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71.
Christopher Boyd 《Results in Mathematics》1999,36(1-2):21-25
We investigate the relationship between the various topologies that can be defined on spaces of holomorphic functions on C(I for I uncountable. Our investigation also leads to some interesting results about the space ${\rm C}^{(I)}{{\hat \otimes} \atop \pi}{\rm C}^{(I)}$ . 相似文献
72.
Donald B. Boyd David W. Smith James J. P. Stewart Erich Wimmer 《Journal of computational chemistry》1988,9(4):387-398
The monocyclic β-lactam [[4(S)-methyl-2-oxo-1-azetidinyl]thia]acetic acid was studied by the semiempirical molecular orbital methods AM1, MNDO, and MINDO/3. Using the reaction coordinate option in the program MOPAC on VAX and Cray X-MP computers, the potential energy curve was calculated for rotation of the C2-N1-S-C torsional angle in the conformationally flexible side chain while optimizing all other geometrical variables in the molecule. The trajectory taken during geometry optimization was found to be sensitive to the computer, the program version, the convergence criteria, and the degree of code optimization used in the calculation. In order to reduce the likelihood of spurious results, conformational or reaction energy hypersurfaces need to be calculated with the more precise SCF convergence and minimization criteria available in programs for MINDO/3, MNDO, and AM1 calculations. The nitrogen in the model β-lactam antibiotic is predicted to invert periodically as the dihedral angle to the exocyclic N-substituent sweeps through 360°. 相似文献
73.
3,3′-Thiobispyridine is prepared by reaction of pyridine-3-thiol with 3-bromopyridine. The base peak in the mass spectrum of 3,3′-thiobispyridine is due to the molecular ion which fragments by loss of H, HCN and CS as well as by central bond rupture. The 1,1′-dimethyl diquaternary salt of 3,3′-thiobispyridine is reduced polarographically by a one electron transfer not involving hydrogen to an unstable radical cation at a potential (Eo) of −0.72 V in the pH range 7.4–11.2. 相似文献
74.
Sylvia Marhold Ernst Koller Isabella Meyer Otto S. Wolfbeis 《Fresenius' Journal of Analytical Chemistry》1990,336(2):111-113
Summary A new fluorimetric assay for cationic surfactants is based on their capability of quenching the fluorescence of 8-octadecyloxypyrene-1,3,6-trisulfonate (PTS-18). It is specific for cationic surfactants which can be determined in the 40–400 g concentration range. The method is considered to be advantageous over former methods in that it only requires addition of the sample solution to the fluorophore solution, followed by measurement of fluorescence intensity of the probe. This is in contrast to existing methods where the detergent/dye ion pair has to be extracted before measurement. 相似文献
75.
76.
G.D. Gunn R.N. Boyd N. Anantaraman D. Shapira J. Toke H.E. Gove 《Nuclear Physics A》1977,275(2):524-532
The 16O(6Li, d)20Ne reaction to the 2?, 4.97 MeV, 3?, 5.63 MeV, and 4?, 7.01 MeV members of the Kπ = 2? band has been studied. Angular distributions were measured at 32 MeV from 7.5° to 145° (lab). Excitation functions were measured at 15° (lab) and 145° (lab) from 31 to 33 MeV and 31.75 to 32.5 MeV, respectively. Results of multi-step and compound nuclear calculations are compared to the data. At this incident energy, both mechanisms appear to contribute to the population of the unnatural parity levels. 相似文献
77.
G. V. Boyd 《Tetrahedron》1966,22(10):3409-3416
Using an internally consistent LCAO-MO method it is shown that pentalene and heptalene are not electronically stable and will tend to gain or lose two electrons, respectively. The treatment is generalized for bicyclic non-alternant hydrocarbons wih a perimeter of 4n atoms by means of first-order perturbation theory and verified numerically. The energy levels of four selected molecules are presented. 相似文献
78.
In the framework of opera house acoustics, the term "balance" refers to the acoustical competition between the singer on the stage and the orchestra in the pit. The mechanism allowing the operatic singers to be heard over the orchestra has to do with their skill in enhancing the vocal emission by a peculiar use of the formant frequencies. This vital factor is sensed by the listeners and, apart from the obvious sound power ratio of the stage and the pit sources, is the main cue that helps to formulate a subjective impression of the balance. To achieve its objective qualification, two calibrated sound sources can be placed on the stage and in the pit, respectively, and their sound level difference is measured at the listeners' seats. The scope of this work is to investigate the relationship between the subjective impression and the objective indicator of the balance and to develop a scale value for the parameter in the case of a historical opera house. For this scope a set of acoustical data from the Teatro Comunale in Ferrara will be used to create synthetic sound fields with controlled conditions of the balance between the stage and the pit. This methodology employs an anechoic piece for soprano (with piano accompaniment) and is implemented in a dead room equipped with an acoustical rendering system. The sound fields are used to investigate the appropriate balance values by means of listening tests. The results of the scaling exercise show that a suitable range of values can be extracted and that the sound from the stage and the pit is perceived as balanced when the loudness difference between the two is comprised within -2.0 dBA and +2.3 dBA. 相似文献
79.
80.
Vinck E Van Doorslaer S Dewilde S Moens L 《Journal of the American Chemical Society》2004,126(14):4516-4517
Human neuroglobin (hNgb) and human cytoglobin (hCygb), two recently discovered members of the vertebrate globin family, are known to be able to form an intramolecular disulfide bridge. Using electron paramagnetic resonance (EPR), we show that formation of a disulfide bridge in ferric hNgb causes a considerable change in the heme pocket structure, whereas this is not so clear for ferric hCygb. The structural results can be related nicely to earlier histidine and dioxygen affinity studies of the ferrous proteins. 相似文献