全文获取类型
收费全文 | 1695篇 |
免费 | 271篇 |
国内免费 | 311篇 |
专业分类
化学 | 915篇 |
晶体学 | 12篇 |
力学 | 59篇 |
综合类 | 2篇 |
数学 | 587篇 |
物理学 | 702篇 |
出版年
2023年 | 24篇 |
2022年 | 40篇 |
2021年 | 79篇 |
2020年 | 74篇 |
2019年 | 52篇 |
2018年 | 32篇 |
2017年 | 44篇 |
2016年 | 72篇 |
2015年 | 58篇 |
2014年 | 112篇 |
2013年 | 125篇 |
2012年 | 161篇 |
2011年 | 170篇 |
2010年 | 146篇 |
2009年 | 142篇 |
2008年 | 116篇 |
2007年 | 157篇 |
2006年 | 141篇 |
2005年 | 100篇 |
2004年 | 87篇 |
2003年 | 56篇 |
2002年 | 52篇 |
2001年 | 32篇 |
2000年 | 31篇 |
1999年 | 38篇 |
1998年 | 42篇 |
1997年 | 25篇 |
1996年 | 26篇 |
1995年 | 18篇 |
1994年 | 11篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有2277条查询结果,搜索用时 15 毫秒
91.
《Communications in Nonlinear Science & Numerical Simulation》2011,16(2):958-965
This paper discusses the synchronization of the chaotic system. Some new and less conservative sufficient conditions are established by impulsive control method with channel time-delay and different time-varying parameter uncertainties. An example and its simulations are finally included to visualize the effectiveness and feasibility of the method. 相似文献
92.
93.
为减少城市交通拥挤,从交通量均分的角度出发,提出了综合反映道路网络局部和整体性质的k最优定向,并且利用奇度点配对的思想为定向问题设计了启发式算法。 相似文献
94.
H. -X. Wang X. -Q. Yang S. Zhao B. -T. Zhang H. -T. Huang J. -F. Yang J. -L. Xu J. -L. He 《Laser Physics》2009,19(8):1824-1827
A compact diode-end-pumped passively Q-switched composite Nd:YAG/Cr4+:YAG laser was demonstrated in this paper. At the incident pump power of 11.8 W, the shortest pulse width of 2.05 ns was obtained, corresponding to average output power of 1.15 W and repetition rate of 17.1 kHz. The single-pulse energy and peak power were estimated to be 67.3 μJ and 32.8 kW, respectively. 相似文献
95.
Ziwen Jiang 《Journal of Applied Mathematics and Computing》1999,6(1):143-161
In this paper, we consider the second order generalized difference scheme for the two-point boundary value problem and obtain optimal order error estimates inL ∞ andW 1, ∞. The results in this paper perfect the theory of the second order generalized difference method. 相似文献
96.
李师正 《应用数学学报(英文版)》2000,16(4):362-365
1. IntroductionLet X be the n-dimensional Euclidean space Rad. Denote the transpose of the columnvector y by yT. Suppose that R7 and nit R= are the n-dimensional vector sets with nonnegative and positive components, whose elements are denoted by y 3 0 and y > 0, respectively.Write R for the nonnegative real number set.Consider a nondiffereatiable convex programming problem:We assume that f(x), gi(x),..', g.(x) are finite reaLvalued continuous, convex functions on X, but not necessarily d… 相似文献
97.
Using the evolutionary game framework to describe the vaccination behaviors of individuals, this work focuses on the impact of other-regarding tendencies on collective decision-making of vaccination. With extensive computational simulations, we find that when the vaccination cost is small or moderate, the variance of vaccination coverage as well as epidemic size is monotonically depending on the other-regarding effect. However, with a high price of vaccine, a moderate deviation from being entirely self-centered results in a poor communal vaccination benefit. In addition, we also find that the other-regarding effect may lead to an optimal total social cost. 相似文献
98.
Dezhan Chen Qingli Wang Honghong Zhang Shizhen Mi Juliang Wang Qiang Zeng Guiqiu Zhang 《International journal of quantum chemistry》2010,110(7):1394-1401
The disproportionation of superoxide radical anions catalyzed by copper‐zinc superoxide dismutase was investigated in detail using density functional theory. The structures of each stationary point and the transition states were located so that the reaction pathways were determined. The results indicate that the reactions proceed by two steps both for the oxidized process of superoxide radical anion and the reduced one. The rate for the determining step of the reaction (2) is in very good agreement with the experimental value. The solvation effect on the reaction was also discussed. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 相似文献
99.
In this article, all calculations are performed at B3LYP/6‐31G** level. For each one of the molecule, including triphenylamine (TPA), N,N′‐diphenyl‐N,N′‐bis(3‐methyllphenyl)‐(1,1′‐biphenyl)‐4,4′‐diamine (TPD), biphenyl (Bp), and their derivatives (TPAs, TPDs, Bps, respectively), the geometry is optimized for both neutral and radical‐cation states. Their reorganization energy is then compared. It seems that it is the monomer, TPAs, and not the central biphenyl moiety that determines the properties of TPDs. However, this is contradictory of some previous results. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
100.
Some class 1 graphs on <Emphasis Type="Italic">g</Emphasis><Subscript><Emphasis Type="Italic">c</Emphasis></Subscript>-colorings 下载免费PDF全文
An edge-coloring of a graph G is an assignment of colors to all the edges of G. A g c -coloring of a graph G is an edge-coloring of G such that each color appears at each vertex at least g(v) times. The maximum integer k such that G has a g c -coloring with k colors is called the g c -chromatic index of G and denoted by \(\chi\prime_{g_{c}}\)(G). In this paper, we extend a result on edge-covering coloring of Zhang and Liu in 2011, and give a new sufficient condition for a simple graph G to satisfy \(\chi\prime_{g_{c}}\)(G) = δ g (G), where \(\delta_{g}\left(G\right) = min_{v\epsilon V (G)}\left\{\lfloor\frac{d\left(v\right)}{g\left(v\right)}\rfloor\right\}\). 相似文献