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排序方式: 共有4691条查询结果,搜索用时 171 毫秒
991.
《Mendeleev Communications》2020,30(3):296-298
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992.
In this study, aqueous organic redox flow batteries(AORFBs) with NaCl as supporting electrolyte were investigated. In AORFBs, the chlorine evolution reaction should be retarded, not the hydrogen evolution reaction. To enhance the catalytic activity of the graphite felt(GF) electrode, the metal oxides were proposed to decorate on the GF surface. Among the loading oxides, significant enhancement of the mass transfer and reaction activity was obtained by the presence of LaSrOx nanoparticles. X-Ray photoelectron spectroscopy and contact angle measurements revealed that the content of oxygen-containing groups and the hydrophilicity were remarkably increased. After the electrode assembled in the battery, the LaSrOx/GF electrode presented huge enhancement of the battery performance, obviously increasing in the battery capacity and efficiency. At a current of 50 Am/cm2, the energy efficiency(EE) of the battery increased from 54.76% to 61.37% by the LaSrOx/GF electrode. Furthermore, the cyclability of the system tested that no obviously fading was observed after 100 cycles, signifying the excellent stability of the LaSrOx/GF electrode. 相似文献
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995.
Meenakshi Rajendiran Harsh M Trivedi Dandan Chen Praveen Gajendrareddy Lin Chen 《Molecules (Basel, Switzerland)》2021,26(7)
Periodontal diseases like gingivitis and periodontitis are primarily caused by dental plaque. Several antiplaque and anti-microbial agents have been successfully incorporated into toothpastes and mouthwashes to control plaque biofilms and to prevent and treat gingivitis and periodontitis. The aim of this article was to review recent developments in the antiplaque, anti-gingivitis, and anti-periodontitis properties of some common compounds in toothpastes and mouthwashes by evaluating basic and clinical studies, especially the ones published in the past five years. The common active ingredients in toothpastes and mouthwashes included in this review are chlorhexidine, cetylpyridinium chloride, sodium fluoride, stannous fluoride, stannous chloride, zinc oxide, zinc chloride, and two herbs—licorice and curcumin. We believe this comprehensive review will provide useful up-to-date information for dental care professionals and the general public regarding the major oral care products on the market that are in daily use. 相似文献
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Masashi Tsuji Towako Aoki Ryosuke Sakai Toshifumi Satoh Harumi Kaga Toyoji Kakuchi 《Journal of polymer science. Part A, Polymer chemistry》2004,42(18):4563-4569
The enantiomer-selective radical polymerization of rac-2,4-pentanediyl dimethacrylate, an equimolar mixture of (2S,4S)-2,4-pentanediyl dimethacrylate (SS- 1 ) and (2R,4R)-2,4-pentanediyl dimethacrylate (RR- 1 ), was carried out with a chiral atom transfer radical polymerization initiating system consisting of methyl 2-bromoisobutyrate ( 3 ), dichlorotris(triphenylphosphine)ruthenium [RuCl2(PPh3)3], and a chiral additive in anisole at 60 °C. When (S)-1,1′-bi-2-naphthol ( a-3 ) was used as the chiral additive, the recovered monomer was enriched in SS- 1 , and the enantiomeric excess was 16.9% at a 22.6% monomer conversion. The specific rotation ([α]435, c 0.3, CHCl3) of the resulting polymer was +40.3° at a 22.6% monomer conversion. For the copolymerization of SS- 1 and RR- 1 with 3 /RuCl2(PPh3)3/ a-3 in anisole at 60 °C, the monomer reactivity ratio for RR- 1 (rR) was determined to be 4.94, and that for SS- 1 (rS) was 0.27. For the homopolymerizations of SS- 1 and RR- 1 with 3 /RuCl2(PPh3)3/ a-3 in anisole at 60 °C, the polymerization rate of RR- 1 was considerably faster than that of SS- 1 , and the rate constants for the homopolymerizations were determined to be kSS = 2.0 × 10−3 h−1 and kRR = 8.2 × 10−3 h−1, respectively. With the values of kSS, kRR, rR, and rS, the relative ratio kSS/kRR/kSR/kRS was determined to be 1.2:4.9:4.5:1, which indicated that both the growing end of SS- 1 and that of RR- 1 preferentially reacted with RR- 1 . © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4563–4569, 2004 相似文献
998.
Najiba DoujaRaluca Malacea Mircea BanciuMichèle Besson Catherine Pinel 《Tetrahedron letters》2003,44(37):6991-6993
The diastereoselective hydrogenation of 2-methyl nicotinic acid covalently bound to proline ester or pyroglutamic ester over supported metallic catalyst yielded moderate diastereoselectivity (26%). The hydrogenation of the corresponding pyridinium salt was studied and similar de's were achieved. 相似文献
999.
面对系统工作频率的不断提高,信号完整性问题愈发严重,串扰问题是其中的主要问题之一。以服务器及工作站级内存模组为例,通过对内存模组中串扰问题产生原因的分析,借助软件模拟,探讨一种优化内存模组设计中串扰问题的方法。 相似文献
1000.
Five hundred meter aperture spherical radio telescope (FAST) 总被引:1,自引:0,他引:1
NAN Rendong 《中国科学G辑(英文版)》2006,49(2):129-148
Five hundred meter aperture spherical radio telescope (FAST) will be the largest radio telescope in the world. The innovative
engineering concept and design pave a new road to realizing a huge single dish in the most effective way. Three outstanding
features of the telescope are the unique karst depressions as the sites, the active main reflector which corrects spherical
aberration on the ground to achieve full polarization and a wide band without involving a complex feed system, and the light
focus cabin driven by cables and servomechanism plus a parallel robot as secondary adjustable system to carry the most precise
parts of the receivers. Being the most sensitive radio telescope, FAST will enable astronomers to jumpstart many of the science
goals, for example, the neutral hydrogen line surveying in distant galaxies out to very large redshifts, looking for the first
shining star, detecting thousands of new pulsars, etc. Extremely interesting and exotic objects may yet await discovery by
FAST. As a multi-science platform, the telescope will provide treasures to astronomers, as well as bring prosperity to other
research, e.g. space weather study, deep space exploration and national security. The construction of FAST itself is expected
to promote the development in high technology of relevant fields. 相似文献