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31.
L.A.M. Turkenburg P.M.L. Blok W.H. de Wolf F. Bickelhaupt 《Tetrahedron letters》1981,22(34):3317-3320
Base induced elimination of HCl from the dichloro[5.3.1]propellane gives a mixture of [5]metacyclophane () and tetrahydrocyclopentacyclooctenes (), while the stereoisomeric affords quantitatively. 相似文献
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H. Blok I. Akimoto S. Milikisyants P. Gast E.J.J. Groenen J. Schmidt 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2009,201(1):57-60
High-frequency pulsed EPR spectroscopy allows FID detection of EPR spectra owing to the short dead time that can be achieved. This FID detection is particularly attractive for EPR and ENDOR spectroscopy of paramagnetic species that exhibit inhomogeneously broadened EPR lines and short dephasing times. Experiments are reported for the metalloprotein azurin at 275 GHz. 相似文献
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Antonella Di Savino Johannes M. Foerster Thijmen La Haye Anneloes Blok Monika Timmer G. Matthias Ullmann Marcellus Ubbink 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(51):23439-23443
Electrostatic interactions can strongly increase the efficiency of protein complex formation. The charge distribution in redox proteins is often optimized to steer a redox partner to the electron transfer active binding site. To test whether the optimized distribution is more important than the strength of the electrostatic interactions, an additional negative patch was introduced on the surface of cytochrome c peroxidase, away from the stereospecific binding site, and its effect on the encounter complex as well as the rate of complex formation was determined. Monte Carlo simulations and paramagnetic relaxation enhancement NMR experiments indicate that the partner, cytochrome c, interacts with the new patch. Unexpectedly, the rate of the active complex formation was not reduced, but rather slightly increased. The findings support the idea that for efficient protein complex formation the strength of the electrostatic interaction is more critical than an optimized charge distribution. 相似文献
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Horn T Aniol K Arrington J Barrett B Beise EJ Blok HP Boeglin W Brash EJ Breuer H Chang CC Christy ME Ent R Gaskell D Gibson E Holt RJ Huber GM Jin S Jones MK Keppel CE Kim W King PM Kovaltchouk V Liu J Lolos GJ Mack DJ Margaziotis DJ Markowitz P Matsumura A Meekins D Miyoshi T Mkrtchyan H Niculescu I Okayasu Y Pentchev L Perdrisat C Potterveld D Punjabi V Reimer P Reinhold J Roche J Roos PG Sarty A Smith GR Tadevosyan V Tang LG Tvaskis V Vidakovic S Volmer J Vulcan W Warren G Wood SA Xu C 《Physical review letters》2006,97(19):192001
The 1H(e,e'pi+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (F(pi)) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which F(pi) is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q2 by one sigma, but is still far from its perturbative quantum chromodynamics prediction. 相似文献
40.
A class of algebras has the finite embeddability property (FEP) if every finite partial subalgebra of an algebra in the class can be embedded into a finite algebra in the class. We
investigate the relationship of the FEP with the finite model property (FMP) and strong finite model property (SFMP).? For quasivarieties the FEP and the SFMP are equivalent, and for quasivarieties with equationally definable principal relative congruences the three notions FEP, FMP and SFMP are equivalent. The variety of intuitionistic linear algebras –which is known to have the FMP–fails to have the FEP, and hence the SFMP as well. The variety of integral intuitionistic linear algebras (also known as the variety of residuated lattices) does possess the FEP, and hence also the SFMP. Similarly contrasting statements hold for various subreduct classes. In particular,
the quasivarieties of pocrims and of BCK-algebras possess the FEP. As a consequence, the universal theories of the classes
of residuated lattices, pocrims and BCK-algebras are decidable.
Received February 16, 2001; accepted in final form November 2, 2001.
RID="h1"
ID="h1"The second author was supported by a postdoctoral research fellowship of the National Research Foundation of South
Africa, hosted by the University of Illinois at Chicago. 相似文献