全文获取类型
收费全文 | 1406篇 |
免费 | 351篇 |
国内免费 | 312篇 |
专业分类
化学 | 591篇 |
晶体学 | 2篇 |
力学 | 37篇 |
综合类 | 2篇 |
数学 | 690篇 |
物理学 | 747篇 |
出版年
2023年 | 30篇 |
2022年 | 40篇 |
2021年 | 51篇 |
2020年 | 42篇 |
2019年 | 36篇 |
2018年 | 37篇 |
2017年 | 16篇 |
2016年 | 30篇 |
2015年 | 57篇 |
2014年 | 95篇 |
2013年 | 104篇 |
2012年 | 113篇 |
2011年 | 116篇 |
2010年 | 150篇 |
2009年 | 165篇 |
2008年 | 120篇 |
2007年 | 181篇 |
2006年 | 186篇 |
2005年 | 91篇 |
2004年 | 69篇 |
2003年 | 66篇 |
2002年 | 65篇 |
2001年 | 62篇 |
2000年 | 45篇 |
1999年 | 34篇 |
1998年 | 23篇 |
1997年 | 15篇 |
1996年 | 7篇 |
1995年 | 13篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
排序方式: 共有2069条查询结果,搜索用时 31 毫秒
101.
Scheme for implementing quantum dense coding with four-particle decoherence-free states in an ion trap 下载免费PDF全文
This paper proposes an experimentally feasible scheme for implementing quantum dense coding of trapped-ion system in decoherence-free states. As the phase changes due to time evolution of components with different eigenenergies of quantum superposition are completely frozen, quantum dense coding based on this model would be perfect. The scheme is insensitive to heating of vibrational mode and Bell states can be exactly distinguished via detecting the ionic state. 相似文献
102.
Considering a two-level atom interacting with the competing two-mode field, this paper investigates the entanglement between the two-level atom and the two-mode field by using the quantum reduced entropy, and that between the two-mode field by using the quantum relative entropy of entanglement. It shows that the two kinds of entanglement are dependent on the relative coupling strength of atom-field and the atomic distribution, and exhibit the periodical evolution. The maximal atom-field entanglement state can be prepared via the appropriate selection of system parameters and interaction time. 相似文献
103.
This paper is the first of two papers on the time discretizationof the equation ut + t 0 ß (t s) Au (s) ds= 0, t > 0, u (0) = u0, where A is a self-adjoint denselydefined linear operator on a Hilbert space H with a completeeigensystem {m, m}m = 1, and ß (t) is completely monotonicand locally integrable, but not constant. The equation is discretizedin time using first-order differences in combination with order-oneconvolution quadrature. The stability properties of the timediscretization are derived in the l1t (0, ; H) norm. 相似文献
104.
Q.?Xie W.?HaiEmail author 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,33(2):265-272
We study two-component Bose-Einstein condensates that behave
collectively as a spin system obeying the dynamics of a quantum
kicked top. Depending on the nonlinear interaction between atoms in
the classical limit, the kicked top exhibits both regular and
chaotic dynamical behavior. The quantum entanglement is physically
meaningful if the system is viewed as a bipartite system, where the
subsystem is any one of the two modes. The dynamics of the
entanglement between the two modes in this classical chaotic system
has been investigated. The chaos leads to rapid rise and saturation
of the quantum entanglement. Furthermore, the saturated values of
the entanglement fall short of its maximum. The mean entanglement
has been used to clearly display the close relation between quantum
entanglement and underlying chaos. 相似文献
105.
High-performance liquid chromatography (HPLC) coupled with UV photodiode-array detection and electrospray ionization mass spectrometry was developed for the simultaneous analysis of caffeic acid derivatives and alkamides in the roots and extracts of Echinacea purpurea. Caffeic acid derivatives and alkamides produced very abundant peaks in the total ion current chromatogram during negative and positive cone voltage switching. Cichoric acid and the isomer pair, dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamide, were used as a standard for quantification of caffeic acid derivatives and alkamides in E. purpurea. This novel method surpasses previously published ones in product quality control and providing the HPLC chromatographic fingerprints of biological active components in E. purpurea. 相似文献
106.
Jiliang Jing 《International Journal of Theoretical Physics》2000,39(6):1687-1696
The quantum correction to the entropy of four-dimensional nonextreme static,spherically symmetric dilaton black holes arising from electromagnetic fields isinvestigated by 't Hooft's brick wall model. The Garfinkle-Horowitz-Strominger,Gibbons-Maeda, and Garfinkle-Horne dilaton black holes areconsidered. It is shown that the one-loop quantum correction arising from theelectromagnetic fields is exactly twice that due to a massless scalar field. Theresult agrees with that of the Schwarzschild and Reissner-Nordström blackholes. 相似文献
107.
运用负值量子条件熵研究了双量子系统一类混合态的纠缠量度.给出了负值量子条件作为条件熵纠缠度的定义,证明了条件熵纠缠满足作为2×2系统一类混合纠缠态量度的四个基本条件.当双量子系统处于纯态时,条件熵纠缠度即为部分熵纠缠度.应用条件熵纠缠度研究了真空腔场中两全同二能级原子之间纯态和一类混合态纠缠的时间演化,比较了相同条件下两全同原子系统concurrence纠缠度的时间演化.结果表明,两纠缠度演化规律完全一致,验证了负值量子条件熵可以作为双量子系统纯态和一类混合态的纠缠量度.
关键词:
双量子系统
负值量子条件熵
条件熵纠缠度
混合态纠缠度 相似文献
108.
理论上研究Rashba自旋-轨道相互作(SOI)量子线在外电磁波辐照下的电子自旋极化输运性质.在自由电子模型下利用散射矩阵方法,发现当Rashba SOI较弱时,自旋极化率与外电磁场频率和电子入射能量无关,而当Rashba SOI较强时,自旋极化率则强烈依赖于外场频率和电子入射能量,其物理根源是Rashba SOI使子带混合引起的.此外,当电子的入射能量增加到打开另一通道阈值时,电子的透射率出现一个反常的台阶结构,这来源于电子与光子的非弹性散射而使电子在子带间的跃迁.
关键词:
量子线
电磁波
自旋极化输运
散射矩阵 相似文献
109.
我们提出了一个在热腔中产生多原子GHZ态的方法来检验量子非定域性。在这个方法中,三个原子被同时送入一个热腔中,它们初始时处于相同的态。这个方法既对腔的衰减不敏感又对热场不敏感,这为检验量子力学的基本方面提供了新的前景。 相似文献
110.