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941.
Bernard Williams 《Metal Powder Report》2003,58(10):31-32
There are around 150 variables in powder injection moulding (PIM) production so developing an economic model to help the designer understand PIM production costs will provide a great boost to PIM producers in making informed decisions on the viability, or otherwise, of targeted components. 相似文献
942.
Steinberg Laurence; Albert Dustin; Cauffman Elizabeth; Banich Marie; Graham Sandra; Woolard Jennifer 《Canadian Metallurgical Quarterly》2008,44(6):1764
It has been hypothesized that sensation seeking and impulsivity, which are often conflated, in fact develop along different timetables and have different neural underpinnings, and that the difference in their timetables helps account for heightened risk taking during adolescence. In order to test these propositions, the authors examined age differences in sensation seeking and impulsivity in a socioeconomically and ethnically diverse sample of 935 individuals between the ages of 10 and 30, using self-report and behavioral measures of each construct. Consistent with the authors' predictions, age differences in sensation seeking, which are linked to pubertal maturation, follow a curvilinear pattern, with sensation seeking increasing between 10 and 15 and declining or remaining stable thereafter. In contrast, age differences in impulsivity, which are unrelated to puberty, follow a linear pattern, with impulsivity declining steadily from age 10 on. Heightened vulnerability to risk taking in middle adolescence may be due to the combination of relatively higher inclinations to seek excitement and relatively immature capacities for self-control that are typical of this period of development. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
943.
944.
The megaspilidDendrocerus carpenteri (Curtis) is a solitary ectohyperparasitoid of aphid primary parasitoids. It avoids superparasitism, but the avoidance rate depends on the amount of time elapsed after the first oviposition. In addition, females discriminate in a time-dependent manner between hosts parasitized by themselves and hosts parasitized by conspecifics. They recognize parasitized hosts by means of two externally perceivable chemical markers that are deposited on the mummy shell. One of the markers is highly active, short-lived, not passable through gas chromatography (GC), and freezing sensitive; the other is moderately active, persistent, GC-passable and freezing tolerant. Using two markers is believed to be advantageous for the hyperparasitoid female, as their ratio provides information on mark age and on the producer of the mark (the female herself or a conspecific female). 相似文献
945.
946.
Recent studies from this laboratory [l, 2] on the reaction mechanism of the pentose phosphate pathway in rabbit and rat liver cells have accentuated the role of enzyme-catalyzed exchange reactions as a means by which tracer carbon is relocated in the absence of a net metabolic flux. While this is an intrinsic property of the group transferring enzymes of the pathway and is seen as a deleterious property of 14C for the mapping and quantitation of metabolic pathways, it has re-emphasized the possible usefulness of isotope exchange reactions in understanding the mechanism of action of nature's catalyst. 相似文献
947.
Anthony W. Thompson James C. Williams 《Metallurgical and Materials Transactions A》1984,15(5):931-937
Age hardening in a Cu-2.5 wt pct Ti alloy has been examined as a function of aging time at 300 and 500 °C. Yield strength
results exhibited a double peak in strength at each temperature,i.e., peaks at two different times. The work-hardening rate, however, increased monotonically with aging time. Slip line measurements
showed that slip became coarser with aging time but remained planar. Lack of sufficient understanding of the details of the
pzecipitation reactions and also of hardening mechanisms means that a convincing explanation of the double peak in strength
cannot yet be made, but research needed to correct this situation was identified. 相似文献
948.
I Karacan JI Thornby M Anch CE Holzer GJ Warheit JJ Schwab RL Williams 《Canadian Metallurgical Quarterly》1976,10(5):239-244
949.
We review the principle of differential imaging and its application to scanning tunnelling microscopy (STM). It is shown that placing a lateral dither on an STM tip at high frequency provides the means for transfering topographic information to a frequency range where noise is small. Differential STM imaging on graphite and gold is demonstrated. A simple relation between the differential image and the conventional topographic image is described. 相似文献
950.