全文获取类型
收费全文 | 456篇 |
免费 | 148篇 |
国内免费 | 40篇 |
专业分类
化学 | 187篇 |
晶体学 | 9篇 |
力学 | 56篇 |
综合类 | 4篇 |
数学 | 75篇 |
物理学 | 313篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2022年 | 11篇 |
2021年 | 15篇 |
2020年 | 26篇 |
2019年 | 17篇 |
2018年 | 18篇 |
2017年 | 26篇 |
2016年 | 29篇 |
2015年 | 25篇 |
2014年 | 36篇 |
2013年 | 40篇 |
2012年 | 39篇 |
2011年 | 33篇 |
2010年 | 23篇 |
2009年 | 24篇 |
2008年 | 21篇 |
2007年 | 31篇 |
2006年 | 32篇 |
2005年 | 27篇 |
2004年 | 26篇 |
2003年 | 21篇 |
2002年 | 21篇 |
2001年 | 14篇 |
2000年 | 10篇 |
1999年 | 14篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 10篇 |
1993年 | 5篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 5篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有644条查询结果,搜索用时 202 毫秒
91.
We consider the effects of anisotropy on two types of localized states with topological charges equal to 1 in two-dimensional nonlinear lattices, using the discrete nonlinear Schr?dinger equation as a paradigm model. We find that on-site-centered vortices with different propagation constants are not globally stable, and that upper and lower boundaries of the propagation constant exist. The region between these two boundaries is the domain outside of which the on-site-centered vortices are unstable. This region decreases in size as the anisotropy parameter is gradually increased. We also consider off-site-centered vortices on anisotropic lattices, which are unstable on this lattice type and either transform into stable quadrupoles or collapse. We find that the transformation of off-sitecentered vortices into quadrupoles, which occurs on anisotropic lattices, cannot occur on isotropic lattices. In the quadrupole case, a propagation-constant region also exists, outside of which the localized states cannot stably exist. The influence of anisotropy on this region is almost identical to its effects on the on-site-centered vortex case. 相似文献
92.
Using the finite-difference time-domain (FDTD) method, we simulate the coupling between a gold nanorod and gold nanoparticles
with different plasmonic resonant frequencies/volumes as well as that between the nanorod and a dielectric nanosphere. The
influences of coupling with different nanoparticles on the excitation of a forbidden longitudinal surface plasmon mode of
the nanorod under normal incidence are investigated. It is found that the cause of this excitation is the broken symmetry
of the local electric field experienced by the nanorod resulting from the charge pileup on the other nanoparticle. This result
is valuable for understanding the near-field optical characterization of plasmonic metal nanoparticles.
Supported by the National Natural Science Foundation of China (Grant Nos. 10821062 and 10804004), the National Basic Research
Program of China (Grant No. 2007CB307001), and the Specialized Research Fund for the Doctoral Program of Higher Education
(Grant No. 200800011023)
Contributed by GONG QiHuang 相似文献
93.
X. Deng R. Citro E. Orignac A. Minguzzi 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,68(3):435-443
Using exact diagonalisation and Density Matrix Renormalisation group (DMRG) approach we analyse the transition to a localised
state of a weakly interacting quasi-1D Bose gas subjected to a quasiperiodic potential. The analysis is performed by calculating
the superfluid fraction, density profile, momentum distribution and visibility for different periodicities of the second lattice
and in the presence (or not) of a weak repulsive interaction. It is shown that the transition is sharper towards the maximally
incommensurate ratio between the two lattice periodicities, and shifted to higher values of the second lattice strength by
weak repulsive interactions. We also relate our results to recent experiments. 相似文献
94.
D. A. Drabold 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,68(1):1-21
In this Colloquium, I describe some current frontiers in the physics of semiconducting amorphous materials and glasses, including
a short, but self-contained discussion of techniques for creating computer models, among them the quench from the melt method,
the Activation-Relaxation Technique, the decorate and relax method, and the experimentally constrained molecular relaxation
scheme. A representative study of an interesting and important glass (amorphous GeSe3:Ag) is provided. This material is a fast-ion conductor and a serious candidate to replace current FLASH memory. Next, I discuss
the effects of topological disorder on electronic states. By computing the decay of the density matrix in real space, and
also computing well-localized Wannier functions, we close with a quantitative discussion of Kohn’s Principle of Nearsightedness in amorphous silicon. 相似文献
95.
96.
With the help of an objective reduction approach (ORA), abundant exact solutions of (2+1)-dimensional higher-order Boussinesq system (including some hyperboloid function solutions, trigonometric function solutions, and a rational function solution) are obtained. It is shown that some novel soliton structures, like single linearity soliton structure, breath soliton structure, single linearity y-periodic solitary wave structure, libration dromion structure, and kink-like multisoliton structure with actual physical meaning exist in the (2+1)-dimensional higher-order Boussinesq system. 相似文献
97.
The existence and properties of intrinsic localized spin-wave modes in a ferromagnetic XXZ spin chain with Dzyaloshinsky-Moriya interaction are investigated analytically in the semiclassical limit. The model Hamiltonian is quantized by introducing the Dyson-Maleev transformation and the coherent state representation is chosen as the basic representation of the system. By making use of the method of multiple scales combined with a quasidiscreteness approximation, the equation of motion for the coherent-state amplitude is reduced to the nonlinear Schrödinger equation. It is shown that a bright intrinsic localized spin-wave mode whose eigenfrequency lies below the bottom of the magnon frequency band can exist in the ferromagnetic system. We also show that the system can produce a dark intrinsic localized spin-wave mode, i.e., nonpropagating kink, whose eigenfrequency is below the upper of the magnon frequency band. In addition, we find that the introduction of the Dzyaloshinsky-Moriya interaction changes wave numbers in the Brillouin-zone corresponding to the appearance of intrinsic localized spin-wave modes. 相似文献
98.
本文综述了离子型液体介质中过剩电子的结构、存在状态及其时间演化动力学特征。基于从头算分子动力学模拟及计算结果,重点阐述了咪唑型、吡啶型、碱金属离子型熔盐氯化物离子液中与过剩电子溶剂化密切相关的溶剂化能量学、结构特征、可能的存在状态以及态-态转化稳态动力学机制,分析了此类离子型介质中电子高效传导的内在本质及离子液组成离子的重要作用。阳离子的最低未占轨道组成的导带结构是离子液中过剩电子的溶剂化态及其稳定性的决定因素,任何能影响或改变其导带结构的因素均能显著影响过剩电子溶剂化。但快速的态-态转化及电子迁移并不明显取决于其组成离子扩散动力学,而是敏感地受离子液涨落所控制。这种基于溶剂化电子的迁移模式构成了此类离子型介质甚至其它液态介质中电子转移的新途径。 相似文献
99.
100.
利用原位还原法成功制备了尺寸均一、超薄完整金壳包覆的NaYF4:Yb,Er@SiO2@Au(NSA)纳米结构,其XRD、TEM、EDX、HRTEM-HAADF、Mapping及吸收光谱表征结果表明,SiO2壳及纳米金壳的平均厚度分别约为5 nm和2 nm。在980 nm连续激光激发下,系统研究了核壳结构的上转换荧光强度与氯金酸浓度的依赖关系。稳态光谱结果显示,NSA与仅SiO2包覆样品(NS)相比Er3+的红绿荧光强度均增强了~2.8倍。通过分析上转换荧光动力学过程及利用FDTD方法模拟,讨论了表面等离激元增强上转换荧光的机制。 相似文献