GaAs光导开关损伤机理研究

光导开关(photoconductive semiconductor switches,PCSS)的损伤分为热击穿和电击穿,2种击穿的原因都由开关基底材料陷阱特性决定,因此对芯片击穿机理与开关制作工艺关系的研究非常重要。文章依据开关芯片的材料特性和半导体工艺知识,研究和分析了光导开关的击穿机理以及开关击穿可能存在的工艺问题。     

正充电性单层有机光导器件的制备及性能研究

制备了新型化合物2,5,7,10-四叔丁基联苯醌,以此作为电子传输材料制备了正充电性有机光导器件,并对其光电性能进行了研究.研究结果表明,该新型化合物作为电子传输材料制备的光导器件具有较好的光电性能.     

808 nm大功率半导体激光器的低频电噪声

对 8 0 8 nm大功率半导体激光器的低频电噪声进行测试 ,给出器件电噪声与频率、注入电流之间关系 ,讨论噪声与电、光导数之间的关系 .结果表明 ,80 8nm大功率半导体激光器的电噪声在低频段主要为 1 /f噪声 ,并在阈值附近有最大值     

光导开关线性工作模式下的计算机模拟

针对光导开关产生的线性电脉冲的实验结果,结合外电路,应用计算机对光导开关进行了数值模拟.结果表明:理论模拟结果与实验结果相比较符合很好,说明模拟计算是成功的,同时线性光导开关的物理机制可以解释光导开关在线性模式下的各种特征.     

光导开关在UWB和THz技术中的应用

光导开关以其优良的性能在众多领域中有着广阔的应用前景和使用价值.本文重点阐述了光导开关在超宽带技术和太赫兹技术中的应用,并指出目前应用研究中存在的主要问题.     

N-苯乙烯基咔唑的电荷转移配合作用

N—乙烯基咔唑与一些电子受体可形成电荷转移配合物,通过聚合或与其它单体共聚(包括电荷转移引发聚合)可生成具有光导性能的聚乙烯咔唑(PKV)及其相应共聚物。它们在电照相技术中是最先实用化的有机光导体,受到人们的普遍关注。近年来,3-取代苯乙烯基咋唑作为电照相材料的光敏组分已见于专利文献,而关于N—苯乙烯基咔     

GaAs光导开关瞬态光电导效应的研究

光导半导体开关自问世以来，以其优良的特性受到人们广泛的关注，其应用领域不断地拓展。本文对立了一个光导开关的瞬态响应模型，对ＧａＡｓ瞬态光电导效应进行了研究，重点研究了是光作用过程的Ｄｅｍｂｅｒ效应和各种重要的复合机制对ＧａＡｓ光导开关光电导响应的影响。     

氯丹蓝偶氮/酞菁氧钛复合体系光电导性能的协同增强效应

在氯丹蓝偶氮/酞菁氧钛复合光生材料中发现了光敏性的非线性增强现象,对复合体系的电子跃迁光谱和X射线衍射图样研究结果表明基态下两种材料之间没有明显电子态相互作用和两种分子间的穿插与缔合,光致放电研究说明该现象来自光激发状态下复合体系中缺陷态导致的隙间态跃迁对光导的贡献,ESR和XPS测试结果都表明酞菁氧钛与氯丹蓝偶氮之间存在着光致激发状态下的、定向的部分电荷转移.酞菁类和偶氮类弱的电子给体与受体复合体系中光导性能的协同增强效应为设计高品质的光导材料与器件提供了新思路.     

正充电性单层有机光导器件的制备及性能研究

制备了新型化合物2,5,7,10-四叔丁基联苯醌,以此作为电子传输材料制备了正充电性有机光导器件,并对其光电性能进行了研究。研究结果表明,该新型化合物作为电子传输材料制备的光导器件具有较好的光电性能。     

2,5,7,10-四叔丁基联苯醌制备及性能研究

本工作制备了新型化合物2,5,7,10-四叔丁基联苯醌,并以之作为电子传输材料制备了正充电性有机光导器件,并对期间的光电性能进行了研究,研究表明新化合物作为电子传输材料制备的光导器件具有较好的光电性能。     

组合性技术在篮球比赛中的运用探微

本文主要通过对篮球几组组合性技术的分析,阐明在篮球运动高速发展的今天,组合技术在高水平篮球比赛中所处的地位和重要性,阐述了这些组合性技术的适用范围,运用这些技术的目的,以及运用这些技术时可能遇到和应当注意的问题。     

Circular dichroism spectra of different structures formed by the oligonucleotides

Under different conditions, oligonucleotides can form several different DNA structures such as duplex, triplex and quadruplex. All these structures exhibit an obvious difference in their CD spectra. The common characteristic is that they show a negative band at 240 nm, while in the range of 260–300 nm, the spectra are different from each other. Many factors such as chain direction, sugar puckering mode, orientation of the glycosyl bond, base stacking and sequence can affect their conformation and then show diversity and complexity in their spectra. By studying and comparing these spectra, more information about their conformations can be obtained to help predict some new structures. Furthermore, the spectra can also provide a base to study their potential biological functions.     

正常儿童心电图的研究

本文对450名正常儿童的心电图进行了分析。结果表明:儿童心率波动幅度大,平均心率随增龄而减慢。心电轴86%以上在正常范围;P波电压与增龄无规律关系,P波时限随增龄有所延长;Rv_1、Rv_3和Sv_5以及Rv_1+Sv_5均随增龄而降低,QRS波时限随增龄而延长;男童T波的电压平均高于女童;年龄愈大、心率愈慢,P-R间期和Q-T间期愈长。我们测定的结果还与国内有关报导同年龄组儿童的心电图进行了比较。     

DNA reveals high dispersal synchronizing the population dynamics of Canada lynx

Population dynamics of Canada lynx (Lynx canadensis) have been of interest to ecologists for nearly sixty years. Two competing hypotheses concerning lynx population dynamics and large-scale spatial synchrony are currently debated. The first suggests that dispersal is substantial among lynx populations, and the second proposes that lynx at the periphery of their range exist in small, isolated patches that maintain cycle synchrony via correlation with extrinsic environmental factors. Resolving the nature of lynx population dynamics and dispersal is important both to ecological theory and to the conservation of threatened lynx populations: the lack of knowledge about connectivity between populations at the southern periphery of the lynx's geographic range delayed their legal listing in the United States. We test these competing hypotheses using microsatellite DNA markers and lynx samples from 17 collection sites in the core and periphery of the lynx's geographic range. Here we show high gene flow despite separation by distances greater than 3,100 km, supporting the dispersal hypothesis. We therefore suggest that management actions in the contiguous United States should focus on maintaining connectivity with the core of the lynx's geographic range.     

Dynamic biogeography and conservation of endangered species

As one moves from the core to the periphery of a species' geographical range, populations occupy less favourable habitats and exhibit lower and more variable densities. Populations along the periphery of the range tend to be more fragmented and, as a result, are less likely to receive immigrants from other populations. A population's probability of extinction is directly correlated with its variability and inversely correlated with density and immigration rate. This has led to the prediction that, when a species becomes endangered, its geographical range should contract inwards, with the core populations persisting until the final stages of decline. Convinced by these logical but untested deductions, conservation biologists and wildlife managers have been instructed to avoid the range periphery when planning conservation strategies or allocating resources for endangered species. We have analysed range contraction in 245 species from a broad range of taxonomic groups and geographical regions. Here we report that observed patterns of range contraction do not support the above predictions and that most species examined persist in the periphery of their historical geographical ranges.     

手性液晶的研究——Ⅶ.苯基嘧啶类铁电液晶

合成了四个系列共十四个化合物,测定了它们的相变温度和相态,对部分化合物进行了电滞回线和螺距的测试,并比较了结构和性能的关系。其中(d)AmPA′Pm(Ⅱ)和(d)HpPA′Pm(Ⅳ)为室温铁电液晶,AP(d)Hp′Pm(Ⅲ)为胆甾相液晶,对产物进行了初步的混合配方探索。     

辽宁岫岩透闪石质河磨老玉中石墨的成因及其指示意义

石墨常出现在岩浆作用、变质作用及热液蚀变交代作用过程中,是成岩成矿物理化学条件的指示性矿物。辽宁岫岩透闪石质玉、特别是其中河磨老玉(子料)中常常含有大量的石墨,目前,对这些石墨形成条件及其与闪石质玉石成因联系知之甚少。通过显微岩相学、拉曼光谱和X射线单晶衍射等分析,探讨了辽宁岫岩河磨老玉中石墨与透闪石质玉矿的成因联系。河磨老玉中的石墨呈条带状、星点状和云雾状3种分布形态,计算获得的石墨化度值在0.562~0.644之间,菱面体多形含量变化在19.52%~23.00%,温度范围为454~623℃,与角闪岩相变质峰期温度基本一致,明显高于前人获得的透闪石质玉的形成温度范围。结果显示,河磨老玉中的石墨与闪石质玉石是不同地质作用产物。结合野外地质产状,推测河磨老玉中的石墨形成早于闪石质玉石,是区域变质作用形成的变质残余矿物。透闪石质河磨老玉石墨的特征暗示辽河群含石墨方解石大理岩、含石墨的透闪变粒岩、透闪岩大理岩可能是河磨老玉主要的原岩,而透闪石玉是多期次/阶段成矿作用产物。     

Crackling noise

Crackling noise arises when a system responds to changing external conditions through discrete, impulsive events spanning a broad range of sizes. A wide variety of physical systems exhibiting crackling noise have been studied, from earthquakes on faults to paper crumpling. Because these systems exhibit regular behaviour over a huge range of sizes, their behaviour is likely to be independent of microscopic and macroscopic details, and progress can be made by the use of simple models. The fact that these models and real systems can share the same behaviour on many scales is called universality. We illustrate these ideas by using results for our model of crackling noise in magnets, explaining the use of the renormalization group and scaling collapses, and we highlight some continuing challenges in this still-evolving field.     

关于股份公司股利政策的理论探讨

针对目前我国实际经济生活中的股利分配方案比较随意，欠规范，有的公司有大量的未分配利润却长期不分配股利，而有的公司一方面计划在资金市场上融资。另一方面又大比例分配股利的现象，就西方国家多年形成的影响股利政策的因素及可供借鉴的股利政策进行了简要的介绍，以期对我国企业股利分配政策的确定有所启示。     

Demographic compensation and tipping points in climate-induced range shifts

To persist, species are expected to shift their geographical ranges polewards or to higher elevations as the Earth's climate warms. However, although many species' ranges have shifted in historical times, many others have not, or have shifted only at the high-latitude or high-elevation limits, leading to range expansions rather than contractions. Given these idiosyncratic responses to climate warming, and their varied implications for species' vulnerability to climate change, a critical task is to understand why some species have not shifted their ranges, particularly at the equatorial or low-elevation limits, and whether such resilience will last as warming continues. Here we show that compensatory changes in demographic rates are buffering southern populations of two North American tundra plants against the negative effects of a warming climate, slowing their northward range shifts, but that this buffering is unlikely to continue indefinitely. Southern populations of both species showed lower survival and recruitment but higher growth of individual plants, possibly owing to longer, warmer growing seasons. Because of these and other compensatory changes, the population growth rates of southern populations are not at present lower than those of northern ones. However, continued warming may yet prove detrimental, as most demographic rates that improved in moderately warmer years declined in the warmest years, with the potential to drive future population declines. Our results emphasize the need for long-term, range-wide measurement of all population processes to detect demographic compensation and to identify nonlinear responses that may lead to sudden range shifts as climatic tipping points are exceeded.