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排序方式: 共有365条查询结果,搜索用时 15 毫秒
101.
Mehdi Ghandi Parham Asgari Abuzar Taheri Alireza Abbasi 《Central European Journal of Chemistry》2010,8(4):899-905
One-pot, three-component condensation of 2-hydroxybenzaldehyde derivatives, primary amines with alkyl isocyanides is reported.
N-alkyl-2-(2-hydroxyphenyl)-2-iminoacetamide derivatives are generated presumably via the preliminary formation of N, N′-disubstituted benzo[b]furan-2,3-diamines and subsequent oxidation with molecular oxygen.
相似文献
102.
A facile one-pot synthesis of chromene bearing novel spiropyrrolidine-oxindoles has been accomplished by the [3+2]-cycloaddition reaction of 3-acetyl-2H-chromen-2-ones with azomethine ylides derived in situ from isatin or N-methyl isatin with sarcosine. 相似文献
103.
In this study, a numerical simulation of copper microchannel heatsink (MCHS) using nanofluids as coolants is presented. The
nanofluid is a mixture of pure water and nanoscale metallic or nonmetallic particles with various volume fractions. Also,
the effects of various volume fractions, volumetric flow rate and various materials of nanoparticles on the performance of
MCHS have been developed. A three-dimensional computational fluid dynamics model was developed using the commercial software
package FLUENT, to investigate the conjugate fluid flow and heat transfer phenomena in micro channel heatsinks. The results
show that the cooling performance of a microchannel heat sink with water based nanofluid containing Al2O3 (vol 8%) is enhanced by about 4.5% compared with micro channel heatsink with pure water. Nanofluids reduce both the thermal
resistance and the temperature difference between the top (heated) surface of the MCHS and inlet nanofluid compared with that
pure water. The cooling performance of a micro channel heat sink with metal nanofluids improves compared with that of a micro
channel heat sink with oxide metal nanofluids because the thermal conductivity of metal nanofluid is higher than oxide metal
nanofluids. Micro channel heat sinks with nanofluids are expected to be good candidates as the next generation cooling devices
for removing ultra high heat flux. 相似文献
104.
Ahmad VU Zubair M Abbasi MA Kousar F Rashid MA Rasool N Tareen RB 《Natural product research》2006,20(1):69-74
Phytochemical investigation of Platytaenia multicaule resulted in the isolation of two new ceramides, N-triacontylpentadecanamide and 1,3,4-trihydroxy-2,dodecanoylamino-(24E)-unacotenene, along with two known compounds, beta-sitosterol and beta-sitosterol glycoside. The structure elucidation of the isolated compounds was based primarily on 1D and 2D NMR analyses, including COSY, NOESY, HMQC, and HMBC correlations. 相似文献
105.
Primary, secondary, tertiary, allylic, and benzylic halides are converted efficiently into symmetric disulfides in high yields using thiourea as the sulfur atom source. The reactions are odorless and are performed at 30-35 °C in wet PEG-200 using MnO2 as an oxidant. 相似文献
106.
Haq Nawaz Ahsen Tahir Nauman Ahmed Ubaid U. Fayyaz Tayyeb Mahmood Abdul Jaleel Mandar Gogate Kia Dashtipour Usman Masud Qammer Abbasi 《Entropy (Basel, Switzerland)》2021,23(11)
Global navigation satellite systems have been used for reliable location-based services in outdoor environments. However, satellite-based systems are not suitable for indoor positioning due to low signal power inside buildings and low accuracy of 5 m. Future smart homes demand low-cost, high-accuracy and low-power indoor positioning systems that can provide accuracy of less than 5 m and enable battery operation for mobility and long-term use. We propose and implement an intelligent, highly accurate and low-power indoor positioning system for smart homes leveraging Gaussian Process Regression (GPR) model using information-theoretic gain based on reduction in differential entropy. The system is based on Time Difference of Arrival (TDOA) and uses ultra-low-power radio transceivers working at 434 MHz. The system has been deployed and tested using indoor measurements for two-dimensional (2D) positioning. In addition, the proposed system provides dual functionality with the same wireless links used for receiving telemetry data, with configurable data rates of up to 600 Kbauds. The implemented system integrates the time difference pulses obtained from the differential circuitry to determine the radio frequency (RF) transmitter node positions. The implemented system provides a high positioning accuracy of 0.68 m and 1.08 m for outdoor and indoor localization, respectively, when using GPR machine learning models, and provides telemetry data reception of 250 Kbauds. The system enables low-power battery operation with consumption of <200 mW power with ultra-low-power CC1101 radio transceivers and additional circuits with a differential amplifier. The proposed system provides low-cost, low-power and high-accuracy indoor localization and is an essential element of public well-being in future smart homes. 相似文献
107.
108.
Abbasi RU Abu-Zayyad T Amann JF Archbold G Bellido JA Belov K Belz JW Bergman DR Cao Z Clay RW Cooper MD Dai H Dawson BR Everett AA Fedorova YA Girard JH Gray RC Hanlon WF Hoffman CM Holzscheiter MH Hüntemeyer P Jones BF Jui CC Kieda DB Kim K Kirn MA Loh EC Manago N Marek LJ Martens K Martin G Matthews JA Matthews JN Meyer JR Moore SA Morrison P Moosman AN Mumford JR Munro MW Painter CA Perera L Reil K Riehle R Roberts M Sarracino JS Sasaki M Schnetzer SR Shen P Simpson KM Sinnis G Smith JD 《Physical review letters》2004,92(15):151101
We have measured the cosmic ray spectrum above 10(17.2) eV using the two air-fluorescence detectors of the High Resolution Fly's Eye observatory operating in monocular mode. We describe the detector, phototube, and atmospheric calibrations, as well as the analysis techniques for the two detectors. We fit the spectrum to a model consisting of galactic and extragalactic sources. 相似文献
109.
Abbasi MA Ahmad VU Zubair M Nawaz SA Lodhi MA Farooq U Choudhary MI 《Natural product research》2005,19(5):509-515
Phytochemical investigation of Symplocos racemosa resulted in the isolation of a new ethyl substituted glycoside, 1-ethyl brachiose-3'-acetate (1) along with four known compounds ketochaulmoogric acid (2), nonaeicosanol (3), triacontyl palmitate (4) and methyl triacontanoate (5). The substitution of ethyl group on 1 was natural because during the course of extraction and purification ethanol was not used. The structural elucidation of the isolated compounds was based primarily on 1D- and 2D-NMR analysis, including COSY, HMQC, and HMBC correlations. The glycoside 1 and triacontyl palmitate (4) displayed the inhibitory potential against lipoxygenase and urease enzyme, respectively. 相似文献
110.