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131.
132.
Hannu?TiitinenEmail author Anna?Mari?M?kel? Ville?M?kinen Patrick?JC?May Paavo?Alku 《BMC neuroscience》2005,6(1):62
Background
The cortical activity underlying the perception of vowel identity has typically been addressed by manipulating the first and second formant frequency (F1 & F2) of the speech stimuli. These two values, originating from articulation, are already sufficient for the phonetic characterization of vowel category. In the present study, we investigated how the spectral cues caused by articulation are reflected in cortical speech processing when combined with phonation, the other major part of speech production manifested as the fundamental frequency (F0) and its harmonic integer multiples. To study the combined effects of articulation and phonation we presented vowels with either high (/a/) or low (/u/) formant frequencies which were driven by three different types of excitation: a natural periodic pulseform reflecting the vibration of the vocal folds, an aperiodic noise excitation, or a tonal waveform. The auditory N1m response was recorded with whole-head magnetoencephalography (MEG) from ten human subjects in order to resolve whether brain events reflecting articulation and phonation are specific to the left or right hemisphere of the human brain. 相似文献133.
Henri-Edouard Audier Marcel Ftizon Jean-Claude Tabet 《Journal of mass spectrometry : JMS》1974,9(3):274-282
The mass spectrometric fragmentations of ethylene ketals corresponding to α substituted ketones were re-examined. A new type of rearrangement has been established. 相似文献
134.
[reaction: see text] A series of alpha,alpha'-bisdiarylamino-capped oligothiophenes C(n) were prepared by the palladium-catalyzed reaction of the dibromo compounds A(i) with diarylamines, N,N-diarylamino-substituted thiophenes or 2,2'-bithiophenes BX(j). These easily oxidizable compounds exhibit a high tendency to form amorphous glasses and characteristic electrochemical and spectroscopic properties that depend significantly on the number of their thiophene moieties. 相似文献
135.
[reaction: see text] To investigate the structural basis for the exceptional selectivity and activity of apoptolidin (1), a strategy has been devised that allows for selective functionalization of seven of its eight hydroxyl groups based on progressive silyl protection, derivatization, and deprotection. The syntheses of these derivatives and their ability to inhibit F(0)F(1)-ATPase are reported. 相似文献
136.
Blewitt G LoSecco JM Bionta RM Bratton CB Casper D Chrysicopoulou P Claus R Cortez BG Errede S Foster GW Gajewski W Ganezer KS Goldhaber M Haines TJ Jones TW Kielczewska D Kropp WR Learned JG Lehmann E Park HS Reines F Schultz J Seidel S Shumard E Sinclair D Sobel HW Stone JL Sulak L Svoboda R van der Velde JC Wuest C 《Physical review letters》1985,55(20):2114-2117
137.
Summary In order to investigate the detection of boldenone in horse mane samples, a boldenone study was conducted on two horses. The
analytical procedure consisted in a hydrolysis using the Sorensen buffer, a liquid-liquid extraction using diethyl ether and
a PFPA derivatization. The instrumental method was a gas chromatography sequential mass spectrometry performed on an ion trap
instrument in full scan mode. The limit of detection was estimated to 1 pg mg−1. The detection of boldenone in the mane was made possible for up to 12 months after administration. 相似文献
138.
An asymmetric synthesis of the aminocyclopentitol pseudosugar of trehazolin has been completed. The synthesis hinges on an asymmetric aldol-ring closing metathesis strategy to construct the five-membered ring with control of both the relative and absolute stereochemistry. 相似文献
139.
Jankowski CK Allain F Dozol JF Virelizier H Tabet JC Moulin C Lamouroux C 《Rapid communications in mass spectrometry : RCM》2003,17(12):1247-1255
The extraction of (135)Cs from high activity waste arising from reprocessing of spent fuel can be achieved by using calix[4]arene crown compounds. The radiolytic degradation of calix[4]arene crowns as well as their solvent, o-nitrophenyloctyl ether (NPOE), was studied using electrospray ionization mass spectrometry (ESI-MS) (that formed Cs(+) or Na(+) adducts) in nitric acid, as well as by chemical ionization tandem mass spectrometry (MS/MS) experiments. The structures of major degradation products were identified with MS and specifically labelled nitric acid. Although NPOE and calix[4]arene crowns alone are relatively stable, under simulated conditions resembling the real industrial processes involving radiolysis in the presence of nitric acid, several products resulting from nitration and oxidation were observed. 相似文献
140.
The Maillard reaction is commonly encountered during food processing or storage, and also in human nutrition, hence there is a need for analytical methodologies to identify and characterize the modified proteins. This paper reports specific methods using mass spectrometric techniques to localize protein modifications induced by lactose and galactose on beta-lactoglobulin (beta-Lg) under solid-state glycation conditions. The extent of glycation was first determined by liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS). The specific identification of lactose-modified amino acid residues was realized using both NanoESI-MS, NanoESI-MS/MS (neutral loss scanning modes) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) (with and without guanidination of lysine residues) on unfractionated digests. The results indicated that, after 8.25 h of incubation, the lysine residues were the main targets of lactose-induced modification. In addition to the 15 lysine residues, Leu1 (NH2 terminal) and the Arg124 were also found to be modified, thus leading to a total of 17 different modified amino acid residues (versus 15 found by LC/ESI-MS measurement). In a second set of experiments, different strategies consisting of constant neutral loss and precursor ion scanning were compared to characterize galactose-induced modifications. Owing to the high level of beta-Lg glycation, the combined use of these different strategies appeared to be necessary for determining the galactose-modified sites after 8.25 h of incubation. Thus, among the 22 galactose adducts deduced from the LC/ESI-MS measurement, apart from the N-terminal and classical lysine residues, we also observed a few arginine residues (Arg40, Arg124 and Arg148) that were modified, and also dialkylations on specific lysine residues (Lys47, Lys75). 相似文献