掺铒nc-Si/SiO_2薄膜中nc-Si和Er~(3+)与非辐射复合缺陷间相互作用对薄膜发光特性的影响

对nc-Si/SiO_2薄膜中纳米硅(nc-Si)、Er~(3+)和非辐射复合缺陷三者间的关系作了研究.在514.5 nm光激发下,nc-Si/SiO_2薄膜在750nm和1.54μm处存在较强的发光,前者与薄膜中的nc-Si有关,后者对应于Er~(3+)从第一激发态4I13/2到基态4I15/2的辐射跃迁.随薄膜中Er3+含量的提高,1.54μm处的发光强度明显增强,750 nm处的发光强度却降低.H处理可以明显增强薄膜的发光强度,但是对不同退火温度样品,处理效果却有所不同.根据以上实验结果,可得如下结论:在nc-Si颗粒附近的Er~(3+)和其他的缺陷组成了nc-Si颗粒内产生的束缚激子的非辐射复合中心,束缚激子通过Er~(3+)的非辐射复合,激发Er~(3+)产生1.54μm处的发光,同时降低了750nm处的发光强度.nc-Si颗粒附近其他非辐射复合中心的存在会降低Er~(3+)被激发的概率,引起1.54μm处的发光强度降低.

一种无需ADC的变步长反馈DC-DC转换器数控方式

数控DC-DC变换器由于其自身的特点，易于与数字系统进行单片集成。DC-DC的数字控制算法有很多种，其中比较复杂的算法（如PID）需要在片内集成ADC，增加了设计难度。较为简单的控制方案只使用单一的比较器作为反馈输入部件，但动态性能较差。本文在已有的单比较器恒定步长反馈数控Buck转换器的基础上，提出了一类变步长反馈的方案。由于仍使用单比较器或窗口比较器，它的结构简单且易于集成。它借鉴了对分搜索的思路，能根据输出电压反馈的结果动态地改变占空比的变化步长，从而明显地提高了原有恒定步长反馈数控变换器的动态性能。

~(183)Au核高自旋态转动带结构研究

通过重离子熔合蒸发反应和在束核谱学实验方法研究了奇A核183Au的高自旋态能级结构.扩展并更新了183Au的能级纲图.首次建立了183Au的πi13/2转动带的能量非优先带.分析并讨论了183Au中πh9/2转动带的能量非优先带和πf7/2转动带间的相互作用.

Health effects of arsenic；fluorine；and selenium from indoor burning of Chinese coal

IEECAS SKLLQG

聚乙二醇模拟干旱对甜高粱幼苗丙二醛、脯氨酸含量的影响；Effects of Drought Stress Simulated by PEG on Malonaldehyde and Proline Contents of Sweet Sorghum Seedlings

以甜高粱品种KFJT-CK及经过碳离子辐照选育出的早熟突变株KFJT-1为材料,用浓度分别为5%,10%和15%的聚乙二醇(PEG)6000模拟干旱对其进行胁迫处理,测定丙二醛(MDA)及脯氨酸(Pro)的含量。随着胁迫时间的延长和胁迫程度的增加,MDA含量持续升高;Pro含量在5%和10%PEG胁迫下持续升高,在15%PEG胁迫下先升高后降低。表明碳离子辐照可能使甜高粱膜脂过氧化特性发生改变,影响Pro的表达。为进一步研究碳离子束辐照对甜高粱的耐旱生理提供一定的基础,并为下一步的育种工作提供有用的参考。

3株酵母样真菌感染河蟹蚤状幼体的电镜观察

３株酵母样真菌感染河蟹蚤状幼体的电镜观察国际翔王丽霞李文清（中科院沈阳应用生态所，沈阳１１００１５）吴兆林丁茂昌韩守谨吕晓民徐欣（营口市水产研究所，营口１１５００４）陈军昌刘权恕王继健刘中石俊艳（营口市卫生防疫站，营口１１５００４）（辽宁省淡水研究所...

Rotamers of m-aminophenol cation studied by mass analyzed threshold ionization spectroscopy and theoretical calculations

The vibrationally resolved spectra of selected rotamers of m-aminophenol have been recorded by mass analyzed threshold ionization spectroscopy in connection with two-color resonant two-photon excitation scheme. The adiabatic ionization energies of the cis and trans rotamers are 61460 +/- 5 and 61734 +/- 5 cm(-1), respectively. The frequencies of modes 1 (breathing) and 18a (in-plane CH bending) are measured to be 744 and 1097 cm(-1) for the cis, and 736 and 1104 cm(-1) for the trans rotamer, respectively. This indicates that different orientation of the OH with respect to the NH2 substituent only slightly influences these two modes. (C) 2004 Elsevier B.V. All rights reserved.

道地药材牛蒡子适宜产区划分

牛蒡子为两年生菊科植物牛蒡(Arctium lappa L.)的干燥成熟果实,又名大力子。牛蒡在全国各地均有分布,据《中华人民共和国药典》记载,牛蒡子主要有四大产区:东北产区、华东产区、西南产区和华中产区。过去认为牛蒡子以浙江一带所产的为好,目前牛蒡子被认为是关药,以东北产的为佳。目前,有关牛蒡子的道地药材产区仍然存在争议。因此,科学划分牛蒡子的道地产区,不仅可以解决争议,而且对牛蒡的引种栽培具有重要的实践指导意义。本研究运用多元统计方法,确定影响牛蒡子道地性各环境因子的权重,在地理信息系统ArcGis9.0的支持下,进行牛蒡子产地适宜性划分,结果表明:牛蒡的最适宜分布区沿西南-东北方向呈现条带状分布,主要分布在东北、华北和西南地区。与《中华人民共和国药典》中记载的产区基本相近。但是,笔者的研究结果与药典记载也存在差异,华北(包括北京、天津、河北、山西、内蒙古)和西北(宁夏、新疆、陕西、甘肃)也是牛蒡的集中分布区;原来以浙江为主的华东产区,现在以山东为主;东北地区的吉林和黑龙江也是牛蒡子的主产区;西南地区牛蒡子的产区除了四川和重庆外,还包括云南和贵州;在华南和华中地区的分布较少。造成这种情况的原因可能是人为干扰(如人为拔除、除草剂的大量使用等)和气候变化影响。

Activated carbons chemically modified by concentrated H2SO4 for the adsorption of the pollutants from wastewater and the dibenzothiophene from fuel oils

The surface properties, porosities, and adsorption capacities of activated carbons (AC) are modified by the oxidation treatment using concentrated H2SO4 at temperatures 150-270 degreesC. The modified AC was characterized by N-2 adsorption, base titration, FTIR, and the adsorption of iodine, chlorophenol, methylene blue, and dibenzothiophene. The treatment of AC with concentrated H2SO4 at 250 degreesC greatly increases the mesoporous volume from 0.243 mL/g to 0.452 mL/g, specific surface areas from 393 m(2)/g to 745 m(2)/g, and acidic surface oxygen complexes from 0.071 meq/g to 1.986 meq/g as compared with the unmodified AC. The base titration results indicate that the amount of acidic surface oxygen groups on the modified AC increases with increasing the treatment temperatures and carboxyls and phenols are the most abundant carbon-oxygen functional groups. The carboxyl groups, COO- species, and hydroxyl groups are detected mainly for the sample treated at 250 degreesC. The mesoporous properties of the AC modified by concentrated H2SO4 were further tested by the adsorption of methylene blue and dibenzothiophene. The AC modified by concentrated H2SO4 at 250 degreesC has much higher adsorption capacities for large molecules (e.g., methylene blue and dibenzothiophene) than the unmodified AC but less adsorption capacities for small molecules (e.g., iodine). The adsorption results from aqueous solutions have been interpreted using Freundlich adsorption models.