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171.
Requejo-Isidro J McGinty J Munro I Elson DS Galletly NP Lever MJ Neil MA Stamp GW French PM Kellett PA Hares JD Dymoke-Bradshaw AK 《Optics letters》2004,29(19):2249-2251
We report the development of a high-speed wide-field fluorescence-lifetime imaging (FLIM) system that provides fluorescence-lifetime images at rates of as many as 29 frames/s. A FLIM multiwell plate reader and a potentially portable FLIM endoscopic system operating at 355-nm excitation have been demonstrated. 相似文献
172.
McLachlan N Nigjeh BK Hasell A 《The Journal of the Acoustical Society of America》2003,114(1):505-511
Musical bells have had limited application due to the presence of inharmonic partials in the lower part of their acoustic spectra. A series of bells has been designed that contains up to seven partial frequencies in the harmonic series beginning at the fundamental frequency. This was achieved by choosing geometries for finite-element analysis models in which as many purely circumferential bending modes as possible occurred at frequencies below any mode with an axial ring node. The bell models were then fine tuned using gradient projection method shape optimization and the resulting profiles were cast in silicon bronze. A range of bell geometries and timbres is analyzed using psycho-acoustic models and is discussed in relation to European carillon bells. 相似文献
173.
We present a nearly model-independent estimate that yields the predictions of a class of simple inflationary and ekpyrotic or cyclic models for the spectral tilt of the primordial density inhomogeneities that enables us to compare the two scenarios. Remarkably, we find that the two produce an identical result, n(s) approximately 0.95. For inflation, the same estimate predicts a ratio of tensor to scalar contributions to the low l multipoles of the microwave background anisotropy of T/S approximately 20%; the tensor contribution is negligible for ekpyrotic or cyclic models, as shown in earlier papers. 相似文献
174.
Beer PD Berry NG Cowley AR Hayes EJ Oates EC Wong WW 《Chemical communications (Cambridge, England)》2003,(19):2408-2409
A novel family of redox-active dinuclear transition metal based cryptands self-assembled from dithiocarbamate ligands has been synthesised; depending upon the nature of the spacer groups these new cryptand systems have been shown to electrochemically recognise the binding of cations or anions. 相似文献
175.
QM/MM calculations show that the potency of a range of inhibitors of adenosine deaminase correlates with the relative stability of the reaction intermediate at the active site, rather than with the inhibitor binding energy. 相似文献
176.
Dobson N McDowell DG French DJ Brown LJ Mellor JM Brown T 《Chemical communications (Cambridge, England)》2003,(11):1234-1235
An FMOC-protected 2'-hydroxyethyl uridine phosphoramidite has been used to synthesise fluorescein-labelled HyBeacon probes and "FAM-ROX" dual-labelled fluorogenic oligonucleotides. 相似文献
177.
Gamblin DP Garnier P Ward SJ Oldham NJ Fairbanks AJ Davis BG 《Organic & biomolecular chemistry》2003,1(21):3642-3644
Controlled site-selective glycosylation can be achieved by combining site-directed cysteine mutagenesis with chemical modification of the introduced thiol; a new class of more efficient chemoselective reagents, glycosyl phenylthiosulfonates, allow rapid glycosylations of representative simple thiols, peptides and proteins. 相似文献
178.
The solvation parameter model is used to identify suitable chromatographic models for estimating the octanol-water partition coefficient for neutral compounds of varied structure by reversed-phase liquid chromatography. The stationary phase Supelcosil LC-ABZ with methanol-water mobile phases affords a series of suitable correlation models for estimating the octanol-water partition coefficient (log KOW) under isocratic and gradient elution conditions. Isocratic separations with mobile phase compositions containing from about 25 to 40% (v/v) methanol provide the most accurate results for log KOW values in the range -0.1 to 4.0. Gradient separations programmed from 5 to 100% (v/v) methanol are suitable for faster separations of compounds with large log KOW values. The standard error in the estimate for the regression models of the predicted log KOW values against literature values are 0.135 log units for the 30% (v/v) methanol-water isocratic system and 0.263 log units for the methanol-water gradient system. Isocratic retention factors predicted from two gradient separations with gradient times of 15 and 45 min afford a poorer fit for the correlation models between log KOW and the estimated retention factors than that of either the above isocratic and gradient models. Plots of the retention factor (log k) as a function of mobile phase composition are generally non-linear. Values of log kw obtained by non-linear extrapolation to a volume fraction of 0% (v/v) methanol do not afford a useful model for estimating log KOW. 相似文献
179.
Hydride addition to either an 80:20 or a 93:7 E/Z isomer ratio of coordinated imine complex 2a occurs with high diastereoselectivity. The high diastereoselectivity regardless of the reagent E/Z ratio is explained by a difference between the relative kinetic acidities of the E and Z isomers of the imine complex. The kinetic acidities of related isopropylimine and 3-pentylimine complexes were used in explaining these results. 相似文献
180.
A procedure for the preparation of high-quality single crystals from concentrated glyme mixtures is presented. Anhydrous single crystals of LiNO(3) and LiClO(4) were prepared in this manner, and the single-crystal structure of LiClO(4) (orthorhombic, Pnma, a = 8.6447(12) A, b = 6.8512(10) A, c = 4.8254(7) A, Z = 4) was determined as an example. This procedure is expected to be widely applicable for not only salts but also a wide range of other materials solvated by glymes. 相似文献