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281.
Back Cover: Ultrafast Intramolecular Relaxation and Wave‐Packet Motion in a Ruthenium‐Based Supramolecular Photocatalyst (Chem. Eur. J. 21/2015)
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282.
Song-Wei Li Wan-Xiang Cui Xia-Juan Huan Margherita Gavagnin Ernesto Mollo Ze-Hong Miao 《Natural product research》2020,34(14):1971-1976
AbstractA new bis-γ-pyrone polypropionate, 4,16-di-epi-onchidiol (1), along with three known related compounds (2–4) were isolated from the marine pulmonate mollusk Onchidium sp. The structure of compound 1 was elucidated by extensive spectroscopic analysis and by comparison the NMR data with its stereoisomers 2–4, whereas its absolute configuration was determined by the combination of X-ray diffraction analysis and TDDFT-ECD calculation. In bioassay, the isolated compounds exhibited broad cytotoxicity against several cancer cell lines with IC50 values ranging from 24.6 to 88.5μM. 相似文献
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Margherita Barile 《Archiv der Mathematik》2006,87(6):516-521
We show that the number of elements generating a squarefree monomial ideal up to radical can always be bounded above in terms
of the number of its minimal monomial generators and the maximum height of its minimal primes.
Received: 12 December 2005 相似文献
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287.
Summary This work is a preliminary analysis of the influence of roughness on wear and on friction coefficient of thermoplastic on metal pairs.The results confirm the influence of steel specimen roughness on wear and suggest the profitability of obtaining further information on this matter through planned experimentation.The limits beyond which is not profitable to increase the quality of the mechanical machining could thus be ascertained.
Sommario Oggetto della presente nota è l'analisi preliminare della influenza della rugosità Ra sull'usura e sul coefficiente di attrito di coppie termoplastico-metallo.I risultati ottenuti, evidenziando l'influenza della rugosità del provino di acciaio sull'usura, riconfermano che l'equazione di Archard per l'usura adesiva, che mette relazione il volume del materiale asportato da uno dei due provini con la durezza, il carico normale, il percorso di strisciamento ed il coefficiente di probabilità, è alquanto semplicistica. Infatti, come in precedenza era stato osservato che il coefficiente di probabilità varia col carico normale, ora se ne può concludere che dipende anche dalla rugosità superficiale del materiale più duro.Dal poco soddisfacente adattamento dell'equazione di regressione ai punti sperimentali se ne può inoltre dedurre che, pur rimanendo indiscussa la sensibile influenza della rugosità superficiale del materiale più duro sull'usura, i parametri considerati non sono sufficienti a rappresentare il fenomeno nella sua complessità.Al fine quindi di valutare in modo rigoroso l'influenza sulla usura dei diversi parametri connessi col fenomeno è stato deciso di proseguire lo studio procedendo all'impostazione di un piano sperimentale.Una chiara ed esauriente valutazione degli effetti della rugosità superficiale sull'usura avrebbe indubbi riflessi pratici in quanto potrebbe indicare i limiti oltre i quali risulta antieconomico spingere la qualità delle lavorazioni meccaniche.相似文献
288.
Margherita De Rosa Sara Di Marino Anna Maria D’Ursi Maria Strianese Annunziata Soriente 《Tetrahedron》2012,68(14):3086-3091
The DNA molecule, recognized as the carrier of genetic information in vivo, can function as an efficient organocatalyst for Michael additions of 1,3-dicarbonyl compounds to activated alkenes in aqueous media. The procedure described here is environmentally benign and offers several advantages in terms of simplicity, generality and efficiency. We have used fluorescence spectroscopy to evaluate the catalytic activity of a molecule of DNA. 相似文献
289.
Margherita Solci 《Mathematical Methods in the Applied Sciences》2012,35(5):598-620
In this paper, we study a homogenization problem for perimeter energies in highly contrasted media; the analysis of the previous paper is carried out by removing the hypothesis that the perforated medium Rn ? E is composed of disjoint compact components. Assuming E to be the union of a finite number N of connected components E1, … ,EN, the Γ‐limit F is a multiphase energy with a ‘decoupled’ surface part, obtained by homogenization from the surface tensions in each E j, a trivial bulk term obtained as a weak limit, and a further interacting term between the phases, involving an asymptotic formula for a family minimum problems on invading an asymptotic formula for a family of minimum problems on invading domains with prescribed boundary conditions. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
290.
Genoveffa Nuzzo Maria Letizia Ciavatta Guido Villani Emiliano Manzo Anna Zanfardino Mario Varcamonti Margherita Gavagnin 《Tetrahedron》2012,68(2):754-760
Nine linear polyoxygenated acetylenes, fulvynes A–I (1–9), exhibiting the uncommon 2-yne carboxylic acid functionality, have been isolated from the butanolic extract of the Mediterranean sponge Haliclona fulva. Their structures possess a long alkyl chain with several oxygenated carbons, and were established by detailed spectroscopic analysis. All fulvynes were found to be active against a chloramphenicol-resistant strain of Bacillus subtilis. 相似文献