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排序方式: 共有129条查询结果,搜索用时 15 毫秒
1.
Roberto Ballini Dennis Fiorini Maria Victoria Gil Alessandro Palmieri 《Tetrahedron》2004,60(12):2799-2804
Nitroalkanes have been found to give good yields in Michael and nitroaldol (Henry) reactions by the use of a catalytic amount (10 mol%) of CTAOH, at room temperature and under solvent free conditions and in very short reaction times. The methods do not need a large excess of the nitroalkanes and show good chemoselectivity toward further functionalities. 相似文献
2.
The synthesis of the title compound 4 by cyclization of 1-(2-ethoxycarbonylthiobenzyl)pyrrole 9 , prepared by treating with ethyl chloroformate the 1-(2-mercaptobenzyl)pyrrole 7 previously obtained by debenzylation of 1-(2-benzylthiobenzyl)pyrrrole 6 , failed. On the other hand 4 was successfully synthesized by intramolecular cyclization of 1-(2-mercaptobenzyl)pyrrole-2-carboxylic acid 15 by DMAP -catalyzed DCC method. The pyrrole 6 and 1-(2-benzylthiobenzyl)pyrrole-2-carboxaldehyde 11 were useful as starting materials to obtain 1-(2-benzylthiobenzyl)pyrrole-2-carbonitrile 13 , which was hydrolyzed to corresponding amide 16 . Debenzylation of 16 afforded 1-(2-mercaptobenzyl)pyrrole-2-carboxyamide 17 , whose hydrolysis led to required acid 15 . 相似文献
3.
Sandra GemmaStefania Butini Caterina FattorussoIsabella Fiorini Vito NacciKatherine Bellebaum Down McKissicAshima Saxena Giuseppe Campiani 《Tetrahedron》2003,59(1):87-93
The synthesis of two new Huperzine A analogues is reported. Both products present an amino substituted benzo-fused system in place of the pyridone ring of the natural alkaloid. The synthetic strategy to the two analogues is based on three different key palladium-catalyzed steps, namely a carbonylation reaction, an epoxide isomerization and a bicycloannulation reaction. 相似文献
4.
A graph G with maximum valency r is called critical if r + 1colours are needed for an edgecolouring, but every proper subgraphrequires at most r. In this note we consider the minimum orderf(r, g) of a critical graph of maximum valency r and girth g.We show that f(r, 3) = r+1 or r+2 according as r is even orodd, f(r, 4) = 2r+1,f(3, 5) = 9 and f(3, 6) = 15. 相似文献
5.
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7.
G. Battistoni C. Bloise P. Campana V. Chiarella A. Ciocio E. Iarocci G. Murtas G. Nicoletti L. Satta E. Bellotti E. Fiorini C. Liguori P. Negri A. Pullia S. Ragazzi M. Rollier P. Serri L. Zanotti G. Bologna C. Castagnoli A. Castellina B. D'Ettorre Piazzoli P. Galeotti G. Mannocchi P. Picchi O. Saavedra S. Vernetto D. Cundy M. Price 《Il Nuovo Cimento C》1986,9(2):196-209
Summary Muon underground data collected in the NUSEX experiment at Mont Blanc have been analysed concerning the following topics:
I) vertical muon intensity, II) prompt muon flux, III) muons from the direction of Cygnus X-3. Preliminary results from the
analysis of more than 20 000 muons are presented and discussed.
Riassunto Gli eventi di muoni rivelati sottoterra nell'esperimento NUSEX al Monte Bianco sono stati analizzati per studiare I) l'intensità verticale dei muoni, II) il flusso di muoni pronti, III) l'eccesso di muoni dalla direzione di Cygnus X-3. In questo lavoro sono presentati c discussi i risultati preliminari ottenuti dal'lanalisi di piú di 20.000 eventi.
Резюме Был проведен анализ данных, собранных в экспеимемнте NUSEX на Мон Блане. Анализировались следующие вопросы: 1) интенсивность вертикальных мюонов, 2) поток мгновенных (быстрых) мюонов, 3) мюоны, движущиеся в направлении от Лебедь X-3. Приводятся и обсуждаются предварительные результаты анализа для более, чем 20 000 муонов.相似文献
8.
C. Curceanu M. Bazzi G. Beer L. Bombelli A. M. Bragadireanu M. Cargnelli G. Corradi A. d??Uffizi C. Fiorini T. Frizzi F. Ghio B. Girolami C. Guaraldo R. S. Hayano M. Iliescu T. Ishiwatari M. Iwasaki P. Kienle P. Levi Sandri A. Longoni V. Lucherini J. Marton S. Okada D. Pietreanu K. Piscicchia M. Poli Lener T. Ponta A. Rizzo A. Romero Vidal A. Scordo H. Shi D. L. Sirghi F. Sirghi H. Tatsuno A. Tudorache V. Tudorache O. Vazquez Doce E. Widmann J. Zmeskal 《Few-Body Systems》2011,50(1-4):447-449
The DA??NE electron?Cpositron collider at the Laboratori Nazionali di Frascati of INFN has made available a unique quality low-energy negative kaons ??beam??. The SIDDHARTA experiment used this beam to perform unprecedented precision measurements on kaonic atoms, while the AMADEUS experiment plans to perform in the coming years precision measurements on kaon?Cnuclei interactions at low-energies, in particular to study the kaonic nuclei. The two experiments are briefly presented in this paper. 相似文献
9.
Nancy E. Clarke Samuel Fiorini Gwenaël Joret Dirk Oliver Theis 《Graphs and Combinatorics》2014,30(1):119-124
We consider the two-player, complete information game of Cops and Robber played on undirected, finite, reflexive graphs. A number of cops and one robber are positioned on vertices and take turns in sliding along edges. The cops win if, after a move, a cop and the robber are on the same vertex. The minimum number of cops needed to catch the robber on a graph is called the cop number of that graph. Let c(g) be the supremum over all cop numbers of graphs embeddable in a closed orientable surface of genus g, and likewise ${\tilde c(g)}$ for non-orientable surfaces. It is known (Andreae, 1986) that, for a fixed surface, the maximum over all cop numbers of graphs embeddable in this surface is finite. More precisely, Quilliot (1985) showed that c(g) ≤ 2g + 3, and Schröder (2001) sharpened this to ${c(g)\le \frac32g + 3}$ . In his paper, Andreae gave the bound ${\tilde c(g) \in O(g)}$ with a weak constant, and posed the question whether a stronger bound can be obtained. Nowakowski & Schröder (1997) obtained ${\tilde c(g) \le 2g+1}$ . In this short note, we show ${\tilde c(g) \leq c(g-1)}$ , for any g ≥ 1. As a corollary, using Schröder’s results, we obtain the following: the maximum cop number of graphs embeddable in the projective plane is 3, the maximum cop number of graphs embeddable in the Klein Bottle is at most 4, ${\tilde c(3) \le 5}$ , and ${\tilde c(g) \le \frac32g + 3/2}$ for all other g. 相似文献
10.
M. Bazzi G. Beer L. Bombelli A. M. Bragadireanu M. Cargnelli M. Catitti C. Curceanu C. Fiorini T. Frizzi F. Ghio B. Girolami C. Guaraldo M. Iliescu T. Ishiwatari P. Kienle P. Lechner J. Marton K. Nikolics P. Levi Sandri A. Longoni V. Lucherini D. Pietreanu T. Ponta D. L. Sirghi F. Sirghi H. Soltau L. Strüder O. Vazquez Doce E. Widmann J. Zmeskal 《Few-Body Systems》2008,44(1-4):79-82
The DEAR experiment performed at the DAΦNE electron-positron collider (Frascati, Italy) studied the strong interaction shift and width of the 1s state in kaonic hydrogen using X-ray spectroscopy. The repulsive character of the kaon-proton interaction at threshold was confirmed and the most precise values of the shift and width were obtained. However, high precision data at the percent level are highly requested to further develop the theories and thus our understanding of the low-energy antikaon-nucleon interaction. Therefore, a new series of precision experiments on kaonic hydrogen and kaonic deuterium are planned at LNF. 相似文献