共查询到19条相似文献，搜索用时 125 毫秒
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雌雄两性黄颡鱼头部形态特征的增长 总被引：4，自引：0，他引：4
测定了黄颡鱼的体长、头长、吻长、眼径、眼间距、眼后头长、头高等形态指标。雌性个体的体长显著小于雄性个体，雌雄两性个体头长、吻长、眼间距、眼后头长随体长的增长呈同速增长．无显著差异。雌性个体在眼径、头高随体长的增长速度显著大于雄性个体。 相似文献
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用PIT-tag标签标记了69(33♀♀,36♂♂),测量了6月龄(亚成体)和成体棘胸蛙的7个形态特征指标(体长、头长、头宽、腹长、前肢长、后肢长和体重),用于分析棘胸蛙两性形态特征在个体发育过程的变化。结果表明:亚成体棘胸蛙两性在头宽和前肢长上差异显著,头宽和前肢长雄性均大于雌性,而其它形态特征差异不显著。成体棘胸蛙除头长这一形态指标没有差异外,其它6个形态特征差异显著,其中腹长雌性大于雄性,而其他五个指标雄性均大于雌性。我们的结果表明,棘胸蛙在个体发育过程中雌性有较大的腹长与生育力选择的作用有关,而雄性具有较大的体长、头宽和前肢长与性选择有关。 相似文献
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测定了彩石鮒的体长、头长、头宽、头高、吻长、眼后头长、眼径、眼间距、体高、尾柄长、尾柄高、尾鳍长、背鳍基前距、背鳍基长、腹鳍基前距、腹鳍臀鳍间距、体重和去内脏体重.各形态特征变量与体长之间的回归关系显著,相关系数在0.65～0.95之间,所有P＜0.000 1.截距的显著性检验结果在不同变量存在差异,其中头高、吻长、体高、背鳍基长、腹鳍基前距、体重和去内脏体重的截距具有显著的统计学意义,即与零假设(a=0)差异显著(所有P＜0.018),占检测的变量总数的41.18%,其余变量(58.82%)的截距与零假设(a=0)差异不显著(所有P＞0.061).本实验的数据说明比值的数据处理方法在形态学数据的统计分析中的使用需要一个变量之间关系性质的条件检验. 相似文献
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蔡垚 《南京晓庄学院学报》2010,26(3):64-66
报道了江西婺源地区蓝尾石龙子（Eumeces elegans）头、体大小的两性异形.蓝尾石龙子成体体长存在显著的两性差异（雄性大于雌性）,雄性个体有较大的头部（头长和头宽）,雄性头部增长速率明显大于雌性,表明成年雄体分配较多的能量用于头部和身体的生长;而成年雌体则相对延缓头部的生长,以维持躯干生长,增大腹腔容纳量,可提高其繁殖输出. 相似文献
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选取70尾2年龄以上的褐牙鲆,测量了全长（X1）、体长、头长（X3）、吻长、体高、尾柄高（X6）和体质量（Y）7项生长性状.采用相关分析、通径分析和多元回归分析,剔除了与全长有共线性的体长及回归方程中不显著的吻长和体高,计算了全长、体长、头长等6个性状与体质量的相关系数以及以全长、头长和尾柄高对体质量通径系数和决定系数,定量分析褐牙鲆生长性状对体质量的影响.结果表明,褐牙鲆6个生长性状均与体质量的相关系数有统计学意义（P〈0.01）;头长对体质量的直接影响（0.365）最大;3个主要生长性状与体质量的决定系数和为0.948.应用逐步多元回归方法,建立了全长、头长和尾柄高对体质量的线性回归方程：Y=-4 123.461＋34.115X1＋168.733X3＋412.045X6,相关系数R=0.974. 相似文献
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实验研究了来自浙江余姚翘嘴红鲌（Erythroculter ilishaeformis）成体的体重、躯干重和16个形态特征指标的两性异形以及雌性个体生育力。结果显示,翘嘴红鲌雌雄个体除背鳍基前距外其余形态学指标以及体重和躯干重均无显著的两性差异,特定体长的雌鱼的背鳍基前距显著大于雄鱼。线性回归分析表明,翘嘴红鲌的怀卵数量与体长和体重呈显著的正相关,由此推断雌鱼主要通过个体体长的增长和体重的增加来提高个体生育力。由以上结果我们推断水生环境因子抑制了生育力选择和性选择对翘嘴红鲌两性异形进化产生影响。 相似文献
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采用生物学常规测定法、解剖法和生物统计法,对30尾从黑仔阶段开始养40个月的花鳗鲡进行主要形态性状的测定及内脏解剖观察。结果表明：花鳗鲡的D-A/D- 头后缘=1.465±0.028;体长与其它形态性状的相关程度依次为：D-A>体宽>头长>D-头后缘>体高>眼间距;体长与体重的关系为W=1.76×10-3L3.11;肠近中部有一“V ”型小弯曲; 生殖腺肉眼见不到,出现时间明显晚于日本鳗鲡和欧洲鳗鲡。 相似文献
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鳝鱼,又名黄鳝,是我国南方各省区极为常见的鱼类。它不但营养丰富,食用价值很高,而且还可以药用,治疗颜面神经麻痹及中耳炎。但黄鳝的性别决定很特殊,在其个体发育中具有性反转现象。经实验解剖发现,黄鳝在体长200毫米以下时全为雌性,而体长530毫米以上的黄鳝则全为雄性。也就是说,黄鳝小时候是雌性的,长大以后就变成雄性的,下面就黄鳝的性反转现象作些分析,供同行参考。 首先,从性染色体来看,一般生物的性别是由性染色体决定的,如 XY型和ZW型性别决定。但长期以来,鱼类的性别决定和性染色体问题一直是悬而未决。在2万多种鱼类中,目前研究查明仅有30多种鱼类有异形的性染色体。一般的看法,鱼类性别的决定机制仍处于很原始状态,性染色体和常染色体在形态上很难区别。从目前对黄鳝的染色体组型分析及显带来看,其染色体数目为2n=24,染色体臂数为N·F=24,所有染色体为端着丝点染色体,没有具次缢痕和随体的染色体,也没有发现异形染色体。这里并不排除黄缮有性染色体的存在,因为黄鳝在鱼类进化上是一个已经特化的种类。但从黄鳝这种自然状态性反转来看,黄鳝是没有性染色体的。假设黄鳝属于XY型性别决定,有XY性染色体存在的话,那么具有XX和XY型性染色体的个体在其自然发育长为成体时应分别为雌性和雄性,这 相似文献
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Marianna Papastephanou 《Educational Philosophy and Theory》2013,45(13-14):1493-1515
Many educational theoretical approaches to cosmopolitanism tend towards an unconditional appreciation of mobility, diversity and rootlessness. The recent interest of educational philosophy in the rhizome, de-territorialization and diversity contributes to this understanding of cosmopolitanism as movement across a borderless and imperfect world. Without downplaying such insights (and related political education), this article displaces and de-temporalizes them. It takes the form of a parody of the rhizome to view those insights from a different perspective and make them strike a different pedagogical note. 相似文献
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Genotypic and environmental variation in cadmium, chromium, arsenic, nickel, and lead concentrations in rice grains 总被引：1，自引：0，他引：1
Genotypic and environmental variation in Cd, Cr, As, Ni and Pb concentrations of grains, and the relationships between these heavy metals and Fe, Zn were investigated using 9 rice genotypes grown in 6 locations for two successive years. Significant genotypic variation was detected in the five heavy metal concentrations in grains, indicating the possibility to reduce the concentration of these heavy metals in grains through breeding approach. The environmental effect varied with metal, with Pb and Ni having greater variation than the other three metals. There was significant genotype-environment （location） interaction of the concentrations of all five heavy metals in grains, suggesting the importance of cultivar choice in producing rice with low heavy metal concentrations in grains for a given location. Correlation analysis showed that Cd and As, Cr and Ni, and As and Pb concentrations in rice grains were closely associated, and that Ni concentration in grains was negatively correlated with Zn concentration. 相似文献
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Simple, reliable and sensitive analytical methods to determine anticariogenic agents, preservatives, and artificial sweeteners contained in commercial gargles are necessary for evaluating their effectiveness, safety, and quality. An ion chromatography (IC) method has been described to analyze simultaneously eight anions including fluoride, chloride, sulfate, phosphate,monofluorophosphate, glycerophosphate (anticariogenic agents), sorbate (a preservative), and saccharin (an artificial sweetener)in gargles. In this IC system, we applied a mobile phased gradient elution with KOH, separation by IonPac AS18 columns, and suppressed conductivity detection. Optimized analytical conditions were further evaluated for accuracy. The relative standard deviations (RSDs) of the inter-day's retention time and peak area of all species were less than 0.938% and 8.731%, respectively,while RSDs of 5-day retention time and peak area were less than 1.265% and 8.934%, respectively. The correlation coefficients for targeted analytes ranged from 0.999 7 to 1.000 0. The spiked recoveries for the anions were 90%～102.5%. We concluded that the method can be applied for comprehensive evaluation of commercial gargles. 相似文献
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Judith A. Lothian 《The Journal of perinatal education》2012,21(1):45-47
In this column, the author explores current understandings of risk and safety in pregnancy and childbirth. An emphasis on risk management places the provider and hospital in control of women’s decisions related to pregnancy and birth and may make pregnancy and birth less safe for mothers and babies. Accepting that no life is risk free, women can let go of fear and make choices that take into account real, not imagined, or exaggerated risk and, in doing so, increase safety for themselves and their babies. The focus of maternity care becomes enhancing safety through evidence-based practice rather than managing risk. 相似文献