全文获取类型
收费全文 | 4687篇 |
免费 | 499篇 |
国内免费 | 296篇 |
专业分类
化学 | 769篇 |
晶体学 | 30篇 |
力学 | 597篇 |
综合类 | 57篇 |
数学 | 2306篇 |
物理学 | 1723篇 |
出版年
2024年 | 5篇 |
2023年 | 46篇 |
2022年 | 72篇 |
2021年 | 99篇 |
2020年 | 125篇 |
2019年 | 139篇 |
2018年 | 127篇 |
2017年 | 135篇 |
2016年 | 146篇 |
2015年 | 103篇 |
2014年 | 184篇 |
2013年 | 387篇 |
2012年 | 197篇 |
2011年 | 219篇 |
2010年 | 180篇 |
2009年 | 297篇 |
2008年 | 254篇 |
2007年 | 261篇 |
2006年 | 299篇 |
2005年 | 198篇 |
2004年 | 216篇 |
2003年 | 195篇 |
2002年 | 177篇 |
2001年 | 146篇 |
2000年 | 157篇 |
1999年 | 133篇 |
1998年 | 129篇 |
1997年 | 93篇 |
1996年 | 82篇 |
1995年 | 74篇 |
1994年 | 56篇 |
1993年 | 69篇 |
1992年 | 53篇 |
1991年 | 38篇 |
1990年 | 45篇 |
1989年 | 40篇 |
1988年 | 47篇 |
1987年 | 42篇 |
1986年 | 37篇 |
1985年 | 32篇 |
1984年 | 26篇 |
1983年 | 15篇 |
1982年 | 24篇 |
1981年 | 14篇 |
1980年 | 10篇 |
1979年 | 11篇 |
1978年 | 17篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1973年 | 7篇 |
排序方式: 共有5482条查询结果,搜索用时 15 毫秒
1.
2.
The chiral phase transition and equation of state are studied within a novel self-consistent mean-field approximation of the two-flavor Nambu-Jona-Lasinio model. In this newly developed model, modifications to the chemical μ and chiral chemical \begin{document}$\mu_5$\end{document} ![]()
![]()
potentials are naturally included by introducing vector and axial-vector channels from Fierz-transformed Lagrangian to the standard Lagrangian. In the proper-time scheme, the chiral phase transition is a crossover in the \begin{document}$T-\mu$\end{document} ![]()
![]()
plane. However, when \begin{document}$\mu_5$\end{document} ![]()
![]()
is incorporated, our study demonstrates that a first order phase transition may emerge. Furthermore, the chiral imbalance will soften the equation of state of quark matter. The mass-radius relationship and tidal deformability of quark stars are calculated. The maximum mass and radius decrease as \begin{document}$\mu_5$\end{document} ![]()
![]()
increases. Our study also indicates that the vector and axial-vector channels exhibit an opposite influence on the equation of state. 相似文献
3.
Rong Yin Jihui Zhang Xudong Shang 《Mathematical Methods in the Applied Sciences》2020,43(15):8736-8752
This paper is dedicated to studying the following Schrödinger–Poisson system Under some different assumptions on functions V(x), K(x), a(x) and f(u), by using the variational approach, we establish the existence of positive ground state solutions. 相似文献
4.
Yoel Shkolnisky Mark Tygert Vladimir Rokhlin 《Applied and Computational Harmonic Analysis》2006,21(3):413-420
Many signals encountered in science and engineering are approximated well by bandlimited functions. We provide suitable error bounds for the approximation of bandlimited functions by linear combinations of certain special functions—the prolate spheroidal wave functions of order 0. The coefficients in the approximating linear combinations are given explicitly via appropriate quadrature formulae. 相似文献
5.
具Hardy-Sobolev临界指数的奇异椭圆方程多解的存在性 总被引:1,自引:0,他引:1
运用变分方法研究了下面问题-Δpu=μupx(s)s-2u f(x,u),x∈Ω,u=0,x∈Ω,多重解的存在性,其中Ω是一个具有光滑边界的有界区域. 相似文献
6.
We study a site analogue of directed percolation. Random trajectories are generated and their critical behavior is studied. The critical behavior corresponds to that of simple percolation in some of the parameter space, but elsewhere the exponents reveal new universality classes. As a byproduct, we use the model to make an improved estimate of the percolation hull exponents and to calculate the site percolation probability for the square lattice. 相似文献
7.
基于LabVIEW的高温超导材料特性测试实验 总被引:4,自引:1,他引:3
高温超导体临界特性的测量是近代物理实验中最为经典的实验之一,本文通过使用GM制冷机,利用Lab-VIEW虚拟仪器软件和高性能采集卡,改进了传统的测量高温超导材料临界特性的实验装置.本测试系统不仅可以测量高温超导体在不同温度下的临界电流,还可以测量其失超传播特性.该实验对于学生了解超导体特性和培养严谨的科学作风十分有益. 相似文献
8.
Cai Xiaochun 《Annals of Differential Equations》2006,22(1):1-6
In this paper, we apply a critical point theorem and obtain the condition for the existence of three solutions to two-point boundary value problem of a second order nonlinear difference equation. 相似文献
9.
Vivek F. Farias 《Operations Research Letters》2006,34(2):180-190
We consider a problem of allocating limited quantities of M types of resources among N independent activities that evolve over T epochs. In each epoch, we assign to each activity a task which consumes resources, generates utility, and determines the subsequent state of the activity. We study the complexity of, and approximation algorithms for, maximizing average utility. 相似文献
10.
Annegret K. Wagler 《Mathematical Methods of Operations Research》2002,56(1):127-149
An edge e of a perfect graph G is critical if G−e is imperfect. We would like to decide whether G−e is still “almost perfect” or already “very imperfect”. Via relaxations of the stable set polytope of a graph, we define two
superclasses of perfect graphs: rank-perfect and weakly rank-perfect graphs. Membership in those two classes indicates how
far an imperfect graph is away from being perfect. We study the cases, when a critical edge is removed from the line graph
of a bipartite graph or from the complement of such a graph. 相似文献