Phase Dependence of Fluorescence Spectrum of a Two-Level Atom in a Trichromatic Field

We examine the phase-dependent effects in resonance fluorescence of a two-level atom driven by a trichromatic modulated field. It is shown that the fluorescence spectrum depends crucially on the sum of relative phases of the sideband components compared to the central component, not simply on the respective phases. The appearance or disappearance of the central peak and the selective elimination of the sideband peaks are achieved simply by varying the sum phase. Once the sum phase is fixed, the spectrum keeps its features unchanged regardless of the respective relative phases.     

A Novel Cholesterol Oxidase Biosensor Based on Pt-nanoparticle /Carbon Nanotube Modified Electrode

A variety of electrochemical biosensors for cholesterol detection have been proposed because of its importance in clinic and food analysis 1-2. Classical devices for the detection were based on monitoring either the consumption of oxygen or the production of H2O2. The amperometric determination of H2O2 oxidation is sensitive and stable, but it requires a high anodic potential (over 0.6 V vs Ag/AgCl) and is affected by co-oxidable substances such as ascorbic acid and uric acid usually presen…     

Timoshenko梁的耗散边界反馈控制

研究Timoshenko梁的非线性耗散边界反馈镇定.首先利用非线性半群理论证明闭环系统的适定性.然后利用LaSalle不变原理证明梁的振动在所建议的非线性控制作用下随时间渐近趋于0.进而对控制的非线性作进一步的限制,利用能量摄动方法得到梁的闭环振动指数稳定.     

服务台可修的GI／M（M／PH）／1排队系统

本文首次讨论一个到达间隔为一般分布的可修排队系统。假定服务时间、忙期服务台寿命都服从指疏分布，修复时间是ＰＨ变量。首先证明该系统可转化为一个经典的ＧＩ／￣ＰＨ／１排队模型，然后给出系统在稳态下的各种排队论指标和可靠性指标。     

锥有效拟凹集的有效点集的连通性

本文引进了锥有效拟凹集的概念，讨论了R ^m-严格拟凹与R ^m－有效拟凹的关系，证明了一个紧集为锥有效拟凹且其有效点集为闭集时，这个有效点集是连通的。     

一步法直接合成碳酸二甲酯催化剂

采用浸渍法以MgO、海泡石（Sep）。γ-Al2O3为载体，制备了一系列金属盐Lewis酸-无机碱双组分负载型催化剂，以环氧丙烷（PO）一步合成碳酸二甲酯（DMC）反应为探针。考察了催化剂的不同载体活性组分和反应条件对合成DMC的产率及选择性的影响。结果表明，催化剂的活性次序为：NaOH—LiCl／MgO）NaOH—LiCl／Sep）NaOH—LiCl／γ-Al2O3；选择性的次序为：NaOH—LiCl／Sep）NaOH—LiCl／MgO）NaOH—LiCl／γ-Al2O3。NaOH—LiCl／SeP催化剂具有较高的活性和选择性；其最佳反应条件为：反应温度160℃。反应时间5h，甲醇与PO的量之比为1：1。在最佳条件下。PO转化率为82．6％，DMC的产率达到7．68％。     

Lagrange、Cauchy、积分中值定理与Taylor公式的统一证明

通过一个定理的结论,给出L agrange、C auchy、积分中值定理和T ay lor公式的统一证明,同时得出计算不定型极限的L′Hosp ita l法则的推广定理.     

反应挤出接枝共聚反应表观链增长常数的测量

以预辐照的LLDPE反应挤出接枝MAA作为研究对象，通过在双螺杆挤出机中的不同部位取样，用FFIR分析接枝物及均聚物的产量，并用ESR测试链增长自由基浓度，设计了测定接枝和均聚反应初始阶段的表观链增长常数的方法,结果表明，在本实验测试范围内表观接枝链增长常数不同于均聚链增长常数；所得的测量值符合理论预测值，证明测试方法适合高温熔融体系的研究。     

直流磁控溅射沉积含He钛膜的研究

研究了用He/Ar混合溅射气体的直流磁控溅射制备钛膜中，He的掺入现象.分析结果表明，大量的He原子（He/Ti原子比高达56%）被均匀地引入到Ti膜中，其He含量可由混合溅射气体的He分量精确控制.通过调节溅射参数，可实现样品中He的低损伤引入.研究还发现，溅射沉积的含氦Ti膜具有较高的He成泡剂量和高的固He能力，这可能是溅射沉积形成了纳米晶Ti膜所致.纳米晶Ti膜较粗晶材料具有很高浓度的He捕陷中心，使He泡密度增大而泡尺寸减小.随He引入量的增加，Ti膜的晶粒尺寸减小，He引起的晶体点阵参数和X射线衍射峰宽度增大，晶体的无序程度增加.Helium trapping in the Ti films deposited by DC magnetron sputtering with a He/Ar mixture was studied. He atoms with a surprisingly high concentration (He/Ti atomic ratio is as high as 56%)incorporate evenly in deposited film. The trapped amount of He can be controlled by the helium partial amount. The introduction of the helium with no extra damage(or very low damage) can be realized by choosing suitable deposition conditions. It was also found that because of the formation of nanophase Ti film a relative high He flux for bubble formation is needed and the amount of the retain He in sputtering Ti films is much higher than that in the coarse grain Ti films. The nanophase Ti film can accommodate larger concentration of trapped sites to He, which results in a high density and small size of the He bubbles. With the increasing He irradiation flux, the grain size of Ti film decreases and the lattice spacing and width of the X ray diffraction peak increase due to the He introduction, and the film tends to amorphous phase.     

Time-resolved Luminescence-based Chemosensor for Fluoride Anion

Design and synthesis of new chemosensors for fluoride anion (F-)1-6 have been of interest to chemists for many years, because F- plays a crucial role in the dental care5 and the treatment of osteoporosis7. Recently, the fluorescent chemosensors of fluorid…