蚧虫体面蜡腺与蜡型的扫描电镜研究

蚧虫又称蚧壳虫 ,属于昆虫纲 (Ｉｎｓｅｃｔａ) ,同翅目 (Ｈｏｍｏｐｔｅｒａ)的蚧总科 (Ｃｏｃｃｏｉｄｅａ)。蚧虫在热带和亚热带地区分布种类最多 ,区系丰富 ,寒冷地区分布相对较少 ,但不同区域有其较优势的种类。全世界已记录的蚧虫大约 6 0 0 0余种 ,我国分布有 6 0 0余种 ,它们大多数是农、林业和观赏植物的重要害虫。蚧虫是植食性昆虫 ,它们的分布又以寄主植物而定。在同一寄主或寄主的某一器官 ,常有几种甚至多种蚧虫同时寄生。蚧虫是固定寄生 ,虫体表面具有多种蜡腺 ,如三格腺、五格腺、多格腺、圆形腺、8字形腺、管腺、刺腺等。这…     

柑桔寄生线虫扫描电镜制样技术比较研究

应用组织导电法(MPA和CLPG导电液)、环氧树脂包埋法、空气干燥法、CO2临界点干燥法(选用不同的固定剂和脱水剂)等六种方法制样，对云南省柑桔寄生线虫：半穿刺线虫(图1)、短体线虫(图2)、螺旋线虫(图3)进行扫描电镜观察，经过比较，认为用戊二醛-锇酸双固定、酒精梯度脱水、CO2临界点干燥法制样效果优于其它方法：虫体表面环纹、侧线、阴门、肛门、交合刺等明显易见，清晰度好。     

功率控制器结温无损伤测量技术研究与实现

固态功率控制器或固体继电器逐步向大功率方向发展,其结温测量与监控成为工程应用中的难题,针对这类具有输入输出隔离功能的器件,采用等功率结温测试法研究了基于MOSFET的功率控制器结温无损伤测量技术。利用MOSFET自身结构,通过研究寄生pn结电压随温度变化规律、器件正向功率和反向功率关系、等功率结温测试与实际结温测试结果对比,提出了适用于工程应用的结温无损伤测量方法。结果表明,采用本方法测试结温准确度在1%以内,并可有效避免器件时间差、测试时间差等问题,可实现多层结构、非气密结构等传统方法难以实现的结温测量,具有良好的工程应用价值。     

人芽囊原虫的超微结构和酶细胞化学研究

人芽囊原虫寄生于人的肠道,早年曾认为属真菌类而称之为人酵母菌,且为非病原体。近年的研究资料和临床报告表明人芽囊原虫属原生动物,为引起腹泻的病原体。我们对该原虫进行了透射电镜观察,以期为研究其生物学特性等提供基础资料。虫体按形态与结构分为空泡型(图1)、复分裂型(图2)、颗粒型和阿米巴型(图3)。空泡型为基本类型,虫体最外层无细胞壁而为细胞膜,表面常可见细胞衣;虫体中部有巨大的中央体(Cb),其并非空泡,而是呈中等电子密度的均质状结构,外包一层单位膜(图1),结合有关资料分析,推测其可能为贮存能源物质的细胞器,故此可随着细胞增殖而分隔或出芽产生颗粒(图2),以便在需要时提供转化为能量的物     

新型超级结MOSFET器件在PFC应用中的优势

超级结(Super-Junction)MOSFET器件基于电荷平衡技术,在减少导通电阻和寄生电容两方面提供了出色的性能,这通常需要折中权衡。有了较小的寄生电容,超级结MOSFET具有极快的开关特性并因此减少了开关损耗。自然地,这种快速开关特性伴有极高的dv/dt和di/dt,会通过器件和印刷电路板中的寄生元件而影响开关性能。特别地,对于在现代高频SMPS中使用的超级结MOSFET,很难抑制频率噪声     

激光对硅片掺杂和退火的研究

集成电路正向高速、高集成度、高可靠性、低成本和低功耗方向发展,正在按比例缩小单元尺寸,因此迫切需要微细加工、薄层外延、低温浅结掺杂。微波二极管、晶体管和太阳电池也需要突变结掺杂,浅结扩散。离子注入虽然已成为低温掺杂的重要方法,但必须解决它所引起的晶格损伤并使注入杂质电激活。我们试图用激光掺杂来制造浅结器件,并做了两个实验。 第一个实验是涂层掺杂。用这种方法可以制造零点几微米的浅结二极管,这一结果对研制微波二极管和浅结集成电路具有重要意义。第二个实验是用激光去退火涂层热扩散片。结果表明,激光退火后,高表面浓度扩散片进一步电激活,使表面掺杂浓度更高;而低表面浓度扩散片由于激光退火时进行再分布,使表面浓度降低,方块电阻上升。     

寄生电感对碳化硅MOSFET开关特性的影响

相比于传统的Si IGBT功率器件而言,碳化硅MOSFET可达到更高的开关频率、更高的工作温度以及更低的功率损耗.然而,快速的暂态过程使开关性能对回路的寄生参数更加敏感.因此,为了评估寄生电感对碳化硅MOSFET开关性能的影响,基于回路电感的概念,将栅极回路寄生电感、功率回路寄生电感以及共源极寄生电感等效成3个集总电感,并且从关断过电压、开通过电流及开关损耗等3个方面,对这3个电感对SiC MOSFET开关性能的影响进行了系统的对比研究.研究表明:共源极寄生电感对开关的影响最大,功率回路寄生电感次之,而栅极回路寄生电感影响最小.最后,基于实验分析结果,为高速开关电路的布局提出了一些值得借鉴的意见.     

1994年国际电子器件会议

1994年国际电子器件会议于12月11日在美国旧金山召开。会议上讨论了当今世界最先进的微电子器件技术。1．MOS晶体管制作工艺技术会议上发表了若干篇有关制作微细、高性能MOS晶体管技术论文。三菱公司的论文指出，既使在硅凝合离子注入制作浅结时，采用无泄漏COSi：法可制作条宽O．15Pm晶体管。松下公司的论文指出，采用倾斜离子注入形成的下方晕状（ha1o）掺杂法可制作条宽0．IPm晶体管。还指出，用skeV超低加速离子注入及RTA工艺制作0．02Pmn”结、004PmP”结，并使栅长为0．05qm的MOS晶体管工作。东芝公司的论文指出，迄今为止…     

肺良性转移性平滑肌瘤的组织发生学研究

目的：探讨肺良性转移性平滑肌瘤(PBML)的组织发生和生物学性质。方法：对1例PBML的肺活检组织进行光镜和电镜观察以及免疫组化研究。结果：中年女性患者,有子宫平滑肌瘤病史。胸部CT显示双肺多发性结节影。巨检：胸膜下和肺内散在灰白色结节,直径0.2至0.4cm不等,边界清楚,无包膜。光镜观察：瘤细胞呈梭形,弥漫排列,其间有柱状上皮构成的腺样结构,分化成熟。免疫组化：梭形瘤细胞表达vimentin、desmin和平滑肌肌动蛋白,不表达CK、EMA、S-100、NSE和嗜铬素A,腺样结构表达甲状腺转录因子-1。超微结构显示梭形瘤细胞分化好,胞质内有肌丝和扩张的粗面内质网,肌丝问有密体,质膜下有密斑,细胞外有大量的胶原纤维。结论：PBML的梭形瘤细胞似分化成熟的平滑肌细胞和肌纤维母细胞,腺样结构起源于呼吸上皮,提示该瘤实为原发于肺的多发性纤维平滑肌瘤性错构瘤。     

基于FPGA的胃起搏装置设计

本文主要介绍一种基于FPGA的胃起搏装置设计,该设计集"检测-刺激-反馈"于一体。胃运动状态可以随着外界的刺激变化而变化类似于谐振,因此采用胃起搏装置可以有效的改善胃动力异常的现象。本设计通对胃电信号和胃阻抗信号的检测和分析,产生相应的刺激信号来引导胃的运动,使它趋于正常状态,并且对刺激效果进行时时反馈,调节刺激参数,从而实现智能化跟踪治疗。     

GEMNET: a generalized, shuffle-exchange-based, regular, scalable,modular, multihop, WDM lightwave network

GEMNET is a generalization of shuffle-exchange networks and it can represent a family of network structures (including ShuffleNet and de Bruijn graph) for an arbitrary number of nodes. GEMNET employs a regular interconnection graph with highly desirable properties such as small nodal degree, simple routing, small diameter, and growth capability (viz. scalability). GEMNET can serve as a logical (virtual), packet-switched, multihop topology which can be employed for constructing the next generation of lightwave networks using wavelength-division multiplexing (WDM). Various properties of GEMNET are studied     

Thermodynamics of copper matte converting: Part III. Steady-state volatilization of Au,Ag, Pb,Zn, Ni,Se, Te,Bi, Sb,and As from slag,matte, and metallic copper

A comprehensive compilation of various thermodynamic data required for a complete analysis of copper matte converting reactions is presented. The data comprise estimated free energies of formation for such gases as SeO, SeS, TeO, TeS, BiO, BiS, SbO, SbS, AsO, and AsS, as well as activity coefficients in dilute copper alloys and vapor pressures of various elements and compounds. The volatilization of minor elements in steady-state reactors comprising gas and several condensed phases is mathematically formulated, and a parameter which governs the volatilization in such reactors is defined and named volatilization constant. The vapor pressures of various volatile species are calculated thermodynamically for the Noranda Process reactor by assuming equilibrium conditions. The volatilization constants of various minor elements are expressed explicitly as functions of oxygen and sulfur activities. Formerly Associate Professor, Department of Metallurgical Engineering, University of Utah, Salt Lake City, UT     

Bits, symbols, bauds, and bandwidth

The use of clear, concise, and unambiguous language in telecommunications engineering is vital to communicate a desired meaning and understanding. Terminology should be based on rigorous engineering principles and traceable to well known and dependable sources. This article deals with four everyday terms commonly encountered in the popular semi-technical press as well as in serious engineering periodicals. The misuse of these and other terms can lead to low-balled cost proposals, court litigation, and patent infringement cases. Imagine how an engineering student can be confused when she/he typically encounters bandwidth measured in bits per second     

Novel planar, square-shaped, dielectric-waveguide, single-, and dual-mode filters

This paper presents a novel concept of a square-shaped dielectric-waveguide resonator, which can easily realize a dielectric-waveguide cross-coupled filter or a dielectric-waveguide dual-mode filter, using the conventional printed circuit board (PCB) process. This planar dielectric-waveguide resonator has a higher Q value than a microstrip resonator. The physical mechanisms of both single- and dual-mode filters are elucidated. Some new coupling structures are developed for undergoing the PCB process. Filter design procedures are detailed. Design curves for the coupling coefficients of internal- and external-coupling structures are determined by full-wave finite-element-method electromagnetic calculations. Measurement results are highly consistent with theory for all trial filters. This study offers an effective means of producing low-cost high-performance planar circuit filters.     

PBX技术.市态.营销.选购

本文介绍了ＰＢＸ交换机的技术及市场需求态势。并提出ＰＢＸ产品的营销要素及其用户在选购时应遵循的原则。     

Dilemmas,uncertainty, risks,and board performance

This paper traces the origins of the words risk, uncertainty, governance and development and argues that a deeper understanding of each allows more effective decision taking in the boardroom. It argues that the role of the board of directors is to balance and rebalance continuously their irresolvable dilemma — ‘how do we drive our enterprise forward while keeping it under prudent control?’ It argues that it is the board’s role to focus on uncertainty, rather than risk, and this requires a different set of intellectual skills from board members to be able to cope with monitoring a range of diverse scenarios. This is crucial for a board to develop stronger ways of both leading their organisation and of ensuring the connectedness of the learning within and between the board and the operational unit’s risk taking. It advocates that to achieve this a board must develop new ways of learning — especially of thinking strategically and becoming more sensitised to the dynamics of their changing external environments. This will take them well beyond the comforts of their specialist managerial disciplines and into the true world of directing. The paper demonstrates the importance of continuous learning in reducing organisational uncertainty and risk. It uses the ‘Learning Board’ process and model as the central processor of both strategic and operational learning to create an annual rhythm for the board’s year.