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31.
32.
Philip L. Southwick R. Madhav James A. Fitzgerald 《Journal of heterocyclic chemistry》1969,6(4):507-516
Methods are described for the synthesis of 6,7-dihydro-5H-pyrrolo[3,4-d]pyrimidines having an aryl substituent in the 6-position. 4-Hydroxy-, 4-amino, 2-amino-4-hydroxy and 2,4-diamino derivatives were obtained. The synthetic route involved the preparation of 1-aryl-4-cyano- or 4-carboalkoxy-3-pyrrolidinones and 1-aryl-4-cyano- or 4-carboalkoxy-3-amino-3-pyrrolines as key intermediates. 相似文献
33.
Summary Polytetrafluorethylene rods in transverse vibration exhibit sharp non-harmonic resonances when subjected to a static tensile
stress during vibration. The extent and location of the resonances are critically dependent on the exact static stress state
and history of the rods. Rods under no external tension have no anomalous behavior in the range 100 to 2000 cps, but under
static tension varying from 1.5×105 to 3.0×106 dynes/cm2 (2.2 to 44 psi) sharp resonances appear in the vicinity of 400 cps. The mechanical resonance dispersions in complex shear
compliance previously reported byFitzgerald are thus substantiated by the present work. The failure of certain other investigators to observe the dispersion in polytetrafluorethylene
is attributed to the fact that insufficient attention was paid to the static stress conditions in their tests.
Zusammenfassung Polytetrafluor?thylen-Streifen zeigen bei transversaler Schwingung scharfe nicht-harmonische Resonanzen, wenn sie w?hrend der Vibration einem statischen Zug unterworfen sind. Intensit?t und Lage der Resonanzen h?ngen kritisch vom statischen Spannungszustand und der Geschichte der Proben ab. Proben unter keiner ?u?eren Spannung zeigen im Bereich von 100–200 Hz kein anomales Benehmen, doch erscheinen bei statischer Belastung zwischen 1,5×105 zu 3,0×106 dyn/cm2 scharfe Resonanzen in der N?he von 400 Hz. Die mechanische Resonanzdispersion der komplexen Scherungsnachgiebigkeit, früher vonFitzgerald mitgeteilt, werden mit der vorliegenden Arbeit best?tigt. Da? anderen Bearbeitern die Beobachtung der Dispersion bei Polytetrafluor?thylen mi?lungen ist, ist der Tatsache zuzuschreiben, da? den statischen Spannungszust?nden in ihren Proben ungenügende Rechnung zuteil wurde.相似文献
34.
Elastic neutron scattering experiments show clear evidence for the lock-in wave vector being in thiourea. A commensurate 9b superstructure is stabilized in the 2 K range just above the ferroelectric transition. A global hysteresis on the wave vector variation is also observed. 相似文献
35.
John A. Taylor Peter E. Tannenwald Neal R. Erickson Gerald F. Dionne James F. Fitzgerald 《International Journal of Infrared and Millimeter Waves》1985,6(8):687-695
A compact, solid state submillimeter-wave heterodyne radiometer has been developed and was used to measure spectral characteristics of a water vapor jet in a space simulation chamber. Features of the 557 GHz water vapor line profile were observed in significantly greater detail than in previous experiments through an increased sensitivity and improved frequency resolution (600 kHz). The local oscillator of the radiometer consisted of a frequency multiplication chain which was driven by an InP Gunn oscillator at 92.6 GHz, and which contained a frequency tripler and harmonic mixer in cascade. The front end of the receiver had a noise temperature of 4500 K (DSB) at 555 GHz, consumed 3 W and weighed 3 kg. This advance in technology is particularly relevant to submillimeter-wave radiometry from a space-based platform. 相似文献
36.
Paulose M Shankar K Yoriya S Prakasam HE Varghese OK Mor GK LaTempa TJ Latempa TA Fitzgerald A Grimes CA 《The journal of physical chemistry. B》2006,110(33):16179-16184
Described is the fabrication of self-aligned highly ordered TiO(2) nanotube arrays by potentiostatic anodization of Ti foil having lengths up to 134 mum, representing well over an order of magnitude increase in length thus far reported. We have achieved the very long nanotube arrays in fluoride ion containing baths in combination with a variety of nonaqueous organic polar electrolytes including dimethyl sulfoxide, formamide, ethylene glycol, and N-methylformamide. Depending on the anodization voltage, pore diameters of the resulting nanotube arrays range from 20 to 150 nm. Our longest nanotube arrays yield a roughness factor of 4750 and length-to-width (outer diameter) aspect ratio of approximately 835. The as-prepared nanotubes are amorphous but crystallize with annealing at elevated temperatures. In initial measurements, 45 mum long nanotube-array samples, 550 degrees C annealed, under UV illumination show a remarkable water photoelectrolysis photoconversion efficiency of 16.25%. 相似文献
37.
Robert W. Fitzgerald 《Journal of Number Theory》2010,130(1):192-197
Text
We prove five of Sun's conjectures on the index of the subgroup of fourth powers in the class group of binary quadratic forms.Video
For a video summary of this paper, please visit http://www.youtube.com/watch?v=jMuO4RAp1Xw. 相似文献38.
Barrera NP Ge H Henderson RM Fitzgerald WJ Edwardson JM 《Micron (Oxford, England : 1993)》2008,39(2):101-110
Fast neurotransmission involves the operation of ionotropic receptors, which are multi-subunit proteins that respond to activation by opening an integral ion channel. Examples of such channels include the GABA(A) receptor, the 5-HT(3) receptor and the P2X receptor for ATP. These receptors contain more than one type of subunit, although the exact subunit stoichiometry and arrangement around the receptor rosette is often unknown. We are using atomic force microscopy (AFM) of purified receptors to address these issues. Measurement of the molecular volume of the receptor permits the determination of the number of subunits that it contains. Furthermore, analysis of the geometry of complexes between receptors and subunit-specific antibodies reveals the subunit arrangement. Our AFM-based approach has so far been dependent on manual data processing, which is both time-consuming and prone to operator bias. In this study, we set out to develop a novel method capable of automatic segmentation and quantitative analysis of both single receptor particles and receptor-antibody complexes. The method was validated using images of wild type and mutant forms of the P2X(6) receptor. We suggest that the automated method will greatly facilitate further progress in the use of AFM for the determination of receptor and multi-protein architecture. 相似文献
39.
40.
Robert W. Fitzgerald 《Proceedings of the American Mathematical Society》1997,125(5):1309-1313
We improve Kula's bounds on the size of possible -regular Witt rings.