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61.
Le Faou JH Suomijärvi T Blumenfeld Y Piattelli P Agodi C Alamanos N Alba R Auger F Bellia G Chomaz P Coniglione R Del Zoppo A Finocchiaro P Frascaria N Gaardhoje JJ Garron JP Gillibert A Lamehi-Rachti M Liguori-Neto R Maiolino C Migneco E Russo G Roynette JC Santonocito D Sapienza P Scarpaci JA Smerzi A 《Physical review letters》1994,72(21):3321-3324
62.
W. D. Wu A. Keren L. P. Le G. M. Luke B. J. Sternlieb Y. J. Uemura D. C. Johnston B. K. Cho P. Gehring 《Hyperfine Interactions》1994,86(1):615-621
Muon spin relaxation (SR) studies have been performed in the normal spinel LiTi2O4 and the A-15 superconductor V3Si to measure the magnetic penetration depth . The relaxation rate(T) 1/2 in field-cooled measurements shows a sharp increase belowT
c
followed by saturation at low temperatures in both systems. This feature implies an isotropic energy gap without anomalous zeros, and most likelys-wave pairing. The low temperature penetration depth (T 0) is determined to be 2100Å for LiTi2O4 and 1300Å for V3Si respectively. Assuming a clean limit relation –2 n
s
/m
*, we derive the Fermi temperatureT
F
n
s/
2/3
m
* from the relaxation rate and the Sommerfeld constant asT
F
3/4–1/4. Unlike conventional superconductors, both LiTi2O4 and V3Si have a large ratio ofT
c
/T
F
0.01, only slightly smaller than those ratios in more exotic superconductors.We thank C. Ballard and K. Hoyle for technical assistance. Work at Columbia University is supported by NSF Grant No. DMR-89-13784 and Packard Foundation (YJU). Ames Laboratory is operated for the U. S. Department of Energy by Iowa State University under Contract No. W-7405-Eng-82. Work at Ames was supported by the Director for Energy Research, Office of Basic Energy Sciences. 相似文献
63.
Lopez-Martens A Hannachi F Dossing T Schück C Collatz R Gueorguieva E Vieu C Leoni S Herskind B Khoo TL Lauritsen T Ahmad I Blumenthal DJ Carpenter MP Gassmann D Janssens RV Nisius D Korichi A Bourgeois C Astier A Ducroux L Le Coz Y Meyer M Redon N Sharpey-Schafer JF Wilson AN Korten W Bracco A Lucas R 《Physical review letters》1996,77(9):1707-1710
64.
65.
Van Bang Le 《Periodica Mathematica Hungarica》1993,27(2):105-124
For a finite or infinite graphG, theGallai graph (G) ofG is defined as the graph whose vertex set is the edge setE(G) ofG; two distinct edges ofG are adjacent in (G) if they are incident but do not span a triangle inG. For any positive integert, thetth iterated Gallai graph
t
(G) ofG is defined by (
t–1(G)), where 0(G):=G. A graph is said to beGallai-mortal if some of its iterated Gallai graphs finally equals the empty graph. In this paper we characterize Gallai-mortal graphs in several ways. 相似文献
66.
We adapted the genetic algorithm to minimize the AMBER potential energy function. We describe specific recombination and mutation operators for this task. Next we use our algorithm to locate low energy conformation of three polypeptides (AGAGAGAGA, A9, and [Met]-enkephalin) which are probably the global minimum conformations. Our potential energy minima are –94.71, –98.50, and –48.94 kcal/mol respectively. Next, we applied our algorithm to the 46 amino acid protein crambin and located a non-native conformation which had an AMBER potential energy 150 kcal/mol lower than the native conformation. This is not necessarily the global minimum conformation, but it does illustrate problems with the AMBER potential energy function. We believe this occurred because the AMBER potential energy function does not account for hydration. 相似文献
67.
ω-Acyloxy n-butylidenetriphenylphosphoranes give α-acyl n-butylidenetriphenylphosphoranes by intermolecular condensation in t-BuOH, and 3,4-dihydro-(2H)-pyrans by intramolecular condensation in toluene. The α-acyl n-butylidene phosphoranes, which are the tautomeric form of α-acyloxaphosphanes, do not lead to cyclobutylketones but to dihydropyrans. 相似文献
68.
Bernard Demerseman Pascale Le Coupanec Pierre H. Dixneuf 《Journal of organometallic chemistry》1985,287(3):C35-C38
13C NMR measurements were performed on [Re3(μ-H)3(CO)10]2? at various temperatures and field strengths. Selective decoupling allowed assignments of the carbonyl resonances. Spin-lattice relaxation time measurements indicated that two mechanisms, scalar coupling and chemical shielding anisotropy, contribute to the relaxation of carbon-13. Variable temperature experiments revealed that more than one mechanism is responsible for the fluxional behaviour. 相似文献
69.
The composition of the essential oil of Bifora radians, an aldehyde-producing weed, has been investigated by capillary gas chromatography, coupled gas chromatography – mass spectrometry, on-line catalytic hydrogenation and coupled gas chromatography – infrared spectrometry. The nineteen compounds identified included eighteen aldehydes: seven alkanals (C6, C9, C10, C11, C12, C13, and C14), ten alkenals, including five (E)-2-alkenals (C12, C13, C14, C15, and C16), and one (E,E)-2,4-alkadienal (C13). Typical Bifora odors were attributed to three major (E)-2-alkenals, C12, C13, and C14. 相似文献
70.
De Wasch K Le Bizec B De Brabander H André F Impens S 《Rapid communications in mass spectrometry : RCM》2001,15(16):1442-1447
In previous work (Le Bizec et al., Rapid Commun. Mass Spectrom. 2000; 14: 1058), it was demonstrated that a boar meal intake could lead to possible false accusations of abuse of 17beta-nortestosterone in antidoping control. The aim of the present study was to identify and quantify endogenous 19-norsteroids in boar edible tissue at concentrations that can alter the steroid urinary profile in humans, and lead to excretion of 19-norandrosterone (19-NA) and 19-noretiocholanolone (19-NE). The samples were analysed in two laboratories. The methodologies used for extraction and detection (GC/MS(EI) and LC/MS/MS(APCI+)) are compared and discussed. 19-Norandrostenedione (NAED), 17beta- and 17alpha-nortestosterone (bNT, aNT), and 17beta- and 17alpha-testosterone (bT, aT) were quantified. The largest concentrations of NAED and bNT were observed in testicles (83 and 172 microg/kg), liver (17 and 63 microg/kg) and kidney (45 and 38 microg/kg). A correlation between the bNT and NAED content of a typical meal prepared with boar parts and the excreted concentrations of 19-NA and 19-NE in human urine was demonstrated. 相似文献