弱信号处理技术的几点讨论

近十几年来,为了获得更为微弱的有用信息,人们除研制各种低噪声器件外,还系统地开展了一套弱信号处理技术.目前,这门技术在物理学实验研究中应用广泛,发展非常迅速.本文拟对弱信号处理技术的若干问题进行探讨. 一、动态范围与信号恢复 任何弱信号处理系统,都是将来自传感器的弱信号(以及噪声)作放大并进行处理,最后将信号显示和记录.因此需要了解系统的总体性能,输入动态范围就是首先考虑的问题.因为不论研究和使用,都希望知道:(1)灵敏度.即输入待测信号能获得的满刻度输出;(2)所能容纳的最大噪声量级:(3)最小可辨别信号电平这三个临界电平…     

坚持党领导 敢于闯新路

在毛主席无产阶级革命路线的指引下,遵照毛主席关于“独立自主、自力更生”的教导,我们和湖北综合勘察院共同承担了国家下达的准直仪的试制任务,在党委的领导下,经过一年时间的努力,取得初步成果,完成了任务的阶段指标,研制成功了大面积金属波带板,完成试验场上的全套激光准直装置,为我国发展长距离准直测量闯出了一条新路.实践使我们认识到,科学研究必须坚持党的领导,坚持“为无产阶级政治服务,为工农兵服务,与生产劳动相结合”的方针,破除迷信,解放思想,敢想敢干,努力攀登科学技术高峰,为我国的社会主义革命和建设作出贡献.     

腐植酸类肥料的多种功能和肥效分析

腐植酸类肥料是养地增产的好肥料腐植酸类肥料,是在“农业学大寨”的群众运动中,广大劳动人民大搞综合利用,就地取材,就地制造,就地施用,发展起来的新的肥料品种。它含有大量有机质,具有农家肥料的多种功能;含有一些速效养分,兼有化肥的某些特性。一般称它为有机无机肥料(或有机矿物肥料),简称“有机化肥”或“腐肥”。十几年来,特别是文化大革命以后,经全国各地试验、推广,增产效果肯定,深受贫下中农欢迎。实践证明:腐肥可以改良土壤,提高土壤肥力,做到用地、养地相结合;可以捉苗、发根、早成熟、壮籽粒,不仅当年增产,而且有后效。由于就地取材,便于自己动手制造和施用腐肥,节约了开支,降低了成本,做到了增产增收。从各地施用情况看,增产幅度一般在10—30%左右,每斤腐植酸铵增产粮食约半斤到一斤。盐、碱、涝、洼以及土质贫瘠的地区,增产幅度更大些。只是个别地块,因肥料质量差,施肥方法不当,或其他原因,造成增产幅度不大。但总的来说,它是养地增产的好肥料。腐肥的特点是含有较高量的“腐植酸”。腐植酸是     

锁相放大器──一种检测微弱信号的手段

一、实验物理中的有力工具 随着科研和生产的发展,越来越需要测量微弱的信号,恢复及记录其变化.特别是各种物理量的精细结构以及在临界点附近的异常现象,往往引起人们的关心.这些情况下的被测信号常常是深埋在噪声中的微弱信号.例如俄歇谱仪是用来进行表面分析的一种新型分析仪器,它可以鉴定厚度仅几个到等效于几分之一个分子层或5—100A的固体表面.但是由于俄歇电子发射是一个二次效应,俄歇峰处于非弹性散射电子的背景中,虽然1925年即已发现了这个效应,可是直到1968年工作进展甚微.用锁相放大器成功地解决了深埋在噪声中的俄歇峰的检出.又…     

齿轮啮合理论的数学基础(一)

关于齿轮啮合的理论引起数学工作者的注意可追溯到 Euler,他引进渐开线齿轮,在工业上起着重要的作用.随着近代工业发展的要求,新型齿轮的设计和制造不断出现,特别值得提出的,例如螺旋锥齿轮和准双曲面齿轮的研制,所牵涉的问题远较过去为复杂.因此从数学的角度,系统地讨论齿轮啮合理论,引进适当的方法,无论对理论还是对实践都有其一定的意义.这方面的工作,就目前而言,不能认为已经完成.随着我国近年工     

液体激光显微光谱仪

激光显微光谱分析是六十年代以来发展起来的一门新技术.主要用于地质、冶金、化工、生物、医学、考古等部门的样品的微区分析. 遵照毛主席“独立自主,自力更生”的教导,我们“三结合”试制小组的全体同志,发扬敢想、敢干的革命精神,因陋就简,从“土”到“洋”,经过一年半的反复实验,于一九七二年十一月试制成功了液体激光显微光谱仪. 一、仪器的工作原理及其结构 液体激光显微光谱仪,是用无机液体PoCl3-SnCl4-Nd3 体系与PoCl3-ZrCl4-Nd3 体系作为激光工作物质的.发射出1.06μ的单色光,经显微镜瞄准分析部位,将激光光束聚焦在分析样品上,…     

LC-MS/MS determination of 2-(4-((2-(2S,5R)-2-Cyano-5-ethynyl-1-pyrrolidinyl)-2-oxoethylamino)-4-methyl-1-piperidinyl)-4-pyridinecarboxylic acid (ABT-279) in dog plasma with high-throughput protein precipitation sample preparation

As an effective DPP-IV inhibitor, 2-(4-((2-(2S,5R)-2-Cyano-5-ethynyl-1-pyrrolidinyl)-2-oxoethylamino)-4-methyl-1-piperidinyl)-4-pyridinecarboxylic acid (ABT-279), is an investigational drug candidate under development at Abbott Laboratories for potential treatment of type 2 diabetes. In order to support the development of ABT-279, multiple analytical methods for an accurate, precise and selective concentration determination of ABT-279 in different matrices were developed and validated in accordance with the US Food and Drug Administration Guidance on Bioanalytical Method Validation. The analytical method for ABT-279 in dog plasma was validated in parallel to other validations for ABT-279 determination in different matrices. In order to shorten the sample preparation time and increase method precision, an automated multi-channel liquid handler was used to perform high-throughput protein precipitation and all other liquid transfers. The separation was performed through a Waters YMC ODS-AQ column (2.0 x 150 mm, 5 microm, 120 A) with a mobile phase of 20 mm ammonium acetate in 20% acetonitrile at a flow rate of 0.3 mL/min. Data collection started at 2.2 min and continued for 2.0 min. The validated linear dynamic range in dog plasma was between 3.05 and 2033.64 ng/mL using a 50 microL sample volume. The achieved r(2) coefficient of determination from three consecutive runs was between 0.998625 and 0.999085. The mean bias was between -4.1 and 4.3% for all calibration standards including lower limit of quantitation. The mean bias was between -8.0 and 0.4% for the quality control samples. The precision, expressed as a coefficient of variation (CV), was < or =4.1% for all levels of quality control samples. The validation results demonstrated that the high-throughput method was accurate, precise and selective for the determination of ABT-279 in dog plasma. The validated method was also employed to support two toxicology studies. The passing rate was 100% for all 49 runs from one validation study and two toxicology studies.     

A highly organocatalytic stereoselective double Michael reaction: efficient construction of optically enriched spirocyclic oxindoles

An effective double Michael reaction has been disclosed to access spirocyclic oxindoles in high yields (up to 98%) and excellent enantioselectivities (up to 98% ee).