全文获取类型
收费全文 | 72篇 |
免费 | 58篇 |
国内免费 | 10篇 |
专业分类
化学 | 14篇 |
晶体学 | 1篇 |
综合类 | 2篇 |
数学 | 3篇 |
物理学 | 120篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 7篇 |
2012年 | 3篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 11篇 |
2007年 | 5篇 |
2006年 | 10篇 |
2005年 | 9篇 |
2004年 | 20篇 |
2003年 | 9篇 |
2002年 | 7篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1997年 | 1篇 |
排序方式: 共有140条查询结果,搜索用时 234 毫秒
131.
人血清白蛋白与3-氨甲基吡啶相互作用的拉曼光谱研究 总被引:4,自引:1,他引:3
测量人血清白蛋白和一种新型仿生配基3-氨甲基吡啶与人血清白蛋白复合物的拉曼光谱。Raman光谱表明3-氨甲基吡啶与人血清白蛋白结合导致人血清白蛋白的构象及其结构的变化。人血清白蛋白的主链构象主要是α-螺旋结构,3-氨甲基吡啶结合不改变其二级结构,但二硫键的构象产生改变,唯一的色氨酸残基外环境由亲水变为疏水,酪氨酸所处的外环境也发生改变。 相似文献
132.
This paper reports on the photoluminescence spectra of ZnSe single crystal with
trace chlorine excited by the femtosecond laser pulse. Three emission bands,
including second-harmonic-generation, two-photon-excited peak and a broad band at
500--700nm, were detected. The thermal strain induced by femtosecond pulse strongly
influences the photoluminescence of ZnSe crystal. The corresponding strain \va in
ZnSe crystal is estimated to be about 8.8 \ti10-3 at room temperature. The
zinc-vacancy, as the main point defect induced by femtosecond pulse, is successfully
used to interpret the broad emission at 500--700nm. The research shows that
self-activated luminescence possesses the recombination mechanism of donor--vacancy
pair, and it is also influenced by a few selenium defects and the temperature. The
rapid decrease in photoluminescence intensity of two-photon-excited fluorescence and
second-harmonic generation emission at lower temperature is attributed to the fact
that more point defects result in the thermal activation of the two-photo-absorption
energy converting to the stronger recombination emission of chlorine--zinc vacancy
in 500--700nm. The experimental results indicate that the femtosecond exciting
photoluminescence shows a completely different emission mechanism to that of He--Cd
exciting luminescence in ZnSe single crystal. The femtosecond laser exhibits a
higher sensitive to the impurity in crystal materials, which can be recommended as
an efficient way to estimate the trace impurity in high quality crystals. 相似文献
133.
利用波长为532 nm的皮秒脉冲激光,研究了掺Er3 玻璃的光限幅特性和反饱和吸收.当入射功率不断增加且超过一定阈值时,透射功率不再随着入射功率快速增大,而是逐渐趋向于较稳定状态,从而实现了对强激光的光限幅效应.进一步利用布居速率方程讨论了其机制并给出了激发态的吸收截面,结果表明激发态吸收是其主要的光限幅机理. 相似文献
134.
Highly selective population of two excited states [2mm]in nonresonant two-photon absorption 下载免费PDF全文
A nonresonant two-photon absorption process can be manipulated by tailoring the ultra-short laser pulse. In this paper, we theoretically demonstrate a highly selective population of two excited states in the nonresonant two-photon absorption process by rationally designing a spectral phase distribution. Our results show that one excited state is maximally populated while the other state population is widely tunable from zero to the maximum value. We believe that the theoretical results may play an important role in the selective population of a more complex nonlinear process comprising nonresonant two-photon absorption, such as resonance-mediated (2+1)-three-photon absorption and (2+1)-resonant multiphoton ionization. 相似文献
135.
Radio-frequency compressed electron pulse-width characterization by cross-correlation between electron bunches and laser-induced plasma 下载免费PDF全文
A method is proposed to determine the temporal width of high-brightness radio-frequency compressed electron pulses based on cross-correlation technique involving electron bunches and laser-induced plasma. The temporal evolution of 2-dimensional transverse profile of ultrafast electron bunches repelled by the formed transient electric field of laser-induced plasma on a silver needle is investigated, and the pulse-width can be obtained by analyzing these time-dependent images.This approach can characterize radio-frequency compressed ultrafast electron bunches with picosecond or sub-picosecond timescale and up to 105 electron numbers. 相似文献
136.
In this paper,we propose a Rayleigh quotient iteration method (RQI)to calculate the Z-eigenpairs of the symmetric tensor,which can be viewed as a generalization of shifted symmetric higher-order power method (SS-HOPM).The convergence analysis and the fixed-point analysis of this algorithm are given.Nu-merical examples show that RQI needs fewer iterations than SS-HOPM while keep the amount of computation per iteration. 相似文献
137.
138.
139.
稠环芳烃有机物的三阶非线性光学性能研究 总被引:1,自引:0,他引:1
采用Nd:YAG皮秒锁模脉冲激光λ=532.0nm,运用3D前向简并四波混频(DFWM)的方法,测量了稠环芳烃中的1.2.5.6二苯并蒽(C22H14),1.2.8.9.二苯并五苯(C30H18)的三阶非线性极化率X^(3),非线性折射系数n2以及三阶非线性的时间响应。发现该类材料具有较大的非线性效应,文中分析了非线性形成机制以及相关的影响因素。 相似文献
140.