Results 61 to 70 of about 207,671 (274)

Metal catalyst-free N-allylation/alkylation of imidazole and benzimidazole with Morita–Baylis–Hillman (MBH) alcohols and acetates

Beilstein Journal of Organic Chemistry, 2023
A highly α-regioselective N-nucleophilic allylic substitution of cyclic MBH alcohols and acetates with imidazole or benzimidazole, in toluene at reflux with an azeotropic distillation, was successfully carried out with no catalysts or additives ...
Olfa Mhasni, Jalloul Bouajila, Farhat Rezgui   +2 more
doaj   +1 more source

Nucleophilic Substitution at Tetracoordinate Phosphorus. Stereochemical Course and Mechanisms of Nucleophilic Displacement Reactions at Phosphorus in Diastereomeric cis- and trans-2-Halogeno-4-methyl-1,3,2-dioxaphosphorinan-2-thiones: Experimental and DFT Studies

Molecules, 2021
Geometrical cis- and trans- isomers of 2-chloro-, 2-bromo- and 2-fluoro-4-methyl-1,3,2-dioxaphosphorinan-2-thiones were obtained in a diastereoselective way by (a) sulfurization of corresponding cyclic PIII-halogenides, (b) reaction of cyclic ...
Marian Mikołajczyk, Barbara Ziemnicka, Jan Krzywański, Marek Cypryk, Bartłomiej Gostyński   +4 more
doaj   +1 more source

Derivation of the exact NSVZ beta-function in N=1 SQED, regularized by higher derivatives, by direct summation of Feynman diagrams

, 2011
For N=1 supersymmetric quantum electrodynamics, regularized by higher derivatives, a method for summation of all Feynman diagrams defining the beta-function is presented.
Adler, Arkani-Hamed, Arnone, Arnone, Arnone, Asorey, Avdeev, Avdeev, Bakeyev, Bardeen, Brink, Brink, Buchbinder, Caswell, Faddeev, Fargnoli, Ferrara, Freedman, Grisaru, Grisaru, Grisaru, Grisaru, Grisaru, Grisaru, Gross, Harlander, Hollik, Howe, Howe, Jack, Jack, Jack, Jones, Jones, Jones, Jones, Jones, K.V. Stepanyantz, Kraus, Krivoshchekov, Mandelstam, Martin, Mas, Morris, Morris, Novikov, Novikov, Novikov, Pimenov, Pimenov, Pimenov, Poggio, Politzer, Pronin, Rosten, Shifman, Shifman, Shifman, Siegel, Siegel, Signer, Slavnov, Slavnov, Smilga, Soloshenko, Soloshenko, Stepanyantz, Stepanyantz, Stepanyantz, Stöckinger, Vainshtein, Vainshtein, Velizhanin, West, West, ʼt Hooft   +75 more
core   +1 more source

Time after time – circadian clocks through the lens of oscillator theory

FEBS Letters, EarlyView.
Oscillator theory bridges physics and circadian biology. Damped oscillators require external drivers, while limit cycles emerge from delayed feedback and nonlinearities. Coupling enables tissue‐level coherence, and entrainment aligns internal clocks with environmental cues.
Marta del Olmo, Carolin Ector, Hanspeter Herzel   +2 more
wiley   +1 more source

A Characterization of Discrete Time Soliton Equations

, 2001
We propose a method to characterize discrete time evolution equations, which generalize discrete time soliton equations, including the $q$-difference Painlev\'e IV equations discussed recently by Kajiwara, Noumi and Yamada.Comment: 13 ...
Conte R., Freeman N. C., Grammaticos B., Hietarinta J., Hirota R., Hirota R., Hirota R., Hirota R., Jimbo M., Joshi N., Kupershmidt B., Narita Y., Nijhoff F., Ohta Y., Quispel G.   +14 more
core   +1 more source

The newfound relationship between extrachromosomal DNAs and excised signal circles

FEBS Letters, EarlyView.
Extrachromosomal DNAs (ecDNAs) contribute to the progression of many human cancers. In addition, circular DNA by‐products of V(D)J recombination, excised signal circles (ESCs), have roles in cancer progression but have largely been overlooked. In this Review, we explore the roles of ecDNAs and ESCs in cancer development, and highlight why these ...
Dylan Casey, Zeqian Gao, Joan Boyes
wiley   +1 more source

Nucleoside cyclic 3′,5′-phosphorothioates with purine and pyrimidine scaffolds. A chemical minireview

European Journal of Medicinal Chemistry Reports, 2022
The common nucleobases purine (adenine and guanine) and pyrimidine (cytosine, uracil and thymine) in naturally occurring nucleosides and their 3′,5′-cyclic phosphates are β-bonded to the anomeric carbon (C1′) of d-ribose or its 2′-deoxy congener.
Kjell Undheim
doaj   +1 more source

Continuum of Mechanisms for Nucleophilic Substitutions of Cyclic Acetals [PDF]

Organic Letters, 2008
The effect of nucleophile strength on diastereoselectivity in the nucleophilic substitution of cyclic acetals was explored. Stereoselectivity remained constant and high as nucleophilicity increased until a threshold value was reached. Beyond this point, however, selection of Lewis acid determined whether stereochemical inversion or erosion was observed.
Jennifer R, Krumper, Walter A, Salamant, K A, Woerpel   +2 more
openaire   +2 more sources

Conserved structural motifs in PAS, LOV, and CRY proteins regulate circadian rhythms and are therapeutic targets

FEBS Letters, EarlyView.
Cryptochrome and PAS/LOV proteins play intricate roles in circadian clocks where they act as both sensors and mediators of protein–protein interactions. Their ubiquitous presence in signaling networks has positioned them as targets for small‐molecule therapeutics. This review provides a structural introduction to these protein families.
Eric D. Brinckman, Anna E. Lester, Brian D. Zoltowski   +2 more
wiley   +1 more source

Effects of the substitution rate of natural gas on the combustion and emission characteristics in a dual-fuel engine under full load

Advances in Mechanical Engineering, 2017
Diesel-piloted natural gas has been considered one of the most promising methods of using natural gas in a compression–ignition engine with few modifications, as this approach benefits from a high thermal efficiency resulting from a high compression ...
Meng Lyu, Chunhua Zhang, Xiaofeng Bao, Jiangyong Song, Zemin Liu   +4 more
doaj   +1 more source