全文获取类型
收费全文 | 238篇 |
免费 | 88篇 |
国内免费 | 16篇 |
专业分类
化学 | 89篇 |
晶体学 | 8篇 |
力学 | 1篇 |
数学 | 6篇 |
物理学 | 222篇 |
综合类 | 16篇 |
出版年
2024年 | 2篇 |
2023年 | 7篇 |
2022年 | 14篇 |
2021年 | 16篇 |
2020年 | 35篇 |
2019年 | 17篇 |
2018年 | 5篇 |
2017年 | 13篇 |
2016年 | 18篇 |
2015年 | 10篇 |
2014年 | 12篇 |
2013年 | 16篇 |
2012年 | 22篇 |
2011年 | 21篇 |
2010年 | 8篇 |
2009年 | 16篇 |
2008年 | 12篇 |
2007年 | 9篇 |
2006年 | 21篇 |
2005年 | 13篇 |
2004年 | 5篇 |
2003年 | 6篇 |
2002年 | 8篇 |
2001年 | 5篇 |
2000年 | 10篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
排序方式: 共有342条查询结果,搜索用时 15 毫秒
101.
J. Novotn� 《Crystal Research and Technology》2000,35(1):65-70
The preparation of a new type of InGaAsP/InP heterostructures for light emitting diodes is presented. The active region of the heterostructure contains thin layers of nondoped InGaAsP (λ=1.3μ) alternating with barrier layers of InGaAsP (λ=1.1μ) doped by cobalt. Properties of prepared heterostructures were tested on edge emitting diodes with the stripe geometry. Curves of the minority carrier lifetime and the optical power versus current are compared with those obtained on classical bulk InGaAsP/InP double heterostructure. It is shown that the new structure is very eligible for construction of high‐ speed noncoherent 1.3μ diodes operating at low pumping current. 相似文献
102.
Summary We show how to compute the optical functions (reflection and transmission) of a semiconductor thin slab, in the vicinity of
nearly degenerate exciton states. Additional boundary conditions are not required in the coherentwave-function approach and
multiple-polariton effects are included since Maxwell equations are satisfied. When the slab thickness is comparable to the
exciton Bohr radius, centre of mass quantization results. When the slab thickness is smaller than the Bohr radius, we obtain,
quantum well polaritons. Numerical examples appropriate to GaAs are given. 相似文献
103.
M. Salvato F. Bobba G. Calabrese C. Cirillo A. M. Cucolo A. De Santis A. Vecchione C. Attanasio 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(1):79-85
Resistivity vs. temperature measurements on
La0.7Ca0.3MnO3/YBa2Cu3O7-δ
/La0.7Ca0.3MnO3 (LCMO/YBCO/LCMO) trilayers with different
YBCO thickness, were performed in external magnetic field H up to 8 T. By
evaluating the activation energy U from the slope of the resistivity
Arrhenius plot, a strong depression of U has been observed when decreasing
the YBCO layer thickness and the absolute U values appear to be reduced with
respect to the values reported in literature in the case of YBCO thin films
and YBCO/insulating multilayers. Moreover, a logarithmic U vs. H dependence is
shown both in the case of thick and thin YBCO layers indicating the
formation of a two dimensional vortex lattice. The experimental data are
discussed considering the strong influence of the ferromagnetic LCMO on the
superconducting YBCO properties which reduces the effective YBCO thickness
more than predicted by the conventional theories. 相似文献
104.
一维纳米结构因其优异的光、电特性,在纳米电子学,光电子学器件等方面有重要的应用价值而倍受关注.在一维半导体纳米材料中,ZnO因激子束缚能大(60meV),可在室温获得高效的紫外发光而成为近年来继GaN材料后的又一研究热点.外延生长一维纳米结构ZnO及其量子阱材料除因量子尺寸效应更适宜做室温紫外发光、激光材料与器件外,还因界面和量子限制效应而具有许多新奇的光、电、和力学特性,可应用于纳米光电子学器件,传感器及存储器件,纳米尺度共振隧道结型器件和场效应晶体管的研制和开发.文章着重介绍了目前ZnO一维纳米结构制备,一维ZnO纳米异质结构和一维ZnO/Zn1-xMgxO多量子阱结构的外延生长和研究进展. 相似文献
105.
Epitaxial La1−x
Pb
x
MnO3 (LPMO) thin films, grown on (100) SrTiO3 substrates by laser ablation technique at different temperatures between 600 and 850°C, have been characterized for electrical
and magnetic properties. The temperature dependence of resistivity showed that the metal-insulator transition temperature
(T
MI) decreases with increasing substrate temperature, which has been attributed to decrease in Pb content in the filsm. The YBa2Cu3O
x
/La1−x
MnO3 heterostructures, exhibiting both superconductivity and ferromagnetism, have been fabricated. 相似文献
106.
Controlled Formation of TiO2/MoS2 Core–Shell Heterostructures with Enhanced Visible‐Light Photocatalytic Activities
下载免费PDF全文
![点击此处可从《Particle & Particle Systems Characterization》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Chuanxi Wang Huihui Lin Zhenyu Liu Jiapeng Wu Zhenzhu Xu Chi Zhang 《Particle & Particle Systems Characterization》2016,33(4):221-227
Most recently, much attention has been devoted to photocatalytic materials that may help to solve the global energy crisis and may provide environmental protection. Herein, novel cocatalysts based on few layered MoS2 and TiO2 nanomaterials have been designed by growing MoS2 nanosheets on the surface of TiO2 nanospheres through a facile hydrothermal method. The method allows the formation of TiO2/MoS2 core–shell heterostructures of uniform morphologies and stable structure and provides a good control over shell thickness. The mechanism that forms these heterostructures is discussed in detail. In addition, as cocatalyst, MoS2 nanosheets can enlarge the light harvesting window to include visible light and improve the photocatalytic ability of TiO2. Using Rhodamine B as the model, the resultant heterostructure is demonstrated to possess excellent and stable photocatalytic activity in the degradation of organic pollutants under visible light illumination. The TiO2/MoS2 heterostructures possess this catalytic activity due to their large surface area and their excellent interface for separating holes and electrons. Therefore, this novel heterostructure nanomaterials possess potential applications in water treatment, degradation of dye pollutants, and environmental cleaning. 相似文献
107.
Fabrication and optical properties of type‐II InP/InAs nanowire/quantum‐dot heterostructures
下载免费PDF全文
![点击此处可从《固体物理学:研究快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The growth and optical properties of InAs quantum dots on a pure zinc blende InP nanowire are investigated. The quantum dots are formed in Stranski–Krastanov mode and exhibit pure zinc blende crystal structure. A substantial blueshift of the dots peak with a cube‐root dependence on the excitation power is observed, suggesting a type‐II band alignment. The peak position of dots initially red‐shifts and then blue‐shifts with increasing temperature, which is attributed to the carrier redistribution among the quantum dots. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
108.
Alexandr G. Oshchepkov Antoine Bonnefont Elena R. Savinova 《Current Opinion in Electrochemistry》2021
Metal/metal (hydr)oxide heterostructures have been proposed as an efficient means to enhance the kinetics of hydrogen electrode reactions (the hydrogen evolution and the hydrogen oxidation reaction) on Pt, Ni, and other electrodes in the alkaline medium. However, the reasons for the faster electrode kinetics are still not fully understood. By considering two electrode materials, namely Pt and Ni, widely studied in hydrogen electrode reactions in alkaline media, this review brings to light differences in their pH-dependent behavior and likely different genesis of the enhancement in the presence of 3d transition metal oxides. 相似文献
109.
Zhen Ma Shuai Li Meng-Meng Xiao Ya-Wen Zheng Ming Lu Haiwen Liu Jin-Hua Gao X. C. Xie 《Frontiers of Physics》2023,18(1):13307
We report that the twisted few layer graphite (tFL-graphite) is a new family of moiré heterostructures (MHSs), which has richer and highly tunable moiré flat band structures entirely distinct from all the known MHSs. A tFL-graphite is composed of two few-layer graphite (Bernal stacked multilayer graphene), which are stacked on each other with a small twisted angle. The moiré band structure of the tFL-graphite strongly depends on the layer number of its composed two van der Waals layers. Near the magic angle, a tFL-graphite always has two nearly flat bands coexisting with a few pairs of narrowed dispersive (parabolic or linear) bands at the Fermi level, thus, enhances the DOS at EF . This coexistence property may also enhance the possible superconductivity as been demonstrated in other multiband superconductivity systems. Therefore, we expect strong multiband correlation effects in tFL-graphite. Meanwhile, a proper perpendicular electric field can induce several isolated nearly flat bands with nonzero valley Chern number in some simple tFL-graphites, indicating that tFL-graphite is also a novel topological flat band system. 相似文献
110.
Yanyan Li Mingjun Yang Yanan Lu Dan Cao Xiaoshuang Chen Haibo Shu 《Frontiers of Physics》2023,18(3):33307
Van der Waals semiconductor heterostructures (VSHs) composed of two or more two-dimensional (2D) materials with different band gaps exhibit huge potential for exploiting high-performance multifunctional devices. The application of 2D VSHs in atomically thin devices highly depends on the control of their carrier type and density. Herein, on the basis of comprehensive first-principles calculations, we report a new strategy to manipulate the doping polarity and carrier density in a class of 2D VSHs consisting of atomically thin transition metal dichalcogenides (TMDs) and α-In2X3 (X = S, Se) ferroelectrics via switchable polarization field. Our calculated results indicate that the band bending of In2X3 layer driven by the FE polarization can be utilized for engineering the band alignment and doping polarity of TMD/In2X3 VSHs, which enables us to control their carrier density and type of the VSHs by the orientation and magnitude of local FE polarization field. Inspired by these findings, we demonstrate that doping-free p−n junctions achieved in MoTe2/In2Se3 VSHs exhibit high carrier density (1013−1014 cm−2), and the inversion of the VHSs from n−p junctions to p−i−n junctions has been realized by the polarization switching from upward to downward states. This work provides a nonvolatile and nondestructive doping strategy for obtaining programmable p−n van der Waals (vdW) junctions and opens the possibilities for self-powered and multifunctional device applications. 相似文献