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441.
In this letter, we develop an efficient method for optimizing the geometry of a dielectric strip over a metallic substrate for subwavelength waveguide applications. We investigate the effect of the design parameters on the light propagation and find the optimum design for both loss and light confinement. The proposed design technique generates optimal waveguide geometries that can support single-mode propagation while simultaneously achieving low loss and small modal sizes 相似文献
442.
Hamid Nejati Tamer Ragheb Arthur Nieuwoudt Yehia Massoud 《Analog Integrated Circuits and Signal Processing》2007,51(2):121-127
In this paper, we present a modeling methodology for fully integrated inductively degenerated cascode ultrawideband low noise
amplifiers (LNA) with generalized filter-based impedance matching networks. Our accurate analytical models capture the impact
of device and passive component parasitics and transistor short channel effects to generate accurate designs. Utilizing our
methodology, we are able to accurately generate an ultrawideband LNA in the 3.1–10.6 GHz frequency band using third and fifth
order Chebyshev filters as input impedance matching networks. The speed and accuracy of the proposed analytical model will
facilitate rapid design space exploration for ultrawideband LNAs. 相似文献
443.
The reaction of 3-mercapto-4-arylideneamino-1,2,4-triazoles 2b-d , 3a-d with ethyl bromoacetate and/or phenacyl bromide in hot DMF and triethylamine affords the stereochemically pure 7-acyl-6-aryl-6,7-dihydro-5H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazines 4b-d , 5a-d , 6b , d in which the consecutive hydrogen atoms N(5)H-C(6)H-C(7)H are cis to each other. This stereochemistry was determined by 1H NMR spectroscopy and confirmed by comparison with the spectrum of 3,6-diphenyl-6,7-dihydro-5H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazine 10 . The latter was prepared by NaBH4 reduction of 3,6-diphenyl-5H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazine 9 . The reported reactions offer two interesting stereospecific syntheses of the condensed heterocyclic compounds. 相似文献
444.
5‐Heteroarylthymine analogs ( 5 ) were synthesized via binucleophilic attack with bidentate thiols on the cyano group of cyanoacetylurea to form the heteroarylurea derivatives ( 2–4 ) followed by their cyclization with formamide. Also, their nucleosides 6a and 6b with 2,3,4,6‐tetra‐O‐acetyl‐α‐D‐glucopyranose were prepared. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:209–212, 2000 相似文献
445.
446.
The crystal and molecular structure of the title complex [Co(CO3)(L1)]ClO4 was determined from X‐ray diffraction data using direct methods. The crystals are monoclinic, a = 13.588(4) Å, b = 9.049(3) Å, c = 15.569(6) Å, β = 114.75(2)°, Z = 4, V = 1738.5(10) Å3, space group P21/n. The structure consists of isolated [Co(CO3)(C12H26N4)]+ complex cations, with distorted octahedral geometry and ClO4‐ counter anions. The results are discussed in relation to similar macrocycle and carbonato analogues. 相似文献