全文获取类型
收费全文 | 15146篇 |
免费 | 1712篇 |
国内免费 | 1554篇 |
专业分类
化学 | 350篇 |
晶体学 | 1篇 |
力学 | 1338篇 |
综合类 | 302篇 |
数学 | 13731篇 |
物理学 | 2690篇 |
出版年
2024年 | 14篇 |
2023年 | 191篇 |
2022年 | 162篇 |
2021年 | 267篇 |
2020年 | 458篇 |
2019年 | 500篇 |
2018年 | 476篇 |
2017年 | 557篇 |
2016年 | 515篇 |
2015年 | 359篇 |
2014年 | 774篇 |
2013年 | 1224篇 |
2012年 | 661篇 |
2011年 | 974篇 |
2010年 | 790篇 |
2009年 | 1000篇 |
2008年 | 1051篇 |
2007年 | 1042篇 |
2006年 | 930篇 |
2005年 | 837篇 |
2004年 | 712篇 |
2003年 | 738篇 |
2002年 | 659篇 |
2001年 | 450篇 |
2000年 | 464篇 |
1999年 | 463篇 |
1998年 | 410篇 |
1997年 | 364篇 |
1996年 | 244篇 |
1995年 | 164篇 |
1994年 | 164篇 |
1993年 | 107篇 |
1992年 | 84篇 |
1991年 | 61篇 |
1990年 | 58篇 |
1989年 | 42篇 |
1988年 | 45篇 |
1987年 | 34篇 |
1986年 | 31篇 |
1985年 | 37篇 |
1984年 | 55篇 |
1983年 | 28篇 |
1982年 | 50篇 |
1981年 | 37篇 |
1980年 | 34篇 |
1979年 | 18篇 |
1978年 | 21篇 |
1977年 | 13篇 |
1976年 | 9篇 |
1936年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
同时考虑了Kudryashov方法和Khalil一致分数阶变换,构造了求解一致分数阶非线性微分方程精确解的新方法,并将其用于求解时间-空间一致分数阶Whitham-Boroer-Kaup方程,得到了Whitham-Boroer-Kaup方程新的精确解,验证了该方法的有效性和可行性. 相似文献
22.
Transient transition behaviors of fractional-order simplest chaotic circuit with bi-stable locally-active memristor and its ARM-based implementation 下载免费PDF全文
Zong-Li Yang 《中国物理 B》2021,30(12):120515-120515
This paper proposes a fractional-order simplest chaotic system using a bi-stable locally-active memristor. The characteristics of the memristor and transient transition behaviors of the proposed system are analyzed, and this circuit is implemented digitally using ARM-based MCU. Firstly, the mathematical model of the memristor is designed, which is nonvolatile, locally-active and bi-stable. Secondly, the asymptotical stability of the fractional-order memristive chaotic system is investigated and some sufficient conditions of the stability are obtained. Thirdly, complex dynamics of the novel system are analyzed using phase diagram, Lyapunov exponential spectrum, bifurcation diagram, basin of attractor, and coexisting bifurcation, coexisting attractors are observed. All of these results indicate that this simple system contains the abundant dynamic characteristics. Moreover, transient transition behaviors of the system are analyzed, and it is found that the behaviors of transient chaotic and transient period transition alternately occur. Finally, the hardware implementation of the fractional-order bi-stable locally-active memristive chaotic system using ARM-based STM32F750 is carried out to verify the numerical simulation results. 相似文献
23.
In the paper mentioned in the title, it is proved the boundedness of the Riesz potential operator of variable order α(x) from variable exponent Morrey space to variable exponent Campanato space, under certain assumptions on the variable exponents p(x) and λ(x) of the Morrey space. Assumptions on the exponents were different depending on whether takes or not the critical values 0 or 1. In this note, we improve those results by unifying all the cases and covering the whole range . We also provide a correction to some minor technicality in the proof of Theorem 2 in the aforementioned paper. 相似文献
24.
25.
《Expositiones Mathematicae》2022,40(4):920-930
We prove an asymptotic version of the Muntz–Szasz theorem, and use it to prove that all monomial operators are vanishing preserving. 相似文献
26.
27.
28.
29.
The purpose of this article is to investigate high‐order numerical approximations of scalar conservation laws with nonlocal viscous term. The viscous term is given in the form of convolution in space variable. With the help of the characteristic of viscous term, we design a semidiscrete local discontinuous Galerkin (LDG) method to solve the nonlocal model. We prove stability and convergence of semidiscrete LDG method in L2 norm. The theoretical analysis reveals that the present numerical scheme is stable with optimal convergence order for the linear case, and it is stable with sub‐optimal convergence order for nonlinear case. To demonstrate the validity and accuracy of our scheme, we test the Burgers equation with two typical nonlocal fractional viscous terms. The numerical results show the convergence order accuracy in space for both linear and nonlinear cases. Some numerical simulations are provided to show the robustness and effectiveness of the present numerical scheme. 相似文献
30.
This paper is devoted to the construction of weak solutions to the singular constant Q-curvature problem. We build on several tools developed in the last years. This is the first construction of singular metrics on closed manifolds of sufficiently large dimension with constant (positive) Q-curvature. 相似文献