全文获取类型
收费全文 | 1895篇 |
免费 | 766篇 |
国内免费 | 173篇 |
专业分类
化学 | 213篇 |
晶体学 | 10篇 |
力学 | 385篇 |
综合类 | 10篇 |
数学 | 61篇 |
物理学 | 2155篇 |
出版年
2024年 | 1篇 |
2023年 | 14篇 |
2022年 | 32篇 |
2021年 | 54篇 |
2020年 | 52篇 |
2019年 | 41篇 |
2018年 | 58篇 |
2017年 | 53篇 |
2016年 | 74篇 |
2015年 | 47篇 |
2014年 | 122篇 |
2013年 | 150篇 |
2012年 | 130篇 |
2011年 | 164篇 |
2010年 | 138篇 |
2009年 | 161篇 |
2008年 | 238篇 |
2007年 | 181篇 |
2006年 | 181篇 |
2005年 | 124篇 |
2004年 | 114篇 |
2003年 | 100篇 |
2002年 | 87篇 |
2001年 | 72篇 |
2000年 | 77篇 |
1999年 | 55篇 |
1998年 | 50篇 |
1997年 | 39篇 |
1996年 | 52篇 |
1995年 | 31篇 |
1994年 | 37篇 |
1993年 | 19篇 |
1992年 | 15篇 |
1991年 | 6篇 |
1990年 | 16篇 |
1989年 | 9篇 |
1988年 | 7篇 |
1987年 | 13篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有2834条查询结果,搜索用时 234 毫秒
91.
Two Solutions to Diluted p-Spin Models and XORSAT Problems 总被引:1,自引:0,他引:1
92.
93.
Woelk K Zwank BL Trautner P Lehnhof E Bargon J Klingler RJ Gerald RE Rathke JW 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2000,145(2):276-290
A finite-difference approach has been developed for precisely determining diffusion coefficient and T1 relaxation time in fluid samples analyzed by magnetization-grating rotating-frame imaging (MAGROFI) with either a surface coil or a toroid cavity detector (TCD). This approach avoids shortcomings of phenomenologically based approximations, such as neglect of sample geometries with singularities at the confines of the sample volume, and accounts for the diffusive edge enhancement observed in fluid imaging. Error limits are discussed. The new method has been applied to the determination of the self-diffusion coefficient for MAGROFI experiments using TCDs filled with acetone. 相似文献
94.
95.
96.
本文提出一个通过原子和腔场相互作用传送未知原子纠缠态的新方案,并且成功概率为100%.在这个方案里,我们主要利用两个原子用来接受被传送的原子纠缠态以及一个双模腔作为量子通道.由于腔场的两个模具有不同的频率和正交极化,因此这两个模能够被区分,并且处于腔场的不同区域.原子和腔场通过J-C哈密顿量发生共振相互作用,当原子和其中一个模相互作用时,另外一个模不受影响.该方案既不需要贝尔态测量,也不需要任何操作重构纠缠初态.这个方案也可以推广到传送N个原子的纠缠态. 相似文献
97.
基于带化学反应的二维轴对称Euler方程,利用带有Superbee限制函数的波传播算法,对共振腔中的氢气-空气预混气的聚心燃烧进行了数值模拟,讨论了共振腔不同抛物面对起爆的影响。数值结果表明,在开始阶段,燃烧诱导的激波在轴心、火焰和固壁的反射,使火焰失稳,随后共振腔中的抛物壁面上产生一定频率和强度的反射激波,不断穿越火焰,使火焰进一步失稳,加剧了燃烧速度,最终导致爆轰的形成。同时,火焰在与激波的作用过程中,形状扭曲变形,呈封闭端小敞口端大的扁平头部蘑菇云。共振腔抛物面的不同形状引起激波聚焦位置的变化,会影响激波和火焰的相互作用,使起爆提前或推迟,甚至不起爆。 相似文献
98.
99.
Margarita A. Deneva Pepa I. Uzunova Marin N. Nenchev 《Optical and Quantum Electronics》2007,39(3):193-212
We report (theory, experimental check) an improved approach for generation of a tunable, subnanosecond pulse (0.1–0.4 ns),
based on a single pulsation (“spike”) separation from the transient oscillations in a dye laser with active mirror (AMIR).
A pumping by 20–50 ns pulses from Q-switched Nd:YAG laser is considered. The separation is in original, two-spectral selective
channels cavity, where the forced by AMIR quenched generation at one of the wavelength stops initially started spiking generation
at the other wavelength after the first spike development. The AMIR quickly starts the quenching generation at a precisely
controlled moment and with necessary intensity thus assuring the desired separation. An advantage is a high reproducibility
of the separation for high (~250%) pump power fluctuations combined with tuning in large range (~20 nm). To obtain such an
operation we form ~1 ns leading front pump pulse by electrooptical temporal cutting of the input pump pulse and use an optical
delay line. This increases also a few times the power in the separated spike (to be ~100 kW). Our approach widens the combinations
of lasers for effective applications of spike separation technique (dye lasers excited by Q-switched solid-state or Cu-vapor
lasers). 相似文献
100.
Zhou Hai-jun 《Frontiers of Physics in China》2007,2(2):238-250
At sufficiently low temperatures, the configurational phase space of a large spin-glass system breaks into many separated
domains, each of which is referred to as a macroscopic state. The system is able to visit all spin configurations of the same
macroscopic state, while it can not spontaneously jump between two different macroscopic states. Ergodicity of the whole configurational
phase space of the system, however, can be recovered if a temperature-annealing process is repeated an infinite number of
times. In a heating-annealing cycle, the environmental temperature is first elevated to a high level and then decreased extremely
slowly until a final low temperature T is reached. Different macroscopic states may be reached in different rounds of the annealing experiment; while the probability
of finding the system in macroscopic state α decreases exponentially with the free energy F
α
(T) of this state. For finite-connectivity spin glass systems, we use this free energy Boltzmann distribution to formulate the
cavity approach of Mézard and Parisi [Eur. Phys. J. B, 2001, 20: 217] in a slightly different form. For the ±J spin-glass model on a random regular graph of degree K = 6, the predictions of the present work agree with earlier simulational and theoretical results.
相似文献