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991.
Chap T. Le 《Biometrical journal. Biometrische Zeitschrift》1988,30(1):87-92
The distribution-free test against ordered alternatives proposed by Jonckheere (1954) is based on the Kendall's rank correlation coefficient τ. A new rank test is proposed and illustrated with a numerical example. The proposed test is based on Spearman's σ and has similar functional structure as the Kruskal-Wallis test. A useful by-product is a test for departure from a trend. 相似文献
992.
A carbon-balance model of the growth of an even-aged, self-thinning,mono-specific stand of trees is derived using a structural frameworkbased on pipe-model theory. Within the pipe-model framework,dry matter arising from extension of roots and shoots is separablefrom that arising from the cross-sectional expansion of stems.This permits the derivation of models describing the growthof average stem length, total basal area, and total volume ofthe stand. Variations of these models are described for twosituations: (1) where the annual rates of substrate productionand feeder-root turnover can be assumed constant over time;and (2) where these rates are expected to change over time,such as in polluted environments. The model describing the growthof stand volume for the first situation fits published yieldtables. Growth-rate models applicable to individual trees arealso described. Carbon-balance model, dry-matter partitioning, pipe-model theory, stand growth, self-thinning 相似文献
993.
T Aureli C Puccetti M E Di Cocco A Arduini R Ricciolini M Scalibastri C Manetti F Conti 《European journal of biochemistry》1999,263(1):287-293
The biochemical pathways involved in acetyl-L-carnitine utilization were investigated in conscious, freely moving rats by 13C NMR spectroscopy. Following 4-h [(1,2-13C2)acetyl]-L-carnitine infusion in fasted animals, the free carnitine levels in serum were increased, and an efflux of unlabelled acetyl-L-carnitine from tissues was observed. [(1,2-13C2)Acetyl]-L-carnitine was found to enter biosynthetic pathways in liver, and the acetyl moiety was incorporated into both cholesterol and 3-hydroxybutyrate carbon skeleton. In accord with the entry of [(1,2-13C2)acetyl]-L-carnitine in the mitochondrial acetylCoA pool associated with tricarboxylic acid cycle, the 13C label was also found in liver glutamate, glutamine, and glutathione. The analysis of the 13C-labelling pattern in 3-hydroxybutyrate and cholesterol carbon skeleton provided evidence that the acetyl-L-carnitine-derived acetylCoA pool used for ketone bodies synthesis in mitochondria was homogeneous, whereas cholesterol was synthesized from two different acetylCoA pools located in the extra- and intramitochondrial compartment, respectively. Furthermore, cholesterol molecules were shown to be preferentially synthesized by the metabolic route involving the direct channelling of CoA-activated mitochondria-derived ketone bodies into 3-hydroxy-3-methylglutarylCoA pathway, prior to equilibration of their acyl groups with extramitochondrial acetylCoA pool via acetoacetylCoA thiolase. 相似文献
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The build-up of neurosecretory material in the median neurosecretory cells and fibre tracts of cultured cockroach brains was demonstrated by staining and bioassay. Examination of the cultured brains by electron microscopy showed active production of neurosecretory granules after 3 days in vitro. The close correlation of the results obtained by these different methods of assay leaves little doubt that a neurohormone is being synthesized and stored. 相似文献
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999.
Spleen cells from rats given experimental pyelonephritis using Escherichia coli and Proteus mirabilis as infecting organisms were evaluated for their ability to respond to the mitogen Concanavalin A. Results indicate an 80% reduction in the response of animals with gross suppuration in the kidney, but no inhibition is observed in animals with kidney infection, but not renal abscesses. The inhibition is not, apparently, due to serum factors. 相似文献
1000.