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在五金、家电、办公用品等行业中,常存在一些零件需要先弯曲成形,再进行冲孔。由于结构设计要求,有些孔到弯曲边的距离尺寸较小,尺寸精度要求较高,因此在这类模具设计中,凹模的强度问题较为突出。从结构设计和工艺设计两方面给出了设计这种模具的一些心得体会。 相似文献
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对重庆市不同大气污染地区女性成人的肺爱气功能和生活环境因素的调查后性发现,大气污染区女性成人的FVC、FEV、及V75、V50等肺功能指标显著低于清洁区;运用逐步回归分析显示,SO2浓度、年龄、身高及被动吸烟与FVC关系密切,典型相关分析提示,肺功能与生活环境因素的相关主要表现为FVC、FEV、及V25与年龄、IP浓度和烧煤的相关。 相似文献
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Female ornaments in species with conventional sex roles often indicate individual quality, but the evolutionary forces maintaining
them are less clear. Sexual competition for breeding opportunities may represent an important role for female signals, especially
in polygynous species, but there is little experimental evidence for this. The wing patch size (WPS) of female collared flycatchers
indicates age and body condition and predicts social mating patterns. We challenged nest-building females with decoy females
of varying WPS and found that the aggressive response of residents increased with decoy WPS, suggesting a role for this female
ornament in territorial competition. Our results explain why female WPS predicts territorial distances when mated to a polygynous
male and indicate that the role of WPS in female competitive interactions is similar to that in males of the same population. 相似文献
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The occurrence of mate solicitation by virgin females was investigated in the butterfly Eurema
hecabe. Young (1-day-old) virgin females rarely showed mate solicitation to male model, however, old (at least 6-day-old) virgin
females frequently showed such flight. The duration of solicitation was significantly longer in older females than in younger
ones. The age-related behavioral change occurs with female oogenesis (Hiroki and Kato 1996), and such behavior may thus be
a result of female adaptation to maximize their fecundity.
Received: 6 November 1997 / Accepted in revised form: 29 June 1998 相似文献
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We examined the influence of female feeding regime on polyandry in the nuptially feeding nursery web spider (Pisaura mirabilis). In this species, the nuptial gift, a dead prey item wrapped in the male’s silk, is physically separate from the ejaculate.
We manipulated female feeding regime (starved or fed) and the presence or absence of a gift with three successive males to
test direct-benefits hypotheses (nuptial gift or sperm supply) for the expression of polyandry. The presence of a gift was
necessary for copulation, as no male without a gift successfully copulated. Female mating behavior most strongly supports
polyandry due to the accumulation of gifted food items (“nuptial gift” direct-benefits hypothesis). Starved females that were
presented with a gift accepted significantly more gifts and inseminations than fed females. Most starved females (74%) copulated
two or more times, as opposed to only 3% of the fed females. Nearly all of the females that accepted a gift subsequently copulated.
The nuptial gift item seems to function as male mating effort and females appear to receive multiple matings as part of a
feeding strategy. 相似文献
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A. Coulomb L'Herminé A. Aboura B. Simon-Bouy F. Robin F. Audibert N. Strouk F. Capron R. Frydman G. Tachdjian 《黑龙江环境通报》2002,22(8):652-655
Interstitial deletions of chromosomal region 9q are rarely seen. We report the first prenatal diagnosis of a de novo interstitial deletion 9q. The fetus was karyotyped for intrauterine growth retardation (IUGR). Conventional and molecular cytogenetics showed female karyotype with a de novo deletion of the chromosomal region 9(q22.2q31.1) leading to a partial monosomy 9q. At autopsy, the fetus showed growth retardation, dysmorphy, and a female pseudohermaphroditism. These results suggest that a gene(s) for genital development reside in chromosomal region 9q22.2q31.1. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献