全文获取类型
收费全文 | 1693篇 |
免费 | 50篇 |
国内免费 | 5篇 |
专业分类
化学 | 1299篇 |
晶体学 | 12篇 |
力学 | 82篇 |
数学 | 175篇 |
物理学 | 180篇 |
出版年
2023年 | 11篇 |
2022年 | 37篇 |
2021年 | 33篇 |
2020年 | 17篇 |
2019年 | 25篇 |
2018年 | 13篇 |
2017年 | 18篇 |
2016年 | 44篇 |
2015年 | 48篇 |
2014年 | 42篇 |
2013年 | 71篇 |
2012年 | 92篇 |
2011年 | 96篇 |
2010年 | 67篇 |
2009年 | 46篇 |
2008年 | 127篇 |
2007年 | 122篇 |
2006年 | 121篇 |
2005年 | 112篇 |
2004年 | 107篇 |
2003年 | 73篇 |
2002年 | 68篇 |
2001年 | 35篇 |
2000年 | 21篇 |
1999年 | 19篇 |
1998年 | 23篇 |
1997年 | 15篇 |
1996年 | 36篇 |
1995年 | 20篇 |
1994年 | 16篇 |
1993年 | 13篇 |
1992年 | 12篇 |
1991年 | 11篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 12篇 |
1984年 | 10篇 |
1983年 | 5篇 |
1982年 | 8篇 |
1981年 | 18篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1973年 | 3篇 |
1971年 | 3篇 |
1929年 | 3篇 |
排序方式: 共有1748条查询结果,搜索用时 328 毫秒
151.
We prove the existence of periodic solutions for first order planar systems at resonance. The nonlinearity is indeed allowed to interact with two positively homogeneous Hamiltonians, both at resonance, and some kind of Landesman-Lazer conditions are assumed at both sides. We are thus able to obtain, as particular cases, the existence results proposed in the pioneering papers by Lazer and Leach (1969) [27], and by Frederickson and Lazer (1969) [18]. Our theorem also applies in the case of asymptotically piecewise linear systems, and in particular generalizes Fabry's results in Fabry (1995) [10], for scalar equations with double resonance with respect to the Dancer-Fu?ik spectrum. 相似文献
152.
153.
154.
Yi -Cheng Zhang Maurizio Serva Mikhail Polikarpov 《Journal of statistical physics》1990,58(5-6):849-861
Interesting physics emerges from studying a population of reproducing individuals. Each can be regarded as a random walker, but it can either duplicate or die. Novel features of the collective behavior are quite surprising: if individuals reproduce or die freely, the life expectation is proportional to the size of the population, and if it is kept constant, the center of mass moves in space as if it were a single walker (i.e., the diffusion constant is independent of population's size). Biology-inspired interactions are also considered. 相似文献
155.
T. Letardi S. Bollanti P. Di Lazzaro F. Flora N. Lisi C. E. Zheng 《Il Nuovo Cimento D》1992,14(5):495-507
Summary Some limitation problems for gas discharge excimer lasers, when scaled to a high pulsed energy output with high repetition
rate are discussed. As an example, we present some experimental results obtained with an X-ray preionized (10×10×100) cm3 active volume, low-repetition-rate-operated gas discharge XeCl laser system.
ENEA student.
ENEA guest. 相似文献
156.
157.
For a linear anisotropic hyperelastic body subjected to a state of pure strain it is shown that there are at least three directions such that the stress and strain tensors are coaxial. 相似文献
158.
159.
We study the dynamics of a noisy network of spiking neurons with spike-frequency adaptation (SFA), using a mean-field approach, in terms of a two-dimensional Fokker-Planck equation for the membrane potential of the neurons and the calcium concentration gating SFA. The long time scales of SFA allow us to use an adiabatic approximation and to describe the network as an effective nonlinear two-dimensional system. The phase diagram is computed for varying levels of SFA and synaptic coupling. Two different population-bursting regimes emerge, depending on the level of SFA in networks with noisy emission rate, due to the finite number of neurons. 相似文献
160.
The complete list of constraint manifolds having the group structure is given. 相似文献