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131.
结合＂单臂电桥测电阻＂这个实验的特点提出了一个设计性实验,并给出了解决方案.在指导学生做该实验时,要求学生来完成这个设计,可以帮助学生理解单臂电桥测量电阻的原理. 相似文献
132.
133.
在常规的傅里叶变换红外光谱学中，干涉图的直流成分为∫＾∞０Ｂ（σ）ｄσ，而在时间分辨ＦＴＩＲ中，直流成分Ｉｄｅ成为∫（∞，０）Ｂ（σ，τ）ｄσ，即与信号出现的时间τ有关，称为定量直流成分。 相似文献
134.
WANG Zhaobing LIAO Yanbiao 《Chinese Journal of Lasers》1998,7(6):485-490
１ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｔｈｅｌａｓｔｆｅｗｙｅａｒｓ，ｃｕｒｅｎｔａｎｄｖｏｌｔａｇｅｍｅａｓｕｒｅｍｅｎｔｓｙｓｔｅｍｓｂａｓｅｄｏｎｏｐｔｉｃａｌｄｅｖｉｃｅｓｈａｖｅｂｅｅｎｄｅｖｅｌｏｐｅｄ．Ａｎｕｍｂｅｒｏｆｑｕｉｔｅｄｉｆｅｒｅｎ... 相似文献
135.
The N-heterocyclic carbene, imidazole-2-ylidene, and its main group (13-15) analogues contain cyclically conjugated 6π electrons. Experimental 1H nuclear magnetic resonance (NMR) spectra suggest an increase in aromaticity along a period from left to right. Whereas the order along a group is as follows: period 2 > period 5 > period 4 > period 3 due to change in structure. To understand the order of aromaticity, the magnetically induced ring currents of the molecules are calculated using aromatic ring current shielding, gauge-including magnetically induced currents (GIMIC) method and Stanger's σ-model applying the gauge-including atomic orbitals NMR technique. It is found that GIMIC best describes the order of aromaticity especially along a group where current-profile changes on the bivalent atom down a group due to change in electron density. Moreover, the GIMIC provides the visualization of current by sign modulus and the anisotropy of the induced current density plots. 相似文献
136.
《中国化学快报》2020,31(6):1593-1597
As one of the most environmentally friendly photovoltaic(PV) conversion equipments,aqueousprocessed CdTe nanocrystal solar cells(NC SCs) have attracted great interest in recent years because of their excellent properties such as high charge-carrier mobility and broad absorption.However,two issues including interfacial recombination and leakage current seriously restrict their performance.In this paper,insulating polymer poly(vinyl pyrrolidone)(PVP) is introduced into CdTe NC SCs to solve the problems.The experimental results of transmission electron microscopy(TEM),atomic force micro scopy(AFM) and dark current measurements,etc.,demonstrate the leakage current is effectively suppressed by introducing PVP.Through further designing device structure,the reduction of interfacial recombination after introducing PVP is confirmed.By strategically taking the advantages of PVP properties(e.g.,water solubility and thermostability),the power conversion efficiency of the devices with PVP is enhanced by almost 37% compared to pure CdTe devices.This work demonstrates an effective and low-cost method to fabricate NC SCs via aqueous route.Moreover,it also proves that appropriate content of insulating polymer is of beneficial in promoting the PV performance. 相似文献
137.
Baoxiang Tan Jingjing Xiong Huizhen Li Jing You 《Journal of separation science》2020,43(12):2409-2418
Pesticides have posed significant threats to aquatic ecosystems, yet little is known about their transformation products. The challenge is to simultaneously analyze various pesticides and transformation products in water as they have distinct physicochemical properties. A mix‐mode solid phase extraction method was established to simultaneously analyze current‐use pesticides and their transformation products using a mixture of hydrophile–lipophile balance, weak anion, and cation exchange resins (2:1:1, w/w/w) in combination with high‐performance liquid chromatography and tandem mass spectrometry for chemical quantification. Neutral, acidic, and alkaline methanol were used as the elution solvent. Box‐Behnken design was applied to optimize extraction conditions. Optimal conditions were as follows: sorbent mass, 200 mg; volume of elution solvent, 5 mL × 3; pH 4. The method was validated for compounds at concentrations from 20 to 1000 ng/L in different types of water samples, with recovery being from 43.5 ± 3.1 to 141 ± 35%. Low method detection limits (0.02?5.6 ng/L) implied that the developed method was sensitive. Finally, the method was applied to monitor current‐use pesticides and their transformation products in natural waters. Frequent detection of transformation products of pesticides indicated that their contribution to aquatic risk should not be ignored. 相似文献
138.
Xiao Sun Dong Pei Wen‐Da Duan Jian‐Fei Liu Duo‐Long Di Xin‐Yi Huang 《Journal of separation science》2020,43(17):3573-3584
Elution‐extrusion counter current chromatography extrudes the most solute retained in the column with the highest possible peak resolution. It can greatly improve the hydrophobic window. In recent years, elution‐extrusion counter current chromatography has received extensive attention in the separation of complex samples. This article first reviews the development and application of elution‐extrusion counter current chromatography, including its origin, mechanism, advantages and disadvantages, and some representative applications. At the same time, this review also shared our visions and ideas on how to improve the elution‐extrusion mode. This article aims to provide certain reference for the research of this technology. 相似文献
139.
The tidal energy industry is progressing rapidly, but there are still barriers to overcome to realise the commercial potential of this sector. Large magnitude and highly variable loads caused by waves acting on the turbine are of particular concern. Composite blades with in-built bend-twist elastic response may reduce these peak loads, by passively feathering with increasing thrust. This could decrease capital costs by lowering the design loads, and improve robustness through the mitigation of pitch mechanisms. In this study, the previous research is extended to examine the performance of bend-twist blades in combined wave–current flow, which will frequently be encountered in the field. A scaled 3 bladed turbine was tested in the flume at IFREMER with bend-twist composite blades and equivalent rigid blades, sequentially under current and co-directional wave–current cases. In agreement with previous research, when the turbine was operating in current alone at higher tip speed ratios the bend-twist blades reduced the mean thrust and power compared to the rigid blades. Under the specific wave–current condition tested the average loads were similar on both blade sets. Nevertheless, the bend-twist blades substantially reduced the magnitudes of the average thrust and torque fluctuations per wave cycle, by up to 10% and 14% respectively. 相似文献
140.