共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
SEASONAL VARIATION IN METABOLIC FUNCTIONS OF BRAMBLINGS 总被引:4,自引:0,他引:4
Seasonal variation in the rate of oxygen consumption during rest at different test temperatures and in the respiratory quotient (RQ) was observed in male Bramblings Fringilla montifringilla which had been caught as immature birds during autumn migration and kept under outdoor conditions for one year. Resting oxygen consumption measured from +31o to – 4oC during one night was significantly lower in late April and October (migratory seasons) as compared to the preceding and the following December. Because of marked seasonal changes in body weight, the significance of differences in metabolic rate between different seasons was largely dependent on the manner of expressing the rate of oxygen consumption, either per bird or as the 0–67 power of body weight (“surface coefficient”). The lower resting rate of oxygen consumption during the migratory seasons was interpreted as one possible factor responsible for allowing fat deposition by reducing total energy expenditure. This modification occurred only in birds kept under quasi-natural conditions outdoors and not in birds which were kept in cages under constant conditions of light and temperature in the laboratory. 相似文献
3.
4.
5.
A prospective panel study was conducted to measure seasonality of mood in a random community sample in Melbourne, Australia (N = 245). Based on research into the structure of human mood, it was predicted that a lowering of mood in winter relative to summer would be observed in positive affect (PA) and behavioral engagement (BE), but not negative affect (NA). These variables were measured across summer and winter for 3 years. Consistent with the majority of research in the Northern Hemisphere, analyses on the entire sample found evidence of a small prospective season effect on the BE scale (explaining 2.1% of variance in BE scores). Also, as expected, no season effect was seen on the NA scale. In the entire sample, the season effect was not significant for PA, but joint factor analysis of the BE, PA, and NA scales confirmed that the season effect seen in the BE scale was largely due to items that were pure measures of PA. Winter pattern seasonality was both reliable across measures and significantly more marked among the subgroup of respondents who self-identified winter pattern of mood on the Seasonal Pattern Assessment Questionnaire. (Chronobiology International, 18(5), 875-891, 2001) 相似文献
6.
7.
8.
STELLAN HEDGREN 《Ibis》1979,121(3):356-361
9.
10.
11.
西湖湖西浮游与着生藻类季节变化及相互关系 总被引:2,自引:0,他引:2
2014年11月至2015年8月调查了西湖湖西沿岸带浮游藻类和不同基质(植物、石块和底泥)上着生藻类的群落结构及季节变化, 分析了着生丝状藻与浮游丝状藻的相互关系以及它们与环境因子的相关性, 探讨湖西生态修复过程中季节性暴发的丝状藻水华的原因。结果表明浮游藻类和植物、底泥、石头上着生藻类中均以硅藻门种类数(分别占52.5%、60.4%、86.7%和72.7%)最多, 蓝藻门(分别占10.1%、8.9%、6.7%和15.2%)和绿藻门(分别占26.3%、19.8%、5.6%和10.6%)次之, 其他门类相对较少, 浮游藻类与着生藻类优势种季节差异较大。附植丝状藻密度显著高于附泥和附石丝状藻, 且狐尾藻上着生丝状藻密度与浮游丝状藻密度呈显著正相关, 表明狐尾藻着生丝状藻可能是浮游丝状藻较重要的来源之一, 该结果可为西湖丝状藻水华的控制提供一些参考。相关性分析表明, 着生藻类和丝状藻与各理化因子(水深、透明度、溶解氧、水温、pH、TN、SRP、TP等)均无显著相关性。 相似文献
12.
SEASONAL VARIATION IN CHEESE STARTER ACTIVITY 总被引:1,自引:1,他引:0
13.
The relationship of seasonal variation in isozymes to systematic studies at the infraspecific level is evaluated. Isozyme variation in peroxidases, esterases, and α-terpineol dehydrogenases was evaluated monthly for one year in J. scopulorum Sarg. Zymograms of α-terpineol dehydrogenases showed one nonvariable band. Isoperoxidases varied quantitatively but not qualitatively, this variation being correlated with seasonal growth and dormancy. Isoesterases showed qualitative variation, with two types of esterases being produced. One type showed seasonal variation and a second was nonvariable. The presence of two types of isoesterases may reflect differing physiological roles for each. The esterase results showed that care should be taken during investigations of isozymes at the population level to assure phenological similarity. 相似文献
14.
沙颍河下游城市黑臭内河沉积物微生物群落季节变化特征 总被引:1,自引:0,他引:1
为了研究沙颍河下游城市黑臭内河不同季节沉积物微生物群落特征,对安徽省阜阳市黑臭内河中清河、七渔河表层沉积物进行16S rDNA高通量测序。结果发现:黑臭河流中沉积物的微生物多样性指数均不高,但是表现出一定的变化规律,即春季>冬季≥夏季>秋季;通过冗余性分析发现微生物多样性受季节与沉积物pH影响较显著。分析沉积物门水平上的微生物群落结构发现,季节、温度、TN及SOM对微生物影响较大。变形杆菌、厚壁菌门、绿弯菌门、疣微菌门、拟杆菌门和放线菌门等优势菌门的相对丰度在季节水平上存在差异,春季厚壁菌门、绿弯菌门、放线菌门和酸杆菌门相对丰度较高,其中绿弯菌门和酸杆菌门是已知指示污染的微生物,变形杆菌门相对较少。秋季疣微菌门与拟杆菌门相对丰度显著减小,变形杆菌门相对其他季节显著增加。样品中共发现16个硫酸盐还原菌(SRB)菌属,其中Desulfoprunum是丰度最高的菌属。春季沉积物中SRB的类群最多,相对丰度最大;硫酸盐还原菌群与SO42-、TN、SOM、Cl–等呈显著正相关。上述结果为营养盐控制时机的选择从而有效避免河流中黑臭物质的产生提供了一定参考。 相似文献
15.
16.
17.
Little, R.M., Verster, A. & Crowe, T.M. 1993. Seasonal and demographical variation in intestinal helminth infection of Greywing Francolin. Ostrich 64:178-181. The proportion of the population carrying intestinal parasites (prevalence of infection) and the mean number of parasites per host within the host population (worm burden) for 312 Greywing Francolin Fran-colinus africanus were recorded on the Stormberg Plateau, eastern Cape Province, during April 1989-De-cember 1990. Most Greywing (86%) had helminths in their small intestine or caeca. Variation in levels of helminth infection (i.e. both prevalence and burdens) was independent of host sex. Nematodes were confined to the caeca where they were present in high numbers throughout the year with two peaks during June-August and November-January. The prevalence and worm burdens of nematodes were independent of host age Nematodes were more prevalent than cestodes. The prevalence and number of cestodes in the small intestine were highest during September-February and Faked during November-December. Levels of prevalence of cestodes were significantly higher in juvenile Greywing than in adults during the austral winter (May-July). The number of cestodes was consistently, but not significantly, higher in juveniles than in adults. Greywing body mass and population density were not significantly correlated with worm burdens. 相似文献
18.
《Chronobiology international》2013,30(4):503-511
Asthma is a “seasonal disease” with symptoms either aggravated by environmental changes during specific seasons or prevalent at certain times of the year for other reasons. We examined whether the heart rate variability (HRV) of asthmatic children changes by season. The HRV during a portion of one night (00:00–04:00) and day (12:00–16:00) and the entire 24h period (00:00–24:00) during each of the four seasons was analyzed. The data of 95 children with asthma and 106 healthy children, as controls, were assessed. In children with asthma during the 24h period, seasonal variation in the low-frequency (LF) band (0.04–0.15 Hz) and the high-frequency (HF) band (0.15–0.4 Hz) were detected (HF: F = 6.81, p =.0003; LF: F = 4.18, p =.008. The HF value in the summer was significantly higher than in autumn and spring (Scheffe test: autumn vs. summer, s = 4.46, p<.001; spring vs. summer, s = 2.86, p<.05), while the LF value in autumn was significantly lower than in summer (s = 3.42, p <.01). In the control group, no seasonal variation in HF, LF, or LF/HF was detected. The findings infer the HRV, a surrogate measure of autonomic nervous system function, of asthmatic children is more susceptible to seasonal changes brought about by either endogenous annual rhythms or environmental weather phenomena. (Chronobiology International, 17(4), 503–511, 2000) 相似文献
19.
James C. Peskin 《The Journal of general physiology》1942,26(1):27-47
1. The accumulation of visual purple in the retina after bleaching by light has been studied in the intact eye of the frog. The data show that duration and intensity of light adaptation, which influence the course of human dark adaptation as measured in terms of visual threshold, have a similar influence on the course of visual purple regeneration. 2. At 25°C. frogs which have been light adapted to 1700 millilamberts and then placed in the dark, show an increase in visual purple concentration which begins immediately and continues for 70 minutes until a maximum concentration is attained. The increase, although beginning at once, is slow at first, then proceeds rapidly, and finally slows up towards the end. Frogs which have been adapted to 9500 millilamberts show essentially the same phenomenon except that the initial slow period is strongly delayed so that almost no visual purple is formed in the first 10 minutes. 3. At 15°C. the initial delay in visual purple regeneration occurs following light adaptation to both 1700 and 9500 millilamberts. The delay is about 10 minutes and is slightly longer following the higher light adaptation. 4. The entire course of visual purple accumulation in the dark takes longer at the lower temperature than at the higher. The temperature coefficient for 10°C. is about 1.8. 5. In contrast to the behavior of the isolated retina which has small amounts of vitamin A and large amounts of retinene immediately after exposure to light, the intact eye has large amounts of vitamin A and little retinene after exposure to light for 10 minutes. In the intact eye during dark adaptation, the amount of vitamin A decreases markedly while retinene decreases only slightly in amount. If retinene is formed in the intact eye, the change from retinene to vitamin A must therefore occur rapidly in contrast to the slow change in the isolated retina. 6. The course of visual purple regeneration may be described by the equation for a first order autocatalyzed reaction. This supposes that the regeneration of visual purple is catalyzed by visual purple itself and accounts for the sigmoid shape of the data. 相似文献
20.
长江口水生动物食物网营养结构及其变化 总被引:1,自引:0,他引:1
为研究长江口水生动物食物网营养结构及其变化, 运用胃含物分析法研究了2016—2017年长江口及其邻近水域捕获的43种水生动物的食性类型与营养结构, 并与20世纪90年代和2006年文献数据进行了比较, 结果表明, 长江口及其邻近水域捕获的水生动物分为4种食性类型: 浮游生物食性、底栖生物食性、游泳生物食性、混合食性, 其中浮游生物食性消费者占绝对优势, 为39.53%; 游泳生物食性消费者所占比例最少, 为11.63%。所分析样品的营养级可分为3级, 其中植食性消费者占优势, 为76.75%; 中级肉食性消费者所占比例最少, 为4.65%; 与20世纪90年代相比, 12种常见鱼类的平均营养级由3.80下降到2.87。长江口水生动物食物网结构较为复杂, 生产者类型包括底栖藻类、浮游植物、有机碎屑3种, 主要由牧食食物链和碎屑食物链构成复杂的食物网。 相似文献