共查询到20条相似文献,搜索用时 15 毫秒
1.
Variations in fifteen metrical measurements and six non-metrical traits in 131 mink skulls were investigated. The skulls were subdivided geographically into three samples: Eastern Norway, Western Norway and Trøndelag. Separation into juveniles and adults was in accordance with the criterion that all sutures are closed in adults. This seemed to work well. No age or sex variations were found in the non-metrical traits. Relatively little geographic variation found in either the metrical measurements or the non-metrical traits indicated little genetic variation. Gene-flow is regarded as one of the reasons for this. 相似文献
2.
Wang Banyue 《古脊椎动物学报》1994,(4)
Inl988-199otheRegionalGeologicalSurveyTeamoftheGeologicalBureauofNingxia(RGSN)foundsomefossilmammalsinthelowerpartoftheHo11g1iugouFormationandtheupperpartoftheOligocene.Inl992ajointteamoflnstituteofVertebratePaleontologyandPaleoanthropo1ogy,AcademiaSinica(IVPP),andtheRGSNwenttoHaiyuailCountyandcollectedmorefossilmamma1sfromtheYuanjia-wowoareausi11gascreen-washingmethodThemammalfaunafromthelowerpartoftheHongliugouFormationiscomposedofAprotodonsp.,Indricotheriidaeindet.,Rhinoceroti… 相似文献
3.
A Celko B Burianová B K?íz V Zikmundová V Zikmund J Stríbrny 《Journal of hygiene, epidemiology, microbiology, and immunology》1985,29(1):83-88
Examinations of 297 sera for diphtheria antitoxin and 160 sera for tetanus antitoxin were carried out in 1981. All sera were obtained from the cord blood of mothers between 15 and 34 years of age. The mothers were divided into four age groups each of which was further subdivided into the primipara and multipara subgroups. The aim was to assess the age-specific variations in response to active immunization against diphtheria and tetanus. The protective level of diphtheria antitoxin (at least 0.01 I.U./ml) was recorded in the serum of 96.3% of examinees and the rates of seropositivity were found to fall with increasing age. The protective level of tetanus antitoxin (at least 0.1 I.U./ml) was found in the serum of 95.2% of mothers. The serologic response encountered in groups of older mothers was a clear-cut demonstration that the country-wide mass immunization against tetanus carried out between 1974 and 1975 was highly effective and fully justified. The variations in the diphtheria and tetanus antitoxin levels found in the primipara and multipara subgroups were not statistically significant. 相似文献
4.
N. C. Bennett 《Journal of Zoology》1990,220(2):225-247
This paper reports qualitative and quantitative behavioural studies of the social mole-rat C. damarensis . The behaviours were subdivided into four major categories: nest, maintenance, interactive and auto-behaviours. Social interactions and behavioural types were analysed by sex, age category and caste. The nest area is a focal point in the burrow system with individuals spending more than 70% of the day there. Many of the interactive behaviours occurred there and the mole-rats showed definite preferences with regard to which individuals they rested next to or avoided.
The Damaraland mole-rat colonies show some division of labour, into frequent and infrequent worker groups; these castes differed significantly in the amount of both digging and soil movement undertaken. 相似文献
The Damaraland mole-rat colonies show some division of labour, into frequent and infrequent worker groups; these castes differed significantly in the amount of both digging and soil movement undertaken. 相似文献
5.
Age and hunting success in the brown pelican: influences of skill and patch choice on foraging efficiency 总被引:1,自引:0,他引:1
C. A. Brandt 《Oecologia》1984,62(1):132-137
Summary Age-related differences in the foraging efficiency of piscivorous birds may be the results of differences in foraging skill, patch usage, or both. Brown pelicans were observed while foraging around a small Caribbean island. Areas where the birds fed were subdivided into small, homogeneous subunits (patches), and the bird's foraging success and patch use were noted and analyzed using multivariate techniques. Adult birds were found to be better at capturing prey under all conditions than were juveniles, but the differences were small in some patches. The density of prey and the birds' foraging success influenced the foraging efforts of adult and juvenile pelicans to similar degrees. Both age groups utilized local enhancement in their foraging, but such behavior augmented the foraging success only of juvenile birds. Both age groups often fed in patches where their foraging success was quite low. Such behaviour was much more costly for juvenile than for adult pelicans. 相似文献
6.
湖北南襄盆地枣阳凹陷第三纪轮藻化石及其地层意义 总被引:1,自引:1,他引:0
本文研究了南襄盆地枣阳凹陷第三系玉皇顶组到凤凰镇组轮藻化石。共划分出4个组合,其时代分别属早始新世、中始新世、晚始新世和渐新世。 相似文献
7.
In industrialized countries, male excess is generally found in early deaths, despite the overall decrease in mortality. We studied the association between sex and some factors generally considered crucial for babies' survival, such as mother's age and education, birth order, and gestational age, in order to gain insight into the causes underlying the persisting higher vulnerability of male sex in early life. The analysis was performed on babies dying during the perinatal period. These were subdivided into those who were stillborn and those who died during the first week of extrauterine life. A higher male excess among babies dying during the neonatal period than among those who were stillborn was always found in all classes of all factors. The finding of such generalized male overmortality in the early extrauterine period of life, together with the patterns shown by the temporal sex ratio in stillbirths and in early deaths, supports the hypothesis of a postponement of male risk from late fetal into neonatal life. 相似文献
8.
Ehrhard Voigt 《Pal?ontologische Zeitschrift》1995,69(1-2):173-179
Septocea septifera n.g. n.sp. (Family Semiceidae Buge) is a very strange free-walled cyclostome bryozoan species of Maastrichtian age with regard to its apertural morphogenesis. The zoarium is erect, eschariform, without heteromorphs, the aperturae lack ringlinke peristoms and are subdivided by vertical septa. The septa are recognized as extern walls of axially budded immature zooecia in the interior of the living chamber. The oval to triangular apertura is subdivided by the septa into one larger and one or two smaller openings. The evidence that axial intrazooecial budding also exists in other, not closely related taxa, proves that these structures are convergent. Their morphogenesis, systematic value and the taxonomic status of the Family Semiceidae are discussed. 相似文献
9.
Chromosome studies were carried out in long-term (142 and 184 d) human lymphocyte in vitro cultures in order to investigate the cytogenetic status of aging lymphocytes. The female donors were subdivided into three subgroups according to their age: 20-40 year-old (three individuals), 70-90 year-old (five persons), and centenarians (three persons). Besides some aneuploidy and structural abnormalities, telomere fusions were detected in all donor cells, and associations of acrocentric chromosomes were found in six persons in the three age-groups. Clonal trisomy 2 was present in three individuals (two from the 70-90 year-group and one centenarian with a clone +2, +8). While telomeric fusions and acrocentric associations seem to be more related to in vitro aging, trisomy 2 also appears dependent on the age of the cell donors. 相似文献
10.
《International journal of bio-medical computing》1985,16(3-4):231-243
This paper proposes two models, one a purely empirical one and the others a mathematical one, which depict the relationship between patient age and nosocomial infection rate. The empirical model is based on the two age-specific phenomena, the acquisition of resistance to infection with age mainly in the early years of life and the deterioration of existing resistance mechanisms with ageing predominantly in the later years of life. The net effect of these two factors is shown to approximate into a quadratic relationship betwen age and nosocomial infection rate, like the type demonstrated in earlier experimental studies. The second mathematical model is derived from studies on cancer research and here the relationship between age and nosocomial infection rate for patients in the age group 30–70 years is represented by a log linear model. The model was tested against experimental data derived from large surveys on nosocomial infection and the resulting correlation coefficient was 0.98. The model was an extremely good fit when tested against posto-operative wound infection rates as well as nasal carriage rate of antibiotic resistant Staph. aureus. Furthermore, when patients in the survey were subdivided into groups of male patients and female patients and into two groups based on the type of operative wound, the model was still found to be a very good fit to the experimental data. This confirmed the validity of the model even in the presence of other patient-related parameters. Finally, the model was tested against the results of a totally different experimental study conducted elsewhere and the resulting correlation coefficient was 0.999, which confirmed the validity of the model in a universal context. 相似文献
11.
人源性神经营养素-6对大鼠面运动神经元逆行溃变的保护作用 总被引:1,自引:0,他引:1
目的:探讨人源性神经营养素-6对受损伤神经元的保护作用,为全面了解人源性NT-6的神经生物学特性以及为临床上退行性神经病变的治疗提供实验依据.方法:将健康成年SD大鼠随机分为两组,即不做任何处理的正常对照组和切断一侧面神经后引起面运动神经元逆行溃变的实验组;实验组又根据面肌内注射物的不同分为空白对照组、人源性NT-6实验组和生理盐水对照组.动物饲养两周后,取脑干切片,行尼氏染色和胆碱乙酰基转移酶免疫组化染色,观察人源性NT-6对逆行溃变的面运动神经元的保护作用.结果:与空白对照组和生理盐水对照组相比,NT-6实验组面神经核尼氏染色的强度值和面神经核内ChAT阳性神经元数目显著增加.结论:人源性NT-6对由于轴突损伤引起逆行溃变的神经元具有保护作用. 相似文献
12.
The study objective was to analyze the integration of psychomotor coordination into other dimensions evaluated. Four morphologic variables (stature, body mass, forearm circumference and triceps skinfold) and 7 motor variables (hand tapping, standing jump, sit-ups, forward bow, bent arm hang, 3-min run and polygon backward) were assessed in a sample of 2205 male children (subdivided into 4 groups) aged 7-11 years, elementary school first- to fourth-graders from the Primorje - Gorski Kotar County, Republic of Croatia. Relations between the set of morphologic-motor variables and the coordination variable (of backward polygon) as a criterion were analyzed Data were processed by use of regression analysis. Study results clearly indicated the values of the criterion variable (coordination) to rise and the criterion prediction using the set of variables to improve with age. Explosive strength, movement frequency and static strength were the best positive criterion predictors, whereas body weight at age 7-10, and skeletal longitudinality and subcutaneous adipose tissue at age 10-11 were the best negative criterion predictors. Also, developmental characteristics of coordination were found to be a major determinant on programming the work in kinesiologic education of elementary school children. 相似文献
13.
Four morphological and 7 motor variables were assessed in a sample of 2,235 female children (subdivided into 4 groups) aged 7-11 years, elementary school first- to fourth-graders from the Primorje-Gorski Kotar County, Republic of Croatia. The study objective was to analyze the morphological-motor structures according to age. Factor analysis was done for each of the four subject groups. Results clearly showed the morphological-motor functioning of the girls to change with age. Developmental processes lead to the formation of a general morphological factor defined as ectomesomorph and two general mechanisms responsible for motor efficiency in the form of strength regulation and speed regulation. The results obtained were found to be consistent with the existing relevant models related to the morphological, motor, functional and cognitive systems. The more so, these results allow for a supramodel to design, which will integrate relevant elements of all these models to define the function of the body as a whole. 相似文献
14.
Willis W. T.; Brooks G. A.; Henderson S. A.; Dallman P. R. 《Journal of applied physiology》1987,62(6):2442-2446
We measured mitochondrial enzyme activities in skeletal muscle under conditions of iron deficiency and endurance training to assess the effects of these interventions on the contents and proportions of non-iron-containing and iron-dependent enzymes and proteins. Male Sprague-Dawley rats, 21 days of age, received a diet containing either 6 (iron deficient) or 50 mg iron/kg diet (iron sufficient). At 35 days of age animals were subdivided into sedentary and endurance training groups (running at 0.7 mph, 0% grade, 45 min/day, 6 days/wk). By 70 days of age, iron deficiency had decreased gastrocnemius muscle cytochrome c by 62% in sedentary animals. In contrast, the activities of tricarboxylic acid cycle enzymes were increased, remained unchanged or were slightly decreased, indicating that iron deficiency markedly altered mitochondrial composition. Endurance training increased cytochrome c (35%), tricarboxylic acid cycle enzymes (approximately 15%), and manganese superoxide dismutase (33%) in iron-deficient rats, whereas the same exercise regimen had no effect on the skeletal muscle of iron-sufficient animals. The interactive effect of dietary iron deficiency and mild exercise on mitochondrial enzymes suggests that adaptation to a training stimulus is, to some extent, geared to the relationship between the energy demand of exercise and the capacity for O2 transport and utilization. 相似文献
15.
Population genetics of marine species: the interaction of natural selection and historically differentiated populations 总被引:6,自引:0,他引:6
Thomas J. Hilbish 《Journal of experimental marine biology and ecology》1996,200(1-2):67-83
High gene flow, particularly as mediated by larval dispersal, has usually been viewed as sufficient to limit geographic isolation as a major source of population differentiation among marine species. Despite the general observation of relatively little geographic variation among populations of high dispersal marine species many cases of divergence have been observed and natural selection has usually been invoked to explain geographic divergence. Detailed study of several allozyme polymorphisms provided additional evidence that selection may be the predominant force that determines genetic divergence in marine systems. There is, however, growing evidence that marine species with high dispersal are more subdivided than originally thought. The use of multi-locus approaches and the application of molecular techniques have provided new insight into the nature of population divergence in marine species. I argue that (1) many species, which were formerly thought to be unstructured, are in fact subdivided into genetically discrete groups, (2) it is often the case that genetically subdivided populations have distinct evolutionary histories, (3) in many cases, natural selection is the consequence of introgression between these groups, and (4) the combination of molecular assays of both nuclear and mitochondrial DNA and allozyme loci provides the best approach to understanding the evolutionary dynamics of these interacting populations. 相似文献
16.
Holoprosencephalic synophthalmia (cyclopia) in an 8 week fetus 总被引:1,自引:0,他引:1
G H Sperber E S Johnson L Honoré G A Machin 《Journal of craniofacial genetics and developmental biology》1987,7(1):7-18
Histopathological examination of an 8-week-old human cyclopic fetus revealed holoprosencephaly, synophthalmia, and malformed midfacial features. The telencephalon was undivided and projected a single median optic stalk partially subdivided into optic vesicles contained in a single orbit. Aberrant midfacial ossification underlay arrhinia and uncleft lips and palate. Maxillary anodontia and mandibular hypodontia prevailed. Postcranial normality was disturbed by pedal postaxial hexadactyly, suggesting trisomy 13. The exceptionally young age of the specimen distinguishes its detailed analysis from the majority of older cyclopic specimens previously reported. 相似文献
17.
Selection for high adult body weight in Drosophila melanogaster was practiced for 18 generations in three selection lines. These lines were genetically similar and of equal size but different in population structure. One line represented a large mass-selected, random-mating population, while the other two lines simulated large populations that had been subdivided into partial isolates or demes. Mass selection and random mating occurred within each deme. These two subdivided lines were different only in the rate of effective migration among the demes (5% and 10%). Selection intensities of approximately 20% were applied to these populations. A fourth line served as a random mating control. Heritability of adult body weight in the base population was estimated to be 0.58± 0.22. The results indicate that significantly greater responses were achieved in the subdivided lines than in the large mass-selected line, in spite of the fact that larger selection differentials were applied to the latter. No significant differences in response were observed between the two subdivided lines. Wright (1930, 1931) postulated that selection would be most efficient in subdivided populations with limited interdeme migration. The present findings appear to support this theory. 相似文献
18.
准噶尔盆地侏罗纪介形类已由众多中外地层古生物工作者进行过数十年的研究并有系统成果问世。本文仅介绍两个侏罗系化石点,作为前人工作之补充,充实已有化石记录,也提出了进一步划分的建议和依据。 相似文献
19.
<正> 南宁盆地脊椎动物化石地点目前所知不下七处。本文着重记述了1974和1979年笔者采自邕宁县五塘公社莲塘村的石炭兽化石,并对盆地东部下第三系作一初步划分。本文首次报道南宁盆地发现脊椎动物化石,对研究石炭兽的演化、发展和分布,对盆地第三系地层的划分和对比,提供了新的依据。一、化石地点及地层概况莲塘村位于南宁市东北约32公里、五塘圩东5公里、邕宾(南宁—宾阳)公路南侧。石炭兽化石产于莲塘村东约300米远的小煤窑、距地表8.3米深的褐煤层顶板(灰色泥质粉砂岩)中。 相似文献
20.
None of the 24 Pseudomonas syringae bacteriophages were found to be identical in the spectrum of lytic action. The phages were subdivided into five groups according to the number of sensitive bacterial strains and their qualitative composition. 相似文献