全文获取类型
收费全文 | 9846篇 |
免费 | 325篇 |
国内免费 | 50篇 |
专业分类
化学 | 6289篇 |
晶体学 | 39篇 |
力学 | 226篇 |
数学 | 1384篇 |
物理学 | 2283篇 |
出版年
2021年 | 113篇 |
2020年 | 153篇 |
2019年 | 144篇 |
2018年 | 96篇 |
2017年 | 82篇 |
2016年 | 222篇 |
2015年 | 195篇 |
2014年 | 239篇 |
2013年 | 477篇 |
2012年 | 483篇 |
2011年 | 560篇 |
2010年 | 367篇 |
2009年 | 293篇 |
2008年 | 498篇 |
2007年 | 561篇 |
2006年 | 508篇 |
2005年 | 521篇 |
2004年 | 462篇 |
2003年 | 366篇 |
2002年 | 343篇 |
2001年 | 191篇 |
2000年 | 177篇 |
1999年 | 132篇 |
1998年 | 105篇 |
1997年 | 125篇 |
1996年 | 137篇 |
1995年 | 99篇 |
1994年 | 106篇 |
1993年 | 104篇 |
1992年 | 128篇 |
1991年 | 103篇 |
1990年 | 101篇 |
1989年 | 97篇 |
1988年 | 67篇 |
1987年 | 72篇 |
1986年 | 84篇 |
1985年 | 132篇 |
1984年 | 122篇 |
1983年 | 100篇 |
1982年 | 103篇 |
1981年 | 105篇 |
1980年 | 86篇 |
1979年 | 85篇 |
1978年 | 101篇 |
1977年 | 81篇 |
1976年 | 68篇 |
1975年 | 79篇 |
1974年 | 88篇 |
1973年 | 90篇 |
1972年 | 62篇 |
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
171.
172.
A model for the pulsatile release of luteinizing hormone releasing hormone (LHRH) can be reduced to a FitzHugh-Nagumo model subject to regular and quasiregular (i.e., with slight random variation in the interstimulus interval), discrete-time stimulation. The relationship of output pulse frequency (OPF) to stimulus frequency is compared between the excitable and oscillatory forms of the model and discussed in the context of results from other pulse-driven model systems. Some examples of the changes in OPF caused by quasiregular and purely Poissonian stimuli are given for the excitable case. The unstimulated system frequently interacts with the stimulation in such a complex manner that the OPF bears little resemblance to the frequency of stimulation or of the unstimulated system. Furthermore, the inability of the oscillatory form of the model to allow complete suppression of output pulses for moderate stimulation frequencies suggests that the LHRH system can be more appropriately described by the excitable form of the model. (c) 1995 American Institute of Physics. 相似文献
173.
Marc A. Rieffel 《Communications in Mathematical Physics》1995,171(1):181-201
LetG be a Lie group. For any Abelian subalgebra
of the Lie algebra g ofG, and any
, the difference of the left and right translates ofr gives a compatible Poisson bracket onG. We show how to construct the corresponding quantum group, in theC
*-algebra setting. The main tool used is the general deformation quantization construction developed earlier by the author for actions of vector groups onC
*-algebras.The research reported on here was supported in part by National Science Foundation grant DMS-9303386. 相似文献
174.
Two partial ordersP andQ on a setX arecomplementary (written asPQ) if they share no ordered pairs (except for loops) but the transitive closure of the union is all possible ordered pairs. For each positive integern we form a graph Pos
n
consisting of all nonempty partial orders on {1, ,n} with edges denoting complementation. We investigate here properties of the graphs Pos
n
. In particular, we show:
| The diameter of Pos n is 5 for alln>2 (and hence Pos n is connected for alln); | |
| With probability 1, the distance between two members of Pos n is 2; | |
| The graphs Pos n are universal (i.e. every graph occurs as an induced subgraph of some Pos n ); | |
|
The maximal size (n) of an independent set of Pos
n
satisfies the asymptotic formula
|
设为首页 | 免责声明 | 关于勤云 | 加入收藏 |
Copyright©北京勤云科技发展有限公司 京ICP备09084417号 |