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61.
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62.
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
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Terence Davis Matthew C Dix Michal J Rokicki Amy JC Brook Caroline S Widdowson David Kipling Mark C Bagley 《Chemistry Central journal》2011,5(1):1-5
To develop more potent small molecules with enhanced free radical scavenger properties, a series of N-substituted isatin derivatives was synthesized, and the cytoprotective effect on the apoptosis of PC12 cells induced by H2O2 was screened. All these compounds were found to be active, and N-ethyl isatin was found with the most potent activity of 69.7% protective effect on PC12 cells. Structure-activity relationship analyses showed the bioactivity of N-alkyl isatins decline as the increasing of the chain of the alkyl group, furthermore odd-even effect was found in the activity, which is interesting for further investigation. 相似文献
68.
Siguara B. L. Silva Franois Oberhnsli Marie‐Aude Tribalat Grgory Genta‐Jouve Jean‐Louis Teyssi Marie‐Yasmine Dechraoui‐Bottein Jean‐Franois Gallard Laurent Evanno Erwan Poupon Olivier P. Thomas 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(2):530-535
Among the outstanding chemical diversity found in marine sponges, cyclic guanidine alkaloids, present in species of the family Crambeidae, are particularly attractive, not only because of their unique chemical features, but also due to a broad range of biological activities. Despite a growing interest in these natural products as therapeutic agents, their metabolic pathway has not been experimentally investigated. Ex situ feeding experiments using radiolabeled precursors performed on the Mediterranean sponge Crambe crambe suggest arginine and fatty acids as precursors in the metabolic pathway of crambescins. A subsequent bio‐inspired approach supported the change of paradigm in the metabolic pathway of cyclic guanidine alkaloids. A large part of the chemical diversity of this family would therefore originate from a tethered Biginelli‐like reaction between C‐2/C‐3 activated fatty acids and a central guanidinylated pyrrolinium. 相似文献
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Ling T Poupon E Rueden EJ Kim SH Theodorakis EA 《Journal of the American Chemical Society》2002,124(41):12261-12267
A unified synthesis of several quinone sesquiterpenes is described herein. Essential to this strategy is a novel radical addition reaction that permits the attachment of a fully substituted bicyclic core 16 to a variably substituted quinone 10. The addition product 15 can be further functionalized, giving access to natural products with a high degree of oxygenation at the quinone unit. The quinone addition reaction is characterized by excellent chemoselectivity, taking place only at conjugated and unsubstituted double bonds, and regioselectivity, being strongly influenced by the resonance effect of heteroatoms located on the quinone ring. These features were successfully applied to the synthesis of avarol (1), avarone (2), methoxyavarones (4, 5), ilimaquinone (6), and smenospongidine (7), thereby demonstating the synthetic value of this new method. 相似文献