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31.
J.Grant Buchanan M.Encarnacion Chacón-Fuertes Alan R. Edgar Simon J. Moorhouse David I. Rawson Richard H. Wightman 《Tetrahedron letters》1980,21(18):1793-1796
Cyclic isopropylidene acetals containing 5,6 and 7-membered rings can be distinguished by measurement of the 13C chemical shifts of the acetal carbon and the methyl groups. 相似文献
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K Itakura N Katagiri C P Bahl R H Wightman S A Narang 《Journal of the American Chemical Society》1975,97(25):7327-7332
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Ohne Zusammenfassung 相似文献
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On behalf of your students your colleagues, and your friends 相似文献
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The phosphoramidite (1S,3R,4S)-3-(2-cyanoethoxy(diisopropylamino)phosphinoxymethyl)-5-N-(4-monomethoxytrityl)-1-(uracil-1-yl)-5-aza-2-oxabicyclo[2.2.1]heptane 18 of a novel bicyclic nucleoside structure was synthesized from the known 1-(3'-deoxy-beta-D-psicofuranosyl)uracil 3. Conformational analysis of its structure verified its expected S-type furanose conformation, and the secondary amino group in the 4'-position allowed for incorporation into oligonucleotides using 5' --> 3' directed oligonucleotide synthesis as previously described for phosphoramidates. Thermal denaturation studies showed rather large decreases in duplex stabilities of -4.3 and -2.7 degrees C per modification toward complementary DNA and RNA, respectively. 相似文献
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This article describes techniques used to synthesize headphone-presented stimuli that simulate the ear-canal waveforms produced by free-field sources. The stimulus synthesis techniques involve measurement of each subject's free-field-to-eardrum transfer functions for sources at a large number of locations in free field, and measurement of headphone-to-eardrum transfer functions with the subject wearing headphones. Digital filters are then constructed from the transfer function measurements, and stimuli are passed through these digital filters. Transfer function data from ten subjects and 144 source positions are described in this article, along with estimates of the various sources of error in the measurements. The free-field-to-eardrum transfer function data are consistent with comparable data reported elsewhere in the literature. A comparison of ear-canal waveforms produced by free-field sources with ear-canal waveforms produced by headphone-presented simulations shows that the simulations duplicate free-field waveforms within a few dB of magnitude and a few degrees of phase at frequencies up to 14 kHz. 相似文献
39.
A technique for polishing the surface of carbon-fiber ultramicroelectrodes to a bevelled tip is described which simplifies electrode preparation. The bevelled surface has an active area that is more than twice that of a disk electrode fabricated from the same material. This results in larger faradaic currents. It is found that the chronoamperometric current at these electrodes is equal to that calculated for a disk of equivalent area to the elliptical area of the electrode. While the area is increased, the residual current is not, and thus quantitative applications of these electrodes as in vivo probes as facilitated. Furthermore, the bevelled tip results in an electrode that minimizes tissue damage during insertion into brain tissues. 相似文献
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Vergés JA Guinea F Galán J van Dongen PG Chiappe G Louis E 《Physical review. B, Condensed matter》1994,49(21):15400-15403