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排序方式: 共有4002条查询结果,搜索用时 15 毫秒
61.
为保证箭上设备的高可靠性,提出一种新型模拟测试系统的设计方法,以FPGA为核心,模拟外部遥测系统所需测量参数。系统采用PCI9054实现与上位机的接口设计,通过各模块硬件电路及软件协议的综合设计实现了-10 V~10 V的各直流模拟信号以及RS485数字信号的高可靠性稳定传输。经长期实验表明:模拟信号输出稳定,输出误差±80 mV,异步串行通信稳定可靠,系统数据传输速率可达到40 Mbit/s。  相似文献   
62.
This paper presents a microsensor chip integrated with a gold nanoparticles‐modified ultramicroelectrode array (UMEA) as the working electrode for the detection of copper ions in water. The microsensor chip was fabricated with Micro‐Electromechanical System technique. Gold nanoparticles were electrodeposited onto the surface of UMEA at a constant potential of ?0.3 V. The ratio d/Rb of interelectrode spacing (d) over the individual electrode’s radius (Rb) was investigated to improve the electrochemical performance. The UMEA with a d/Rb of 20 showed the best hemispherical diffusion mode, resulted in fast response time and high current response. The gold nanoparticles increased the active surface area of UMEA by not changing the geometries of UMEA, and the current response was increased further. Incorporating the optimized characteristic of UMEA and gold nanoparticles, the microsensor showed a good linear range from 0.5 to 200 µg L?1 of copper ions in the acetate buffer solutions with the method of square wave stripping voltammetry. Compared with the gold nanoparticles‐modified disk electrode, the gold nanoparticles‐modified UMEA showed higher sensitivity (0.024 µA mm?2 µg?1 L) and lower limit of detection (0.2 µg L?1). Water samples from river water and tap water were analyzed by the microsensor chip with recovery ranging from 100.7 % to 107.8 %.  相似文献   
63.
A glass liquid–liquid extraction (LLE) microchip with three parallel 3.5 cm long and 100 μm wide interconnecting channels was optimized in terms of more environmentally friendly (greener) solvents and extraction efficiency. In addition, the optimized chip was successfully hyphenated with nano-liquid chromatography with ultraviolet and mass spectrometric detection (nanoLC–UV–MS) for on-line analysis. In this system, sample pretreatment, separation and detection are integrated, which significantly shortens the analysis time, saves labor and drastically reduces solvent consumption. Strychnine was used as model analyte to determine the extraction efficiency of the optimized 3-phase chip. Influence of organic solvent, pH of feed phase, type of alkaloid, and flow rates were investigated. The results demonstrated that the 3-phase chip nanoLC–UV/MS hyphenation combines rapid (∼25 s) and efficient (extraction efficiency >90%) sample prep, with automated alkaloid analyses. The method was applied to real samples including Strychnos nux-vomica seeds, Cephaelis ipecacuanha roots, Atropa belladonna leaves, and Vinca minor leaves.  相似文献   
64.
The construction and evaluation of a Low Temperature Co-fired Ceramics (LTCC)-based continuous flow potentiometric microanalyzer prototype to simultaneously monitor the presence of two ions (potassium and nitrate) in samples from the water recycling process for future manned space missions is presented. The microsystem integrates microfluidics and the detection system in a single substrate and it is smaller than a credit card. The detection system is based on two ion-selective electrodes (ISEs), which are built using all-solid state nitrate and potassium polymeric membranes, and a screen-printed Ag/AgCl reference electrode. The obtained analytical features after the optimization of the microfluidic design and hydrodynamics are a linear range from 10 to 1000 mg L−1 and from 1.9 to 155 mg L−1 and a detection limit of 9.56 mg L−1 and 0.81 mg L−1 for nitrate and potassium ions respectively.  相似文献   
65.
66.
A novel microfluidic chip‐based fluorescent DNA biosensor, which utilized the electrophoretic driving mode and magnetic beads‐based “sandwich” hybridization strategy, was developed for the sensitive and ultra‐specific detection of single‐base mismatch DNA in this study. In comparison with previous biosensors, the proposed DNA biosensor has much more robust resistibility to the complex matrix of real saliva and serum samples, shorter analysis time, and much higher discrimination ability for the detection of single‐base mismatch. These features, as well as its easiness of fabrication, operation convenience, stability, better reusability, and low cost, make it a promising alternative to the SNPs genotyping/detection in clinical diagnosis. By using the biosensor, we have successfully determined oral cancer‐related DNA in saliva and serum samples without sample labeling and any preseparation or dilution with a detection limit of 5.6 × 10?11 M, a RSD (n = 5) < 5% and a discrimination factor of 3.58–4.54 for one‐base mismatch.  相似文献   
67.
Describes the functions, background applications and features of the resolver, in order to calculate the angle position of the resolver signals, this paper choose AD7656 precision chip, proposed the resolver algorithm for calculating resolver angle by measuring the output voltage and excitation voltage of the resolver. Mainly introduce AD7656 and its hardware circuit design, and flowchart of the algorithm for arctangent. This algorithm is simple and reliable. Experimental results show that the system design is reasonable, measurement algorithms of resolver angle meets the requirements. Analyze the error for this result and prepare for the study.  相似文献   
68.
田晓丹  张会新  刘文怡 《应用声学》2015,23(7):2604-2606
为适应航天领域遥测外系统的快速发展,提出了一种新型多功能信号源系统的设计。系统以FPGA为逻辑控制单元,采用PCI总线接口实现了与上位机的通信,同时结合AD5628、AQY210及RS422接口芯片稳定地输出了多路模拟信号、开关信号及一路PCM信号。重点阐述了信号源系统硬件及软件设计中的关键技术。试验结果表明,该系统能够提供多种高精度、高可靠性的信号,且工作性能稳定,抗干扰能力强,数据传输速率达到40Mbps,PCM码率高达983.04kbps,满足了系统设计的要求。  相似文献   
69.
基于表面等离子体子共振成像(SPRi)技术提出了一种实时、非标记的新型抗癌药物药效评估方法. 以聚二甲基硅氧烷(PDMS)为材料,制作了包含微柱结构的微流控芯片作为流通反应池,配合自行设计组装的SPRi生物传感器完成肿瘤细胞的特异性捕获及检测,研究了苏拉明和顺铂对肝癌细胞HepG2的生长抑制作用. 同时引入辅助验证实验,即采用常规八肽胆囊收缩素(简称CCK-8)法测定上述药物对肝癌细胞增殖的抑制作用. SPRi检测结果表明,苏拉明和顺铂能抑制肿瘤细胞HepG2增殖并呈现剂量、时间依赖关系.  相似文献   
70.
A low-cost and straightforward hybrid NOA (Norland optical adhesive) 81-glass microchip electrophoresis device was designed and developed for protein separation using indirect fluorescence detection. This new microchip was first characterized in terms of surface charge density via electroosmotic mobility measurement and stability over time. A systematic determination of the electroosmotic mobility (μeo) over a wide pH range (2–10) and at various ionic strengths (20–50 mM) was developed for the first time via the neutral marker approach in an original simple frontal methodology. The evolution of μeo was proved consistent with the silanol and thiol functions arising from the glass and the NOA materials, respectively. The repeatability and reproducibility of the measurements on different microchips (RSD < 14%) and within 15 days (less than 5% decrease) were successfully demonstrated. The microchip was then applied for the efficient electrophoretic separation of proteins in a zonal mode coupled with indirect fluorescence detection, which is, to our knowledge, the first proof of concept of capillary zone electrophoresis in this hybrid microsystem.  相似文献   
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