全文获取类型
收费全文 | 12785篇 |
免费 | 1244篇 |
国内免费 | 1111篇 |
专业分类
化学 | 2295篇 |
晶体学 | 30篇 |
力学 | 850篇 |
综合类 | 320篇 |
数学 | 8789篇 |
物理学 | 2856篇 |
出版年
2024年 | 25篇 |
2023年 | 142篇 |
2022年 | 192篇 |
2021年 | 252篇 |
2020年 | 319篇 |
2019年 | 340篇 |
2018年 | 320篇 |
2017年 | 386篇 |
2016年 | 496篇 |
2015年 | 306篇 |
2014年 | 601篇 |
2013年 | 1112篇 |
2012年 | 560篇 |
2011年 | 742篇 |
2010年 | 679篇 |
2009年 | 763篇 |
2008年 | 819篇 |
2007年 | 881篇 |
2006年 | 735篇 |
2005年 | 669篇 |
2004年 | 604篇 |
2003年 | 599篇 |
2002年 | 571篇 |
2001年 | 445篇 |
2000年 | 418篇 |
1999年 | 344篇 |
1998年 | 328篇 |
1997年 | 253篇 |
1996年 | 223篇 |
1995年 | 167篇 |
1994年 | 119篇 |
1993年 | 108篇 |
1992年 | 102篇 |
1991年 | 88篇 |
1990年 | 45篇 |
1989年 | 53篇 |
1988年 | 39篇 |
1987年 | 28篇 |
1986年 | 32篇 |
1985年 | 36篇 |
1984年 | 32篇 |
1983年 | 16篇 |
1982年 | 22篇 |
1981年 | 20篇 |
1980年 | 17篇 |
1979年 | 25篇 |
1978年 | 15篇 |
1977年 | 17篇 |
1976年 | 9篇 |
1973年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Mira Bozzini Licia Lenarduzzi Robert Schaback 《Advances in Computational Mathematics》2002,16(4):375-387
We present an adaptive method to extract shape-preserving information from a univariate data sample. The behavior of the signal is obtained by interpolating at adaptively selected few data points by a linear combination of multiquadrics with variable scaling parameters. On the theoretical side, we give a sufficient condition for existence of the scaled multiquadric interpolant. On the practical side, we give various examples to show the applicability of the method. 相似文献
62.
In this paper the sufficient conditions for the existence of positive solutions of the neutral difference equations with positive and negative coefficients are established. The results improve some known conclusions in the literature 相似文献
63.
TAN Xiaojiang 《数学年刊B辑(英文版)》2002,23(4):531-538
Lei X be an arbitrary smooth irreducible complex projective curve, E (?) X a rank two vector bundle generated by its sections. The author first represents E as a triple {D1,D2,f}, where D1 , D2 are two effective divisors with d = deg(D1) + deg(D2), and f ∈ H0(X, [D1] |D2) is a collection of polynomials. E is the extension of [D2] by [D1] which is determined by f. By using f and the Brill-Noether matrix of D1 + D2, the author constructs a 2g X d matrix WE whose zero space gives Im{H0(X,[D1]) (?) H0(X, [D1] |D1)}(?)Im{H0(X, E) (?) H0(X,[D2]) (?) H0(X,[D2] |D2)}. From this and H0(X,E) = H0(X, [D1]) (?) Im{H0(X, E) (?) H0(X, [D2])}, it is got in particular that dimH0(X, E) = deg(E) - rank(WE) + 2. 相似文献
64.
设 G=(A,△)为紧矩阵量子群,G为A的所有有限维光滑的、不可约余表示等价类的集合.本文通过(A,△)的一个余表示Vo构造了两个相互配对的集合,利用Hilbert C*-模的理论证明它们分别为A和Baaj与Skandalis构造的量子群A,并且证明了对任意的α∈G,在A中都对应一个有限维投影算子Pα,满足 dim(α)=dim(pα). 相似文献
65.
吕海深 《Annals of Differential Equations》2004,20(2):133-139
Under suitable conditions on f(·,u), it is shown that the two-point boundaryvalue problem((u'))' + λq(t)f(u) = 0in (0, 1),u(0) = u(1) = 0,has two positive solution or at least one positive solution for λ in a compatibleinterval. 相似文献
66.
本利用矩阵给出了几类数列的通项公式的求法,把数列通项公式的求法转化为矩阵幂的计算,思路简单、计算简便,并能判别其敛散性。 相似文献
67.
Operator Matrix Forms of Positive Operators 总被引:2,自引:0,他引:2
If a 3-tuple (A:H1→H1,B:H2→H1,C:H2→H2)of operators on Hibert spaces is given,we proved that the operator ~↑A:=(↑A ↓B^*↑B ↓C) on H=H1 H2 is ≥0 is and only if A≥0,R(B)∪→R(A^1/2) and C≥B^* A^ b,where A^ is the generalized inverse of A.In general,A^ is a closed operator,but since R(B)∪→R(A^1/2,B^* A^ B is bounded yet. 相似文献
68.
TheImprovementofFischer'sInequalityandHadamard'sInequalityHuangLiping(黄礼平)(DepartmentofBasicSciences,XiangtanMiningInstitute,... 相似文献
69.
The object of the paper is to study the absolute matrix summability problem of Fourier series, conjugate series and some associated
series under a new set of conditions on matrix methods, generalising many known results in the literature. 相似文献
70.
The morphology of blends of styrenic polymers in a matrix of 75% Nylon-6 prepared in a Brabender Plasti-Corder was examined by scanning electron microscopy. Styrene/acrylonitrile copolymers (SAN) form smaller particles as the AN level increases owing to the corresponding decrease in the SAN–polyamide interfacial tension. Various styrenic polymers containing functional groups, maleic anhydride or oxazoline type, that can react with Nylon-6 during melt processing were added to the SAN phase which also led to a decrease in the particle size owing to the graft copolymer formed in situ. The effects of functional group type, amount of functional groups per chain, amount of functional polymer added, and the miscibility of the styrene/maleic anhydride (SMA) and SAN copolymers on the morphology of the styrenic phase in the Nylon-6 matrix are described. © 1992 John Wiley & Sons, Inc. 相似文献