全文获取类型
收费全文 | 3725篇 |
免费 | 345篇 |
国内免费 | 457篇 |
专业分类
化学 | 82篇 |
晶体学 | 1篇 |
力学 | 227篇 |
综合类 | 52篇 |
数学 | 3329篇 |
物理学 | 836篇 |
出版年
2024年 | 6篇 |
2023年 | 46篇 |
2022年 | 41篇 |
2021年 | 59篇 |
2020年 | 80篇 |
2019年 | 94篇 |
2018年 | 90篇 |
2017年 | 98篇 |
2016年 | 104篇 |
2015年 | 107篇 |
2014年 | 161篇 |
2013年 | 269篇 |
2012年 | 118篇 |
2011年 | 174篇 |
2010年 | 143篇 |
2009年 | 226篇 |
2008年 | 326篇 |
2007年 | 229篇 |
2006年 | 230篇 |
2005年 | 202篇 |
2004年 | 165篇 |
2003年 | 215篇 |
2002年 | 202篇 |
2001年 | 145篇 |
2000年 | 165篇 |
1999年 | 135篇 |
1998年 | 112篇 |
1997年 | 111篇 |
1996年 | 87篇 |
1995年 | 50篇 |
1994年 | 55篇 |
1993年 | 39篇 |
1992年 | 25篇 |
1991年 | 28篇 |
1990年 | 16篇 |
1989年 | 12篇 |
1988年 | 18篇 |
1987年 | 13篇 |
1986年 | 13篇 |
1985年 | 17篇 |
1984年 | 13篇 |
1983年 | 6篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 16篇 |
1979年 | 8篇 |
1978年 | 12篇 |
1977年 | 10篇 |
1976年 | 4篇 |
1975年 | 4篇 |
排序方式: 共有4527条查询结果,搜索用时 218 毫秒
11.
G. S. Asanov 《Foundations of Physics Letters》2002,15(2):199-207
Granted the post-Lorentzian relativistic kinematic transformations are described in the Finslerian framework, the uniformity between the actual light-velocity anisotropy change and the anisotropic deformation of measuring rods can be the reason proper for the null results of the Michelson-Morley-type experiments at the first-order level. 相似文献
12.
Fillmore在[1]中得到一个定理:设A,T是Banach空间X上的线性变换,A有界,若Lat(A) Lat(T)且AT=TA,则T是A的多项式.在本文里,以此作为引理,讨论了Banach空间上可逆线性变换A在什么情况下,A-1可表示为A的多项式.本文最主要的结论是定理3.4:设X是Banach空间,A是X上的有界线性变换,且可逆,则A-1是A的多项式当且仅当A-1是A的局部多项式. 相似文献
13.
Shinji Takesue 《Journal of statistical physics》1989,56(3-4):371-402
This is the first part of a series devoted to the study of thermodynamic behavior of large dynamical systems with the use of a family of fully-discrete and conservative models named elementary reversible cellular automata (ERCAs). In this paper, basic properties such as conservation laws and phase space structure are investigated in preparation for the later studies. ERCAs are a family of one-dimensional reversible cellular automata having two Boolean variables on each site. Reflection and Boolean conjugation symmetries divide them into 88 equivalence classes. For each rule, additive conserved quantities written in a certain form are regarded as a kind of energy, if they exist. By the aid of the discreteness of the variables, every ERCA satisfies the Liouville theorem or the preservation of phase space volume. Thus, if an energy exists in the above sense, statistical mechanics of the model can formally be constructed. If a locally defined quantity is conserved, however, it prevents the realization of statistical mechanics. The existence of such a quantity is examined for each class and a number of rules which have at least one energy but no local conservation laws are selected as hopeful candidates for the realization of thermodynamic behavior. In addition, the phase space structure of ERCAs is analyzed by enumerating cycles exactly in the phase space for systems of comparatively small sizes. As a result, it is revealed that a finite ERCA is not ergodic, that is, a large number of orbits coexist on an energy surface. It is argued that this fact does not necessarily mean the failure of thermodynamic behavior on the basis of an analogy with the ergodic nature of infinite systems. 相似文献
14.
Given a tree
with leaf set X, there are certain ways of arranging the elements of X in a circular order so that
can be embedded in the plane and ‘preserve’ this ordering. We investigate some new combinatorial properties of these ‘circular orderings.’ We then use these properties to establish two results concerning dissimilarity maps on X that are induced by edge-weighted trees with leaf set X. 相似文献
15.
We introduce the notion of an invariant of characteristics for a system of first-order partial differential equations. We prove that the existence of invariants is connected with passiveness of some systems. We describe a few methods for construction of new invariants from those already known. We give a scheme for application of the invariants to reduction and integration of systems of partial differential equations. As an application we consider the equation of gas dynamics. 相似文献
16.
Keye Martin 《Applied Categorical Structures》2003,11(1):27-40
We introduce the triangle inequality for measurement. This is a property that when satisfied by a measurement enables one to construct a metric on the set of elements with measure zero that yields the relative Scott topology. The naturality of this construction permits a categorical solution to the model problem in domain theory for locally compact metric spaces. The first time such a solution has been achieved. 相似文献
17.
Jeong Ryeol Choi 《International Journal of Theoretical Physics》2004,43(4):947-958
We derived the WKB wave function for the general time-dependent quadratic Hamiltonian system using a unitary transformation method. We applied our research to sinusodially drived Caldirola–Kanai oscillator and confirmed that the time evolution of our approximated WKB wave function is similar to that of the exact one. This wave function can be used to analyze the interference between the probability amplitudes contributed by the area of overlap in phase space of quantum states. 相似文献
18.
相对论重离子碰撞实验中混合事件方法的研究 总被引:1,自引:0,他引:1
把RQMD(Relativistic Quantum Molecular Dynamics)产生器产生的数据输入作为原始事例取样,讨论了在比较复杂的背景情况下,一种新的混合事件方法,用以证实在相对论重离子碰撞实验中高能量激发共振态的存在.并以共振态重子Δ++为例演示了这一方法的应用. 相似文献
19.
20.
A. J. Zaslavski 《Journal of Optimization Theory and Applications》2004,123(3):695-712
In our previous work, a generic well-posedness result (with respect to variations of the integrand of the integral functional) without the convexity condition was established for a class of optimal control problems satisfying the Cesari growth condition. In this paper, we extend this generic well-posedness result to classes of constrained variational problems in which the values at the endpoints and constraint maps are also subject to variations. 相似文献