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81.
Application of capillary electrophoresis to monitoring the concentration of material penicillin and the intermediates in the manufacturing process of semisynthetic penicillins was investigated. Factors affecting the precision of analysis were screened and optimised by orthogonal array designs. Compared to conventional HPLC methods, the capillary electrophoresis method gives better resolution and faster sample throughput. Other advantages of the capillary electrophoresis method over HPLC methods include much less consumption of buffer solution and the absence of organic solvents in the analysis. 相似文献
82.
An efficient solution-processable route employing Pb(Ac)2 as lead source and anti-solvent treatment to achieve fully covered and homogenous perovskite films is reported. 相似文献
83.
84.
Circular high-performance thin-layer chromatography (HPTLC) has been used to differentiate a series of twelve tricyclic neuroleptics, using both normal phase and reverse phase procedures. The use of normal phase systems also allows the resolution of geometric isomers of chlorprothixene, clopenthixol and flupenthixol. Thirteen sulphonamides and Trirnethoprim may also be distinguished using HPTLC. 相似文献
85.
Two Novel Myrinsol Diterpenes from Euphorbia prolifera 总被引:1,自引:1,他引:1
Two novel diterpenes,Euphorprolitherin A(1) and Euphorprolitherin B(2), were isolated from the roots of Euphorbia prolifera. Their structures were elucidated on the basis of spectroscopic methods. 相似文献
86.
通过X射线衍射分析和超导量子干涉磁强计(SQUID)磁性测量,研究了Co替代Fe含量对居里温度在室温以上的磁制冷材料La(Fe1-xCox)11.7Al1.3(x=0.072,0.081)磁结构和磁性能的影响。La(Fe1-xCox)11.7Al1.3材料的居里温度随Co的含量增加而增加,La(Fe0.919Co0.081)11.7Al1.3的居里温度为311 K。当外场变化为1.9 T时磁熵变达到3.6 J·kg^-1·K^-1,RCP值为168.6 J·kg^-1,虽然它的磁熵变小于具有巨磁熵变的磁制冷材料,但是它在磁场为1.9 T时的制冷能力与这些材料相当。 相似文献
87.
Fuxian Wan Riwei Wang Bin Yu Yuanhong Zhang Ying Li Lili Zhang Shiyun Ai Lin Jiang 《大学化学》1986,35(12):110-117
Considering COVID-19 epidemic prevention and control, education materials were excavated and refined, such as chemical disinfectants, typical drugs used in clinical treatment or trial and materials for preparation of medical protective equipment. We have carried out thematic teaching on "The important role of chemistry in the fight against COVID-19 epidemic", and integrated ideological and political education into the thematic teaching. Through thematic teaching, we can make students feel the charm of chemistry subject, stimulate students' interest in learning chemistry, fully mobilize students' learning enthusiasm and initiative, strengthen students' confidence and courage to overcome difficulties, cultivate the students' professional disciplines literacy and scientific literacy, activate students' love for the motherland, the people and the Communist Party of China. 相似文献
88.
He X Pu W Han J Chen J Lu J Jiang C Wan C 《The journal of physical chemistry. B》2005,109(49):23141-23144
A method is proposed based on mode coupling theory in which the ion transference number is introduced into the theory. The ionic limiting molar conductivities of LiPF6, LiClO4, LiBF4, LiCF3SO3, Li(CF3SO3)2N, LiC4F9SO3, and LiAsF6 in PC(propylene carbonate), GBL(gamma-butyrolactone), PC(propylene carbonate)/EMC(ethylmethyl carbonate), and PC(propylene carbonate)/DME(dimethoxyethane) are calculated based on this method, which does not involve any adjustable parameter. The results fit well to the literature data which are calculated by an empirically adjusted formula. This presents a potential way to calculate the conductivities of Li-ion battery electrolytes. 相似文献
89.
The photoluminescence of Co-Al-layered double hydroxide 总被引:1,自引:0,他引:1
Shuai Sun Wan Guo Hou 《中国化学快报》2007,18(11):1371-1373
We report a new optical behaviour of pure Co-Al-layered double hydroxide (LDH).It was found that the Co-Al-LDH sample could emit fluorescence without any fluorescent substances intercalated.Its excitation spectrum shows a maximum peak near the wavelength 370nm,the maximum emission peak appears at 430 nm and the photoluminescence colour of the Co-Al-LDH sample is blue.This new optical property will be expected to extend the potential applications of LDHs in optical materials field. 相似文献
90.
Brousmiche DW Xu M Lukeman M Wan P 《Journal of the American Chemical Society》2003,125(42):12961-12970
Evidence is presented for the photochemical generation of novel biphenyl quinone methide (BQM)-type intermediates on photolysis of hydroxybiphenyl alkenes 7 and 8 and hydroxybiphenyl alcohols 9 and 10. Mechanistic investigations utilizing product, fluorescence, and nanosecond laser flash photolysis (LFP) studies indicate two distinct pathways for the formation of these BQMs depending upon the functional groups of the progenitor. Formal excited-state intramolecular proton transfer (ESIPT) between the phenol and the alkene led to BQMs upon irradiation of the hydroxybiphenyl alkenes 7 and 8, while excited-state proton transfer (ESPT) to solvent followed by dehydroxylation was responsible for BQM formation from the hydroxybiphenyl alcohols 9 and 10. Photolysis of 7 and 8 in aqueous CH(3)CN gave photohydration products via attack of water on the respective BQMs, while photolysis of the analogous methyl ethers (of the phenolic moiety) gave only carbocation intermediates. Hydroxybiphenyl alcohols 9 and 10 yielded the corresponding photomethanolysis products in aqueous methanol, through attack of CH(3)OH on the respective BQMs. Although no evidence was found for BQM formation in LFP studies of 8 and 10, due to its suspected short lifetime, the respective diaryl carbocation (lambda(max) 420 nm, tau = 8.5 micros) has been observed upon irradiation of 8 in 2,2,2-trifluoroethanol. A BQM (lambda(max) 580 nm) was observed for 9 but not for 10, the latter having more complex chemistry on laser excitation, resulting in a transient that appears to mask any BQM absorption. Significant quenching of fluorescence from the hydroxybiphenyl alkenes at low water content implies that H(2)O is directly involved in reaction from the singlet excited state. The decrease in fluorescence intensity of 8 was found to depend on [H(2)O](3); however, the distance required for ESIPT in these systems is too large to be bridged by a water trimer. The nonlinear quenching has been attributed to deprotonation of the phenol by two water molecules, with concerted protonation at the alkene by another molecule of water. Fluorescence quenching of the hydroxybiphenyl alcohols required much higher water content, implying a different mechanism of reaction, consistent with the proposal of ESPT (to solvent water) followed by dehydroxylation. 相似文献