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KF‐Melamine formaldehyde resin (KF‐MFR) was demonstrated to be a highly efficient heterogenious catalyst for cross‐aldol condensation under microwave irradiation. In this synthesis, various aldehydes and ketones were condensed together in the presence of supported KF on melamine‐formaldehyde resin to afford different chalcone derivatives in good to excellent yields. KF‐MFR proved to have unique termal and chemical resistance and can be reused for many consecutive runs without remarkable loss in catalytic activity. 相似文献
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A combination of molybdatophosphoric acid and NaNO2 in the presence of wet SiO2 was used as an effective oxidizing agent for the oxidation of 1,2‐dihydroquinolines to their corresponding quinoline derivatives in dichlomethane at room temperature with excellent yields. 相似文献
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Sepehri S Feaver A Shaw WJ Howard CJ Zhang Q Autrey T Cao G 《The journal of physical chemistry. B》2007,111(51):14285-14289
Ammonia borane (AB) is of great interest for storing hydrogen, an important issue in the growing field of hydrogen technology. The reaction pathways leading to the thermal decomposition of solid-state AB incorporated in carbon cryogels (CC) have been studied by spectroscopic methods. The time-dependent thermal decomposition was followed by in situ 11B nuclear magnetic resonance (NMR) and showed a significant increase in hydrogen release kinetics for AB in CC compared to neat AB. Both 11B NMR and Fourier transform infrared spectroscopy show a new reaction product, formed in the thermal decomposition of AB in CC scaffold (CC-AB) that is assigned to reactions with surface oxygen groups. The results indicate that incorporation of AB in CC enhances kinetics because of the reactions with residual surface-bound oxygen functional groups. The formation of new products with surface -O-B bonds is consistent with the greater reaction exothermicity observed when hydrogen is released from CC-AB materials. Scanning electron microscopy shows different morphology of AB in CC-AB nanocomposite as compared to neat AB. 相似文献
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In this note, we enumerate all nonisomorphic 3‐factorizations of K10. © 2001 John Wiley & Sons, Inc. J Combin Designs 9: 379–383, 2001 相似文献
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A. Najafi F. Golestani-Fard H. R. Rezaie N. Ehsani 《Journal of Sol-Gel Science and Technology》2011,59(2):205-214
Nano sized β-SiC particles were synthesized from sol–gel process. Mono dispersed β-SiC nano particles with semi spherical
morphology were obtained by employing APC as a dispersant agent and adjusting pH in the range of 2.5–4. Phenolic resin and
TEOS were employed as precursors and heat treatment was conducted up to 1500 °C. Different techniques such as XRD, DTA, FTIR,
PSA, SEM and TEM were used to characterize the formation of β-SiC. The (Si–O-C) bonds were formed by hydrolysis and condensation
reactions in the gel while the nucleation of crystalline β-SiC was found to be initiated at 1400 °C. The primary particles
in the sol were found to be (< 10 nm) while the size distribution in the final product was recorded in the range of 30–50 nm. 相似文献
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Feaver A Sepehri S Shamberger P Stowe A Autrey T Cao G 《The journal of physical chemistry. B》2007,111(26):7469-7472
Coherent carbon cryogel-ammonia borane (C-AB) nanocomposites were synthesized, and improved H2 storage properties are reported. Porous carbon cryogels were impregnated with AB in tetrahydrofuran solution at 25 degrees C under argon; 30% of the carbon cryogel pore volume was filled to produce a 24 wt % C-AB nanocomposite. Nitrogen sorption isotherms, X-ray diffraction, differential scanning calorimetry, differential thermal/thermal gravimetric analyses, mass spectrometry, and 11B NMR were used to characterize the coherent C-AB nanocomposites. Findings include a merged two-step hydrogen release reaction with an appreciable reduction in the dehydrogenation temperature to <90 degrees C as well as the suppression of borazine release. The possible nanosize effects on the H2 storage properties are discussed. 相似文献
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Faroughi Niya Homayoun Hazeri Nourallah Rezaie Kahkhaie Mahboobeh Maghsoodlou Malek Taher 《Research on Chemical Intermediates》2020,46(3):1685-1704
Research on Chemical Intermediates - In this study, an efficient and novel procedure has been reported for loading sulfanilic acid on the surface of magnetite Fe3O4 nanoparticles using... 相似文献
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A set of trivial necessary conditions for the existence of a large set of t‐designs, LS[N](t,k,ν), is for i = 0,…,t. There are two conjectures due to Hartman and Khosrovshahi which state that the trivial necessary conditions are sufficient in the cases N = 2 and 3, respectively. Ajoodani‐Namini has established the truth of Hartman's conjecture for t = 2. Apart from this celebrated result, we know the correctness of the conjectures for a few small values of k, when N = 2 and t ≤ 6, and also when N = 3 and t ≤ 4. In this article, we show that similar results can be obtained for infinitely many values of k. © 2003 Wiley Periodicals, Inc. J Combin Designs 11: 144–151, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.10027 相似文献