全文获取类型
收费全文 | 5885篇 |
免费 | 914篇 |
国内免费 | 617篇 |
专业分类
化学 | 2080篇 |
晶体学 | 52篇 |
力学 | 789篇 |
综合类 | 98篇 |
数学 | 1473篇 |
物理学 | 2924篇 |
出版年
2024年 | 6篇 |
2023年 | 45篇 |
2022年 | 73篇 |
2021年 | 126篇 |
2020年 | 129篇 |
2019年 | 132篇 |
2018年 | 117篇 |
2017年 | 167篇 |
2016年 | 202篇 |
2015年 | 198篇 |
2014年 | 343篇 |
2013年 | 500篇 |
2012年 | 386篇 |
2011年 | 418篇 |
2010年 | 298篇 |
2009年 | 403篇 |
2008年 | 418篇 |
2007年 | 427篇 |
2006年 | 335篇 |
2005年 | 340篇 |
2004年 | 336篇 |
2003年 | 276篇 |
2002年 | 236篇 |
2001年 | 219篇 |
2000年 | 166篇 |
1999年 | 183篇 |
1998年 | 168篇 |
1997年 | 146篇 |
1996年 | 99篇 |
1995年 | 94篇 |
1994年 | 78篇 |
1993年 | 65篇 |
1992年 | 49篇 |
1991年 | 38篇 |
1990年 | 23篇 |
1989年 | 16篇 |
1988年 | 33篇 |
1987年 | 15篇 |
1986年 | 18篇 |
1985年 | 17篇 |
1984年 | 23篇 |
1983年 | 8篇 |
1982年 | 11篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1977年 | 6篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 2篇 |
排序方式: 共有7416条查询结果,搜索用时 109 毫秒
41.
Monia Belhabri Jack Legrand Nathalie LeSauze Abdellah Arhaliass 《Particle & Particle Systems Characterization》2004,21(5):365-371
Emulsions are of great importance to industry. They are involved in many engineering operations, including chemical reactions, extraction, emulsification and suspension polymerization, etc. However, an important problem for these processes is how to control the size distribution of the dispersed phase. Indeed, off‐line analysis of the emulsion may generate uncertainties due to sampling and dilution of the product, which are likely to change the dispersion state and physico‐chemical properties. In this work, an on‐line optical method is proposed to characterize dispersed media in real flowing conditions. This method is based on the time‐analysis of back‐scattered light fluctuations. The present paper deals with the development of this method and its application to dispersions of alumina in water. The results obtained with the on‐line optical method are compared with those acquired by classical laser light scattering and microscopy. 相似文献
42.
通过对爆炸抛撒图象的处理,得到液体界面的曲线.采用盒维数的计算方式,计算界面曲线的分形维数.通过对各时刻液体界面分形维数的变化研究,分析爆炸抛撒近场阶段的变化过程,同时观察到蘑菇状尖顶的出现与破碎,以及空化区域的形成和消失现象。 相似文献
43.
B. G. Konopelchenko L. Martínez Alonso E. Medina 《Theoretical and Mathematical Physics》2007,151(3):820-830
Based on the Lenard relations, we completely classify integrable deformations of general algebraic curves. We construct the
general solution of the Lenard relation from the invariance condition with respect to an element of the Galois group of the
curve. We give some examples and also some associated conservation laws.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 151, No. 3, pp. 458–469, June, 2007. 相似文献
44.
Qing Shi Dong Yang Yanlei Su Jian Li Zhongyi Jiang Yanjun Jiang Weikang Yuan 《Journal of nanoparticle research》2007,9(6):1205-1210
Lipase from Candida rugosa was covalently anchored onto acid-treated multi-walled carbon nanotubes (MWNTs) through a self-catalytic mechanism. A variety
of characterization techniques including FTIR, Raman spectroscopy, and XPS were employed to demonstrate the formation of the
ester linkage between lipase and MWNTs. The MWNTs-lipase biocomposites showed significantly increased solubility in some common-used
organic solvents, such as THF, DMF and chloroform. This study may offer a novel and facile route for covalent modification
of carbon nanotubes, and expand the potential utilization of both lipases and MWNTs in the fields of biocatalyst and biosensor. 相似文献
45.
Using the appropriate harmonic oscillator states and reasonable approximations, we construct coherent wavepackets corresponding
to the solutions of the Klein-Gordon equation for the attractive potentialV(r)=−k/r, k>0, in two and three space dimensions. We deduce the corresponding classical limit in two dimension by requiring that the
expectation value 〈r〉 of the radial variable is large. In the case of three dimensions, besides the condition of large 〈r〉, we make the uncertainty Δr=[〈r
2〉 − 〈r〉2]1/2 a minimum with respect to certain parameter of the wavepacket. We then investigate the trajectory traversed by the wavepacket
in the classical limit. We find that the classical limit of this relativistic quantal problem gives, in the leading order,
the same expression for the rate of motion of the perihelion as that given by the solution of the corresponding special relativistic
classical dynamical problem. We also briefly discuss some of the subtle aspects of the classical limit of the relativistic
quantal system, in general. 相似文献
46.
47.
48.
结合2006年全国大学生数学建模竟赛D题,借助Matlab软件,通过数学建模,计算出有关煤矿瓦斯和煤尘的3个主要安全指标,从而为解决煤矿实际安全生产提供了参考. 相似文献
49.
多波长啁啾叠栅的矩阵分析 总被引:1,自引:0,他引:1
在分析多波长啁啾叠栅特征的基础上,提出了多波长啁啾叠栅的矩阵分析模型,采用矩阵分析模型对4波长和8波长啁啾叠栅的反射谱特性进行了理论分析,数值分析结果与实验结果非常一致.还首次数值模拟了波长间隔0.8 nm的16波长啁啾叠栅.此方法对多波长啁啾叠栅的设计和制作具有参考价值. 相似文献
50.
DIELECTRIC EFFECT ON THE RADIO-FREQUENCY CHARACTERISTICS OF A RECTANGULAR WAVEGUIDE GRATING TRAVELING WAVE TUBE 总被引:2,自引:0,他引:2
Zhigang Lu Yubin Gong Yanyu Wei Wenxiang Wang 《International Journal of Infrared and Millimeter Waves》2006,27(8):1095-1108
A new type of partial-dielectric-loaded rectangular waveguide grating slow-wave structure (SWS) for millimeter wave traveling
wave tube (TWT) is presented in this paper. The radio-frequency characteristics including the dispersion properties, the longitudinal
electric field distribution and the beam-wave coupling impedance of this structure are analyzed. The results show that the
dispersion of the rectangular waveguide grating circuit is weakened, the phase velocity is reduced and the position of the
maximum E
z
is basically invariant after partially filling the dielectric materials in the rectangular waveguide grating SWS. Although
the coupling impedance decreases a little, it still keeps above 40 Ω. 相似文献