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Molecular and Cellular Biochemistry - Excitation–contraction coupling in normal cardiac function is performed with well balanced and coordinated functioning but with complex dynamic...  相似文献   
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Three-dimensional single crystals of wild-type and mutated 50 S ribosomal subunits from Bacillus stearothermophilus, as well as crystals of reconstituted subunits containing heavy-atom clusters and complexes of these subunits with tRNA and a short nascent polypeptide chain, were grown from polyethylene glycol in the presence of salts at low concentrations. Within experimental error, all these crystals are isomorphous, packed with monoclinic symmetry (C2) in unit cells of a = 300 A, b = 546 A, c = 377 (+/- 1%) A and beta = 112 degrees. Using synchrotron radiation at 85 to 100 K they diffract to 11 A resolution and can be irradiated for hours without disintegrating, so that a complete data set could be collected from a single crystal.  相似文献   
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Recent studies of the motor system using functional imaging have served to emphasize the complexity of the control of even relatively simple movements. The results of these studies suggest that the behavioral context of the movement is an important determinant of functional activation within cortical motor areas.  相似文献   
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Abstract Size and weight measurements were made for all the life stages of Bemisia tabaci (Gennadius) B biotype from field grown cotton ( Gossypium hirsutum L.) and cantaloupe ( Cucumis melo L., var. cantalupensis ) in Phoenix, AZ and Fargo, ND, USA in 2000 and 2001. Nymphal volumes were derived from the measurements. The average nymphal volume increase for settled 1 st to the late 4th instar was exponential. The greatest increase in body volume occurred during development from the 3rd to early 4th instar. Nymphs on cotton leaves were wider, but not longer compared with those on cantaloupe. Ventral and dorsal depth ratios of nymphal bodies from 1 st to late 4th instars from cantaloupe leaves were significantly greater compared with those from cotton leaves. During nymphal development from 1st to 4th instar, the average (from the two host species) ventral body half volume increased by nearly 51 times compared with an increase of 28 times for the dorsal body half volume. Adult female and male average lengths, from heads to wing tips, were 1 126 μm and 953 μm, respectively. Average adult female and male weights were 39 and 17 μg, respectively. Average widths, lengths, and weights of eggs from cotton and cantaloupe were, 99 μm, 197 μm, and 0.8 μg, respectively. Average widths, lengths, and weights for exuviae of non-parasitized nymphs from both cotton and cantaloupe were 492 μm, 673 μm, and 1.20 μg, respectively; and widths, lengths, and weights of parasitized nymph exuviae were 452 μm, 665 μm, and 3.62 μg, respectively. Both exuviae from non-parasitized and parasitized nymphs from cotton leaves were wider, longer, and heavier than those from cantaloupe leaves.  相似文献   
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