全文获取类型
收费全文 | 9428篇 |
免费 | 379篇 |
国内免费 | 37篇 |
专业分类
化学 | 7329篇 |
晶体学 | 74篇 |
力学 | 147篇 |
数学 | 1096篇 |
物理学 | 1198篇 |
出版年
2023年 | 100篇 |
2022年 | 88篇 |
2021年 | 451篇 |
2020年 | 278篇 |
2019年 | 273篇 |
2018年 | 234篇 |
2017年 | 204篇 |
2016年 | 368篇 |
2015年 | 287篇 |
2014年 | 391篇 |
2013年 | 617篇 |
2012年 | 680篇 |
2011年 | 737篇 |
2010年 | 497篇 |
2009年 | 385篇 |
2008年 | 596篇 |
2007年 | 573篇 |
2006年 | 513篇 |
2005年 | 409篇 |
2004年 | 336篇 |
2003年 | 255篇 |
2002年 | 219篇 |
2001年 | 122篇 |
2000年 | 88篇 |
1999年 | 77篇 |
1998年 | 71篇 |
1997年 | 56篇 |
1996年 | 66篇 |
1995年 | 52篇 |
1994年 | 51篇 |
1993年 | 49篇 |
1992年 | 52篇 |
1991年 | 46篇 |
1990年 | 36篇 |
1989年 | 45篇 |
1988年 | 32篇 |
1987年 | 38篇 |
1986年 | 34篇 |
1985年 | 60篇 |
1984年 | 40篇 |
1983年 | 28篇 |
1982年 | 44篇 |
1981年 | 29篇 |
1980年 | 31篇 |
1979年 | 19篇 |
1978年 | 14篇 |
1977年 | 14篇 |
1976年 | 16篇 |
1974年 | 11篇 |
1973年 | 10篇 |
排序方式: 共有9844条查询结果,搜索用时 15 毫秒
31.
In this paper we generalize to coisotropic actions of compact Lie groups a theorem of Guillemin on deformations of Hamiltonian
structures on compact symplectic manifolds. We show how one can reconstruct from the moment polytope the symplectic form on
the manifold.
Received: 21 March 2006 相似文献
32.
CV Tomy D Pal SS Banerjee S Ramakrishnan AK Grover S Bhattacharya MJ Higgins G Balakrishnan McK Paul 《Pramana》2002,58(5-6):925-935
The weakly pinned single crystals of the hexagonal 2H-NbSe2 compound have emerged as prototypes for determining and characterizing the phase boundaries of the possible order-disorder
transformations in the vortex matter. We present here a status report based on the ac and dc magnetization measurements of
the peak effect phenomenon in three crystals of 2H-NbSe2, in which the critical current densities vary over two orders of magnitude. We sketch the generic vortex phase diagram of
a weakly pinned superconductor, which also utilizes theoretical proposals. We also establish the connection between the metastability
effects and pinning. 相似文献
33.
In [3] it was shown that a (real) signed measure on a cyclic coarse-grained quantum logic can be extended, as a signed measure,
over the entire power algebra. Later ([9]) this result was re-proved (and further improved on) and, moreover, the non-negative
measures were shown to allow for extensions as non-negative measures. In both cases the proof technique used was the technique
of linear algebra. In this paper we further generalize the results cited by extending group-valued measures on cyclic coarse-grained
quantum logics (or non-negative group-valued measures for lattice-ordered groups). Obviously, the proof technique is entirely
different from that of the preceding papers. In addition, we provide a new combinatorial argument for describing all atoms
of cyclic coarse-grained quantum logics. 相似文献
34.
Antoni Leon Dawidowicz Najemedin Haribash Anna Poskrobko 《Mathematical Methods in the Applied Sciences》2007,30(7):779-787
The problem of the existence of the invariant measure is important considering its connections with chaotic behaviour. In the papers (Zesz. Nauk. Uniw. Jagiellońskiego, Pr. Mat. 1982; 23 :117–123; Ann. Pol. Math. 1983; XLI :129–137; J. Differential Equations 2004; 196 :448–465) the existence of invariant and ergodic measures according to the dynamical system generated by the Lasota equation was proved, i.e. the equation describing the dynamics and becoming different of the population of cells. In this paper, the existence of such measure for the quasi‐linear Lasota equation is proved. This measure is the carriage of the measure described by Dawidowicz (Zesz. Nauk. Uniw. Jagiellońskiego, Pr. Mat. 1982; 23 :117–123). Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
35.
R. G. Makitra G. G. Midyana E. Ya. Pal’chikova 《Russian Journal of Applied Chemistry》2006,79(1):43-49
The influence of physicochemical properties of organic solvents on the distribution constants of aromatic carboxylic acids between the organic and aqueous phases was examined. 相似文献
36.
Anna Tramontano 《Physics of life reviews》2004,1(2):103-127
The availability of the complete genomic sequences of many species, including human, has raised enormous expectations in medicine, pharmacology, ecology, biotechnology and forensic sciences. However, knowledge is only a first step toward understanding, and we are only at the early stage of a scientific process that might lead us to satisfy all the expectations raised by the genomic projects. In this review I will discuss the present status of computational methods that attempt to infer the unique three-dimensional structure of proteins from their amino acid sequences. Although this problem has been defined as the “holy grail” of biology, it represents only one of the many hurdles in our path towards the understanding of life at a molecular level. 相似文献
37.
Anna Jenčová 《International Journal of Theoretical Physics》2004,43(7-8):1635-1649
We use a class of generalized relative entropies on density matrices to obtain one-parameter families of torsion-free affine connections. 相似文献
38.
Maria G. Semenova Larisa E. Belyakova Anna S. Antipova Yu. N. Polikarpov Lida Klouda Anna Markovic Michael M. Il'in 《Colloids and surfaces. B, Biointerfaces》2003,31(1-4):47-54
We report on the effect of commercially important polysaccharides (maltodextrins with variable dextrose equivalent (Paselli SA-2, MD-6 and MD-10) on the surface activity at the air–water interface of small-molecule surfactants (sms), possessing different hydrophobic–lipophilic balance ((SSL (Na+), the main component is a sodium salt of stearol–lactoyl lactic acid, and PGE (080), polyglycerol ester of C18 fatty acid), and widely used in food products. A marked change of the surface activity of sms was found in the presence of maltodextrins by tensiometry. The combined data of laser multiangle light scattering and mixing calorimetry have suggested that this result is governed by specific complex formation between maltodextrins and sms in aqueous medium. Measurements have been made of the molar mass, the second virial coefficient and the enthalpy of intermolecular interactions in aqueous solutions. The implication of a degree of polymerization of maltodextrins in this phenomenon was shown. The interrelation between the molecular parameters of the formed complexes and their surface activity at the air–water interface has been revealed and discussed. 相似文献
39.
Anna Avallone 《Mathematica Slovaca》2007,57(2):129-140
We prove the existence of separating points for every countable family of nonatomic σ-additive modular measures on a σ-complete lattice ordered effect algebra.
相似文献
40.
Anna Canale 《Journal of Mathematical Analysis and Applications》2003,287(1):101-117
In unbounded domains we state some a priori bounds for solutions of the Dirichlet problem for linear second order elliptic differential equations in nondivergence form with discontinuous coefficients in weighted spaces. The weight function is related to the distance function from a fixed subset S of ∂Ω. 相似文献