全文获取类型
收费全文 | 12228篇 |
免费 | 929篇 |
国内免费 | 486篇 |
专业分类
化学 | 1143篇 |
晶体学 | 50篇 |
力学 | 796篇 |
综合类 | 70篇 |
数学 | 8492篇 |
物理学 | 3092篇 |
出版年
2023年 | 110篇 |
2022年 | 173篇 |
2021年 | 235篇 |
2020年 | 320篇 |
2019年 | 313篇 |
2018年 | 295篇 |
2017年 | 265篇 |
2016年 | 283篇 |
2015年 | 248篇 |
2014年 | 477篇 |
2013年 | 1282篇 |
2012年 | 547篇 |
2011年 | 624篇 |
2010年 | 549篇 |
2009年 | 760篇 |
2008年 | 765篇 |
2007年 | 754篇 |
2006年 | 600篇 |
2005年 | 480篇 |
2004年 | 401篇 |
2003年 | 439篇 |
2002年 | 403篇 |
2001年 | 367篇 |
2000年 | 391篇 |
1999年 | 313篇 |
1998年 | 304篇 |
1997年 | 223篇 |
1996年 | 181篇 |
1995年 | 160篇 |
1994年 | 163篇 |
1993年 | 103篇 |
1992年 | 118篇 |
1991年 | 94篇 |
1990年 | 82篇 |
1989年 | 76篇 |
1988年 | 64篇 |
1987年 | 76篇 |
1986年 | 54篇 |
1985年 | 107篇 |
1984年 | 71篇 |
1983年 | 42篇 |
1982年 | 56篇 |
1981年 | 33篇 |
1980年 | 39篇 |
1979年 | 37篇 |
1978年 | 26篇 |
1977年 | 40篇 |
1976年 | 26篇 |
1974年 | 15篇 |
1973年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Esa Nummelin 《Journal of Theoretical Probability》1994,7(4):739-756
The paper is concerned with characterization results for distributional regeneration. It is shown that distributional regeneration is equivalent to renewal representation of the associated (shift) Markov operator. A sufficient condition for the distributional regeneration of the transfer operator in terms of variation is also formulated. Finally, a minorization condition is formulated and proved to be sufficient for recurrent co-Feller operators. 相似文献
32.
In this paper, we propose and analyze an SQP-type method for solving linearly constrained convex minimization problems where the objective functions are too complex to be evaluated exactly. Some basic results for global convergence and local superlinear convergence are obtained according to the properties of the approximation sequence. We illustrate the applicability of our approach by proposing a new method for solving two-stage stochastic programs with fixed recourse. 相似文献
33.
T. Schäfer 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):403-408
We review many-body calculations of the equation of state of dilute neutron matter in the context of effective-field theories
of the nucleon-nucleon interaction. 相似文献
34.
Optimality conditions are obtained for a nonlinear fractional multiobjective programming problem involving η-semidifferentiable functions. Also, a general dual is formulated and a duality result is proved using concepts of generalized ρ-semilocally type I-preinvex functions. 相似文献
35.
36.
Andreas Rößler 《BIT Numerical Mathematics》2006,46(1):97-110
A general class of stochastic Runge–Kutta methods for Itô stochastic differential equation systems w.r.t. a one-dimensional Wiener process is introduced. The colored rooted tree analysis is applied to derive conditions for the coefficients of the stochastic Runge–Kutta method assuring convergence in the weak sense with a prescribed order. Some coefficients for new stochastic Runge–Kutta schemes of order two are calculated explicitly and a simulation study reveals their good performance. 相似文献
37.
Let G(x,y) and GD(x,y) be the Green functions of rotationally invariant symmetric α-stable process in Rd and in an open set D, respectively, where 0<α<2. The inequality GD(x,y)GD(y,z)/GD(x,z)?c(G(x,y)+G(y,z)) is a very useful tool in studying (local) Schrödinger operators. When the above inequality is true with c=c(D)∈(0,∞), then we say that the 3G theorem holds in D. In this paper, we establish a generalized version of 3G theorem when D is a bounded κ-fat open set, which includes a bounded John domain. The 3G we consider is of the form GD(x,y)GD(z,w)/GD(x,w), where y may be different from z. When y=z, we recover the usual 3G. The 3G form GD(x,y)GD(z,w)/GD(x,w) appears in non-local Schrödinger operator theory. Using our generalized 3G theorem, we give a concrete class of functions belonging to the non-local Kato class, introduced by Chen and Song, on κ-fat open sets. As an application, we discuss relativistic α-stable processes (relativistic Hamiltonian when α=1) in κ-fat open sets. We identify the Martin boundary and the minimal Martin boundary with the Euclidean boundary for relativistic α-stable processes in κ-fat open sets. Furthermore, we show that relative Fatou type theorem is true for relativistic stable processes in κ-fat open sets. The main results of this paper hold for a large class of symmetric Markov processes, as are illustrated in the last section of this paper. We also discuss the generalized 3G theorem for a large class of symmetric stable Lévy processes. 相似文献
38.
Koen Thas 《Journal of Algebraic Combinatorics》2006,24(1):5-22
In this paper, we classify the finite generalized quadrangles of order (s,t), s,t > 1, which have a line L of elation points, with the additional property that there is a line M not meeting L for which {L, M} is regular. This is a first fundamental step towards the classification of those generalized quadrangles having a line of
elation points.
Mathematics Subject Classification (2000): 51E12, 51E20, 20B25, 20E42 相似文献
39.
The generalized Mycielskians (also known as cones over graphs) are the natural generalization of the Mycielski graphs (which were first introduced by Mycielski in 1955). Given a graph G and any integer m?0, one can transform G into a new graph μm(G), the generalized Mycielskian of G. This paper investigates circular clique number, total domination number, open packing number, fractional open packing number, vertex cover number, determinant, spectrum, and biclique partition number of μm(G). 相似文献
40.
If g and G are the pdf and the cdf of a distribution symmetric around 0 then the pdf 2g(u)G(λ
u) is said to define a skew distribution. In this paper, we provide a mathematical treatment of the skew distributions when
g and G are taken to come from one of Pearson type II, Pearson type VII or the generalized t distribution.
相似文献