全文获取类型
收费全文 | 3170篇 |
免费 | 596篇 |
国内免费 | 114篇 |
专业分类
化学 | 239篇 |
晶体学 | 22篇 |
力学 | 130篇 |
综合类 | 46篇 |
数学 | 393篇 |
物理学 | 3050篇 |
出版年
2024年 | 3篇 |
2023年 | 8篇 |
2022年 | 34篇 |
2021年 | 45篇 |
2020年 | 51篇 |
2019年 | 24篇 |
2018年 | 41篇 |
2017年 | 90篇 |
2016年 | 91篇 |
2015年 | 75篇 |
2014年 | 206篇 |
2013年 | 207篇 |
2012年 | 174篇 |
2011年 | 221篇 |
2010年 | 149篇 |
2009年 | 187篇 |
2008年 | 249篇 |
2007年 | 256篇 |
2006年 | 207篇 |
2005年 | 182篇 |
2004年 | 193篇 |
2003年 | 171篇 |
2002年 | 163篇 |
2001年 | 145篇 |
2000年 | 119篇 |
1999年 | 110篇 |
1998年 | 93篇 |
1997年 | 62篇 |
1996年 | 68篇 |
1995年 | 42篇 |
1994年 | 39篇 |
1993年 | 31篇 |
1992年 | 26篇 |
1991年 | 34篇 |
1990年 | 27篇 |
1989年 | 10篇 |
1988年 | 18篇 |
1987年 | 13篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有3880条查询结果,搜索用时 15 毫秒
1.
2.
甲基紫掺杂聚乙烯醇薄膜材料在两束相干光照射下生成相位光栅.当改变一束相干光光程,通过监测相位光栅的一级衍射信号强度的变化,可以检测相位光栅的生长和擦除过程.在此实验基础上,讨论了甲基紫掺杂聚乙烯醇薄膜材料多重全息存储的原理与结果. 相似文献
3.
4.
5.
A novel and simple two-frequency Brillouin fiber laser is presented. It is based on a fiber Fabry-Perot cavity with fiber Bragg gratings as reflectors. The model of stimulated Brillouin scattering in fiber grating-based Fabry-Perot resonator is investigated. The laser allows conversion efficiency of close to 100% and suppresses the higher-order Stokes waves. The theoretical prediction is presented and the experimental demonstration is realized. 相似文献
6.
The diffraction efficiency and morphology of the transmission modes of holographic polymer dispersed liquid crystals were studied with respect to the molecular structure of poly(urethane acrylate) (PUA), the film (polymer/liquid crystal) and resin (oligomer/monomer) compositions, and the cell thickness. PUA, based on N‐vinylpyrrolidone and ethyl hexyl acrylate, with low‐molecular‐weight poly(propylene glycol) at a low oligomer content, showed high diffraction efficiency. The results were interpreted in terms of the monomer reactivity and polymer elasticity. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 613–620, 2004 相似文献
7.
8.
胡迪鹤 《数学物理学报(B辑英文版)》2005,25(1):23-29
This paper is a continuation of [8]. In Section 1, three kinds of communication are introdnced for two states and the relations among them are investigated. In Section 2, two kinds of period of a state are introdnced and it is obtained that the period is a “class property” ,i.e. two states x and y belong to same class implies the period of x is equal to the period of y. 相似文献
9.
Hirohisa Yokota Kenji Kamoto Jun-ichi Igarashi Norihiko Mouri Yutaka Sasaki 《Optical Review》2002,9(1):9-12
A new configuration for an ASE reduction filter in EDFA repeaters for WDM optical transmission systems using optical fiber grating couplers (FGCs) was proposed and first demonstrated. The filtering characteristics of the proposed filter for amplified single wavelength signal and 2-channel WDM signals using EDFA were identified. It was found that the filter was effective to improve SNR in optical domain by reducing ASE noise. The required FGC characteristics for the filter were theoretically predicted under the condition that the total filter loss did not exceed 3 dB. More than 70% of drop efficiency was required in each FGC for the application of the proposed filter to an 8-channel WDM system using EDFA repeaters. 相似文献
10.
F-H实验仪与光栅光谱仪连用观测253.7nm谱线 总被引:1,自引:0,他引:1
通过F-H实验仪和光栅光谱仪的连用,可实时观测汞原子从6s6s1So态激发到6s6sSP1态,退激时,辐射出能量为4.9eV的光量子,其波长为253.7nm. 相似文献