人工神经网络吸光光度法同时测定钛和铌

确立了钛 4,5-二溴邻硝基苯基荧光酮 - CTMAB显色体系 ,在此基础上确立了钛和铌同时测定的显色体系 ,应用三层 ANN- BP网络解析钛和铌吸收光谱 ,吸光光度法同时测定铌和钛。方法选择性好 ,表观摩尔吸光系数 εTi557=1 .2 4× 1 0 5L· mol-1· cm-1,εNb54 0 =1 .63× 1 0 5L· mol-1·cm-1。对合金钢中铌和钛进行了同时测定 ,钛和铌的平均相对误差分别为 1 .30 %和 1 .0 8%。使用改进的 BP算法 ,避免了可能产生的麻痹现象。提出了便于网络参数选择的收敛评价函数。     

(S)-异丝氨酸的合成研究

以L -天冬氨酸为原料 ,经酯化、重氮化 -水解、氨解、Hofmann降解等反应合成了具有良好光学纯度的 (S) -异丝氨酸。总收率不低于35 %     

HIRFL-CSR六极磁铁数字电源研究与设计

设计了一台用于兰州重离子加速器HIRFL-CSR的六极磁铁数字电源, 该电源以H桥变换器为主拓扑结构电路, 采用Cyclone II FPGA作为核心硬件, 以Verilog语言实现了全数字化的PI调节算法。 电源输出电流达到了340 A, 直流电流稳定度达到了3.14×10-5, 达到了1×10-4的设计指标。One digital power supply was designed for the sextupole magnets of Cooler Storage Ring of the Heavy Ion Research Facility in Lanzhou (HIRFL CSR). It adopts H Bridge convertor as the main topology circuit and Cyclone II FPGA as the main hardware, and has realized fully digitized PI regulation arithmetic by Verilog language. The peak current of the power supply reaches 340 A and the stability approaches 3.14×10-5. Finally the power supply has achieved the designed specification of 1×10-4.     

辐射化学

由於原子能的和平利用而产生了許多新的科学部門,輻射化学就是其中的一个部门。最初的研究工作是在二十世纪初期当发現放射性现象之后就立即开始了。但是只有在建成了大量的原子核反应堆、高能量的X-射线装置和各种类型的带电粒     

单片机显微摄影控制系统

本文介绍了实现显徼摄影系统智能化的设计思想和实现方法,并研制了一个以8039单片机为核心,能与显微镜及摄影装置组成微电脑控制自动曝光摄影显微系统的数据处理控制系统。这一系统采用了软件校正误差处理方法,克服了环境温度,光敏器件的非线性等因素的影响,使系统在光照度变化范围很大的条件下均能自动地获得准确的摄影曝光时间,并实现自动拍摄和自动卷片。它克服了目前国内生产的显微摄影装置采用手动控制所带来的工作速度慢、可靠性差、操作不方便、效率低等缺点。     

THE FUNCTIONAL ROLE OF 23 kD AND 24 kD POLYPEPTIDES OF THYLAKOID IN Mg~(2+)-INDUCED CHANGE OF EXCITATION ENERGY DISTRIBUTION BETWEEN TWO PHOTOSYSTEMS IN THE CHLOROPLASTS FROM Codium fragile

In contrast to the chloroplasts from higher plants, Mg~(2+)-induced PS--Ⅱ fluorescence inten-sity increase does not relate to Mg~(2+)-induced surface charge density decrease of thylakoidin the chloroplasts from Codium fragile. Tbe extraction of the green alga chloroplasts withCa~(2+) to remove the 30--31kD polypeptide (Q_B protein) on the thylakoid surface does notaffect the above Mg~(2+)-induced phenomena. If the Ca~(2+)-treated chloroplasts are further di-gested by trypsin to remove the 23kD and 24kD polypeptides on the membrane surface,the Mg~(2+)-induced fluorescence effect will completely disappear whereas the property ofMg~(2+)-induced surface charge density changes remains unchanged. These results not onlyshow that the 23kDa and 24kDa polypeptides on the thylakoid surface are the specific act-ing sites of the cation that induce Chla fluorescence change, but also demonstrate that thecation-induced change of excitation energy distribution between two photosystems is not con-trolled by the electros     

无机化学课程的规范化建设和改革

无机化学课程的规范化建设和改革余荣泮，杨良准，刘华俊，陈显堂（湖北襄阳师范专科学校４４１０５３）师范专科学校的培养目标是合格的中学教师。长期以来，人们认为培养的学生只要能胜任普通中学的教学工作，成为“知识型”人才，就算达到了目的。但随着改革开放的深入...     

对电导法测量乙酸乙酯皂化反应速率常数的一点改进

电导法测量乙酸乙酯皂化反应速率常数的实验,是二级反应动力学的一个较经典实验。目前高等学校物理化学实验教材中均有介绍。但在数据处理中都用到当时间 t→∽时的电导率 L(?)数据。一般采用二种方法进行测量L(?):一是让反应达到平衡后测定其电导率(一     

次声频脉动流横掠圆柱体传热实验研究

为研究次声频脉动流中圆柱体对流换热的特性,搭建了脉动流强化传热实验台架,研究了不同脉动频率(f=6~20 Hz)的脉动流横掠圆柱体的对流换热问题,脉动波的有效压力振幅Prms固定为22 Pa。结果表明:低频小振幅的脉动流横掠热圆柱体时,对流换热相对努塞尔数随着频率的降低线性增大,最大值可达4.0以上;辐射热流率占总热流率的比例随着频率的降低而呈指数下降。     

Anisotropic dewetting polydimethylsiloxane surface fabricated using ultrashort laser pulses

Anisotropic dewetting polydimethylsiloxane(PDMS) surfaces, which consist of groove-like micro/nanostructures(so-called hierarchical structures), are fabricated using an ultrashort pulsed laser. The contact angles(CAs) are measured parallel to the microgrooves, which are always larger than those measured perpendicular to the microgrooves, exhibiting a superhydrophobic anisotropy of approximately 4° on these fabricated PDMS surfaces at optimized parameters. These pulsed-laser irradiated surfaces exhibit enhanced hydrophobicity with CAs that increase from 116° to 156° while preserving the anisotropic dewetting. Additionally, the wettability of the surfaces with different morphologies is investigated. The temporal evolution of the wettability of the pulsed-laser irradiated PDMS surface is also observed within the first few hours after pulsed laser irradiation.