全文获取类型
收费全文 | 18241篇 |
免费 | 1080篇 |
国内免费 | 1505篇 |
专业分类
化学 | 6329篇 |
晶体学 | 78篇 |
力学 | 751篇 |
综合类 | 224篇 |
数学 | 9061篇 |
物理学 | 4383篇 |
出版年
2023年 | 201篇 |
2022年 | 307篇 |
2021年 | 386篇 |
2020年 | 366篇 |
2019年 | 422篇 |
2018年 | 414篇 |
2017年 | 432篇 |
2016年 | 459篇 |
2015年 | 396篇 |
2014年 | 640篇 |
2013年 | 1220篇 |
2012年 | 642篇 |
2011年 | 761篇 |
2010年 | 710篇 |
2009年 | 1084篇 |
2008年 | 1205篇 |
2007年 | 1246篇 |
2006年 | 1102篇 |
2005年 | 841篇 |
2004年 | 732篇 |
2003年 | 735篇 |
2002年 | 741篇 |
2001年 | 595篇 |
2000年 | 579篇 |
1999年 | 526篇 |
1998年 | 484篇 |
1997年 | 366篇 |
1996年 | 256篇 |
1995年 | 207篇 |
1994年 | 189篇 |
1993年 | 176篇 |
1992年 | 255篇 |
1991年 | 140篇 |
1990年 | 111篇 |
1989年 | 85篇 |
1988年 | 102篇 |
1987年 | 96篇 |
1986年 | 83篇 |
1985年 | 86篇 |
1984年 | 95篇 |
1983年 | 54篇 |
1982年 | 106篇 |
1981年 | 177篇 |
1980年 | 201篇 |
1979年 | 191篇 |
1978年 | 175篇 |
1977年 | 114篇 |
1976年 | 114篇 |
1973年 | 79篇 |
1972年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
胡迪鹤 《数学物理学报(B辑英文版)》2005,25(1):23-29
This paper is a continuation of [8]. In Section 1, three kinds of communication are introdnced for two states and the relations among them are investigated. In Section 2, two kinds of period of a state are introdnced and it is obtained that the period is a “class property” ,i.e. two states x and y belong to same class implies the period of x is equal to the period of y. 相似文献
72.
Máté Matolcsi 《Acta Mathematica Hungarica》2005,108(1-2):129-136
Summary He present work deals with estimations of the n-th linear polarization constant c(H)n of an n-dimensional real Hilbert space H. We provide some new lower bounds on the value of sup║y║=1 │1,y> ... n,y>│, where x1, ... ,xn are unit vectors in H. In particular, the results improve an earlier estimate of Marcus. However, the intriguing conjecture c(H) n= nn/2 remains open. 相似文献
73.
In this paper, we evaluate various analytic Feynman integrals of first variation, conditional first variation, Fourier-Feynman
transform and conditional Fourier-Feynman transform of cylinder type functions defined over Wiener paths in abstract Wiener
space. We also derive the analytic Feynman integral of the conditional Fourier-Feynman transform for the product of the cylinder
type functions which define the functions in a Banach algebra introduced by Yoo, with n linear factors. 相似文献
74.
本文是[1,12]的继续,研究描述架中概念的结构;本文讨论后半部分,内容涉及概念内涵与外延的转换,清晰关系的内投影与内变换,概念的结构*以及有关问题的注记。 相似文献
75.
本文得到了广义区间空间中几个参数型非空交定理,并用此结果证明了一些新型极大极小定理,截口定理,重合定理,以及变分不等式解的存在性定理。本文中的结果包含(1,3,5-12,14-16)中相应结果。 相似文献
76.
Xu Tianzhou 《东北数学》1997,(1)
ModulesoverOperatorAlgebrasandItsModuleMapsXuTianzhou(许天周)(DepartmentofMathematics,NanjingUniersity,Nanjing,210093)AbstractLe... 相似文献
77.
Sérgio d'Amorim Santa-Cruz 《Annals of Global Analysis and Geometry》1997,15(4):361-377
We study the hyperkähler geometry of complex adjoint orbits from the point of view of twistor theory. We introduce, for complex semisimple adjoint orbits, the associated spectral curve and construct the twistor space as a union of certain regular adjoint orbits; we also exhibit the family of twistor lines. Furthermore, we show how our methods may be applied for describing hyperkähler metrics associated to more general spectral curves. In particular, we give an algebraic characterisation of the twistor lines. 相似文献
78.
B. Sadashive Gowda G.S.V.L. Narasimham M.V. Krishna Murthy 《International Journal of Heat and Fluid Flow》1997,18(6):613-624
In this paper, a mathematical model for forced-air precooling of spherical food products in bulk is developed. The foods are arranged in horizontal layers stacked one above the other to form a rectangular parallelepiped with a vertical gap in between the product layers. The foods are cooled by chilled air blown along the height of the package. The governing equations for the conduction heat transfer in the foods, simultaneous heat and mass transfer at the food-air interface and in the air stream are solved numerically using finite-difference methods. A comprehensive numerical study is performed by varying the process parameters over a wide range. Typical results showing the variation of moist air properties along the height of the package and the effect of each parameter on the process time are presented. The ranges of parameters for advantageous operation of the precooling system are identified. Correlations are obtained for the process time based on the product center and mass-averaged temperatures in terms of process parameters. 相似文献
79.
E. Hatta H. Hosoi H. Akiyama T. Ishii K. Mukasa 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,2(3):347-349
We have observed a remarkable two-armed spiral in the collapse process of a floating monolayer at the air-water interface
by phase contrast microscopy. This demonstrates that the floating monolayer as a form of soft condensed matter reorganizes
itself due to a certain kind of macroscopic or collective behavior of molecules as it collapses. This pattern formation is
caused by the breakdown of a critical dynamical balance between the deformation of solid domain and the applied surface pressure.
The fragility as well as the flexibility of the floating monolayer can be associated with the observed pattern growth. There
are also observed interesting, periodically arranged collections of molecules in numerous collapsed regions.
Received: 8 July 1997 / Accepted: 4 November 1997 相似文献
80.
Alexander Afriat 《Foundations of Physics Letters》1995,8(5):467-480
We consider the question of factorizability in tensor product spaces, and argue that the correlations associated with entangled states are even more problematic in the general case involving any tensor product of Hilbert spaces, than in the Einstein, Podolsky, and Rosen case with only two [1]. 相似文献