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排序方式: 共有313条查询结果,搜索用时 15 毫秒
41.
Hofmann S Sharma R Ducati C Du G Mattevi C Cepek C Cantoro M Pisana S Parvez A Cervantes-Sodi F Ferrari AC Dunin-Borkowski R Lizzit S Petaccia L Goldoni A Robertson J 《Nano letters》2007,7(3):602-608
We present atomic-scale, video-rate environmental transmission electron microscopy and in situ time-resolved X-ray photoelectron spectroscopy of surface-bound catalytic chemical vapor deposition of single-walled carbon nanotubes and nanofibers. We observe that transition metal catalyst nanoparticles on SiOx support show crystalline lattice fringe contrast and high deformability before and during nanotube formation. A single-walled carbon nanotube nucleates by lift-off of a carbon cap. Cap stabilization and nanotube growth involve the dynamic reshaping of the catalyst nanocrystal itself. For a carbon nanofiber, the graphene layer stacking is determined by the successive elongation and contraction of the catalyst nanoparticle at its tip. 相似文献
42.
Henik Avishai; Ro Tony; Merrill David; Rafal Robert; Safadi Ziad 《Canadian Metallurgical Quarterly》1999,25(1):198
To examine interactions between color and word attributes, participants responded, either manually or vocally, to a central target (color patch or word) flanked by a Stroop stimulus. Color and word attributes of the flanker affected both vocal and manual responding to color patches. Color and word flankers also affected manual responding to word targets, but only word flanker affected vocal responding to word targets. These results are not consistent with models (e.g., translational models) of Stroop tasks, which posit that interactions between colors and words occur only when vocal responding is required. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
43.
Z. H. Qiu L. C. Wrobel H. Power 《International journal for numerical methods in engineering》1998,41(5):899-914
This paper describes a boundary element scheme for solving steady-state convection–diffusion problems at high Péclet numbers. A special treatment of the singular integrals is included which uses discontinuous elements and a regularization procedure. Transformations are performed to avoid directly evaluating Bessel functions for Cauchy principal value and hypersingular integrals. Test examples are solved with values of Péclet number up to 107 to assess the numerical scheme. © 1998 John Wiley & Sons, Ltd. 相似文献
44.
Determination of fatty acid methyl esters in cosmetic castor oils by flow injection–electrospray ionization–high‐resolution mass spectrometry
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45.
Rafal Strzalka Tobias Gabriel Erhart Ursula Eicker 《Applied Thermal Engineering》2013,50(2):1418-1426
The paper deals with analysis and optimization of the performance of the combustion process in a biomass furnace at a biomass cogeneration plant. For the purpose a thermodynamic model for the biomass burning process in a grate furnace was developed. The mathematical model describes both, the thermal decomposition of the fuel on the grate as well as gas phase combustion in the secondary zone. The presented approach is based on energy equations for each individual step of the biomass combustion process.Measurement results from a biomass-fired cogeneration plant were used to validate the model. Comparison between simulation and measurement results shows good agreement. The model predicts accurately the temperature profiles in the combustion chamber.The presented approach is suitable for model based analysis and optimization of control strategies. The developed model was used to optimize the performance of the recirculation system of the combustion appliance. The simulation based analysis showed, that the flow rate of the recirculated exhaust fumes can be significantly reduced which results in energy savings of 17% of the auxiliary electrical power demand. 相似文献
46.
Sobotník J Hanus R Kalinová B Piskorski R Cvacka J Bourguignon T Roisin Y 《Journal of chemical ecology》2008,34(4):478-486
The behavioral and electroantennographic responses of Prorhinotermes canalifrons to its soldier frontal gland secretion, and two separated major components of the secretion, (E)-1-nitropentadec-1-ene and (E,E)-α-farnesene, were studied in laboratory experiments. Behavioral experiments showed that both the frontal gland secretion
and (E,E)-α-farnesene triggered alarm reactions in P. canalifrons, whereas (E)-1-nitropentadec-1-ene did not affect the behavior of termite groups. The alarm reactions were characterized by rapid walking
of activated termites and efforts to alert and activate other members of the group. Behavioral responses to alarm pheromone
differed between homogeneous and mixed groups, suggesting complex interactions. Antennae of both soldiers and pseudergates
were sensitive to the frontal gland secretion and to (E,E)-α-farnesene, but soldiers showed stronger responses. The dose responses to (E,E)-α-farnesene were identical for both soldiers and pseudergates, suggesting that both castes use similar receptors to perceive
(E,E)-α-farnesene. Our data confirm (E,E)-α-farnesene as an alarm pheromone of P. canalifrons. 相似文献
47.
Kos M Houshyani B Achhami BB Wietsma R Gols R Weldegergis BT Kabouw P Bouwmeester HJ Vet LE Dicke M van Loon JJ 《Journal of chemical ecology》2012,38(1):100-115
The cabbage aphid Brevicoryne brassicae is a specialist herbivore that sequesters glucosinolates from its host plant as a defense against its predators. It is unknown to what extent parasitoids are affected by this sequestration. We investigated herbivore-mediated effects of glucosinolates on the parasitoid wasp Diaeretiella rapae and the predator Episyrphus balteatus. We reared B. brassicae on three ecotypes of Arabidopsis thaliana that differ in glucosinolate content and on one genetically transformed line with modified concentrations of aliphatic glucosinolates. We tested aphid performance and the performance and behavior of both natural enemies. We correlated this with phloem and aphid glucosinolate concentrations and emission of volatiles. Brevicoryne brassicae performance correlated positively with concentrations of both aliphatic and indole glucosinolates in the phloem. Aphids selectively sequestered glucosinolates. Glucosinolate concentration in B. brassicae correlated negatively with performance of the predator, but positively with performance of the parasitoid, possibly because the aphids with the highest glucosinolate concentrations had a higher body weight. Both natural enemies showed a positive performance-preference correlation. The predator preferred the ecotype with the lowest emission of volatile glucosinolate breakdown products in each test combination, whereas the parasitoid wasp preferred the A. thaliana ecotype with the highest emission of these volatiles. The study shows that there are differential herbivore-mediated effects of glucosinolates on a predator and a parasitoid of a specialist aphid that selectively sequesters glucosinolates from its host plant. 相似文献
48.
Thermodynamic optimization combines exergy analysis with dynamical modeling to determine optimal design parameters. In this work we apply exergy analysis to an analytically solvable model of a single-medium stratified thermal storage device. We consider a simple one-dimensional model that includes conductive losses to the environment. Competition between mixing and conductive losses gives rise to a thermodynamically optimum charging time for the system. The model can treat the full range of stratification from the fully-mixed limit to perfect stratification and we are therefore able to determine the effect of stratification on the thermodynamic optimum. We show that stratification increases the overall efficiency and shortens the thermodynamically optimum charging time. 相似文献
49.
The relation between reflexive and voluntary orienting of visual attention was investigated with 4 experiments: a simple detection task, a localization task, a saccade toward the target task, and a target identification task in which discrimination difficulty was manipulated. Endogenous and exogenous orienting cues were presented in each trial and their validity was manipulated orthogonally to examine whether attention mechanisms are mediated by separate systems and whether they have additive and independent effects on visual detection and discrimination. The results showed that each orienting mechanism developed its typical and independent effect in every case except for the difficult identification task. A theoretical framework for understanding the relationship between endogenous and exogenous orienting of attention is proposed, tested, and confirmed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
50.
Wojciech Polkowski Natalia Sobczak Grzegorz Bruzda Artur Kudyba Rafal Nowak Adelajda Polkowska Izabela Krzak Adam Tchrz Donatella Giuranno 《SILICON》2020,12(7):1639-1649
Silicon-boron alloys have been recently pointed out as novel ultra-high temperature phase change materials for applications in Latent Heat Thermal Energy S 相似文献