula and an error estimation in terms of higher order modulus of continuity for these operators.
相似文献
42.
We propose objectives consisting of two mirrors with central holes for passage of a light beam. The optical layout ensures
multiple reflection of rays from both mirrors. We consider several approaches to calculating the design parameters for which
three and four aberrations do not occur. The objectives can be used in optical devices operating in the UV and IR regions
of the spectrum.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 267–270, March–April, 2007. 相似文献
43.
Brian Hartwig 《Linear algebra and its applications》2007,422(1):219-235
Recently Terwilliger and the present author found a presentation for the three-point sl2 loop algebra via generators and relations. To obtain this presentation we defined a Lie algebra ? by generators and relations and displayed an isomorphism from ? to the three-point sl2 loop algebra. In this paper we classify the finite-dimensional irreducible ?-modules. 相似文献
44.
Brian A. Hagler 《Linear algebra and its applications》2007,422(1):100-118
Definitions, theorems and examples are established for a general model of Laurent polynomial spaces and ordered orthogonal Laurent polynomial sequences, ordered with respect to ordered bases and orthogonal with respect to inner products ·=L°⊙ decomposed into transition functional ⊙ and strong moment functional, or, more generally, sample functional L couplings. Under this formulation that is shown to subsume those in the existing literature, new fundamental results are produced, including necessary and sufficient conditions for ordered OLPS to be sequences of nth numerators of continued fractions, in contrast to the classical result concerning nth denominators which is shown to hold only in special cases. 相似文献
45.
We give a new independent self-dual 3-basis for the trivial variety with two binary operations.
Received October 24, 2006; accepted in final form January 25, 2007. 相似文献
46.
S. -S. Chow 《Numerische Mathematik》1989,54(4):373-393
Summary In this paper we shall consider the application of the finite element method to a class of second order elliptic boundary value problems of divergence form and with gradient nonlinearity in the principal coefficient, and the derivation of error estimates for the finite element approximations. Such problems arise in many practical situations — for example, in shock-free airfoil design, seepage through coarse grained porous media, and in some glaciological problems. By making use of certain properties of the nonlinear coefficients, we shall demonstrate that the variational formulations associated with these boundary value problems are well-posed. We shall also prove that the abstract operators accompanying such problems satisfy certain continuity and monotonicity inequalities. With the aid of these inequalities and some standard results from approximation theory, we show how one may derive error estimates for the finite element approximations in the energy norm. 相似文献
47.
48.
C. Praagman 《Aequationes Mathematicae》1987,33(1):251-259
In this paper it is proved that having a logarithm is equivalent to having roots of arbitrary order in the group of automorphisms of a formal power series ring, and in algebraic subgroups too 相似文献
49.
A survey of the contributions of Aldo Cossu in finite geometry is given.
Dedicated to the memory of Professor Aldo Cossu 相似文献
50.
This work is supported in part by the fund OTKA (No. 5-134). 相似文献