全文获取类型
收费全文 | 3071篇 |
免费 | 314篇 |
国内免费 | 231篇 |
专业分类
化学 | 323篇 |
晶体学 | 4篇 |
力学 | 545篇 |
综合类 | 47篇 |
数学 | 1511篇 |
物理学 | 1186篇 |
出版年
2024年 | 7篇 |
2023年 | 32篇 |
2022年 | 50篇 |
2021年 | 68篇 |
2020年 | 95篇 |
2019年 | 92篇 |
2018年 | 61篇 |
2017年 | 68篇 |
2016年 | 102篇 |
2015年 | 76篇 |
2014年 | 122篇 |
2013年 | 252篇 |
2012年 | 139篇 |
2011年 | 214篇 |
2010年 | 145篇 |
2009年 | 177篇 |
2008年 | 161篇 |
2007年 | 190篇 |
2006年 | 179篇 |
2005年 | 153篇 |
2004年 | 139篇 |
2003年 | 131篇 |
2002年 | 124篇 |
2001年 | 113篇 |
2000年 | 111篇 |
1999年 | 81篇 |
1998年 | 71篇 |
1997年 | 62篇 |
1996年 | 56篇 |
1995年 | 36篇 |
1994年 | 39篇 |
1993年 | 25篇 |
1992年 | 28篇 |
1991年 | 35篇 |
1990年 | 15篇 |
1989年 | 18篇 |
1988年 | 15篇 |
1987年 | 16篇 |
1986年 | 15篇 |
1985年 | 9篇 |
1984年 | 16篇 |
1983年 | 9篇 |
1982年 | 15篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1978年 | 5篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1973年 | 4篇 |
排序方式: 共有3616条查询结果,搜索用时 0 毫秒
91.
Anjan Biswas Swapan Konar Essaid Zerrad 《International Journal of Theoretical Physics》2007,46(1):157-169
The intra-channel collision of optical solitons, with dual-power law nonlinearity, is studied in this paper by the aid of
quasi-particle theory. The perturbation terms that are considered in this paper are the nonlinear gain and saturable amplifiers
along with filters. The suppression of soliton-soliton interaction, in presence of these perturbation terms, is acheived.
The numerical simulations support the quasi-particle theory.
OCIS codes: 060.2310; 060.4510; 060.5530; 190.3270; 190.4370. 相似文献
92.
We propose an aggregation model of a two-species system to mimic the growth of cities' population and assets,in which irreversible coagulation reactions and exchange reactions occur between any two aggregates of the same species,and the monomer-birth reactions of one species occur by the catalysis of the other species.In the case with population-catalyzed birth of assets,the rate kernel of an asset aggregate Bκ of size k grows to become an aggregate Bκ 1through a monomer-birth catalyzed by a population aggregate Aj of size j is J(k,j) = Jkjλ.And in mutually catalyzed birth model,the birth rate kernels of population and assets are H(k,j) = Hkjη and J(k,j) = Jkjλ,respectively.The kinetics of the system is investigated based on the mean-field theory.In the model of population-catalyzed birth of assets,the long-time asymptotic behavior of the assets aggregate size distribution obeys the conventional or modified scaling form.In mutually catalyzed birth system,the asymptotic behaviors of population and assets obey the conventional scaling form in the case ofη =λ= 0,and they obey the modified scalingform in the case of η = 0,λ= 1.In the case of η = λ = 1,the total mass of population aggregates and that of asset aggregates both grow much faster than those in population-catalyzed birth of assets model,and they approaches to infinite values in finite time. 相似文献
93.
本文对各向同性极端相对论快电子呈幂律分布等离子体中横振荡色散关系进行了解析和数值研究.得到长波支和短波支色散关系的解析表达式.由于解析近似对波数的限制,无法得到全波数空间色散曲线,因此对色散方程进行了数值求解.研究表明,在满足长波支和短波支条件时,解析色散曲线与数值色散曲线完全符合.此外,利用多项式回归的方法对数值结果进行拟合,得到不同参数下快电子分布等离子体横振荡色散关系近似表达式,该结果为进一步研究快电子分布等离子体的性质提供了重要的理论依据.
关键词:
相对论性等离子体
快电子分布
色散关系
数值计算 相似文献
94.
95.
Product probability property, known in the literature as statistical independence, is examined first. Then generalized entropies are introduced, all of which give generalizations to Shannon entropy. It is shown that the nature of the recursivity postulate automatically determines the logarithmic functional form for Shannon entropy. Due to the logarithmic nature, Shannon entropy naturally gives rise to additivity, when applied to situations having product probability property. It is argued that the natural process is non-additivity, important, for example, in statistical mechanics [C. Tsallis, Possible generalization of Boltzmann-Gibbs statistics, J. Stat. Phys. 52 (1988) 479-487; E.G.D. Cohen, Boltzmann and Einstein: statistics and dynamics—an unsolved problem, Pramana 64 (2005) 635-643.], even in product probability property situations and additivity can hold due to the involvement of a recursivity postulate leading to a logarithmic function. Generalized entropies are introduced and some of their properties are examined. Situations are examined where a generalized entropy of order α leads to pathway models, exponential and power law behavior and related differential equations. Connection of this entropy to Kerridge's measure of “inaccuracy” is also explored. 相似文献
96.
The impulsive control of chaotic systems, which are subjected to
unbounded exogenous perturbations, is considered. By using the
theory of impulsive differential equation together with the fuzzy
control technique, the authors propose an impulsive robust chaos
controlling criterion expressed as linear matrix inequalities
(LMIs). Based on the proposed control criterion, the procedure for
designing impulsive controllers of common (perturbed) chaotic
systems is provided. Finally, a numerical example is given to
demonstrate the obtained theoretical result. 相似文献
97.
98.
按照新课程标准的要求,针对高中物理粤版选修教材中存在的不足,在制作原电池方面做了相应的改进.用重铬酸钾做电解质溶液中的氧化剂,用蓬松棉做盐桥,并用碳棒做电池正极.同时将该方法制做的原电池引入探究原电池内电压和外电压的关系和电池内电阻的大小2个实验中. 相似文献
99.
100.
Transformation of Gaussian beams propagating through an axially asym-metric optical system is studied in detail by means of the complex curvature tensor andthe tensor ABCD law.Some important propagation characteristics of Gaussian beamswith simple or general astigmatism are demonstrated by typical numerical examples. 相似文献