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61.
Raphael A. Seidel Björn Schowtka Maurice Klopfleisch Toni Kühl Andreas Weiland Alexander Koch Helmar Görls Diana Imhof Georg Pohnert Matthias Westerhausen 《Tetrahedron letters》2014
Bilirubin oxidation end products (BOXes) show significant physiological effects and are connected to severe diseases such as subarachnoid hemorrhage induced cerebral vasospasm. BOX B (2-(4-ethenyl-3-methyl-5-oxo-1,5-dihydro-2H-pyrrol-2-ylidene)ethanamide) was prepared via a five-step synthesis starting from methyl (4-bromo-3-methyl-5-oxofuran-2(5H)-ylidene)ethanoate that was vinylated and then reacted with NH4OAc, LiOH, (COCl)2, and finally with ammonia yielding Z-BOX B. Derivatives of Z-BOX A and Z-BOX B with [15N]labeled lactam rings were synthesized accordingly. 相似文献
62.
R. Cuthill J. Jackson R. M. Wick F. Alten H. Weiland 《Analytical and bioanalytical chemistry》1935,103(7-8):317-319
63.
64.
E. Müller A. Luber C. Riess A. Papayannis E. Weinberger K. Ziegler V. Kubelka V. Nêmec F. Berka F. A. Ssapegin M. S. Strojew I. D. Clarke R. W. Frey M. Bergmann F. Mecke G. F. Smith V. R. Sullivan L. J. Weiland W. J. Seymour A. W. Greenstein E. Stiasny H. B. Merrill C. Benrud und J. A. Wilson 《Fresenius' Journal of Analytical Chemistry》1938,114(7-8):310-319
Ohne Zusammenfassung 相似文献
65.
66.
Under very minimal regularity assumptions, it can be shown that 2n−1 functions are needed to generate an orthonormal wavelet basis for L2(ℝn). In a recent paper by Dai et al. it is shown, by abstract means, that there exist subsets K of ℝn such that the single function ψ, defined by
, is an orthonormal wavelet for L2(ℝn). Here we provide methods for construucting explicit examples of these sets. Moreover, we demonstrate that these wavelets
do not behave like their one-dimensional couterparts. 相似文献
67.
Time-scale for critical growth of partial and supercavitation development over impulsively translating projectiles 总被引:1,自引:0,他引:1
A physical mechanism is proposed to explain an experimentally observed critical time scale that governs the partial cavity development over blunt free flying cylindrical projectiles. The projectiles were ejected using a modified gas-gun mechanism consisting of a barrel and explosive charge. Upon ignition, high-pressure gases forced a projectile down the launch barrel and into quiescent water. Results indicate that initial small cavities created at the projectile forebody are convected downstream where they subsequently grow towards the forebody, partially enveloping the projectile in a vapor cavity. The time at which the initially stable bubbles rapidly expand signifies that the partial cavity development process has begun. When this time is quantified and is non-dimensionalized appropriately, a time-scale for the critical growth (CGTS) for the cavitation is revealed. A plausible explanation of the partial cavity development process observed in these experiments is that the process is due to the interaction between small cavitation bubbles shed from the projectile forebody and the vortex ring generated by the impulsively started projectile. This interaction mediates the destabilization and spontaneous growth of small unstable bubbles resulting in the formation of partial cavitation over the projectile. An additional supercavitation formation mechanism was observed and is attributed to the launch mechanism. This process is not due to pure hydrodynamic cavitation, but rather an effect we term “gas-leakage” whereby the driving gases contaminated the aft flow field near the projectile and thus facilitated supercavitation to occur on a reduced time scale. This mechanism is equivalent to off-body ventilated supercavitation. 相似文献
68.
J. Forrer S. Pfenninger G. Sierra G. Jeschke A. Schweiger B. Wagner Th. Weiland 《Applied magnetic resonance》1996,10(1-3):263-279
Probeheads and instrumentation for modern X-band pulse EPR and ENDOR experiments with chirped radio-frequency pulses and rapidB 0-field pulses are described. The resonant frequency, the quality factor and, for the first time, the response of a pulse ENDOR resonator structure to a microwave pulse in the subnanosecond time scale have been calculated. The performance of the probeheads for time-domain chirp ENDOR and electron Zeeman-resolved EPR is demonstrated. 相似文献
69.
In an open cycle traveling wave thermoacoustic engine, the hot heat exchanger is replaced by a steady flow of hot gas into the regenerator to provide the thermal energy input to the engine. The steady-state operation of such a device requires that a potentially large mean temperature difference exist between the incoming gas and the solid material at the regenerator's hot side, due in part to isentropic gas oscillations in the open space adjacent to the regenerator. The magnitude of this temperature difference will have a significant effect on the efficiencies of these open cycle devices. To help assess the feasibility of such thermoacoustic engines, a numerical model is developed that predicts the dependence of the mean temperature difference upon the important design and operating parameters of the open cycle thermoacoustic engine, including the acoustic pressure, mean mass flow rate, acoustic phase angles, and conductive heat loss. Using this model, it is also shown that the temperature difference at the regenerator interface is approximately proportional to the sum of the acoustic power output and the conductive heat loss at this location. 相似文献
70.
The title compound (20R)-19-nor-5β,14β-pregnane-3β,14,20-triol 3,20-diacetate crystallizes in the monoclinic space group P21 with 4 formula units C24H38O5 in the unit cell. The lattice parameters are a = 14.324, b = 12.569, c = 12.685 Å, β = 90.21°. The crystal structure was determined by direct methods and refined by the least-squares procedure to the discrepancy factor R = 0.042. Bond length, bond angles, ring conformations, as well as the absolute configuration at C20 were determined. In the crystal the molecules are linked to infinite chains by two hydrogen bonds. 相似文献