共查询到20条相似文献,搜索用时 234 毫秒
1.
2.
1985年4月1992年12月,作者采用夹日法对萧山围垦农区臭Qu种群动态进行了连续逐月定点定时的研究。结果表明:臭Qu种群相对数量的季节消长呈后峰型双峰曲线,5月和10月各出现一次高,怀孕率在2月和7月各出现一次高峰,平均胎仔数在5-6月和8-9月相对较多。室外群种相对数量高峰在4月和9-10月;室内种群在5月和10月,前峰不及室外种群明显。室内种群雌体怀孕率明显于室外种群。种群相对数量的季节变 相似文献
3.
呼和浩特地区蒙,汉族女生月经初潮年龄的变化 总被引:2,自引:0,他引:2
作者于1987,1990,1993年份3次调查了呼和浩特区4个群体的月经初潮年龄,并按出生年份和初潮年份分组研究了4个群体月经初潮年龄的变化趋势,研究结果显示:(1)1963至1972年出生的蒙,汉族女性平均妆潮年龄(MMA)提前速度较快,1972年后出生的城市女性MMA提高速度已减慢,农村女性提前速度仍较快;(2)1963于1977年出生的的农村女性MMA提前速度略快于城市;(3)蒙古族女性MM 相似文献
4.
利用SSR标记定位水稻糊化温度的QTLs 总被引:27,自引:1,他引:26
糊化温度(GT)是决定稻米蒸煮食用品质的一个重要指标。研究了以碱消值表示的糊化温度(ASV-GT)的遗传和QTL位点,选择在ASV-GT上具有显著差别的灿稻品种南特号和粳稻品种Balilla杂交,并以Balilla回交得到含有142株的回交群体,ASV-GT的测定表明,在分离群体中ASV-GT表现为双峰连续分布,说明在该群体中ASV-GT是由一主效基因控制的,并伴有微效基因的修饰,进一步用119个在双亲间具有多态性的微卫星(SSR)标记构建了全基因组的分子标记连锁图,采用区间作图法对控制碱消值的基因进行了定位分析,结果表明,位于第6染色体的qASV6-1为一主效基因,其贡献率高达87.6%,来自于亲本南特号中的等位基因可降低碱消值3.26;其余5个QTLs(qASV2,qASV3,qASV6-2,qASV9,qASV11)为微效基因,分别位于第2,3,6,9和11染色体上,双亲中都带有增效和减效等位基因。 相似文献
5.
R-藻蓝蛋白的分离及其结构表征 总被引:15,自引:0,他引:15
本文对传统藻胆蛋白的分离方法进行改进,利用柱层析法直接从新鲜多管藻提取分离出纯的R-藻蓝蛋白。分别用凝胶柱层析法和电泳法测定了其分子量。结果表明:通常实验条件下:R-藻蓝蛋白的最稳定聚集态是三聚体,其分子量为122.8KD,它由分子量分别为18.1KD(α)和20.5KD(β)两个亚基组成,其分子组成为(αβ)3。利用吸收和荧光光谱研究了R-藻蓝蛋白的光谱性质。R-PC的三聚体在可见光范围有两个明显的吸收峰,分别为546nm和614nm,与同系的C-PC和PEC明显不同,表明各类色团光谱特性在三聚体状态基本不变,说明三聚体内色团间无强相互作用。R-PC荧光发射峰位于640nm,与同系的C-PC和PEC基本一致,说明三聚体保证了高效的能量传递。单体的荧光发射呈现双峰(566nm,643nm),说明单体内能量传递效率不高。从光谱性质可知,在PC家族中,R-PC具有最高的光能捕获效率 相似文献
6.
7.
棉铃虫[Helicoverpa armigera(Hubner)]蛾复眼视网膜电位研究 总被引:2,自引:0,他引:2
动用视网膜电位(Electroretinogram,ERG)技术研究了棉铃虫「Helicoverpa armigera(Hubner)」成虫在暗适应过程中对单色光和复合光(即白光)刺激的光感受性变化,并初步分析了ERG的波形成分组成及影响因素。结果显示:⑴依ERG振幅大小(峰-峰值),棉铃虫蛾的光谱敏感曲线在340-605nm波谱内有三个大小不等的峰,其中第一峰位于绿-黄光区的562nm,第二峰位 相似文献
8.
棉铃虫[Helicoverpa armigera(Hübner)]蛾复眼视网膜电位研究 总被引:4,自引:1,他引:3
运用视网膜电位(Electroretinogram , ERG) 技术研究了棉铃虫[ Helicoverpa armigera(Hübner)] 成虫在暗适应过程中对单色光和复合光( 即白光) 刺激的光感受性变化, 并初步分析了ERG 的波形成分组成及影响因素。结果显示:(1) 依ERG 振幅大小( 峰- 峰值) ,棉铃虫蛾的光谱敏感曲线在340 - 605nm 波谱内有三个大小不等的峰,其中第一峰位于绿- 黄光区的562nm ,第二峰位于蓝光区的483nm ,第三个峰在近紫外区的400nm ,显示其复眼至少具有三种感受器类型。(2) 一定光强度范围内, 一定日龄的棉铃虫蛾的ERG 值随单色光和白光刺激光强度的增强而增大, 至一定光强度时增加变缓,呈近似S 型曲线式样。表明该蛾复眼具有较强的光强度自调节和适应机制。(3) 棉铃虫蛾复眼的ERG 波形成分由4 个部分组成:开光反应、正相电位、持续负电位和闭光反应,波长、光强度及光刺激时程对其各成分有不同影响。 相似文献
9.
笼养白腹锦鸡觅食活动的观察 总被引:8,自引:2,他引:8
笼养条件下白腹锦鸡(Chrysolophus amherstiae)的日觅食活动呈现早(7:00-8:00)和晚(18:00-19:00)两个明显高峰期,不同季节和天气其觅食节律有一定的差异;在一年中9月翌年4月的觅食频次较高,这可能与鸟类补充繁殖期能量消耗、积累能量御寒和保证生殖腺发育有关;逐步回归分析结果表明:影响雄鸟觅食活动的主要因素为求偶、理羽和游走;影响雄鸟觅食的主要因素是游走、理羽和静 相似文献
10.
中国乡村少女月经初潮的影响因素解析 总被引:4,自引:0,他引:4
以全国29个省市区10-18岁汉族农村少女32256人为对象,研究其月经初潮的各种环境影响因素及各因素间相互关系,分析指标分地理气候,社会经济及群体发育状况三方面,计29项,首先利用方差最大正交旋转法从全体指标中抽提因子;然后在对各因子相关分析基础上将29个群体按初潮平均年龄的早晚分两组作典则判别分析,根据判别结果,对那些造成我国部分地区乡村少女月经初潮相对迟滞的因素作进一步比较分析,本研究结果为 相似文献
11.
The age at menarche and menopause of three groups of Bhotia females living at high altitude, Himalayan region — Uttar Pradesh, North India, were studied. The Johari Bhotia women had earliest menarche (¯X=15.1±1.1 years) as compared to Rang Bhotias, settled (¯X=15.6±0.9 years) and Rang Bhotias, migratory (¯X=16.0±1.0 years). The differences between all these three groups for age at menarche were significant. A trend towards increase in age at menarche with an increase in altitude has been observed, but the total fertility period in the three groups remained similar as early menarche has been found to be associated with early onset of menopause and late menarche with late menopause. 相似文献
12.
Seasonal characteristics of and age at menarche 总被引:2,自引:0,他引:2
Data from approximately 600 U.S. women were analyzed for seasonality in menarche. Data were converted to the ratio of observed (O) to expected (E) cases, based on an equal distribution of events over the year, per considered time span of the year. The greatest O/E ratio in menarche (1.55) occurred during January, followed by August (1.43) and July (1.24). The lowest O/E ratio in menarche occurred in February and May (0.68). Seasonal patterns in menarche were detected for the separate cohorts of women born during the 1940s, 1950s, and 1960s, with a shift from a December-January peak in menarche for those born in the 1940s and 1950s to an August-September peak for those born in the 1960s. Girls who were younger (8-14 yrs) at menarche exhibited a seasonal difference in the peak number of menarches by about 6 months in comparison to the pattern for girls who were older (15-17 yrs). Girls who experienced menarche during August-October were statistically significantly younger (p less than 0.05) than those born during the other three seasons. Season of birth was not statistically significantly associated with season of menarche. Overall, no 12-month pattern was substantiated by cosinor analysis in the month of menarche. However, a 6-month rhythm was detected in menarche for women born between 1940 and 1960 (p = 0.004, A = 29% M, phi = January and July). 相似文献
13.
体感皮层神经元放电间隔的概率密度函数与分布参数 总被引:2,自引:0,他引:2
本文建立了估计ISI概率密度函数的标准化ISI直方图和分布参数拟合方法,对34例猫体感皮层神经元自发和诱发放电活动进行了统计分析. 相似文献
14.
The energy demands of pregnancy and lactation together with the accumulation of stored fat in human females during development suggest that a critical level of fat may be required for menarche; but multivariate analyses have supported the alternative view that skeletal growth is the main factor. However, significant differences between upper- and lower-body (gluteofemoral) fat suggest that fat distribution may be more relevant than total fat. Using cross-sectional data from the third National Health and Nutrition Examination Survey (NHANES III) for females aged 10-14, we show that menarche is more closely related to fat distribution than to skeletal maturity. Unit increases in hip circumference are associated with 24% higher odds of menarche while increases in waist circumference and triceps skinfold lower the odds by 7 and 9%, respectively. Those with menarche despite low levels of total body fat have relatively more fat stored in gluteofemoral depots than those without menarche or those with menarche and greater total amounts of fat. In young women with completed growth, age at menarche is negatively related to hip and thigh circumference and positively related to waist circumference, stature, and biiliac breadth; and blood leptin levels are much more strongly related to gluteofemoral than upper-body fat, suggesting that leptin may convey information about fat distribution to the hypothalamus during puberty. Fat distribution may be relevant because gluteofemoral fat may provide neurodevelopmentally important fatty acid reserves. 相似文献
15.
E. Saar C. Shalev I. Dalal U. A. Sod-Moriah 《International journal of biometeorology》1988,32(1):33-35
Age at menarche was studied by the recollection method in two groups of Causasian Jewish high school girls, inhabitants of two towns in Israel, Safad and Elat. The two towns differ mainly in climatic conditions. The age at menarche was found to be significantly lower (P<0.02) in the hot town of Elat than in the temperate town of Safad: 13.30±1.21 and 13.58±0.9 years, respectively (mean ±SD). A significant association was found between the age at menarche and the town in which the girls lived. Accordingly, in the hot town of Elat, the percentage of girls who had their first menstrual cycle by the age of 12 years and earlier, was more than double that of the girls in Safad (17.9% and 7.1%, respectively). It is concluded that the environmental temperature, with or without any possible interaction of humidity, is probably responsible for the tendency for an earlier onset of menarche in girls living in the hot town of Elat. 相似文献
16.
Sylvia Kirchengast Doris Gruber Michael Sator Johannes Huber 《American journal of physical anthropology》1998,105(1):9-20
The present study focuses on the impact of age at menarche on body composition development during adulthood. With 459 healthy middle-class women between 18 and 67 years (x = 41.5) the association between age at menarche and body composition was tested. Body composition, described by absolute and relative amount of fat mass, lean body mass, and bone mass, was estimated by means of dual energy x-ray absorptiometry. In order to exclude the influence of the menopausal transition on body composition, pre- and postmenopausal females were examined separately. The absolute amount of body fat was significantly lower within the group of women whose menarche occurred later. However, postmenopausal females exhibit less significant relations between the two trait systems than premenopausal women. This may be due to the impact of menopausal transition which affected the hormone levels and body composition development independently from the adolescent hormonal transition. While in both proband groups the quantitative amount of body fat was significantly related to menarcheal age, a significant relation between menarcheal age and adult body fat distribution could not be verified. Am J Phys Anthropol 105:9–20, 1998. © 1998 Wiley-Liss, Inc. 相似文献
17.
性发育对女性最大吸氧量的影响 总被引:2,自引:0,他引:2
根据是否发生月经,将11-13岁女童分为未来潮组及已来潮组,比较两组身高,体重,瘦体重及最大吸氧量的差。结果表明同龄月经来潮组女童身高,体重,瘦体重,VO2max绝对值,VO2max/身高及VO2max/HRmax均低于已来潮女童,而VO2max/体重及VO2max/瘦体重略高于已来潮组女童,产生这种差异的可能原因。 相似文献
18.
Body mass index (BMI) is widely used as an index of obesity in people from the school age children to adults. However, the relationship between the change in BMI with age and the coming of menarche has not been discussed as there are few reports on the changes in BMI with age. In this study, the change in BMI with age was examined by applying the wavelet interpolation method (WIM), and a critical period for body fat in terms of the coming of menarche was estimated from the growth velocity. We investigated delayed menarche according to the influence of stress in athletes by comparing delayed menarche between athletes and non-athletes in relation to the critical period. Data were obtained from 144 female athletes in their first year at university in the Tokai area, all of whom had competed in a national sports competition in high school (athlete group). Health examination records showing these subjects' heights and weights from the first grade of elementary school to the final year of high school (1984-1995) were collected and BMI was calculated for each grade. Ages at menarche were ascertained from questionnaires. A control group of 73 non-athletes was similarly examined. The age at maximum peak velocity (MPV) derived from the growth (aging) distance curve of BMI was determined in the control group to be 11.96+/-0.97 years old. This age at MPV of BMI was almost the same as the age at menarche (12.11+/-0.93 years old). Therefore, this age at MPV of BMI is estimated to be the critical period of body fat for the coming of menarche. The interval between the age at MPV of BMI and age at menarche was 0.74+/-1.30 years in the athlete group and 0.15+/-0.81 years in the control group, so there was a significant difference (P<0.01) between the two groups. It is suggested that the delayed menarche in athletes is influenced by the stress of regular sports training. 相似文献
19.
An initial group of 200 girls, 7-17 years old, was investigated longitudinally 4 times at 1.5-, 1.5- and 5-year intervals. The present study gives information of the impact of early menarche, a risk factor for breast cancer, on some physical and endocrine characteristics in these subjects. The frequency of ovulation depended significantly on both the time since menarche and the age at menarche. Early menarche was associated with early onset of ovulatory cycles. Even in early puberty, before menarche, the subjects who displayed early menarche during follow-up had higher serum FSH and estradiol concentrations than the girls whose menarche took place after the age of 13.0 years. Adrenal androgen secretion (dehydroepiandrosterone) was not influenced by age at menarche but it increased, as expected, on the basis of chronological age. The group with early menarche was characterized by high circulating estradiol concentrations also after menarche, even in the oldest subjects so far studied, 17-25 years of chronological age. At these ages, the differences in the frequencies of ovulatory cycles were disappearing between the groups formed on the basis of age at menarche. The present findings in pre- and postmenarcheal subjects suggest that the increased risk of breast cancer associated with early menarche is created over several years of exposure to high-level estrogen stimulus. 相似文献
20.
Henk Talma Yvonne Sch?nbeck Paula van Dommelen Boudewijn Bakker Stef van Buuren Remy A. HiraSing 《PloS one》2013,8(4)