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91.
Dr. Flávio Figueira Igor Marques Dr. Andreia S. F. Farinha Prof. Dr. Augusto C. Tomé Prof. Dr. José A. S. Cavaleiro Prof. Dr. Artur M. S. Silva Prof. Dr. Jonathan Sessler Prof. Dr. Vítor Félix Prof. Dr. João P. C. Tomé 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(40):14349-14355
A novel sapphyrin derivative was obtained from the reaction between a free‐base sapphyrin and dimethyl acetylenedicarboxylate (DMAD). The formation of the new compound involved a double aza‐Michael addition of two pyrrolic NH groups to a DMAD molecule, with the formation of a disubstituted ethano bridge. The NMR spectral data reveal a product with an unsymmetrical structure; DFT calculations provided support for a structure in which the ethano bridge links two adjacent pyrrole units. The present study provides a seemingly unprecedented example of an N,N′‐dinucleophile reacting with DMAD to form a heterocyclic compound in which the two N‐atoms are linked to the two sp3 carbon atoms derived from a substituted acetylene. 相似文献
92.
93.
By using a method developed by Coz, Arnold and MacKellar the local equivalent of a single-particle potential discussed in a previous work is constructed and analyzed. The accuracy of the method is checked in the present case. The numerical examples refer to the low-energy elastic scattering of neutrons from nuclei described by a hole in a closed shell. The single-particle bound states are approximately described by harmonic oscillator wave functions. The results are similar to those derived by Coz, Arnold and MacKellar from non-local Hartree-Fock potentials. 相似文献
94.
Karl Flöscher 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1979,30(2):201-208
Zusammenfassung Es wird ein Algorithmus zur Berechnung der Vielfachheiten der Gewichte von Darstellungen halbeinfacher Lie-Gruppen angegeben, der auf der Division des Weyl'schen Quotienten für den Charakter beruht. Dabei wird diese Division im Stiefel-Diagramm geometrisch interpretiert.
Meinem verehrten Lehrer, Professor E. Stiefel gewidmet 相似文献
This paper is concerned with the multiplicities of the weights of representations of semisimple Lie groups. an algorithm for the calculation of these multiplicities using the division of Weyl's quotient for the character is given. By means of the Stiefel diagram this division is geometrically interpreted.
Meinem verehrten Lehrer, Professor E. Stiefel gewidmet 相似文献
95.
Upper critical field measurements of the A15 type compounds Nb~3Au,Nb3Au0.7Pt0.3 and Nb3Pt having Tc values of 10.7, 13.0 and 8.7K, respectively, show Hc2(0) values of 235, 295 and 125 kG, respectively. The data for the compounds containing Au fit closely calculations for a dirty type II superconductor with no paramagnetic limiting, but data for Nb3Pt are slightly above these calculations. 相似文献
96.
G. Alexander L. Criegee H.C. Dehne K. Derikum R. Devenish G. Flügge G. Franke Ch. Gerke E. Hackmack P. Harms G. Horlitz Th. Kahl G. Knies E. Lehmann R. Schmitz U. Timm P. Waloschek K. Wacker 《Physics letters. [Part B]》1978,78(1):162-166
The decay of the heavy lepton τ into πv has been established using the magnetic detector PLUTO. The branching ratio is determined to be BR(τ→πv)=(9.0 ± 2.9)% with an additional systematic uncertainty of 2.5%. This value is in good agreement with the theoretical prediction. 相似文献
97.
Zúñiga-Pérez J Muñoz-Sanjosé V Palacios-Lidón E Colchero J 《Physical review letters》2005,95(22):226105
The surface electrical properties of ZnO thin films grown along the nonpolar [1120] direction have been investigated by Kelvin probe microscopy on a nanometer scale. Two different charge domains, with a 75 meV work function difference, coexist within the ZnO surface, which is covered by rhombohedral pyramids whose sidewalls are shown to be {1011}-type planes. The presence and relative orientation of the two kinds of charge domains are explained in terms of the atomic arrangement at the {1011} polar surfaces. 相似文献
98.
Water capillaries bind together grains of sand. They also can bind an atomic force microscope tip to a substrate. The kinetics of capillary condensation at the nanoscale is studied here using friction force microscopy. At 40% relative humidity we find that the meniscus nucleation times increase from 0.7 to 4.2 ms when the temperature decreases from 332 to 299 K. The nucleation times grow exponentially with the inverse temperature 1/T obeying an Arrhenius law. We obtain a nucleation energy barrier of 7.8 x 10(-20) J and an attempt frequency ranging between 4 and 250 GHz, in excellent agreement with theoretical predictions. These results provide direct experimental evidence that capillary condensation is a thermally activated phenomenon. 相似文献
99.
Research carried out in the last 40 years has shown the scientific importance of groundwater circulation both in the Northern Adriatic sea bed and within the uppermost sedimentary layers of the Venice lagoon and of the Venice plain. Hydrodynamic processes are strictly controlled by a well-cemented sedimentary horizon lying under and around Venice ('caranto'), which plays the role of regional aquitard. This layer was attributed to the subaerial cementation of the Flandrian (8-10 ka Before Present) sedimentary surface. The caranto is generalised as a continuum horizon, being an easy explanation for several environmental, hydrogeological and geotechnical problems, e.g., a base layer for landfills, a confining layer for deep aquifers and the best substratum for locating the oak wooden pile-dwelling needed to support the largest buildings. The preservation of the isotope signal within the deep aquifers and aquiclude system records the changes in surface and groundwater characteristics and suggests the present and past recharge regimes. In this region, the heavily perturbed hydrodynamic conditions do not allow for the use of isotopic signals to derive a correct reconstruction of the present recharge. The perturbations induced by the intensive anthropogenic activity force to follow climate evolution by considering deep groundwater and pore waters. In addition, the presence of carbonatic rocks inside terrigeneous sediments affects the reconstruction of the past. Results indicate that carbonatic rocks are created by seepage, through the sediments, of gaseous carbon compounds from decaying organic layers. The gas interactions with the intra-sedimentary saline and fresh waters produce CO2, inducing the cementation of the sediments. 相似文献
100.
Galzerano G Sani E Toncelli A Della Valle G Taccheo S Tonelli M Laporta P 《Optics letters》2004,29(7):715-717
Continuous-wave laser action at approximately 2 microm is demonstrated in a Tm-Ho:KYF4 single crystal at room temperature. Crystal growth, spectroscopic measurements, and laser results are presented. An output power in excess of 250 mW is obtained with a tuning range of 99 nm, the largest ever published, to our knowledge, for Tm-Ho in any crystalline host. 相似文献