排序方式: 共有13条查询结果,搜索用时 15 毫秒
1.
3-Methyl-2-butenenitrile (1) cyclodimerised on treatment with lithium diisopropylamide in dimethoxyethane at temperatures between ?78°C and 0°C to 3-amino-4-cyano-1,5,5-trimethyl-1,3-cyclohexadiene (2) the structure of which was established by acid hydrolysis to the known 4-cyano-1,5,5-trimethyl-1-cyclohexene-3-one (3). 相似文献
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M.H. Majles Ara SR. Hosseini M.H. Rezvani M. Abolhassani 《Journal of Physics and Chemistry of Solids》2011,72(11):1367-1372
In this paper, the parametric scattering of a single extraordinary polarized beam of laser in BaTiO3 photorefractive crystal has been investigated experimentally and theoretically. The resulting pattern consists of beam fanning, isotropic ring, and anisotropic one. Among all parts of scattering pattern, isotropic ring has not been studied as much as beam fanning and anisotropic ring, and there still are some differences in reports about it. Therefore, the study has mainly focused on this part. In this experimental configuration, isotropic ring is just visible in positive angles although the other parts of parametric scattering pattern can be visible from behind and in front of the crystal. In addition to steady state pattern in forward and backward directions, its transient behavior with the rotation of crystal has been studied. The results of experiments have been analyzed carefully, and their theoretical explanations have been presented based on the standard theory of parametric scattering in photorefractive crystals. It has been shown that this configuration corresponds to the so called parametric B-process scattering. 相似文献
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Srinivasu Gunnam Nagesh Kumar Kandukuri Ramachandra Bondigalla Thirupathi Choppari Lakshmi Narayana Chennuru Parameswara Murthy Cherla 《Chromatographia》2018,81(12):1705-1710
A group of DPP-4 inhibitors such as alogliptin, linagliptin and saxagliptin were selected for enantioseparation for this study. Crown ether columns contain a chiral crown ether ring as a chiral selector is suitable for the compounds having primary amino groups. Since the selected compounds contain free amino groups, a crown ether column was selected for enantiomeric separation of dipeptidyl peptidase-4 inhibitors. Dipeptidyl peptidase-4 inhibitors are a class of oral hypoglycemics that block dipeptidyl peptidase-4 enzyme and can be used to treat diabetes mellitus type 2. A sensitive HPLC method was developed to separate the enantiomers of each dipeptidyl peptidase-4 inhibitor. Effects of various parameters such as type of solvents, selection of additives, effect of pH and column temperature on chromatographic results were studied. The optimal conditions for the chiral separation of dipeptidyl peptidase-4 inhibitors without any derivatization were investigated. 相似文献
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MA Freitas SR Dillon RC Dougherty AG Marshall 《Rapid communications in mass spectrometry : RCM》1999,13(15):1622-1625
The self-chemical ionization of diethylzinc is examined by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry and semiempirical molecular orbital calculations. Electron impact of diethylzinc neutral produces the radical cation, C(4)H(15)Zn(+) (m/z x 122), which reacts further with the neutral (C(2)H(5))(2)Zn to give the following product ions: Zn(+) (m/z x 64), C(2)H(5)Zn(+) (m/z x 93), C(4)H(9)Zn(+) (m/z x 121), C(4)H(11)Zn(2)(+) (m/z x 187), and C(6)H(15)Zn(2)(+) (m/z x 215). To determine the structure and pathways for production of these ions, monoisotopic (12)C(4)H(15)(64)Zn(+), (64)Zn(+) and (12)C(2)H(5)(64)Zn(+) were individually isolated and reacted with the neutral background. We also performed semiempirical molecular orbital calculations (ZINDO/1). The molecular orbital calculations and experimental data are consistent in predicting that the ethyl group on the diethylzinc cation carries the positive charge. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
6.
Kurma Srimathi Dasari Gouthami Nukala Satheesh Kumar Ravula Sharada Kandukuri Padma Bandari Srinivas 《Russian Journal of General Chemistry》2022,92(7):1326-1332
Russian Journal of General Chemistry - A series of new quinoxaline-1,2,4-thiadiazoles amide hybrids has been synthesized and evaluated for their anti-proliferative activity on four different human... 相似文献
7.
怀孕期头发中一些元素含量的变化趋势 总被引:5,自引:1,他引:4
用同步辐射激发X射线荧光分析,对11个产妇怀孕期间头发内一些元素含量的变化趋势进行了测量,在各自对比的基础上,得到了一些结果。 相似文献
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X‐Ray Characterization of an Electron Donor–Acceptor Complex that Drives the Photochemical Alkylation of Indoles
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Dr. Sandeep R. Kandukuri Ana Bahamonde Dr. Indranil Chatterjee Dr. Igor D. Jurberg Eduardo C. Escudero‐Adán Prof. Dr. Paolo Melchiorre 《Angewandte Chemie (International ed. in English)》2015,54(5):1485-1489
A metal‐free, photochemical strategy for the direct alkylation of indoles was developed. The reaction, which occurs at ambient temperature, is driven by the photochemical activity of electron donor–acceptor (EDA) complexes, generated upon association of substituted 1H‐indoles with electron‐accepting benzyl and phenacyl bromides. Significant mechanistic insights are provided by the X‐ray single‐crystal analysis of an EDA complex relevant to the photoalkylation and the determination of the quantum yield (Φ) of the process. 相似文献
10.
A De A Mitra A Ray SR Banerjee M Sengupta A Chatterjee S Kailas HS Patel MG Betigiri SK Dutta 《Pramana》1999,53(3):549-552
In this paper, we report our measurements of back-angle oxygen and carbon particle yields from 16O+89Y, 12C+93Nb reactions forming the same compound nucleus 105Ag at the same excitation energy and spin distribution. We find anomalously large oxygen yield and entrance channel dependence
at high excitation energies from 16O+89Y reaction implying formation of a dinuclear orbiting complex. Possible connection between nuclear orbiting and fast fission
is also discussed. 相似文献