全文获取类型
收费全文 | 1744篇 |
免费 | 322篇 |
国内免费 | 101篇 |
专业分类
化学 | 987篇 |
晶体学 | 28篇 |
力学 | 30篇 |
综合类 | 5篇 |
数学 | 22篇 |
物理学 | 1095篇 |
出版年
2024年 | 6篇 |
2023年 | 15篇 |
2022年 | 36篇 |
2021年 | 65篇 |
2020年 | 71篇 |
2019年 | 57篇 |
2018年 | 54篇 |
2017年 | 62篇 |
2016年 | 113篇 |
2015年 | 80篇 |
2014年 | 105篇 |
2013年 | 133篇 |
2012年 | 137篇 |
2011年 | 137篇 |
2010年 | 93篇 |
2009年 | 114篇 |
2008年 | 141篇 |
2007年 | 123篇 |
2006年 | 105篇 |
2005年 | 101篇 |
2004年 | 72篇 |
2003年 | 68篇 |
2002年 | 39篇 |
2001年 | 27篇 |
2000年 | 45篇 |
1999年 | 26篇 |
1998年 | 24篇 |
1997年 | 14篇 |
1996年 | 21篇 |
1995年 | 17篇 |
1994年 | 18篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 7篇 |
1989年 | 9篇 |
1988年 | 1篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1979年 | 2篇 |
排序方式: 共有2167条查询结果,搜索用时 23 毫秒
101.
A novel plasmonic nanolens formed by a tapered subwavelength metal slit surrounded by surface dielectric gratings is proposed and demonstrated numerically. By patterning surface corrugations on the output surface, the beam can be focused, by regulating the aperture, the focal length can be controlled effectively. Numerical simulations using Finite-Difference Time-Domain (FDTD) method coupled with anisotropic perfectly matched layer (APML) boundary conditions verify that the proposed metallic lens can focus the radiation on the scale of a wavelength below the substrate and the method is effective for the design of nano-optical devices such as optical microprobes. 相似文献
102.
High-performance oxide vertical-cavity surface-emitting (VCSEL) laser is fabricated, and its usefulness is demonstrated as a suitable transmitting light source at 850 nm operating wavelength for Gigabit Ethernet application. Utilization of barrier reduction layers reveals low-threshold current requirement for operation at high modulation bandwidth. The electrical and optical characteristics, measured from the fabricated VCSEL, are simulated for Gigabit Ethernet transmission. Data rates of 1.25 Gbps with a bit error rate of 10−11 are achieved by the use of a specific multimode network simulator. 相似文献
103.
Material structures and device structures of a 100-GHz InP based transferred-electron device are designed in this paper. In order to successfully fabricate the Gunn devices operating at 100 GHz, the InP substrate was entirely removed by mechanical thinning and wet etching. The Gunn device was connected to a tripler link and a high RF(radio frequency)output with power of 2 mW working at 300 GHz was obtained, which is high enough for applications in current military electronic systems. 相似文献
104.
Nadal F Argoul F Kestener P Pouligny B Ybert C Ajdari A 《The European physical journal. E, Soft matter》2002,9(4):387-399
We report a theoretical and experimental study of the hydrodynamic flow induced by an a.c. electric field in the vicinity
of a dielectric stripe deposited on a conducting plate. In the theoretical part, we model the stripe as a small change of
the surface capacitance of the plate, and a perturbative approach is used to perform the calculations. This approach predicts
an outwards rectified electro-osmotic slip along the surface that generates two steady counter-rotating rolls, the size of
which decreases with the frequency. In the experimental section, we use tracers to determine the structure of the flow and
investigate its dependence on the frequency and the amplitude of the applied voltage. The structure and amplitude of the observed
flow compares satisfactorily with the theoretical analysis. This could guide the design of surface-controlled flows and help
to understand the collective behavior of colloids near electrodes.
Received 20 June 2002
RID="a"
ID="a"e-mail: nadal@crpp.u-bordeaux.fr 相似文献
105.
We propose a simple scheme to generate two-mode entangled coherent state in two separated cavities and realize the entanglement
reciprocation between the superconducting charge qubits and continuous-variable system. By measuring the state of charge qubits,
we find that the entanglement of two charge qubits, which are initially prepared in the maximally entangled state, can be
transferred to the two-cavity field, and at this time the two-cavity field is in the entangled coherent state. We also find
that the entanglement can be retrieved back to the two charge qubits after measuring the state of the two-cavity field.
相似文献
106.
A new thin-film electro-optic switch employing two stable states of polarization is proposed and investigated. The design can be further employed to realize a TE-TM polarization converter by constructing a Mach-Zehnder type interferometer integrated optical switch. The limitations and design procedures for electro-optic devices are also discussed. 相似文献
107.
A review of physical principles of design as well as some ways of technical realization of controlled resonance semiconductor devices at millimeter and submillimeter wavelengths is presented. The operation of such devices is based on cyclotron and magnetoplasma resonances as well as on Fabry-Perot resonance. Such choice has been made due to the fact that these resonance phenomena are the most typical ones for the magnetized semiconductor plasma. 相似文献
108.
109.
110.