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排序方式: 共有269条查询结果,搜索用时 15 毫秒
61.
62.
陈昶 《太原师范学院学报(自然科学版)》2011,10(3):78-81
文章介绍了通信系统中的吞除脉冲技术,然后分析了专用数字集成锁相频率合成器MC145152-2芯片的结构特点及应用原理,最后详细介绍了一种用MC145152-2芯片配合外置分频器MC12018构成吞除脉冲式数字锁相频率合成器电路的设计方法. 相似文献
63.
马跃洲 《兰州理工大学学报》1996,(4)
研制了一种可靠、实用的晶闸管整流焊接电源单片机同系统,重点阐述了其电路原理、控制算法、抗干扰措施以及在手弧焊、脉冲TIG焊、埋弧焊和带极堆焊中的应用. 相似文献
64.
The properties of bulk salt solutions over wide concentration ranges are explored by a combination of simple physical theory and Monte Carlo (MC) simulations. The corrected Debye–Hückel (CDH) theory which incorporates ion size effects in a linear response approximation is extended to yield free energy and other thermodynamic properties by integration of the chemical potential over concentration. Charging integration which is usually used to obtain an electrostatic contribution of total free energy of electrolytes is avoided in this new direct approach. MC simulations are performed with a modified Widom particle insertion method, which also provides directly the ionic activity coefficients. The validity of the CDH theory is tested by comparison with the MC simulation data for 1:1, 2:1, 2:2 and 3:1 restricted primitive model (RPM) electrolytes over a wide concentration range and at various ion sizes. Mean ionic activity and osmotic coefficients calculated by the CDH theory in RPM approximation of electrolyte are fitted to experimental data by adjusting only a mean ionic diameter. Good fits up to 1 molal (m) concentration are obtained for a large number of salt solutions. MC simulations data for unrestricted primitive model (UPM) of 1:1 and 2:1 electrolytes are also fitted to the experimental data by varying the cation radius while keeping the anion radius fixed at a crystallographic value. The success of this approach is found to be salt specific. For example good fits up to 2 and 3.5 m concentrations were obtained for LiCl and LiBr, respectively. However in the case of less dissociated salts such as NaCl and KI the experimental data could only be fitted up to one molal concentration. Possibility of extending the applicability range of the CDH theory to concentrations >2 m is explored by including a concentration dependent dielectric constant as measured in experiments. Mean ionic activity coefficients for a number of salts could successfully be fitted up to 3 m concentration by adjusting only a mean ionic diameter. Difficulties encountered in simultaneously fitting the mean ionic activity and osmotic coefficients at salt concentrations >2 m are discussed. 相似文献
65.
Libert F Coudoré F Richard D Durif F Eschalier A 《Journal of mass spectrometry : JMS》2005,40(12):1521-1525
A method was developed and validated for the analysis of R(-)-apomorphine, (R-)-apocodeine and R(-)-norapomorphine in human plasma and urine with N-propylnorapomorphine as internal standard using gas chromatography/mass spectrometry (GC/MS) and single-ion monitoring after a single liquid-liquid extraction and silylation of compounds. The quantification limits were 1 ng/ml for apomorphine and apocodeine and 25 ng/ml for norapomorphine. Calibration curves were linear, within the range 1-100 ng/ml. Variation in intraday and interday precision was below 10%. This method was applied to study apomorphine bioavailability in nine patients with Parkinson's disease before and after coadministration of a catechol-O-methyl transferase inhibitor. 相似文献
66.
67.
提出了一种基于蓝牙技术和单片机技术的无线心音、呼吸音监护系统.经过临床试用,证明了医务人员不用直接接触病人就可及时获得病人准确的心音、呼吸音信息,有效地避免医务人员和病人的交叉感染.本系统尤其适用于烈性传染病人的心音和呼吸音的监护,具有较高的临床实用价值和社会价值. 相似文献
68.
以E.coli MC4100染色体DNA为模板使用PCR扩增技术克隆了鸟苷酸还原酶基因guaC,该基因全长1044bp,编码相对分子质量为37ku的蛋白质。将该基因直接克隆于PET—16b质粒的T7启动于下游,得到质粒pEXP1。转化E.coli BL21(DE3),经异丙基硫代半乳糖苷(IPTG)诱导,获得了高效的表达。含表达质粒的菌体胞内粗提液经酶活分析表明,鸟苷酸还原酶的活性为不含质粒的宿主菌的80-85倍。 相似文献
69.
徐月华 《华南理工大学学报(自然科学版)》2006,34(9):35-39
为了采集、分析和处理配电变压器的参数,选用高精度的参数采集模块、高性能微处理器和西门子无线通信模块来设计终端监测器,实现配电变压器当前状态、历史曲线(数据)的查询、远程监控以及报警等多种功能.实际运行结果表明:该监控器功能齐全,性能稳定,布线简单,是配电变压器智能化、网络化的理想设备. 相似文献
70.
邓力 《广西民族大学学报》2006,12(3):85-88
通过对MC145026的编码原理进行分析,提出了对MC145026进行单片机软件解码的方法,建立了MC145026的信号仿真函数. 相似文献