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DR Matravers 《Contemporary Physics》2013,54(3):251-254
The history of absolute measurements of gravity is mentioned and the reasons for making absolute measurements are indicated. The principles and main advantages and difficulties of the main method—reversible pendulum, free fall, symmetrical free motion—are discussed and examples of each method are described. Problems of comparison of different determinations and of estimating systematic errors are considered. 相似文献
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[formula: see text] An efficient and unique route to the 5-7-6 core of guanacatepene A (1) is described. The installation of the desired stereochemistry at the C8 position was achieved via the desymmetrization of the cyclohexadienone by reductive ring closure of the seven-membered ring. That the closure of the seven-membered ring produced only the desired isomer is hypothesized to be a result of the more stable trans relationship between the C8 and C11 methyl groups. 相似文献
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Speech error data have been used to argue for the psychological reality of distinctive features and phonemes as well as the hierarchical ordering levels of processing for speech production. The models of production that have emerged from analysis of these data are nearly unanimous in characterizing (implicitly or explicitly) the motor output level as entirely governed by prior selection and processing of larger units, especially the phoneme. This study reports on the laboratory elicitation of sublexical speech errors by means of tongue twisters. Simultaneous audio and electromyographic recordings were analyzed. Where possible, single-motor unit discrimination was carried out to preclude the possibility of signal contamination by activation of adjacent musculature. The results indicate that traditional methods of data collection on which most speech error corpora are based are inadequate. Production models based on these corpora are not supported by the electromyographic data and must accordingly be revised. 相似文献