全文获取类型
收费全文 | 48篇 |
免费 | 21篇 |
国内免费 | 22篇 |
专业分类
化学 | 38篇 |
力学 | 2篇 |
综合类 | 5篇 |
数学 | 15篇 |
物理学 | 31篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 3篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 6篇 |
2012年 | 1篇 |
2011年 | 5篇 |
2010年 | 4篇 |
2009年 | 6篇 |
2008年 | 10篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 5篇 |
2001年 | 3篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有91条查询结果,搜索用时 15 毫秒
11.
We report the stimulated emission from a dye doped polymer plane waveguide with TiO2 particles. This waveguide consists of a poly (methylmethacrylate) (PMMA) film containing laser dye DCM as a gain medium. The emission spectrum of the film pumped by the Nd:YAG laser is different from the amplified spontaneous emission of the dye-doped film without particles. It is shown that when the excitation intensity reaches the threshold 9.6 μJ, the broad band emission spectrum narrows into multiple separate peaks with central wavelength of 608 nm. The linewidth of the sharp peak is 0.5 nm. According to our analyses, this phenomenon is due to the multiscattering of the disordered TiO2 particles inside the gain polymer film. 相似文献
12.
13.
Field emission properties of a-C and a-C:H films deposited on silicon surfaces modified with nickel nanoparticles 下载免费PDF全文
The a-C and a-C:H films are deposited on silicon surfaces modified with and without nickel nanoparticles by using mid-frequency magnetron sputtering. The microstructures and morphologies of the films are analyzed by Raman spectroscopy and atomic force microscopy. Field emission behaviors of the deposited films with and without nickel nanoparticles modification are comparatively investigated. It is found that the hydrogen-free carbon film exhibits a high field emission current density and low turn-on electric field compared with the hydrogenated carbon film. Nickel modifying could increase the current density, whereas it has no significant effect on the turn-on electric field. The mechanism of field electron emission of a sample is discussed from the surface morphologies of the films and nickel nanoparticle roles in the interface between film and substrate. 相似文献
14.
Protection of entanglement from disturbance of the environment is an essential task marion processing. We examine the validity and limitation of the weak measurement and reversal in quantum infor- (WMR) operation in the protection of distributed entanglement from various decoherence sources. Since the entanglement variation can be investigated analytically for an arbitrarily entangled bipartite pure state under three kinds of typical noisy quantum channels, we show explicitly that the WMR operation indeed helps for protecting distributed entanglement from ampli- tude damping and phase damping, but not for depolarizing. Bxperimental feasibility for testing our results is discussed using current laboratory techniques. 相似文献
15.
采用中频磁控溅射Ti80Si20复合靶在单晶硅表面制备了共掺杂的类金刚石薄膜.研究了沉积温度对薄膜生长速率、化学成分、结构、表面性质和力学性能的影响.结果表明:随沉积温度升高,薄膜生长速率降低,薄膜Ti和Si原子浓度增加,C原子浓度降低;在高温下沉积的薄膜具有低sp3C含量、低表面接触角、低内应力和高的硬度与弹性模量.基于亚表层注入生长模型分析了沉积温度对薄膜生长和键合结构的影响,从薄膜生长机制和微观结构解释了表面性质和力学性能的变化. 相似文献
16.
砂-膨润土混合屏障材料渗透性影响因素研究 总被引:1,自引:0,他引:1
建立了一个新的结构-尾流振子耦合模型. 流场近尾迹动力学特征被模化为非线性阻尼
振子,采用van der Pol方程描述. 以控制体中结构与近尾迹流体间受力互为反作
用关系来实现流固耦合. 采用该模型进行了二维结构涡激振动计算,得到了合理的
振幅随来流流速的变化规律和共振幅值,并正确地预计了共振振幅值$A_{\max}^\ast$
随着质量阻尼参数$\left( {m^\ast + C_A } \right)\zeta
$的变化规律,给出了预测$A_{\max }^\ast
$值的拟合公式. 采用该模型计算了三维柔性结构在均匀来流和简谐波形来流作用下的VIV
响应. 结构在均匀来流作用下振动呈现由驻波向行波的变化过程, 并最后稳定为行波振动形态.
在简谐波形来流作用下,结构呈现混合振动形态,幅值随时间呈周期变化. 相似文献
17.
We propose a scheme to engineer a non-local two-qubit
phase gate between two remote quantum-dot spins. Along with
one-qubit local operations, one can in principal perform various
types of distributed quantum information processing. The scheme
employs a photon with linearly polarisation interacting one after
the other with two remote quantum-dot spins in cavities. Due to the
optical spin selection rule, the photon obtains a Faraday rotation
after the interaction process. By measuring the polarisation of the
final output photon, a non-local two-qubit phase gate between the
two remote quantum-dot spins is constituted. Our scheme may has very
important applications in the distributed quantum information
processing. 相似文献
18.
Properties on the distant distribution of entanglement for arbitrary two-qubit pure states via noisy quantum channels 下载免费PDF全文
This paper investigates the change of entanglement for transmitting
an arbitrarily entangled two-qubit pure state via one of three
typical kinds of noisy quantum channels: amplitude damping
quantum channel, phase damping quantum channel and depolarizing
quantum channel. It finds, in all these three cases, that the output
distant entanglement (measured by concurrence) reduces
proportionately with respect to its initial amount, and the decaying
ratio is determined only by the noisy characteristics of quantum
channels and independent of the form of initial input state. 相似文献
19.
电化学表面等离子体共振(electrochemical surface plasmon resonance, ESPR)技术是近年发展起来的、将表面等离子体共振技术与电化学方法联用的一种新方法.本文在阐明ESPR基本原理及其主要联用方法的基础上,对ESPR技术在金属离子定性/定量分析、纳米薄膜原位动力学研究、电化学聚合反应过程研究、ESPR生物传感等方面的应用进行了详细评述,并提出了提高ESPR检测灵敏度、ESPR与其他技术的联用以及测量装置的微型化、自动化是今后ESPR技术的发展方向. 相似文献
20.
废轮胎热解炭的分析及其活化特性的研究 总被引:1,自引:5,他引:1
用常规分析方法分析了废轮胎热解炭的成分和性质,用X射线能谱分析法、压汞法、N2吸附法等测定了热解炭的孔隙结构特性,并用CO2、含2%氧气的氮气流和水蒸气等活化气体对热解炭进行活化方面的研究。结果表明,热解炭灰分和硫含量比较高;两种不同粒径热解炭的比孔容积均在r≈25 nm处有最大值;在相同活化时间和活化剂流速下,温度越高,活化炭烧失率越大,比表面积也越大;在一定温度和活化剂流速下,烧失率和比表面积随着活化时间的增加而增大;对所有试验工况,烧失率越大,活化炭比表面积也越大。总体上水蒸气活化炭与CO2的活化效果较好,而含2%O2的氮气流活化的效果则次之。活化炭与商业活性炭的比较显示,前者具有较发达的孔隙结构,在进行大分子物质吸附时,具有替代商业活性炭的潜力。 相似文献