全文获取类型
收费全文 | 1371篇 |
免费 | 67篇 |
国内免费 | 1篇 |
专业分类
化学 | 687篇 |
晶体学 | 24篇 |
力学 | 57篇 |
数学 | 197篇 |
物理学 | 387篇 |
无线电 | 87篇 |
出版年
2023年 | 11篇 |
2022年 | 23篇 |
2021年 | 40篇 |
2020年 | 33篇 |
2019年 | 41篇 |
2018年 | 64篇 |
2017年 | 38篇 |
2016年 | 58篇 |
2015年 | 51篇 |
2014年 | 44篇 |
2013年 | 66篇 |
2012年 | 89篇 |
2011年 | 94篇 |
2010年 | 72篇 |
2009年 | 59篇 |
2008年 | 72篇 |
2007年 | 47篇 |
2006年 | 53篇 |
2005年 | 52篇 |
2004年 | 28篇 |
2003年 | 23篇 |
2002年 | 32篇 |
2001年 | 19篇 |
2000年 | 24篇 |
1999年 | 14篇 |
1998年 | 19篇 |
1997年 | 16篇 |
1996年 | 12篇 |
1995年 | 8篇 |
1994年 | 15篇 |
1993年 | 12篇 |
1992年 | 14篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1981年 | 12篇 |
1980年 | 9篇 |
1979年 | 16篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 9篇 |
1974年 | 7篇 |
1972年 | 9篇 |
排序方式: 共有1439条查询结果,搜索用时 15 毫秒
121.
Yury Yu. Rusakov Leonid B. Krivdin Stephan P. A. Sauer Ekaterina P. Levanova Galina G. Levkovskaya 《Magnetic resonance in chemistry : MRC》2010,48(1):44-52
Experimental measurements and second‐order polarization propagator approach (SOPPA) calculations of 77Se? 1H spin–spin coupling constants together with theoretical energy‐based conformational analysis in the series of 2‐substituted selenophenes have been carried out. A new basis set optimized for the calculation of 77Se? 1H spin–spin coupling constants has been introduced by extending the aug‐cc‐pVTZ‐J basis for selenium. Most of the spin–spin coupling constants under study, especially vicinal 77Se? 1H couplings, demonstrated a remarkable stereochemical behavior with respect to the internal rotation of the substituent in the 2‐position of the selenophene ring, which is of major importance in the stereochemical studies of the related organoselenium compounds. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
122.
A multicriteria Boolean programming problem with linear cost functions in which initial coefficients of the cost functions are subject to perturbations is considered. For any optimal alternative, with respect to parameterized principle of optimality “from Condorcet to Pareto”, appropriate measures of the quality are introduced. These measures correspond to the so-called stability and accuracy functions defined earlier for optimal solutions of a generic multicriteria combinatorial optimization problem with Pareto and lexicographic optimality principles. Various properties of such functions are studied and maximum norms of perturbations for which an optimal alternative preserves its optimality are calculated. To illustrate the way how the stability and accuracy functions can be used as efficient tools for post-optimal analysis, an application from the voting theory is considered. 相似文献
123.
Yury Grabovsky Vladislav A. Kucher Lev Truskinovsky 《Continuum Mechanics and Thermodynamics》2011,23(2):87-123
In the case of Lipschitz extremals of vectorial variational problems, an important class of strong variations originates from
smooth deformations of the corresponding non-smooth graphs. These seemingly singular variations, which can be viewed as combinations
of weak inner and outer variations, produce directions of differentiability of the functional and lead to singularity-centered
necessary conditions on strong local minima: an equality, arising from stationarity, and an inequality, implying configurational
stability of the singularity set. To illustrate the underlying coupling between inner and outer variations, we study in detail
the case of smooth surfaces of gradient discontinuity representing, for instance, martensitic phase boundaries in non-linear
elasticity. 相似文献
124.
Adrian P Higson Yury E Tsvetkov Michael A.J Ferguson Andrei V Nikolaev 《Tetrahedron letters》1999,40(52):297-9284
The triglycosyl monophosphate 1, heptaglycosyl triphosphates 2 and 3, and octaglycosyl triphosphate 4, which are fragments of the phosphoglycan part of Leishmania major lipo- and proteo-phosphoglycans have been prepared using di- and tri-saccharide H-phosphonates for construction of the phosphodiester bridges. 相似文献
125.
126.
A. V. Nezhdanov D. O. Filatov D. A. Antonov S. Yu. Zubkov A. I. Mashin A. V. Ershov 《Semiconductors》2011,45(1):56-60
The results of studies of the morphology, electronic structure, and optical properties of self-assembled silicon nanostructures on the surface of highly oriented pyrolytic graphite are reported. The structures are fabricated by electron-beam-assisted evaporation in high-vacuum conditions. It is found that, at thicknesses of about one monolayer, the atomic structure of the layer is similar to that of graphene with the interatomic spacing ~2.4 Å. At film thicknesses larger than one monolayer, clusters about 5 nm in dimensions are formed on the substrate surface. 相似文献
127.
Yury J. Ionin 《Discrete Mathematics》2006,306(14):1557-1568
The first infinite families of symmetric designs were obtained from finite projective geometries, Hadamard matrices, and difference sets. In this paper we describe two general methods of constructing symmetric designs that give rise to the parameters of all other known infinite families of symmetric designs. The method of global decomposition produces an incidence matrix of a symmetric design as a block matrix with each block being a zero matrix or an incidence matrix of a smaller symmetric design. The method of local decomposition represents incidence matrices of a residual and a derived design of a symmetric design as block matrices with each block being a zero matrix or an incidence matrix of a smaller residual or derived design, respectively. 相似文献
128.
Yury Nikulin 《Journal of Heuristics》2008,14(4):391-402
This paper addresses the robust spanning tree problem with interval data, i.e. the case of classical minimum spanning tree
problem when edge weights are not fixed but take their values from some intervals associated with edges. The problem consists
of finding a spanning tree that minimizes so-called robust deviation, i.e. deviation from an optimal solution under the worst
case realization of interval weights. As it was proven in Kouvelis and Yu (Robust Discrete Optimization and Its Applications,
Kluwer Academic, Norwell, 1997), the problem is NP-hard, therefore it is of great interest to tackle it with some metaheuristic approach, namely simulated
annealing, in order to calculate an approximate solution for large scale instances efficiently. We describe theoretical aspects
and present the results of computational experiments. To the best of our knowledge, this is the first attempt to develop a
metaheuristic approach for solving the robust spanning tree problem. 相似文献
129.
V. A. Antonov 《Algebra and Logic》1994,33(5):265-286
An earlier conjecture suggests that the lattice of centralizers is modular in the title groups. We prove it to hold for two classes of groups whose lattice of centralizers has finite length — groups with the normalizer condition and locally finite groups.Translated fromAlgebra i Logika, Vol. 33, No. 5, pp. 475–513, September–October, 1994. 相似文献
130.
In this paper, the stochastic theory of developed turbulence is considered within the framework of the quantum field renormalization
group and operator expansions. The problem of justifying the Kolmogorov-Obukhov theorem in application to the correlation
functions of composite operators is discussed. An explicit expression is found for the critical dimension of a general-type
composite operator. For an arbitrary UV-finite composite operator, the second Kolmogorov hypothesis (the viscosity-independence
of the correlator) is proved and the dependence of various correlators on the external turbulence scale is determined. It
is shown that the problem involves an infinite number of Galilean-invariant scalar operators with negative critical dimensions.
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 110, No. 1, pp. 122–136, January, 1997. 相似文献