还原糖直接滴定法的改进

针对在还原糖直接滴定法中诸多条件对滴定的本质影响是引起反应液碱度变化,为此将实验仪器进行改进,把滴定中蒸发的水蒸气冷凝回流,使平行实验中反应液碱度尽可能一致,减小了偶然误差,使分析结果的相对标准偏差由国标法的 ０．６１％ 降低到改进法的０．２７％ 。     

Optical memory using a vertical-cavity surface emitting laser

Data are presented demonstrating optical switching and memory in a bistable vertical-cavity surface-emitting laser (VCSEL). Optical switching from lasing to nonlasing or from nonlasing to lasing in the vertical-cavity laser was demonstrated using an AlGaAs probe laser at ~0.78 μm     

DDS与PLL频率合成数字系统设计

直接数字合成(DDS)是近年发展起来的一种新型合成技术.有频率分辨率高.转换时间短.相位噪声低等特点.与锁相合成技术IPLL)配合.可以设计出频带宽.分辨率高的频率合成器.本文介绍了一种DDS+PLL的混合结构.实现了一个高稳定度的锁相频率合成系统.     

国外无人机发展趋势及关键技术

介绍了网络中心战(NCW)对无人机(UAV)的性能需求,归纳了当前国外无人机发展领域的热点和趋势,着重针对影响无人机关键性能的几大前沿技术的各自特点、研制现状及方向进行了分析和综述,并对其近期发展前景做出了预测,最后对国内无人机的相关研制工作提出了一些建议.     

多通信途径的交通广播数字地图服务系统

提出一种新的广播交通信息数字地图服务系统设计方案,作为对现阶段国内广播交通信息服务的补充。新系统包括两个子系统,交通信息发布子系统与交通信息接收子系统。两个子系统间通过GPRS和短信息两种方式传递信息。该系统的示范样品已经实现,经过实际测验,达到预期的设计效果。     

Magnetoconductance of polymer–fullerene bulk heterojunction solar cells

The organic magnetoconductance (MC) effects in poly(3-hexylthiophene): [6,6]-phenyl-C61-butyricacid methylester based bulk heterojunction solar cells were studied in dark and under illumination. The correlations between the MC and current character were revealed in this study. Results show that the dark current always exhibits a negative MC whereas a sign change in MC under illumination occurs at the bias around the open circuit voltage V_oc. We suggest that the positive MC in photocurrent is due to the field dependent conversion of singlet electron–hole pairs to triplet states and the negative MC is associated with space charge limited current with traps. Other possible mechanisms about the magnetoconductance effects are also discussed.     

激光制造中金属熔池光谱检测系统设计及波长校准

针对激光制造过程中的高温金属熔池光谱特征分析,提出采用CCD光栅检测光谱技术检测其分布.检测了钨灯、钠灯、氘灯和汞灯的光谱曲线,得到了其在对应特征波长处光强随波长的分布,根据检测结果对系统进行了波长校准.结果表明,系统有比较高的波长准确度,对连续光谱、线光谱均能实现较稳定的检测.结合激光制造的实际情况,避开强激光反射的影响,该系统将能用于激光制造过程中的熔池光谱检测,为进一步分析激光熔池动态信息提供新的技术手段.     

Solution‐Processed Extremely Efficient Multicolor Perovskite Light‐Emitting Diodes Utilizing Doped Electron Transport Layer

A specially designed n‐type semiconductor consisting of Ca‐doped ZnO (CZO) nanoparticles is used as the electron transport layer (ETL) in high‐performance multicolor perovskite light‐emitting diodes (PeLEDs) fabricated using an all‐solution process. The band structure of the ZnO is tailored via Ca doping to create a cascade of conduction energy levels from the cathode to the perovskite. This energy band alignment significantly enhances conductivity and carrier mobility in the CZO ETL and enables controlled electron injection, giving rise to sub‐bandgap turn‐on voltages of 1.65 V for red emission, 1.8 V for yellow, and 2.2 V for green. The devices exhibit significantly improved luminance yields and external quantum efficiencies of, respectively, 19 cd A^?1 and 5.8% for red emission, 16 cd A^?1 and 4.2% for yellow, and 21 cd A^?1 and 6.2% for green. The power efficiencies of these multicolor devices demonstrated in this study, 30 lm W^?1 for green light‐emitting PeLED, 28 lm W^?1 for yellow, and 36 lm W^?1 for red are the highest to date reported. In addition, the perovskite layers are fabricated using a two‐step hot‐casting technique that affords highly continuous (>95% coverage) and pinhole‐free thin films. By virtue of the efficiency of the ETL and the uniformity of the perovskite film, high brightnesses of 10 100, 4200, and 16,060 cd m^?2 are demonstrated for red, yellow, and green PeLEDs, respectively. The strategy of using a tunable ETL in combination with a solution process pushes perovskite‐based materials a step closer to practical application in multicolor light‐emitting devices.     

Boosting the Charge Transport Property of Indeno[1,2‐b]fluorene‐6,12‐dione though Incorporation of Sulfur‐ or Nitrogen‐Linked Side Chains

Alkyl chains are basic units in the design of organic semiconductors for purposes of enhancing solubility, tuning electronic energy levels, and tailoring molecular packing. This work demonstrates that the carrier mobilities of indeno[1,2‐b ]fluorene‐6,12‐dione ( IFD )‐based semiconductors can be dramatically enhanced by the incorporation of sulfur‐ or nitrogen‐linked side chains. Three IFD derivatives possessing butyl, butylthio, and dibutylamino substituents are synthesized, and their organic field‐effect transistors (OFET) are fabricated and characterized. The IFD possessing butyl substituents exhibits a very poor charge transport property with mobility lower than 10^?7 cm² V^?1 s^?1. In contrast, the hole mobility is dramatically increased to 1.03 cm² V^?1 s^?1 by replacing the butyl units with dibutylamino groups ( DBA‐IFD ), while the butylthio‐modified IFD ( BT‐IFD ) derivative exhibits a high and balanced ambipolar charge transport property with the maximum hole and electron mobilities up to 0.71 and 0.65 cm² V^?1 s^?1, respectively. Moreover, the complementary metal–oxide–semiconductor‐like inverters incorporated with the ambipolar OFETs shows sharp inversions with a maximum gain value up to 173. This work reveals that modification of the aromatic core with heteroatom‐linked side chains, such as alkylthio or dialkylamino, can be an efficient strategy for the design of high‐performance organic semiconductors.