全文获取类型
收费全文 | 9352篇 |
免费 | 205篇 |
国内免费 | 201篇 |
专业分类
化学 | 1233篇 |
晶体学 | 67篇 |
力学 | 105篇 |
综合类 | 29篇 |
数学 | 7420篇 |
物理学 | 904篇 |
出版年
2023年 | 29篇 |
2022年 | 87篇 |
2021年 | 56篇 |
2020年 | 71篇 |
2019年 | 265篇 |
2018年 | 255篇 |
2017年 | 134篇 |
2016年 | 122篇 |
2015年 | 118篇 |
2014年 | 303篇 |
2013年 | 585篇 |
2012年 | 322篇 |
2011年 | 692篇 |
2010年 | 505篇 |
2009年 | 575篇 |
2008年 | 622篇 |
2007年 | 674篇 |
2006年 | 523篇 |
2005年 | 406篇 |
2004年 | 313篇 |
2003年 | 317篇 |
2002年 | 230篇 |
2001年 | 208篇 |
2000年 | 190篇 |
1999年 | 196篇 |
1998年 | 216篇 |
1997年 | 138篇 |
1996年 | 189篇 |
1995年 | 181篇 |
1994年 | 171篇 |
1993年 | 145篇 |
1992年 | 112篇 |
1991年 | 77篇 |
1990年 | 93篇 |
1989年 | 69篇 |
1988年 | 50篇 |
1987年 | 53篇 |
1986年 | 31篇 |
1985年 | 74篇 |
1984年 | 54篇 |
1983年 | 41篇 |
1982年 | 57篇 |
1981年 | 52篇 |
1980年 | 28篇 |
1979年 | 21篇 |
1978年 | 32篇 |
1977年 | 28篇 |
1976年 | 19篇 |
1975年 | 9篇 |
1974年 | 8篇 |
排序方式: 共有9758条查询结果,搜索用时 15 毫秒
31.
Yasufumi Hashimoto 《Journal of Number Theory》2007,122(2):324-335
In [P. Sarnak, Class numbers of indefinite binary quadratic forms, J. Number Theory 15 (1982) 229-247], it was proved that the Selberg zeta function for SL2(Z) is expressed in terms of the fundamental units and the class numbers of the primitive indefinite binary quadratic forms. The aim of this paper is to obtain similar arithmetic expressions of the logarithmic derivatives of the Selberg zeta functions for congruence subgroups of SL2(Z). As applications, we study the Brun-Titchmarsh type prime geodesic theorem and the asymptotic formula of the sum of the class number. 相似文献
32.
Sans résumé
相似文献
相似文献
33.
Takashi Kishimoto 《Journal of Pure and Applied Algebra》2007,208(1):189-204
Let X?(T,D) be a compactification of an affine 3-fold X into a smooth projective 3-fold T such that the (reduced) boundary divisor D is SNC. In this paper, as an affine counterpart to the work due to S. Mori (cf. [S. Mori, Threefolds whose canonical bundles are not numerically effective, Ann. of Math. 116 (1982) 133-176]), we shall classify (K+D)-negative extremal rays on T. In particular, if such an extremal ray R=R+[C] intersects K non-negatively, we shall describe the log flips and divisorial contractions appearing explicitly. 相似文献
34.
Zero-schemes on smooth complex projective varieties, forcing all elements of ample and free linear systems to be reducible, are studied. Relationships among the minimal length of such zero-schemes, the positivity of the line bundle associated with the linear system, and the dimension of the variety are established. Bad linear spaces are also investigated. 相似文献
35.
C. Foias A. E. Frazho I. Gohberg M. A. Kaashoek 《Integral Equations and Operator Theory》1997,29(4):455-490
The family of all solutions of the three chains completion problem with a prescribed tolerance is described explicitly. It is shown that this family can be parameterized by a natural set of contractive upper triangular operators. As an application all solutions to a suboptimal nonstationary Nehari problem are described. 相似文献
36.
37.
Shin Ichi Aihara 《Acta Appl Math》1994,35(1-2):131-151
The purpose of this paper is to study the identification problem of a spatially varying discontinuous parameter in stochastic hyperbolic equations. In previous works, the consistency property of the maximum likelihood estimate (MLE) was explored and the generating algorithm for MLE proposed under the condition that an unknown parameter is in a sufficiently regular space with respect to spatial variables.In order to show the consistency property of the MLE for a discontinuous coefficient, we use the method of sieves, i.e. the admissible class of unknown parameters is projected into a finite-dimensional space. For hyperbolic systems, we cannot obtain a regularity property of the solution with respect to a parameter. So in this paper, the parabolic regularization technique is used. The convergence of the derived finite-dimensional MLE to the infinite-dimensional MLE is justified under some conditions. 相似文献
38.
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
39.
LetC(X,E) andC(Y,F) denote the spaces of continuous functions on the Tihonov spacesX andY, taking values in the Banach spacesE andF, respectively. A linear mapH:C(X,E)→C(Y,F) isseparating iff(x)g(x)=0 for allx inX impliesHf(y)Hg(y)=0 for ally inY. Some automatic continuity properties and Banach-Stone type theorems (i.e., asserting that isometries must be of a certain
form) for separating mapsH between spaces of real- and complex-valued functions have already been developed. The extension of such results to spaces
of vector-valued functions is the general subject of this paper. We prove in Theorem 4.1, for example, for compactX andY, that a linear isometryH betweenC(X,E) andC(Y,F) is a “Banach-Stone” map if and only ifH is “biseparating (i.e,H andH
−1 are separating). The Banach-Stone theorems of Jerison and Lau for vector-valued functions are then deduced in Corollaries
4.3 and 4.4 for the cases whenE andF or their topological duals, respectively, are strictly convex.
Research supported by the Fundació Caixa Castelló, MI/25.043/92 相似文献
40.
A model for the interaction of near-infrared laser pulses with metal powders in selective laser sintering 总被引:4,自引:0,他引:4
P. Fischer N. Karapatis V. Romano R. Glardon H.P. Weber 《Applied Physics A: Materials Science & Processing》2002,74(4):467-474
A thermal model of the interaction of pulsed near-infrared laser radiation from a Nd:YAG laser was made, taking the measured
powder properties such as reflectance, optical penetration depth and thermal conductivity into account. It allows an estimation
of the evolution of two different temperatures: the average temperature of the powder (taken over the grains in a volume given
by the laser beam diameter and the optical penetration depth) and the temperature distinction within a single grain. It showed
that in pulsed mode consolidation can be achieved at much lower average power as the surface of the powder particles are molten
but their cores remain at nearly room temperature. This leads to a much lower average temperature and therefore a dramatic
decrease in residual thermal stresses in the finished piece. The results of the model were experimentally tested and confirmed.
Received: 26 July 2001 / Accepted: 23 November 2001 / Published online: 23 January 2002 相似文献