全文获取类型
收费全文 | 106篇 |
免费 | 65篇 |
专业分类
化学 | 8篇 |
晶体学 | 1篇 |
力学 | 1篇 |
综合类 | 2篇 |
物理学 | 159篇 |
出版年
2022年 | 3篇 |
2021年 | 1篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 7篇 |
2016年 | 3篇 |
2015年 | 7篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 16篇 |
2011年 | 13篇 |
2010年 | 7篇 |
2009年 | 6篇 |
2008年 | 11篇 |
2007年 | 7篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1983年 | 1篇 |
排序方式: 共有171条查询结果,搜索用时 40 毫秒
41.
42.
Linewidth narrowing and other quantum coherent effects based on three-photon coherent population trapping (CPT) in Ca+ ions are investigated. If the propagation directions of the three lasers obey the phase matching condition, the dark linewidth resulting from the CPT can be very narrow, and it can be controlled by adjusting the parameters of the lasers. 相似文献
43.
K. A. Vereschagin V. V. Smirnov O. M. Stel'makh V. I. Fabelinsky W. Clauss M. Oschwald 《Journal of Raman spectroscopy : JRS》2010,41(8):902-906
We demonstrate the feasibility of single laser shot coherent anti‐Stokes Raman scattering thermometry with simultaneous measurement of intensities of hydrogen Q‐branch lines and their linewidths in a pulsed CH4/O2 combustion chamber operating at 20 MPa pressure and 3000 K temperature—parameters that are typical for full‐scale rocket engines. The measurements were done by means of a spectrograph combined with an interferometer having orthogonal directions of dispersions. This approach allows correct temperature evaluation that takes into account the directly measured linewidths. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
44.
离焦写入线宽的动态高斯模型 总被引:1,自引:0,他引:1
为提高集成光学器件中的多线宽制作效率,提出了基于激光直接写入技术的离焦加工模式,即加工时激光束的聚焦点不落在胶层表面而是在其前方或后方;同时还建立了基于多个加工参量的线宽数学模型。此线宽模型首先假定激光束经物镜变换后,在像方任意离焦面上的能量仍保持高斯分布,其次还考虑了光束动态扫描引起的光斑线度对曝光能量分布的影响,故称其为动态高斯模型。此线宽模型涉及光功率、基片离焦量、光束扫描速度、胶层曝光能量阈值等加工参量。对线宽模型的验证在自行研发的极坐标型激光图形发生器上进行,实验表明:相对于不考虑光斑运动的静态高斯模型,动态高斯模型更为符合实验结果。 相似文献
45.
HU Zongfu SHEN Huiming 《Chinese Journal of Lasers》2000,9(1):20-23
1 Introduction Sincelasercameout,muchattentionhasbeenpaidtonarrowlinewidthlasers,andmanyprogresseshavebeenmadeinthisfield[1~3].A... 相似文献
46.
用光纤延时自差法测量二极管激光纵向泵浦单频运转的Nd:YVO4激光器的线宽。在1秒时间内,激光线宽为25kHz。还测量了线宽与激光器腔长和输出功率的关系。 相似文献
47.
Xiaoqing Zhang Masahiko Shimoda Akinobu Toyoda 《Journal of Polymer Science.Polymer Physics》1994,32(8):1399-1406
The molecular motion of crosslinked polyepichlorohydrin (PECH) is studied qualitatively by NMR techniques. The results of temperature dependence of 1H T2 and T1 indicate that the crosslinking (crosslink density < 3%) restricts molecular motions of the polymer even far above its Tg. The 1H T1 minimum, corresponding to the large-scale chain-motion of crosslinked PECH, shifts to higher temperatures with increasing crosslink density. 1H T2 data also show that the crosslinking hinders free chain motions of the polymer above its Tg. The 13C T1 relaxation time is sensitive to such motional changes as well. 13C linewidths of crosslinked PECHs vary with the crosslink density in both the swollen state and the solid state. The mechanism of 13C linewidth broadening of crosslinked polymers is discussed in detail. In the case of PECH, the linewidth broadening is caused by changing molecular environment due to crosslinking (such as presence of various chemical shift structures and freezing effects in conformational environment as chain mobility decreases), rather than increasing correlation times, which shorten the relaxation time (T2) of polymer chains. © 1994 John Wiley & Sons, Inc. 相似文献
48.
纳米尺寸CdS半导体微晶的光致发光线宽宽化研究 总被引:2,自引:1,他引:1
测量了各种温度下玻璃中掺杂纳米尺寸CdS半导体微晶的光致发光光谱,研究了其光致发光带的峰值能量和线宽对温度的依赖关系.考虑CdS微晶的LO声子的相互作用,拟合了其带隙发光带的线宽随温度的变化曲线,获得样品的非均匀线宽.CdS微晶的非均匀线宽主要是由于微晶的尺寸分布引起的. 相似文献
49.
We present modelling results investigating the carrier dynamics of an SOA composed of an inhomogeneous array of quantum dots
designed to produce broad gain amplification when optically pumped. We use a set of rate equations that describe the QDs inhomogeneity
and include an energy dependent occupation factor within each inhomogeneously broadened level and numerically solve them with
the propagation equation to investigate the amplification of optical signals in the waveguide. By treating the carrier filling
according to the quasi-equilibrium distribution, we are able to investigate the effect of band-filling (BFE) on the gain and
refractive index. The linewidth enhancement factor (α) is computed and analysed with respect to optical signal intensity as
well as electrical current density. 相似文献
50.
A. Hgele B. Aln F. Bickel R. J. Warburton P. M. Petroff K. Karrai 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):175
We show how the resonant absorption of the ground state neutral exciton confined in a single InGaAs self-assembled quantum dot can be directly observed in an optical transmission experiment. A spectrum of the differential transmitted intensity is obtained by sweeping the exciton energy into resonance with laser photons exploiting the voltage induced Stark-shift. We describe the details of this experimental technique and some example results which exploit the 1 μeV spectral resolution. In addition to the fine structure splitting of the neutral exciton and an upper bound on the homogeneous linewidth at 4.2 K, we also determine the transition electric dipole moment. 相似文献