全文获取类型
收费全文 | 11518篇 |
免费 | 255篇 |
国内免费 | 273篇 |
专业分类
化学 | 1421篇 |
晶体学 | 31篇 |
力学 | 77篇 |
综合类 | 17篇 |
数学 | 9713篇 |
物理学 | 787篇 |
出版年
2023年 | 18篇 |
2022年 | 38篇 |
2021年 | 26篇 |
2020年 | 42篇 |
2019年 | 247篇 |
2018年 | 281篇 |
2017年 | 150篇 |
2016年 | 99篇 |
2015年 | 120篇 |
2014年 | 290篇 |
2013年 | 713篇 |
2012年 | 350篇 |
2011年 | 671篇 |
2010年 | 605篇 |
2009年 | 901篇 |
2008年 | 870篇 |
2007年 | 872篇 |
2006年 | 661篇 |
2005年 | 428篇 |
2004年 | 382篇 |
2003年 | 299篇 |
2002年 | 235篇 |
2001年 | 217篇 |
2000年 | 231篇 |
1999年 | 255篇 |
1998年 | 255篇 |
1997年 | 177篇 |
1996年 | 244篇 |
1995年 | 251篇 |
1994年 | 251篇 |
1993年 | 193篇 |
1992年 | 171篇 |
1991年 | 125篇 |
1990年 | 142篇 |
1989年 | 142篇 |
1988年 | 91篇 |
1987年 | 95篇 |
1986年 | 105篇 |
1985年 | 139篇 |
1984年 | 110篇 |
1983年 | 57篇 |
1982年 | 94篇 |
1981年 | 67篇 |
1980年 | 78篇 |
1979年 | 58篇 |
1978年 | 60篇 |
1977年 | 39篇 |
1976年 | 33篇 |
1975年 | 24篇 |
1973年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
71.
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
72.
73.
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
74.
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
75.
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
76.
Maengseok Noh 《Journal of multivariate analysis》2007,98(5):896-915
The restricted maximum likelihood (REML) procedure is useful for inferences about variance components in mixed linear models. However, its extension to hierarchical generalized linear models (HGLMs) is often hampered by analytically intractable integrals. Numerical integration such as Gauss-Hermite quadrature (GHQ) is generally not recommended when the dimensionality of the integral is high. With binary data various extensions of the REML method have been suggested, but they have had unsatisfactory biases in estimation. In this paper we propose a statistically and computationally efficient REML procedure for the analysis of binary data, which is applicable over a wide class of models and design structures. We propose a bias-correction method for models such as binary matched pairs and discuss how the REML estimating equations for mixed linear models can be modified to implement more general models. 相似文献
77.
A. Kontogeorgis 《Journal of Pure and Applied Algebra》2007,210(2):551-558
We give a relation between the dimension of the tangent space of the deformation functor of curves with automorphisms and the Galois module structure of the space of 2-holomorphic differentials. We prove a homological version of the local-global principle similar to the one of J. Bertin and A. Mézard. Let G be a cyclic subgroup of the group of automorphisms of a curve X, so that the order of G is equal to the characteristic. By using the results of S. Nakajima on the Galois module structure of the space of 2-holomorphic differentials, we compute the dimension of the tangent space of the deformation functor. 相似文献
78.
Perch Melik-Adamyan 《Complex Analysis and Operator Theory》2007,1(3):423-438
An analog of the Kreĭn–Saakyan formula is derived for any pair of relatively prime self-adjoint extensions of a minimal symmetric
canonical differential operator. This allows us to deduce a trace formula in the matrix case.
I am grateful to Sh. Saakyan for his interest in this work and lively discussion.
Received: December 8, 2006. Accepted: December 30, 2006. 相似文献
79.
The purpose of the present note is to establish some new delay integral inequalities, which provide explicit bounds on unknown functions and generalize some results of Li et al. [Some new delay integral inequalities and their applications, J. Comput. Appl. Math. 180 (2005) 191–200]. The inequalities given here can be used to investigate the qualitative properties of certain delay differential equations and delay integral equations. 相似文献
80.
Jun-ichi Miyachi 《Archiv der Mathematik》2006,86(4):317-320
Let Λ be a left Artinian ring, D+(mod Λ) (resp., D−(mod Λ), D(mod Λ)) the derived category of bounded below complexes (resp., bounded above complexes, unbounded complexes) of
finitely generated left Λ-modules. We show that the Grothendieck groups K0(D+(mod Λ)), K0(D−(mod Λ)) and K0(D(mod Λ)) are trivial.
Received: 7 April 2005 相似文献