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(一)前言利用国产光栅光谱仪组装成光电直读仪,国内已有不少单位作过这方面工作,得到了实际应用。有关文献黄本立等同志已作过总结介绍。但组装这类仪器,通常碰到的问题是在光谱仪恒温控制、温度补偿以及电子控制和测量线路等方面。这些问题能否很好解决,关系到仪器整机性能的好坏,甚至影响到仪器能否正常工作。针对上述情况,我们组装光栅光电直读仪着重考虑了仪器局部恒温控制,光栅微调机构的设计和加工,以及电子线路的改进等方面。并应用转盘电极溶液分析技术,进行了铀矿石定量分析的研究。 (二)仪器概况 1.光学系统:组装采用国产W-100型一 相似文献
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近年来,快速分析检测技术在化学检测、医学诊断、司法鉴定、环境监测和食品检测等领域具有广泛的应用。这一仪器分析检测工作过去往往需要求助于某些特定单位(机构),如科研单位、医院、分析测试中心等。仪器分析方法具有高测定精度和低检出限,但由于所用仪器一般是大型精密仪 相似文献
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WS-Ⅰ型微量水份测定仪的研制 总被引:1,自引:0,他引:1
测定气体中痕量水份有露点仪、电解水份仪、压电水份仪和氧化铝水份仪等,各有优缺点;就灵敏度、连续性和操作繁简来说,以氧化铝水份仪为佳。1941年Kaller首先发表了氧化铝作介质的电容电阻湿度计。Cutting和Jason为现代氧化铝湿度计奠定了理论和实践方面的基础。美国Pana公司和爱尔兰Shaw公司已生产多种型号的商品仪器。而国内,未见有报导。WS—I型微量水份仪即根据氧化铝电容、电阻原理而设计並研制的仪器。可连续测定氢、氮、氩、空气等洁净气体中的水份,测量范围为-90℃~-20℃露点(相当于0.1~1000ppmv);测量准确度为±3℃露点;测量重复性为±1℃露点。 相似文献
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为了帮助人们了解现代实验仪器,普及实验科学知识,北京市理化分析测试技术学会应广大生产和科研单位的要求,正在组织专家编写《现代实验仪器丛书》。这套丛书分为电镜、光谱仪、色谱仪、质谱仪、波谱仪、超速离心机等11个分册,它以通俗易懂的文字介绍有关现代实验仪器的许多知识。内容主要有:实验仪器和技术发 相似文献
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The pulsed galvanostatic method of studying corrosion processes is applied together with the pulsed galvanostatic method of measuring the electrode capacitance, which makes it possible to more rigorously determine the number of components of an equivalent circuit for the electrode. In order to recognize the processes characterized by small time constants, it is advisable to take one more measurement with a polarizing-current pulse whose magnitude is several times greater but the length is shorter. The time interval for calculating still next RC circuit must be selected so that the residual transient, obtained after subtracting the contribution made by this circuit, should have a horizontal portion in the time interval from RC to 3RC. Parameters of the assumed last RC circuit can be calculated in a roundabout way, from the electrode capacitance measured by a pulsed method. It is established that, with an anodic measuring pulse, an equivalent circuit for an Ni electrode in 1 N H2SO4 comprises two RC circuits; for a Cu electrode in 1 N NaCl, a Warburg circuit and two RC circuits; and for an Ni electrode in 1 N NaCl, a Warburg circuit and four RC circuits. 相似文献
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Universal equivalent circuit of electrochemical cell 总被引:1,自引:0,他引:1
N. A. Sekushin 《Russian Journal of Electrochemistry》2009,45(3):350-355
A detailed analysis of the mathematical model of a random-structure RC two-terminal network is performed. It is shown that a circuit of any RC two-terminal network can be reduced to a universal form consisting of a set of parallel branches. Each branch corresponds to a single relaxation process and represents a circuit of serially connected resistance and capacitor. The equivalent circuit under consideration is a compact representation of experimental data obtained using the impedance spectroscopy method. It is recommended to use the universal circuit as an intermediate model of an electrochemical cell. 相似文献
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O'Connor PB Costello CE Earle WE 《Journal of the American Society for Mass Spectrometry》2002,13(12):1370-1375
A high voltage RF oscillator circuit has been designed and constructed for driving multipole ion guides. The circuit is tunable from 500 kHz to 1.5 MHz by changing a capacitor and provides 0–1000 Vp-p that is controlled by a 0–10 V input using a negative feedback circuit. This inexpensive circuit uses a set of high voltage transistors oscillating in tandem and does not require tuning of the resonance drive frequency as the oscillator automatically resonates at the (LC)−1/2 frequency. Matrix-assisted laser desorption/ionization-Fourier transform mass spectrometry (MALDI-FTMS) mass spectra were acquired using this tunable RF oscillator circuit to allow transmission of protein ions in the 8.5–39 kDa range through the quadrupole ion guide from the ion source to the mass analyzer. 相似文献
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苯胺自催化聚合反应的混合电位 总被引:2,自引:0,他引:2
在苯胺自催化聚合反应的开路电位实验中,Pt、Pd和聚苯胺膜具有远正于其它金属的开路电位.该实验结果可以根据混合电位理论来解释.由于苯胺自催化聚合反应具有电化学机理,因此该反应的基底材料将具有同时对应于阳极半反应和阴极半反应的混合电极电位.混合电位在实验上表现为开路电位,其数值大小可以看作是苯胺自催化聚合反应能否进行的标志.有关开路电位的实验结果进一步证明了苯胺自催化聚合反应的电化学机理. 相似文献
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Equations predicting the response of thermometric circuits constructed from operational amplifiers with NTC and NTC—PTC hybrid thermistors are derived and tested. Sensitivities and time constants were determined experimentally and are compared with theoretical predictions. The circuit with the NTC—PTC hybrid is characterized by greater sensivity than a NTC circuit and greater linearity than a PTC circuit. 相似文献
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We present a simple method to increase the efficiency of a direct ethanol fuel cell by a periodic modulation of the load(pulsed mode). The fuel cell was periodically short circuited with a resistor(1 Ω) for a few seconds(high load period) followed by a low load period of up to 100 s when the resistor was disconnected. The open circuit voltage(OCV) values before and after the short circuit of the cell showed an increase of up to 70 mV. The higher OCV was due to the oxidation and removal of strongly adsorbed CO during the electric short circuit when the electric potential of the anode was increased to be close to the cathode potential. The depoisoned anode surface was much more active directly after the short circuit. The slow decrease of the OCV observed after the short circuit was caused by the subsequent poisoning of the anode surface, which can be neutralized by another short circuit. In general, a stable increase in cell performance was obtained by repetition of the electric short circuit. The data showed that the pulse mode gave an increase in the power generated by the direct ethanol fuel cell by up to 51% and was 6% on average. It is anticipated that this mode of operation can be used also in different types of polymer electrolyte membrane fuel cells where CO poisoning is a problem, and after optimization of the parameters, a much higher gain in efficien-cy can be obtained. 相似文献
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JONES电导池系统的交流阻抗由电极过程的相关阻抗和电极间溶液的电阻两部分组成,可用适当的等效电路模拟。采用LCR电桥测量JONES电导池中溶液的电阻时需要选择合适的等效电路为模型解析测量的交流阻抗。通过等效电路的分析发现,选择串联电路作为LCR电桥的解析等效电路测量JONES型电导池中溶液的电阻时引入的误差比并联电路小。 相似文献
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In the present study, a highly sensitive and specific bio-sensing platform for enzyme-free and colorimetric detection of nucleic acids has been developed. The biosensor is composed of two DNA nanostructures and two fuel strands that construct the foundation of a feed-forward catalytic DNA circuit. Upon binding the target strand to a specific DNA nanostructure, the circuit is run in order that at the end a hemin-binding aptamer, with the ability to convert a colorless substrate into a colored substance is released. Based on this strategy, 4 pM of the target DNA can be easily detected in serum samples by naked eyes after only a two-hour incubation with the circuit; meanwhile, if the incubation time is extended to 3 h, the biosensor can detect 1 pM of the target DNA. Besides the elevated sensitivity, the circuit can truly discriminate a spurious target containing one nucleotide mismatch with high specificity. Overall, the enzyme-free catalytic DNA circuit can be used as a sensitive alternative method to enzyme-based biosensors for the specific and cost-effective detection of nucleic acids. 相似文献
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锂金属是具有高能量密度的负极材料,是下一代高能量密度电池研究的重点。在锂金属负极的改性研究中,锂对称电池是最常用的测试对象,但判断其短路的依据尚未统一,因此存在部分对短路数据的解析错误。本文利用原位电池对锂沉积过程中由于枝晶生长导致的短路现象进行了描述,对锂金属对称电池在充放电过程中的短路现象进行了分类和讨论。通过区分硬短路、软短路及电池活化过程,提出了判断锂对称电池中枝晶生长及电池短路的依据,为判定锂金属负极改性方法的有效性提供参考。 相似文献