全文获取类型
收费全文 | 563篇 |
免费 | 70篇 |
国内免费 | 6篇 |
专业分类
化学 | 67篇 |
晶体学 | 10篇 |
力学 | 10篇 |
综合类 | 1篇 |
数学 | 22篇 |
物理学 | 529篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 18篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2017年 | 14篇 |
2016年 | 12篇 |
2015年 | 16篇 |
2014年 | 36篇 |
2013年 | 40篇 |
2012年 | 16篇 |
2011年 | 34篇 |
2010年 | 27篇 |
2009年 | 36篇 |
2008年 | 27篇 |
2007年 | 25篇 |
2006年 | 23篇 |
2005年 | 33篇 |
2004年 | 20篇 |
2003年 | 27篇 |
2002年 | 38篇 |
2001年 | 22篇 |
2000年 | 22篇 |
1999年 | 17篇 |
1998年 | 12篇 |
1997年 | 18篇 |
1996年 | 19篇 |
1995年 | 11篇 |
1994年 | 8篇 |
1993年 | 10篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 8篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1975年 | 1篇 |
排序方式: 共有639条查询结果,搜索用时 31 毫秒
71.
D'Orazio A. Desario M. Giasi C. Mescia L. Petruzzelli V. Prudenzano F. 《Optical and Quantum Electronics》2004,36(6):507-526
A realistic design of evanescent field optical sensors, constituted by three different kinds of planar waveguides covered
by a sensing polymeric overlay, is performed. More precisely, the slab, the embedded strip and the ridge waveguides are considered.
The sensor operation is simulated, in both the cases of lossy guided and leaky mode propagation, via a home made computer code. The optimal waveguide transverse section and length are identified, the advantages and drawbacks
are shown. The ridge waveguide sensor exhibits appreciable characteristics: for a concentration C
w = 200 ppm of toluene in water, the absorbance pertaining to a device L = 2.6 cm long and for the guided quasi-TE00 mode is A ≅ 5, while it is A ≅ 0.054 for a device long L ≅ 24.1 μm and the leaky quasi-TE10 mode. The simulation results suggest that a selective excitation of the suitable propagation mode can enhance the sensor
performance. 相似文献
72.
The behaviour of an array of photonic crystal waveguides is numerically investigated. It is shown that high dispersion may
be achieved in the telecommunication window around 1550 nm, with a device whose dimensions are in the order of half a mm2. 相似文献
73.
74.
A method to design a corrugated optical waveguide filter by modulating the corrugation width profile is proposed. This method is based on combined applications of the Fourier transformation and the F-matrix formalism. The method achieves the spatial profile of the corrugation width required to design a filter with any specified spectral profile of the reflection coefficient. The idea of the technique is that the spatial variation of the effective refractive index can be transformed, with the help of the F-matrix formalism, to variation of the corrugation width while maintaining a constant amplitude of the refractive index variation. Two examples are given applying the technique to the design of optical waveguide filters with reflectivity profiles of two- and four-rejection bands. 相似文献
75.
We report on our systematic and detailed study of fabrication and characterization of HNR120 photoresists thin-film optical waveguides. Various waveguide properties, such as refractive index, optical losses as a function of temperature, waveguide thickness, dispersion and birefringence have been studied. The optical loss are found to be <1.4 dB cm−1. 相似文献
76.
Ying-Tung Chen Kris Naessens Roel Baets Yunn-Shiuan Liao Ampere A. Tseng 《Optical Review》2005,12(6):427-441
For many years, the development of effective ablation or laser machining techniques for making micro-optical components has
been the key factor in the birth of new photonic devices and systems. In this article, the ablation characteristics of two
types of the most important transparent materials, transparent polymers and glasses, are studied. Simple shaped microcavities
are first machined for studying the fundamental ablation parameters, including threshold fluence, effective absorption coefficient,
and ablation rate. In studying polymer ablation, five standard grades and five proprietary polymeric compounds are selected.
Ablation techniques using these transparent polymers for making arrayed ferrules and curved microlenses are presented. Applications
of these ablated microstructures for optical fiber connectors, optical fiber coupling and alignment, and transparent chip
encapsulants, are introduced and demonstrated with emphasis on the quality of the ablated profiles and dimensions to satisfy
the required performance. In glass ablation, borosilicate glasses are considered and their associated ablation behaviors are
studied. The procedures to ablate glass-based arrayed microstructures with flat and curved surfaces are described. The utilizations
of these arrayed microstructures for optical waveguide, wave absorber, and beam guider, are specifically discussed. Finally,
concluding remakes for future trends are presented. 相似文献
77.
Keh-Yi Lee Chia-Chen Tsai Tsong-Cheng Weng Yi-Lin Kuo Chih-Wei Kao Kuei-Yuan Chen Yu-Jen Lin 《Fiber and Integrated Optics》2006,25(1):29-40
There are several key factors that affect the transmission characteristics of the 90° (L-shaped) bent photonic crystal waveguides. The first factor is the direct coupling efficiency from the incident lights into the waveguides. The second one is the bandgap deviations of the photonic crystals. And the third factor is the optical reflections in the bent corners. In this article, we compare three types of L-shaped bent photonic crystal waveguides. One is the original type, which has an abrupt right-angle bend. Another is an improved 90° bend with a 45°-mirror. The other is an L-shaped bent photonic crystal waveguide with a 45°-transitional section. We investigate their respective frequency responses and observe the improvements in the total transmission efficiencies provided by the latter types. 相似文献
78.
Zhiyi P. Zhang 《Fiber and Integrated Optics》2003,22(6):357-371
Computer simulation was used to understand the adhesive-based coupling of optical fibers to planar waveguides with a view to adhesive development. Satisfactory coupling performance could be achieved with facet-angled fibers and waveguides, regardless of the adhesive's index and optical loss. A high-temperature epoxy adhesive was developed for coupling applications based on the simulation. The adhesive is able to achieve a material-related loss of -0.05 dB and a back-reflection loss of less than -50 dB in the coupling. In addition, the adhesive has excellent mechanical and thermal properties and can easily meet the Telcordia standard GR1221 while withstanding high temperatures and high optical power. 相似文献
79.
T. Kishii 《Optics & Laser Technology》1982,14(2):75-80
Graded-index planar optical waveguides and surface compression layers were formed simultaneously in the surface layer of glass plates by ion exchange. A change in the refractometer patterns was observed. Before ion exchange, only a critical ray fringe was observed, but with ion exchange a guided wave fringe appeared on the high effective refractive index side of the ‘critical ray’ fringe, and the number of guided wave fringes increased. The guided wave fringe or fringes were birefringent, whereas the ‘critical ray’ fringe was kept nonbirefringent. It was concluded that the ‘critical ray’ propagated along the bottom of a waveguide, ie at the foot of the refractive index distribution. 相似文献
80.
We have analysed the mode structure of a wideband radiofrequency excited waveguide CO2 laser by using different waveguide diameters and optical cavities. In particular we have observed the phase shift of some linear polarized waveguide modes in the transition region between the guided and the free Gaussian propagation. 相似文献