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21.
采用深能级瞬态谱仪(DLTS)测定了In0.53Ga0.47As/InP异质结光电二极管的DLTS谱。发现存在一电子陷阱,该陷阱能级位于导带底以下0.44eV处,能级密度为3.10×1013cm-3,电子俘获截面为1.72×10-12cm-2。由于深能级的存在,导致了该器件存在一种新的“暗电流”──“深能级协助隧穿电流”。 相似文献
22.
By combining the theory with the practice,the dynamic current shar-ing in paralleling power MOSFET is analysed.The principles of choosing parameters in-fluencing dynamic current sharing are described,and some experiment results are given on the basis of these steps. 相似文献
23.
文章描述熔断器,尤其是真空熔断器的发展方向及发展前途,并且与其它各类型的熔器例如限流式熔断器和喷射式熔断器进行了对比分析。 相似文献
24.
25.
The rg structure of cyclopentene oxide has been determined by the simultaneous least squares analysis of electron diffraction and microwave spectroscopic data. The investigation has reaffirmed previous studies indicating that the molecule prefers a boat conformation. The methylene and epoxide flap angles obtained are 152.3±2.1° and 104.7±1.0° respectively. Other structural parameters determined are: rg (C-H avg.) = 1.120±0.004 Å; rg (C-C avg.) = 1.538±0.002 Å; rg (C-O) = 1.443±0.003 Å, and rg (C-C) = 1.482±0.004 Å for the carbon-carbon bond in the three membered epoxide ring. These results compare favorably with the reported structures of ethylene oxide and cyclohexene oxide. A tentative rationalization of the unusual boat conformation is also offered. 相似文献
26.
Stuart D. R.?GallowayEmail author Elizabeth M.?Broad 《Monatshefte für Chemie / Chemical Monthly》2005,136(8):1391-1410
Summary. Oral L-carnitine supplementation is frequently reported to have beneficial effects on exercise capacity in clinical populations and has been considered as a potential ergogenic aid for endurance athletes. However, this latter view is largely unsubstantiated possibly due to many experimental studies being poorly controlled or difficult to compare. The potential for oral L-carnitine supplementation to influence skeletal muscle carnitine content has been questioned and there are several key factors identified that may explain variations between study outcomes. Recent more well controlled research suggests some potential for L-carnitine to act as a key regulator of cellular stress, possibly through an impact on the integration of carbohydrate and lipid metabolism, and this work should be followed up in future by well controlled studies in both athlete and clinical subject groups. 相似文献
27.
Irina B. Svir Alexander I. Oleinick Richard G. Compton 《Journal of Electroanalytical Chemistry》2003,560(2):117-126
The simulation of transport to double microband electrodes in generator–collector mode is reported focusing especially on the ‘titration curve’ approach to electroanalysis in which a titrant is electrogenerated from a redox active precursor on the generator electrode and reacts homogeneously with the target analyte. The current on the detector electrode reflects the amount of titrant ‘surviving’ passage between the two electrodes. The form of the titration curve – plots of detector current as a function of generator current – is shown to be highly sensitive to the electrode kinetics of the redox couple driven at the generator electrode. Accordingly the naïve use of such methodology for analysis without accompanying simulation and kinetic analysis is fraught with danger. Use of the conformal mapping approach in combination with the ADI method for investigation of the ‘titration’ current distributions at the double band system gives fast and precise simulation of this and similar problems. Convergence analysis is described which allows for the automatic selection of the simulation grid size so as to obtain a chosen accuracy (for example 1%) of the current for all experimentally meaningful values of the geometrical and physico-chemical parameters of the system to be investigated. 相似文献
28.
Chemistry is a central science. However, the public's recognition of chemistry needs to be promoted, and the prejudice needs to be reduced. Chemical science popularization is a long-term, complex and arduous social education project, which is of great significance to promote social harmony and improve people's quality of life. This paper summarizes the current status of chemical science popularization in China, and puts forward the innovative development countermeasures which focus on improving public participation, training popular science talents, carrying out popular science popularization education at different levels, creating high-quality science popularization works and opening up new positions and approaches of chemical science popularization. This paper has the reference value for the science popularization colleagues. 相似文献
29.
C. V. Rode M. M. Telkar R. Jaganathan R. V. Chaudhari 《Journal of molecular catalysis. A, Chemical》2003,200(1-2):279-290
Liquid phase hydrogenation of styrene oxide using 1% Pd/C and NaOH as a promoter was found to give selectively β-phenethyl alcohol (PEA) under very mild conditions (313–333 K; 0.68–5.5 MPa). The kinetics of this system was investigated by collecting initial rate data in a batch slurry reactor. Rate of hydrogenation was found to decrease beyond a certain concentration of both hydrogen (>3 MPa) and styrene oxide (>0.5 kmol/m3). A Langmuir–Hinshelwood type rate equation has been proposed based on the initial rate data in the kinetic regime. The model predictions agree very well with the experimentally observed concentration–time data indicating the applicability of the proposed rate model. 相似文献
30.
A variety of 1-(-alkylphenyl)- and 1-(-'-dialkylphenyl)- pyrrolidines and -piperidines were prepared by the gas phase alumina mediated condensation of tetrahydrofuran (THF), tetrahydropyran (THP) or the corresponding diols with primary aromatic amines in fair to high yield. This methodology can also be used for the synthesis of 1-phenylhexahydroazepine from aniline. A mechanistic interpretation of the catalytic action of alumina is presented. 相似文献