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排序方式: 共有498条查询结果,搜索用时 286 毫秒
491.
Ugo Chiacchio Vincenzina Barbera Roberta Bonfanti Gian Luigi Broggini Agata Campisi Silvia Gazzola Rosalba Parenti Giovanni Romeo 《Bioorganic & medicinal chemistry》2013,21(18):5748-5753
A series of 1,7,8,8a-tetrahydro-3H-oxazolo[3,4-a]pyrazin-6(5H)-ones has been synthesized by an intramolecular, palladium(II) catalyzed, aminooxygenation of alkenyl ureas, readily available from glycine allylamides as starting materials. Biological tests showed that the obtained compounds are endowed with an interesting antitumoral activity against two human thyroid cancer cell lines, namely FTC-133 and 8305C, by promoting the apoptotic pathway and DNA fragmentation. 相似文献
492.
Murray Goodman Alvin Steinfeld Alan Tonelli Ugo Lepore Manlio Palumbo Bernard Donzel 《Bioorganic chemistry》1974,3(2):184-203
The synthesis of the cyclo-hexadepsipeptide [l-valyl-d-hexahydromandelyl]3 is described. Examination of this macrocyclic compound by 220-MHz nuclear magnetic resonance spectroscopy shows that symmetrical conformations are stabilized in strongly polar solvents (trifluoroacetic acid, acetonitrile), whereas asymmetric conformations are preferred in nonpolar or slightly polar media such as carbon tetrachloride, chloroform, cyclohexane, and benzene.From analysis of the temperature dependence of the chemical shift and of the coupling constants, together with conformational energy calculations, a model is proposed for the preferred conformation of this molecule in nonpolar solvents. 相似文献
493.
Ann-Sofie Dam Ian P. G. Marshall Nils Risgaard-Petersen Laurine D. W. Burdorf Ugo Marzocchi 《Environmental microbiology》2021,23(5):2605-2616
Cable bacteria (CB) are Desulfobulbaceae that couple sulphide oxidation to oxygen reduction over centimetre distances by mediating electric currents. Recently, it was suggested that the CB clade is composed of two genera, Ca. Electronema and Ca. Electrothrix, with distinct freshwater and marine habitats respectively. However, only a few studies have reported CB from freshwater sediment, making this distinction uncertain. Here, we report novel data to show that salinity is a controlling factor for the diversity and the species composition within CB populations. CB sampled from a freshwater site (salinity 0.3) grouped into Ca. Electronema and could not grow under brackish conditions (salinity 21), whereas CB from a brackish site (salinity 21) grouped into Ca. Electrothrix and decreased by 93% in activity under freshwater conditions. On a regional scale (Baltic Sea), salinity significantly influenced species richness and composition. However, other environmental factors, such as temperature and quantity and quality of organic matter were also important to explain the observed variation. A global survey of 16S rRNA gene amplicon sequencing revealed that the two genera did not co-occur likely because of competitive exclusion and identified a possible third genus. 相似文献
494.
Bacitracin action on membranes of mycobacteria 总被引:6,自引:0,他引:6
495.
Chromosoma - Heterochromatin protein 1 (HP1) is a non-histone chromosomal protein first identified in Drosophila as a major component of constitutive heterochromatin, required for stable epigenetic... 相似文献
496.
M C Navarro I M Cesari R N Incani 《Comparative biochemistry and physiology. B, Comparative biochemistry》1992,102(3):471-474
1. Enzyme polymorphism, analyzed by starch gel electrophoresis, was found to be zero for acid phosphatase, phosphoglucomutase, phosphoglucose isomerase, glucose 6-phosphate dehydrogenase, lactate dehydrogenase, malate dehydrogenase and malic enzyme, in one Brazilian and two Venezuelan strains of Schistosoma mansoni. 2. All loci studied were monomorphic within strains, but the isoenzymic patterns were, however, different among the strains. 3. Results suggest a drastic loss of the genetic variability usually found in natural populations. 相似文献
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