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131.
Recent experiments have demonstrated that the (13)C NMR spectra of iodoalkynes exhibit a strong solvent effect because of complexation with Lewis-basic solvents. This paper describes DFT NMR calculations (B3LYP-GIAO with LanL2DZ or Sadlej pVTZ basis set) of iodoalkynes and their Lewis acid-base complexes, interpreted by using Natural Chemical Shift (NCS) analysis within the framework of the Ramsey formalism for chemical shift. In particular, the paper presents calculations on diiodoethyne and its complexes with one and two ammonia molecules. Examination of the orbital changes upon forming the mono- and bisammonia complexes indicates that mixing of the nitrogen lone pair with the C-I antibonding orbital increases the paramagnetic deshielding at C1. Further increases can be attributed to increased polarization of the iodine lone-pair orbitals onto C1. The haloiodoalkyne series XCCI (X = F, Cl, Br, I) offers additional support for this model of the solvent effect. 相似文献
132.
Sui X Xu Y Giovannelli JL Ho NT Ho C Yang D 《Angewandte Chemie (International ed. in English)》2005,44(32):5141-5144
133.
134.
Pichora-Fuller MK Schneider BA Benson NJ Hamstra SJ Storzer E 《The Journal of the Acoustical Society of America》2006,119(2):1143-1155
Gap detection thresholds for speech and analogous nonspeech stimuli were determined in younger and older adults with clinically normal hearing in the speech range. Gap detection thresholds were larger for older than for younger listeners in all conditions, with the size of the age difference increasing with stimulus complexity. For both ages, gap detection thresholds were far smaller when the markers before and after the gap were the same (spectrally symmetrical) compared to when they were different (spectrally asymmetrical) for both speech and nonspeech stimuli. Moreover, gap detection thresholds were smaller for nonspeech than for speech stimuli when the markers were spectrally symmetrical but the opposite was observed when the markers were spectrally asymmetrical. This pattern of results may reflect the benefit of activating well-learned gap-dependent phonemic contrasts. The stimulus-dependent age effects were interpreted as reflecting the differential effects of age-dependent losses in temporal processing ability on within- and between-channel gap detection. 相似文献
135.
Zhou W Shultz JW Murphy N Hawkins EM Bernad L Good T Moothart L Frackman S Klaubert DH Bulleit RF Wood KV 《Chemical communications (Cambridge, England)》2006,(44):4620-4622
New highly sensitive latent bioluminescent luciferin substrates were designed and synthesized for monitoring mammalian glutathione S-transferase (GST) and Schistosoma japonicum enzyme activities. 相似文献
136.
We consider four-dimensional variational data assimilation (4DVar) and show that it can be interpreted as Tikhonov or L2-regularisation, a widely used method for solving ill-posed inverse problems. It is known from image restoration and geophysical problems that an alternative regularisation, namely L1-norm regularisation, recovers sharp edges better than L2-norm regularisation. We apply this idea to 4DVar for problems where shocks and model error are present and give two examples which show that L1-norm regularisation performs much better than the standard L2-norm regularisation in 4DVar. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
137.
An Al85Ni10La5 amorphous alloy, produced via gas atomization, was selected to study the mechanisms of nanocrystallization induced by thermal exposure. High resolution transmission electron microscopy results indicated the presence of quenched-in Al nuclei in the amorphous matrix of the atomized powder. However, a eutectic-like reaction, which involved the formation of the Al, Al11La3, and Al3Ni phases, was recorded in the first crystallization event (263°C) during differential scanning calorimetry continuous heating. Isothermal annealing experiments conducted below 263°C revealed that the formation of single fcc-Al phase occurred at 235°C. At higher temperatures, growth of the Al crystals occurred with formation of intermetallic phases, leading to a eutectic-like transformation behaviour at 263°C. During the first crystallization stage, nanocrystals were developed in the size range of 5 ~ 30 nm. During the second crystallization event (283°C), a bimodal size distribution of nanocrystals was formed with the smaller size in the range of around 10 ~ 30 nm and the larger size around 100 nm. The influence of pre-existing quenched-in Al nuclei on the microstructural evolution in the amorphous Al85Ni10La5 alloy is discussed and the effect of the microstructural evolution on the hardening behaviour is described in detail. 相似文献
138.
ADI公司最新推出Blackfin BF51X系列产品,包括BF512、BF514、BF516和BF518。
这四款新型16/32bit BF51x处理器都具有高达400MHz(800MMACS)的时钟速率,内置116kBRAM,以及可选择的4Mbit串行(SPI)闪存。每款器件还都集成了用于代码与内容保护的LockbOX安全技术。Blackfin处理器拥有出色的低功耗性能,支持丰富的媒体应用程序,片内集成特性确保其能够轻松地与多种音频、视频、图像和通信外设以及多种类型的存储器进行连接。 相似文献
139.
Myla Archer Hongping Lim Nancy Lynch Sayan Mitra Shinya Umeno 《Design Automation for Embedded Systems》2008,12(1-2):139-170
Timed I/O automata (TIOA) is a mathematical framework for modeling and verification of distributed systems that involve discrete and continuous dynamics. TIOA can be used for example, to model a real-time software component controlling a physical process. The TIOA model is sufficiently general to subsume other models in use for timed systems. The Tempo Toolset, currently under development, is aimed at supporting system development based on TIOA specifications. The Tempo Toolset is an extension of the IOA toolkit, which provides a specification simulator, a code generator, and both model checking and theorem proving support for analyzing specifications. This paper focuses on the modeling of timed systems and their properties with TIOA and on the use of TAME4TIOA, the TAME (Timed Automata Modeling Environment) based theorem proving support provided in Tempo, for proving system properties, including timing properties. Several examples are provided by way of illustration. 相似文献
140.
Synchrotron users and experts from Australia, New Zealand, and further afield congregated in November for the Australian Synchrotron User Meeting 2014. Around 200 members of the synchrotron community attended the highly anticipated meeting held, in conjunction with the New User Symposium, at the Australian Synchrotron's National Centre for Synchrotron Science. Early career researchers played a prominent role at the meeting. Their achievements highlighted the promising capabilities of the region's next generation of synchrotron scientists. 相似文献