用于半导体探测器研制的数字影像显微系统

光学显微检测在半导体探测器研制的多个环节具有重要意义。利用较低价单元、部件组装了一套数字影像光学显微系统,性能与国外中档产品相当,性价比卓越。该系统拥有微机控制的高清晰数字摄影装置,配置大屏幕监视器,搭载高倍干系物镜,分辨率达到0.2μm,可以进行明暗场、偏光、干涉观测。它可以方便的用于缺陷、沾污控制,图形检测,表面光洁度检验,材料鉴定等方面,还可用于测试、封装、修理等精细操作。通过观察焊点的表面形貌,钎料合金的显微结构,可以鉴定焊点质量。如果结合多光束干涉技术可用于表面起伏的精细测量。论文叙述了该系统在半导体探测器研制上的应用,详述了其建造细节。

兰州储存环上小丸内靶的速度分析

小丸内靶是在兰州储存环主环上进行强子物理实验的主要候选内靶之一.小丸速度是该内靶的一个重要物理参数.大的靶丸速度可以缩短单个靶丸与束流的接触时间,从而使靶丸有较小的温度变化和质量损失,保证内靶系统工作稳定.从流体力学方面对小丸内靶的速度进行了分析,优化了影响小丸靶速度的各种实验条件,并指出靶丸的速度上限在100m/s左右.

二维形变谐振子系统中的量子经典对应

通过引入等效普朗克常数 ,将量子系统中基本动力学变量的期望值和经典系统中基本动力学变量的精确值的时间演化行为相比较 ,分析了两者产生差异的因素 ,规则运动主要是和量子效应有关 ,而混沌运动则是和动力学效应有关 ,即与系统的动力学对称性破坏相联系 .在此基础上 ,比较了量子相空间测不准度和李雅谱诺夫指数 ,给出了令人满意的说明

Calibration of an audio-frequency ion trap mass spectrometer

A method for calibration of an audio-frequency (AF) ion trap mass spectrometer is described. The method is proposed to surmount the obstacle that there is a lack of a proper calibrant for mass spectrometers in the mass-to-charge ratio (m/z) range of 10(6) to 10(10). To calibrate such mass spectra, we determine the point of ejection, q(eject), on the stability diagram of the ion trap operated in a mass-selective axial instability mode. This is accomplished by measuring the radial secular frequencies (and therefore, the m/z value) of a single trapped particle using a light scattering method, followed by monitoring the action of particle ejection in real time to obtain the q(eject). A delayed ejection with q(eject) = 0.949 +/- 0.004 is found at a trap driving frequency of Ohm/2pi = 200-600Hz. Theoretical analysis for the origin of the delayed ejection indicates that the delay is predominantly resulted from the existence of multipole components in the fields due to trap imperfections. Inclusion of -3% of the octopole with respect to the basic quadrupole field can satisfactorily account for our observations. An m/z accuracy approaching 0.1% is attainable after proper calibration of the AF ion trap mass spectrometer. (Int J Mass Spectrom 214 (2002) 63-73) (C) 2002 Elsevier Science B.V. All rights reserved.

黄土高原地区粮食生产趋势及其策略研究

根据建国以后黄土高原粮食生产进程经历了振荡期 (1 949— 1 964)、徘徊期 (1 965— 1 983年 )、增长期 (1 984— 1 997)三个阶段 ,分析了粮食发展的趋势 ,预测了 2 0 0 0— 2 0 2 3年七个不同年份全区和分区粮食的总产 ,并在对黄土高原粮食生产进行综合考察与定位试验的基础上 ,结合区域各地粮食生产及地貌类型、土壤侵蚀程度、生产环境、农业生产条件和国家粮食政策 ,提出了粮食可持续发展的经济对策和技术对策

黄芪幼苗N,P,K营养缺乏症状和生理特性研究

黄芪是我国重要的传统大宗药材,以豆科紫云英属植物膜荚黄芪Astragalus membranaceus(Fisch.)或蒙古黄芪A.membranaceus(Fisch.)Bge.Var.mongolicusBge.Hsiao.的干燥根系入药[1],具有补中益气、降压利尿、排脓消痈、脱毒生肌、滋养肌肤等多种功效,现代临床及药理研究证明,黄芪还有增强肌体免疫功能,促进抗体合成等作用,有关黄芪的药理活性及其有效成分已得到了较为深入的研究[2-4],随着黄芪市场需求量的增加,野生黄芪资源已难以满足需求,人工栽培黄芪受到重视,并且初具规模。田间栽培黄芪的营养特性和施肥管理是人工栽培质量和产量的理论基础。有关氮磷钾化肥用量及其比例对黄芪生长及产量的影响已有一些研究[5,6],但由于黄芪生长中的营养元素比例不平衡现象时常发生,至于某一种营养元素缺乏时黄芪的外观特征表现,目前尚未见报道,出现缺素症状时难以判断,限制对黄芪及时进行营养调控,对人工栽培黄芪的质量与产量产生影响。本研究的目的是研究黄芪生长中的营养缺乏时的外观表现特征和生理特性变化。本试验采用溶液培养的方法,在氮、磷、钾营养元素缺乏条件下,对黄芪的生长发育状况、营...

黄土高原粮食发展趋势及策略研究

根据建国以后黄土高原地区粮食生产进程经历了振荡期 (1 949～ 1 964年 )、徘徊期 (1 965～ 1 983年 )、增长期(1 984～ 1 997年 )三个阶段 ,分析了粮食发展趋势 ,预测了 2 0 0 0～ 2 0 30年七个不同年份全区和分区粮食的总产 ,并在对黄土高原粮食生产进行综合考察与定位试验的基础上 ,结合区域内各地粮食生产及地貌类型、土壤侵蚀程度、生态环境、农业生产条件和国家粮食政策 ,提出了粮食可持续发展的经济对策和技术对策

土壤干层量化指标初探

土壤干层是黄土高原一种常见的土壤物理现象。近年来 ,以林草地地力衰退为特征的人工林草地土壤干化日益严重 ,其直接后果就是形成土壤干层 ,导致土地退化 ,植被生长速率减缓 ,群落衰败以至大片死亡 ,严重地威胁到我国北方地区特别是黄土高原地区的生态环境建设 ,由此土壤干层及其危害才逐渐受到人们的重视。根据影响水分性质的质地因素及水分动态分布规律 ,初步探讨了土壤干层的量化指标和分级 ,以便今后系统深入研究和解决黄土高原的土壤干层问题

乙炔抑制型基质氮肥养分释放模式初探

将(NH4)2SO4中加入占其纯N质量2%的乙炔前体——电石,用一种疏水性材料将其胶结造粒,制成基质型缓释氮肥,通过土壤溶出实验与作物栽培实验表征其养分释放模式。结果表明,其养分释放模式为扩散控制型,释放模式可看作包膜肥料的非线性组合,疏水材料的物理阻滞力与乙炔(C2H2)的硝化抑制作用能形成较好的"缓释接力"效应,且C2H2的硝化抑制率要优于同条件下的双氰胺(DCD),同时期乙炔处理的作物生物量也高于DCD处理。

Effects of divalent metal ions on electrochemiluminescence sensor with Ru(bPY)(3)(2+) immobilized in Eastman-AQ membrane

Different effects of divalent metal ions on electrochemiluminescence (ECL) sensor with Ru(bPY)(3)(2+) immobilized in Eastman-AQ membrane were investigated. Mg2+,Ca2+ and Fe2+ can elevate the ECL of Ru(bpY)(3)(2+)/proline; while metal ions that underwent redox reactions on the electrode such as Mn2+ and Co2+ presented intensive quenching effects on Ru(bpy)(3)(2+) ECL. Also, the quenching effect of Mn2+ on the ECL sensor with Ru(bpY)(3)(2+) immobilized in Eastman-AQ membrane enhanced to about 30-folds compared with the case that Ru(bpy)(3)(2+) was dissolved in phosphate buffer, and the enhanced quenching effects of Mn2+ were studied.

Extraction and recovery of cerium(IV) along with fluorine(I) from bastnasite leaching liquor by DEHEHP in [C(8)mim]PF6

BACKGROUND: Ionic liquids (ILs) as environmentally benign solvents have been widely studied in the application of solvent extraction. However, few applications have been successfully industrialized because of the difficult stripping of metal ions or the loss of components of the ILs. More work needs to be done to investigate the extraction behaviour of IL-based extraction systems. In this work, the extraction behaviour of Ce(IV), Th(IV) and some trivalent rare earth (RE) nitrates by di(2-ethylhexyl) 2-ethylhexylphosphonate (DEHEHP) in the IL, 1-methyl-3-octylimidazolium hexafluorophosphate ([C(8)mim]PF6), was investigated and compared with that in the n-heptane system. In particular, the effect of F(I) on the extraction mechanism for Ce(IV) and its separation from Th(IV) was investigated. Otherwise, the recovery efficiency of Ce(IV) and F(I) from a practical bastnasite leach liquor was examined using IL based extraction.

Extraction kinetics of cerium(IV) from sulfuric acid medium by the primary amine N1923 using a constant interfacial area cell with laminar flow

BACKGROUND: Thermodynamic studies on Ce(IV) extraction with primary amine N1923 demonstrate that primary amine N1923 is an excellent extractant for separation of Ce(IV) from Re(III). In order to clarify the mechanism of extraction and to optimize the parameters in practical extraction systems used in the rare earth industry, the extraction kinetics was investigated using a constant interfacial area cell with laminar flow in the present work.RESULTS: The data indicate that the rate constant (k(ao).) becomes constant when stirring speed exceeds 250 rpm. The apparent forward extraction rate is calculated to be 10(-1.70). The activation energy (E.) was calculated to be 20.5 kJ/mol from the slope of log kao against 1000/T. The minimum bulk concentration of the extractant necessary to saturate the interface (C-min) is lower than 10(-5) mol L-1.CONCLUSION: Studies of interfacial tension and the effects of stirring rate and specific interfacial area on the extraction rate show that the extraction rate is kinetically controlled, and a mass transfer model has been proposed. The rate equation has been obtained as: -d[Ce(IV)]/dt = 10(-1.70)[Ce(IV)] [(RNH3)(2)SO4](1.376). The rate-controlling step has been evaluated from analysis of the experimental results.