全文获取类型
收费全文 | 1180篇 |
免费 | 818篇 |
国内免费 | 84篇 |
专业分类
化学 | 216篇 |
晶体学 | 47篇 |
力学 | 9篇 |
综合类 | 15篇 |
数学 | 8篇 |
物理学 | 1787篇 |
出版年
2024年 | 12篇 |
2023年 | 14篇 |
2022年 | 33篇 |
2021年 | 25篇 |
2020年 | 44篇 |
2019年 | 25篇 |
2018年 | 38篇 |
2017年 | 80篇 |
2016年 | 74篇 |
2015年 | 73篇 |
2014年 | 141篇 |
2013年 | 160篇 |
2012年 | 163篇 |
2011年 | 176篇 |
2010年 | 134篇 |
2009年 | 141篇 |
2008年 | 140篇 |
2007年 | 117篇 |
2006年 | 135篇 |
2005年 | 85篇 |
2004年 | 90篇 |
2003年 | 62篇 |
2002年 | 63篇 |
2001年 | 13篇 |
2000年 | 11篇 |
1999年 | 9篇 |
1998年 | 5篇 |
1997年 | 10篇 |
1996年 | 5篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1991年 | 1篇 |
排序方式: 共有2082条查询结果,搜索用时 0 毫秒
991.
992.
Hongting Jia Kiyotoshi Yasumoto 《International Journal of Infrared and Millimeter Waves》2005,26(9):1291-1306
A new approach for modal analysis of coupled cavity waveguides (CCW) in two-dimensional photonic crystals is presented. The mode propagation constants and the mode field profiles can be accurately derived by a simple matrix calculation, using a one-dimensional lattice sums, a T-matrix of an isolated circular cylinder, and generalized reflection matrices. Numerical examples have confirmed that the convergence of numerical solutions is very fast and the accuracy is very high.* Supported by the 21st Century
COE Program “Reconstruction of Social Insfrastructure Related to
Information Science and Electrical Engineerings”. 相似文献
993.
Humio Inaba 《Optical Review》1997,4(1):A1-A10
In advanced sensing photonics it is of great importance to explore the detection limits of extremely weak optical signals
and imaging using state-of-the art technology. In this paper we describe recent progress in photonic sensing technology achieved
in practice in the standard quantum limit of optical detection imposed by the signal-limited shot noise, which can be realized
by both the optical heterodyne detection and photon counting techniques. Then, with particular attention on imaging of ultraweak
photonic signals by these techniques, their applications in developing new frontiers in the field of biophotonics such as
laser computed tomography, and the imaging and characterization of ultraweak biophoton emission phenomena are described and
discussed as one of the typical examples of future trends in this field. 相似文献
994.
995.
Ying Huang 《中国物理 B》2022,31(5):54211-054211
A circular photonic crystal fiber (C-PCF) based on As2Se3 is designed, which has three zero dispersion wavelengths and flat dispersion. Using this fiber, a wide mid-infrared supercontinuum (MIR-SC) can be generated by launching a femtosecond pulse in the first anomalous dispersion region. The simulation results show that the MIR-SC is formed by soliton self-frequency shift and direct soliton spectrum tunneling on the long wavelength side and self-phase modulation, soliton fission on the short wavelength side. Further, optical shocking and four-wave mixing (FWM) are not conducive to the long-wavelength extension of MIR-SC, while the number and intensity of fundamental solitons have a greater effect on the short-wavelength extension of MIR-SC. The generation of optical shocking waves, FWM waves and fundamental solitons can be obviously affected by changing the fiber length and input pulse parameters, so that the spectrum range and flatness can be adjusted with great freedom. Finally, under the conditions of 4000 W pulse peak power, 30 fs pulse width, 47 mm fiber length, and 0 initial chirp, a wide MIR-SC with a coverage range of 2.535 μm-16.6 μm is obtained. These numerical results are encouraging because they demonstrate that the spread of MIR-SC towards the red and blue ends can be manipulated by choosing the appropriate incident pulse and designing optimized fiber parameters, which contributes to applications in such diverse areas as spectroscopy, metrology and tomography. 相似文献
996.
997.
通过改变一个薄电介质层的折射率来研究其对金属-电介质-金属光子晶体(M-D-MPhC)强透射特性的影响。采用与CMOS工艺兼容技术制作了由折射率分别为[nd(SU-8)=1.6,nd(SiO2.1N0.3)=1.6和nd(SiO0.6N1)=1.8]组成的三个正方形晶格圆孔阵列M-D-MPhC结构,利用傅里叶变换红外光谱仪测量其透射光谱。实验结果发现,金-SiO2.1N0.3-金结构能够获得较强的光透射增强效果和较窄的透射峰,证明了M-D-MPhC强透射特性既与中间电介质折射率大小有关,又与其材料制作工艺差异有关。采用时域有限差分(FDTD)法模拟了在相同条件下折射率分别为1.6和1.8组成的M-D-MPhC透射光谱和电场强度密度分布,模拟结果较好地符合了实验发现。 相似文献
998.
设计了基于自准直效应的硅光子晶体TE模式13和12光下路分束器。13光下路分束器由4个分束镜组成,而12下路分束器由3个分束镜和1个反射镜组成。利用多光束干涉原理推导出光下路分束器各个出口的透射谱理论公式。通过选择合适的分束镜,可以得到不同分束比例的光下路分束器。对于13光下路分束器,设计了1∶1∶1和1∶2∶3两种分束比例;对于12光下路分束器,设计了1∶1和1∶2两种分束比例。再利用时域有限差分软件数值模拟了透射谱,其结果与理论设计一致。当下路波长为1550 nm时,13和12两种光下路分束器的大小均约为10 m 10 m,自由光谱区为36 nm,覆盖了整个光通信C波段。 相似文献
999.
近年来,GaN基光子晶体发光二极管(light emitting diode,LED)的研究已经取得了一定的进展,利用光子晶体的光子带隙效应和光栅衍射原理,在LED上制作光子晶体结构将会提高出光效率.本文为了提高AlGaInP系LED的光提取效率,分析了常规LED光提取效率受到限制的原因,将光子晶体结构引入了AlGaInP系LED的器件结构设计,通过理论分析与实验验证,结果显示:光子晶体结构对于提高AlGaInP系LED的光提取效率同样起到了明显的效果,引入光子晶体后,LED的输出光强比常规结构LED平均
关键词:
AlGaInP系LED
光子晶体
光提取效率
光强 相似文献
1000.
We propose a novel method to achieve highly nonlinear photonic crystal fiber (PCF) by filling highly nonlinear liquid chloroform in the core of hollow-core PCF (HCPCF). The dispersion properties and electric field distribution of the fundamental mode are calculated by using the full-vector finite element method (FVFEM). Simulation results indicate that the zero-dispersion wavelength (ZDWL) of the chloroform-filled PCF is adjustable around 800 nm. Hence the femtosecond laser pulses with central wavelength at 800 nm can propagate in anomalous dispersion regime of the PCF, inducing the spectra broadening. 相似文献