全文获取类型
收费全文 | 22249篇 |
免费 | 1513篇 |
国内免费 | 1091篇 |
专业分类
化学 | 9650篇 |
晶体学 | 119篇 |
力学 | 280篇 |
综合类 | 149篇 |
数学 | 13193篇 |
物理学 | 1462篇 |
出版年
2023年 | 140篇 |
2022年 | 232篇 |
2021年 | 292篇 |
2020年 | 431篇 |
2019年 | 585篇 |
2018年 | 539篇 |
2017年 | 402篇 |
2016年 | 544篇 |
2015年 | 533篇 |
2014年 | 814篇 |
2013年 | 1471篇 |
2012年 | 960篇 |
2011年 | 1339篇 |
2010年 | 1211篇 |
2009年 | 1601篇 |
2008年 | 1664篇 |
2007年 | 1663篇 |
2006年 | 1335篇 |
2005年 | 1026篇 |
2004年 | 983篇 |
2003年 | 860篇 |
2002年 | 546篇 |
2001年 | 452篇 |
2000年 | 483篇 |
1999年 | 495篇 |
1998年 | 463篇 |
1997年 | 391篇 |
1996年 | 411篇 |
1995年 | 400篇 |
1994年 | 341篇 |
1993年 | 254篇 |
1992年 | 220篇 |
1991年 | 169篇 |
1990年 | 168篇 |
1989年 | 162篇 |
1988年 | 118篇 |
1987年 | 110篇 |
1986年 | 114篇 |
1985年 | 149篇 |
1984年 | 127篇 |
1983年 | 65篇 |
1982年 | 107篇 |
1981年 | 83篇 |
1980年 | 93篇 |
1979年 | 62篇 |
1978年 | 67篇 |
1977年 | 43篇 |
1976年 | 40篇 |
1975年 | 28篇 |
1974年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
111.
We give several equivalent characterisations of left (and hence, by duality, also of right) supported algebras. These characterisations are in terms of properties of the left and the right parts of the module category, or in terms of the classes L0 and R0 which consist respectively of the predecessors of the projective modules, and of the successors of the injective modules. 相似文献
112.
We answer some questions posed in [L. Grunenfelder, M. Mastnak, On bimeasurings, J. Pure Appl. Algebra 204 (2006) 258-269] concerning the universal bimeasuring bialgebra via a construction of suitable subcoalgebras of the universal measuring coalgebra. 相似文献
113.
S.V. Astashkin F.A. Sukochev 《Journal of Mathematical Analysis and Applications》2007,336(2):1231-1258
We catalogue all Marcinkiewicz function and sequence spaces with the Banach-Saks property and present necessary and sufficient conditions for a wide subclass of spaces to possess the p-Banach-Saks property, 1<p<∞. We apply our results to several open problems. 相似文献
114.
In this article, we generalize the theory of motivic integration on formal schemes topologically of finite type and the notion
of motivic Serre invariant, to a relative point of view. We compute the relative motivic Serre invariant for curves defined
over the field of fractions of a complete discrete valuation ring R of equicharacteristic zero. One aim of this study is to understand the behavior of motivic Serre invariants under ramified
extension of the ring R. Thanks to our constructions, we obtain, in particular, an expression for the generating power series, whose coefficients
are the motivic Serre invariant associated to a curve, computed on a tower of ramified extensions of R. We give an interpretation of this series in terms of the motivic zeta function of Denef and Loeser. 相似文献
115.
116.
In this paper we define and study an extension of the g-Drazin for elements of a Banach algebra and for bounded linear operators based on an isolated spectral set rather than on
an isolated spectral point. We investigate salient properties of the new inverse and its continuity, and illustrate its usefulness
with an application to differential equations. Generalized Mbekhta subspaces are introduced and the corresponding extended
Mbekhta decomposition gives a characterization of circularly isolated spectral sets. 相似文献
117.
Wujie Shi 《Frontiers of Mathematics in China》2007,2(1):123-125
Let G be a finite group, and let π
e
(G) be the set of all element orders of G. In this short paper we prove that π
e
(B
n
(q)) ≠ π
e
(C
n
(q)) for all odd q.
相似文献
118.
Michael Demuth Peter Stollmann Günter Stolz Jan van Casteren 《Integral Equations and Operator Theory》1995,23(2):145-153
We give trace norm estimates for products of integral operators and for diffusion semigroups. These are applied to differences of heat semigroups. A natural example of an integral operator with finite trace which is not trace class is given. 相似文献
119.
Wei-yi SU~ 《中国科学A辑(英文版)》2007,50(7):1005-1014
The Lipschitz class Lipαon a local field K is defined in this note,and the equivalent relationship between the Lipschitz class Lipαand the Holder type space C~α(K)is proved.Then,those important characteristics on the Euclidean space R~n and the local field K are compared,so that one may interpret the essential differences between the analyses on R~n and K.Finally,the Cantor type fractal functionθ(x)is showed in the Lipschitz class Lip(m,K),m<(ln 2/ln 3). 相似文献
120.
N-Acylalkylation of neutral and anionic N-nucleophiles with α-halocarbonyl compounds was investigated by quantum chemical methods
in terms of the density functional theory and by experimental methods for 2,3-dihydroimidazo[2,1-b]quinazolin-1(10)H-5-one, its N-anion, and simpler model structures. High reactivity of these reagents is determined primarily by stabilization
of transition states (TS) by bridge bonds involving halogen or nitrogen atoms rather than by conjugation, as has been commonly
accepted. Bridged TS are formed by both the substitution mechanism S
N
2 and the addition-elimination mechanism. α-Haloalkyl-substituted zwitterions, which are potential intermediates of stepwise
N-acylalkylation of neutral N-nucleophiles, do not exist in the isolated state, but they are rather efficiently stabilized
upon solvation. These zwitterions, as well as analogous O-anions generated from anionic N-nucleophiles, can serve as intermediates
of N-acylalkylation, as was demonstrated by localization of the corresponding TS.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1150–1164, June, 2007. 相似文献