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排序方式: 共有214条查询结果,搜索用时 213 毫秒
21.
Teste K Colombeau L Hadj-Bouazza A Lucas R Zerrouki R Krausz P Champavier Y 《Carbohydrate research》2008,343(9):1490-1495
This paper describes an efficient procedure for selective 3'-O- or 3-N-protection of 5'-O-tert-butyldimethylsilylthymidine, depending on the use of aprotic polar solvents with low or high dielectric constant, respectively. These syntheses were activated by either ultrasound or microwaves. Several alkyl bromides offer a convenient route to prepare 3'-O- or 3-N-protected and functionalized thymidine derivatives. 相似文献
22.
Andrea C. Bruttomesso Alicia Baldessari 《Journal of Molecular Catalysis .B, Enzymatic》2004,29(1-6):149-153
A series of acetoxy derivatives of androstane and pregnane was deacetylated in organic solvents by microbial lipases. The best results were obtained with lipase from Candida antarctica (CAL B), Candida rugosa (CRL) and Pseudomonas sp. (PSL). In some derivatives, CAL B and CRL showed a regioselective behaviour towards the removal of the 3β- or 16/16β-acetyl group. The results of the enzymatic deacetylation of pregnanes and androstanes substituted by various groups containing an sp2-hybridised C-atom in ring D could suggest that CAL B activity seems to be conditioned by the occurrence of a polar carbon double bond in this part of the steroid skeleton. Ten new steroid derivatives were obtained through this approach. 相似文献
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Chemo-enzymatic preparation of resveratrol derivatives 总被引:1,自引:0,他引:1
Giovanni Nicolosi Carmela Spatafora Corrado Tringali 《Journal of Molecular Catalysis .B, Enzymatic》2002,16(5-6):223-229
Regioselective derivatisation of resveratrol (1) at positions 3, 5 or 4′ was achieved by a chemo-enzymatic procedure based on standard chemical reactions and esterification or alcoholysis in organic solvents catalysed by the commercially available Pseudomonas cepacia (PcL) and Candida antarctica (CaL) lipases. 相似文献
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沉默信息调节因子1(SIRT1)是Sirtuin 家族中的一员,属于烟酰胺(NAD+)依赖的Ⅲ类组蛋白去乙酰化酶,能通过对多种非组蛋白及组蛋白赖氨酸残基进行去乙酰化修饰调节基因表达。近来的研究发现,SIRT1不仅能使肿瘤抑制因子去乙酰化,促进肿瘤发生,还能使肿瘤促进因子去乙酰化,抑制肿瘤发生。SIRT1与肿瘤的生物学特性密切相关,影响肿瘤分期及患者预后。在消化系统肿瘤中,SIRT1具有双面性,既可作为抑癌因子,也可发挥癌因子的作用。近年来,许多研究对SIRT1在肿瘤中的作用靶点及相关信号通路做了深入研究,关于SIRT1在肿瘤中作用机制的新研究不断出现。SIRT1已成为人们攻克肿瘤的一个研究热点。本文通过对SIRT1在肿瘤中的双重作用,尤其是在消化系统肿瘤中的不同作用靶点和参与的信号通路作一综述,希望为临床上治疗消化系统肿瘤提供更有说服力的证据。 相似文献
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Ryuji Tsunekawa Kengo Hanaya Shuhei Higashibayashi 《Bioscience, biotechnology, and biochemistry》2018,82(8):1316-1322
Fisetin and 2′,4′,6′-trihydroxydihyrochalcone 4′-O-β-neohesperidoside were synthesized from commercially available quercetin and naringin in five steps. The key steps are site-selective deacetylation and subsequent deoxygenation. The target molecules were obtained in 37% and 23% yields from the starting materials, respectively. 相似文献
28.
Nuclear lipid mediators: Role of nuclear sphingolipids and sphingosine‐1‐phosphate signaling in epigenetic regulation of inflammation and gene expression
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29.
Fenfen Li Rui Wu Xin Cui Lin Zha Liqing Yu Hang Shi Bingzhong Xue 《The Journal of biological chemistry》2016,291(9):4523-4536
30.
Kohji Ishihara Nobuyoshi Nakajima Toshiyuki Itoh Hitomi Yamaguchi Kaoru Nakamura Tsutomu Furuya Hiroki Hamada 《Journal of Molecular Catalysis .B, Enzymatic》1999,7(5-6):307-310
The practical synthesis of vinyl p-coumarate (vinyl 4-hydroxycinnamate) and vinyl ferulate (vinyl 4-hydroxy-3-methoxycinnamate) was accomplished via a transesterification to the corresponding aromatic acid using vinyl acetate and a catalytic amount of PdCl2, followed by the lipase-catalyzed regioselective alcoholysis in EtOH. 相似文献