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排序方式: 共有164条查询结果,搜索用时 15 毫秒
1.
Ultrastructural and chemical evidence that the cell wall of green cotton fiber is suberized 总被引:9,自引:1,他引:8 下载免费PDF全文
Green cotton (Gossypium hirsutum L.) fibers were shown by electron microscopy to have numerous thin concentric rings around the lumen of the cell. These rings possessed a lamellar fine structure characteristic of suberin. LiA1D4 depolymerization and gas chromatography-mass spectrometry analysis showed the presence of a suberin polymer in the green cotton with the major aliphatic monomers being ω-hydroxydocosanoic acid (70%) and docosanedoic acid (25%). Ordinary white cotton was shown by chemical and ultrastructural examination to be encircled by a thin cuticular polymer containing less than 0.5% of the aliphatic components found in green cotton. 相似文献
2.
Isolation of edestin from aleurone grains of Cannabis sativa 总被引:3,自引:0,他引:3
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Spherosomes of cotyledons of germinating peanuts (Arachis hypogea L.) were examined by electron microscopy and found to be particles about 1.0 to 2.0 μ in diameter bounded by a limiting membrane. Isolated spherosomes appear similar to spherosomes in situ. The isolated spherosomes are composed of 98.1% total lipids, 0.77% phospholipid and 1.27% protein by dry weight. The amounts of protein and phospholipid associated with the isolated spherosomes are sufficient to account for limiting membranes. Spherosomes amply account for the lipid in a peanut cotyledon. The activity of lipase and fatty acyl-Coenzyme A synthetase is not associated with the isolated spherosomes. This suggests that peanut spherosomes are principal sites of lipid storage but not of lipid degradation. 相似文献
4.
Xenobrama microlepis gen. et sp. nov. is described on the basis of 17 adult and subadult specimens collected by surface gill nets, bottom trawl
and midwater trawl from the subantarctic waters of the South Pacific Ocean. This monotypic new genus is distinguished from
other bramid genera by the following characters: inner lower edges of mandible touching each other (except near symphysis);
gill rakers short, thick, and stout; subpectoral region very narrow; interpelvic space flat and wide; vertebrae 49–51; and
scales in longitudinal series more than 83. The new taxon is widely distributed in the high seas of the South Pacific, 38–54°S,
79–176°W, but is rather rare compared toBrama spp. in catches of drift gill nets. 相似文献
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Ikeno Takeyuki Hashimoto Seiichi Kuzuya Hiroshi Nagatsu Toshiharu 《Molecular and cellular biochemistry》1977,18(2-3):117-123
1. Two different molecular forms of dopamine-beta-hydroxylase were isolated from human serum; a major component (Peak I enzyme) with a molecular weight of 368000 and with a higher specific activity and a minor component (Peak II enzyme) with a molecular weight of 188000 and with a lower specific activity. 2. Both forms require ascorbic acid for the activity, and are stimulated by fumarate. Addition of N-ethylmaleimide or copper also increased the activity. The optimal pH of both forms in the presence of 20mM tyramine as substrate is 5.0. 3. Km values toward tyramine of Peak I enzyme and Peak II enzyme were 1.67 mM and 14.2 mM respectively. 4. Both Peak I enzyme and Peak II enzyme are glycoprotein. 相似文献
7.
The Receptor-Mediated Activation of Tyrosine Hydroxylation in the Superior Cervical Ganglion of the Rat 总被引:10,自引:5,他引:5
Takeyuki Ikeno Geneva Dickens Tom Lloyd Gordon Guroff 《Journal of neurochemistry》1981,36(5):1632-1640
The addition of carbachol to superior cervical ganglia causes a rapid increase in tyrosine hydroxylation in situ. The increase occurs in ganglia from both newborn and adult animals, and in ganglia from animals pretreated with reserpine. The increase is not due to increased transport of the substrate. The increase is dependent upon the presence of calcium, and is additive to the stimulation produced by dibutyryl cyclic AMP. The stimulation seems specific for tyrosine hydroxylation; dopamine beta-hydroxylation is not increased. Preincubation experiments suggest that the carbachol-induced stimulation is due to a change in the availability of, or the affinity of the enzyme for, reduced pterin cofactor. The stimulation is inhibited by atropine and also by low concentrations of phenoxybenzamine or haloperidol, which suggests that it is caused by an action of carbachol on the interneurons in the ganglia. 相似文献
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I. Katanuma Y. Tatematsu K. Ishii T. Saito M. Ichimura Y. Nakashima K. Yatsu 《Plasma Physics Reports》2002,28(9):734-749
A new type of ambipolar trap is proposed, where a minimum-B magnetic field is used to confine the particles radially and to provide plasma macroscopic stability. The particles are confined axially by creating the plug potentials at both end-mirror cells of the ambipolar trap. The plug potential is produced by only electron cyclotron resonance heating, the mechanism of which is proposed. 相似文献