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ABSTRACT The investigation of regular F-abundant semigroups is initiated. In fact, F-abundant semigroups are generalizations of regular cryptogroups in the class of abundant semigroups. After obtaining some properties of such semigroups, the construction theorem of the class of regular F-abundant semigroups is obtained. In addition, we also prove that a regular F-abundant semigroup is embeddable into a semidirect product of a regular band by a cancellative monoid. Our result is an analogue of that of Gomes and Gould on weakly ample semigroups, and also extends an earlier result of O'Carroll on F-inverse semigroups. 相似文献
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Two new monoterpenoid indole alkaloids, tabervarines A (1) and B (2), along with seven known monoterpenoid indole alkaloids, were isolated from the methanol extract of the twigs and leaves of Tabernaemontana divaricata. The structures including the absolute configurations of the new alkaloids were elucidated based on MS, NMR, and ECD calculation. The in vitro cytotoxic activities of the isolated alkaloids against several human cancer cell lines were also evaluated. 相似文献
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Lin Xiao Ruan Qing Lin Ling Zhang Xuran Duan Xiaojiang Teng Yanguo Zhang Junbo 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(3):1463-1468
Journal of Radioanalytical and Nuclear Chemistry - To develop novel 99mTc labeled nitroimidazole imaging agents for imaging tumor hypoxia, 99mTc labeled ethylene diamine tetraacetic acid derivative... 相似文献
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Xiaojiang Zheng Dazhai Zhou Dongshan Xiang Wensheng Huang Shaofang Lu 《Russian Journal of Electrochemistry》2009,45(10):1183-1187
A poly(L-cysteine) thin film was prepared onto electrode surface via electropolymerization. In pH 7.0 phosphate buffer, L-cysteine was oxidized during the cyclic potential sweep between −0.60 and 2.00 V, forming a thin film at the glassy carbon
electrode (GCE) surface. The electrochemical behaviors of ascorbic acid at the bare GCE and the poly(L-cysteine) film-coated GCE were investigated. The oxidation peak potential of ascorbic acid shifts to more negative potential
at the poly(L-cysteine) film-modified GCE. Moreover, the oxidation peak current significantly increases at the poly(L-cysteine) film-modified GCE. These phenomena indicate that poly(L-cysteine) film shows highly-efficient catalytic activity to the oxidation of ascorbic acid. Based on this, a sensitive and
simple electrochemical method was proposed for the determination of ascorbic acid. The oxidation peak current of ascorbic
acid is proportional to its concentration over the range from 1.0 × 10−6 to 5.0 × 10−4 mol l−1. The limit of detection is evaluated to be 4.0 × 10−7 mol l−1. 相似文献
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本文综述了我国特有的粉花绣线菊复合群7个变种化学与生物学研究,以新生物碱的发现为起点,从二萜与二萜生物碱化学结构、化学转化、化学合成、仿生合成与生源途径、植物化学分类与生物地理、生物活性等方面阐明了相关的科学问题,从宏观、微观层次形成了较系统的学术观点。 相似文献
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Xiaojiang Guo 《Semigroup Forum》2001,64(1):90-100
It is proved that each compact semigroup with precisely one regular D -class has the congruence extension property if and only if it has the algebraic congruence extension property. 相似文献