نتایج جستجو برای: double bond

تعداد نتایج: 306165  

2014
Ioannis Tiritiris Stefan Saur Willi Kantlehner

In the cation of the title salt, C4H10NO(+)·C24H20B(-)·C2H3N, the C-N bond lengths are 1.2864 (16), 1.4651 (17) and 1.4686 (16) Å, indicating double- and single-bond character, respectively. The C-O bond length of 1.2978 (15) Å shows double-bond character, pointing towards charge delocalization within the NCO plane of the iminium ion. C-H⋯π inter-actions are present between the methine H atom a...

ژورنال: مجله دندانپزشکی 2005
ناصح, رویا , هروی, فرزین ,

Background and Aim: Recycling of brackets can significantly reduce the price of fixed orthodontic appliances but if the bond is more prone to failure during treatment, this potential benefit will disappear. The aim of this study was to investigate the effect of chemical recycling on bond strength of metal orthodontic brackets and failure pattern of recycled brackets. Material and Methods: In th...

پایان نامه :وزارت بهداشت، درمان و آموزش پزشکی - دانشگاه علوم پزشکی و خدمات بهداشتی درمانی مشهد - دانشکده دندانپزشکی 1392

علیرغم پیشرفتهای قابل توجه در زمینه ایجاد باند مناسب مواد ترمیمی همرنگ با نسج دندان ، بقای باند ایجاد شده از مسائل چالش برانگیز است. به نظر می رسد استفاده از عوامل ایجادکننده کراس لینک (مانند اسید تانیک و کلرهگزیدین) می تواند به حفظ و افزایش استحکام باند رزین- عاج کمک نماید. هدف از انجام این مطالعه،مقایسه اسیدتانیک و کلرهگزیدین بر استحکام باند برشی سیستم های ادهزیو etch&rinse و self etch در عا...

2017
Abhijnan Ray Choudhury Madhu Sudan Manna Santanu Mukherjee

A formal umpolung strategy is presented for the enantioselective installation of an alkenyl group with a terminal double bond at a tertiary center. This one-pot two-step sequence relies on the unique features of the nitro group, which after inverting the polarity of the alkenylating agent toward the desired bond formation, itself serves as a leaving group. The application of this protocol to cy...

2012
Ioannis Tiritiris

In the title salt, C6H14N3(+)·C3H5O3(-), the C-N bond lengths in the central CN3 unit of the carboxamidinium cation are 1.3262 (18), 1.3359 (18) and 1.3498 (18) Å, indicating partial double-bond character. The central C atom is bonded to the three N atoms in a nearly ideal trigonal-planar geometry and the positive charge is delocalized in the CN3 plane. The piperidine ring is in a chair conform...

Journal: :Chemical science 2017
Jiwen Jian Wei Li Xuan Wu Mingfei Zhou

The organo-boron species formed from the reactions of boron atoms with acetylene in solid neon are investigated using matrix isolation infrared spectroscopy with isotopic substitutions as well as quantum chemical calculations. Besides the previously reported single C-H bond activation species, a cyclic-HBC2BH diboron species is formed via double C-H bond activation of acetylene. It is character...

2013
Hendryk Würfel Helmar Görls Dieter Weiss Rainer Beckert

The title compound, C12H9BrN2OS2, was obtained by reacting 6-bromo-benzo[d]thia-zole-2-carbo-nitrile in iso-propanol with ethyl 2-mercapto-2-methyl-propano-ate at reflux temperature for several hours. The resulting di-methyl-oxyluciferin derivative shows partial double-bond character of the carbon-carbon bond between the two heterocyclic moieties [C-C = 1.461 (3) Å]. This double bond restricts ...

Journal: :Environmental science & technology 2006
Nga L Ng Jesse H Kroll Melita D Keywood Roya Bahreini Varuntida Varutbangkul Richard C Flagan John H Seinfeld Anita Lee Allen H Goldstein

Biogenic hydrocarbons emitted by vegetation are important contributors to secondary organic aerosol (SOA), but the aerosol formation mechanisms are incompletely understood. In this study, the formation of aerosols and gas-phase products from the ozonolysis and photooxidation of a series of biogenic hydrocarbons (isoprene, 8 monoterpenes, 4 sesquiterpenes, and 3 oxygenated terpenes) are examined...

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