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1.
新疆盘羊(Ovis ammon)的地理分布特征   总被引:6,自引:0,他引:6  
新疆盘羊(Ovis ammon)分布可划分为三个阶段:10 000~5000年前为石器时代分布,5000~50年前为历史分布,50年前至今为现代分布。新疆盘羊分布非常广泛,从南边的昆仑—阿尔金山至最北的阿尔泰山,从东天山到准噶尔界山,甚至罗布泊和帕米尔都有分布。在昆仑—阿尔金山、中天山、巴尔鲁克山和玛依勒山,盘羊为连续分布;其它地区为成片分布、零星分布和季节性分布。盘羊栖息的海拔高度可从920~4600 m,垂直分布由于高程-纬度效应,从南到北一般随着纬度升高而降低。在水源缺乏的地区,其垂直分布还受地表水和泉水分布的制约。  相似文献   

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Mating by young males or low male‐to‐female ratios can decrease pregnancy rates and postpone birthdates in ungulates, thereby hindering population growth. Young (2.5–3.5 yr old) male bighorn (Ovis canadensis) behave differently than older males, and age, horn size, mating behavior, and social rank help determine reproductive success. We estimated birthdates in two populations of bighorn sheep in Utah, USA, to determine if mating by young males or low male‐to‐female ratios resulted in fewer young born per female, a shift in mean timing of births, or asynchronous births. When reintroduced, the Rock Canyon population consisted of four males (two each of 2.5 yr old and 1.5 yr old) and a 1 to 7.5 ratio of males (>2 yr old) to adult females (≥3.5 yr old); the Mount Nebo population consisted of four males ≤1.5 yr old and a 0 to 12 ratio of males to adult females. For both populations, the number of young born per female did not differ between the first parturition period after reintroduction (where females were impregnated by males from their source populations) and the second period of parturition (where females were impregnated by young, reintroduced males). Mean birthdates and synchrony (SD) of births did not differ for Rock Canyon (May 12, 2001 ± 4.5 d, May 14, 2002 ± 3.2 d) or Mount Nebo (May 23, 2005 ± 8.1 d, May 22, 2006 ± 10.2 d) between the first and second years following reintroduction. Mating by young males or low male‐to‐female ratios had no demonstrable effect on the number of young born per female or timing and synchrony of births in these populations.  相似文献   

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The aim of this experiment was to investigate differences in spacing behaviour, measured by the individual distance when resting and feeding, between two breeds of sheep with a different selection history. Eight groups of four pregnant ewes from the Nor‐X breed (a heavy, composite breed mainly selected for growth and meat quality) and eight groups of four pregnant ewes of the coloured Spæl breed (a light breed, mainly selected for wool quality) were placed in oblong experimental pens for 7 d. The distance between animals was measured from digital video recordings. The heavy Nor‐X ewes kept a significantly larger individual distance to their pen mates both during resting and feeding compared with the lighter Spæl ewes. Spæl ewes also kept a significantly smaller individual distance during resting than during feeding, but this difference was not found in Nor‐X ewes. Our results indicate that selection for growth and meat quality might influence spacing behaviour in sheep. Looking at the selection history of these two breeds, we discovered differences in how long they had coexisted with large carnivores. The possible effects of previous exposure to carnivores and the role of domestication in modifying spacing behaviour are also discussed.  相似文献   

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The Punjab Urial (Ovis vignei punjabiensis) is an endangered subspecie of ovidae, distributed as small scattered populations in the forest belt of the Himalayan foothills of Pakistan and in the areas enclosed by the Indus and the Jhelum rivers. The present study was conducted to evaluate the liquid storage of Punjab Urial spermatozoa in different extenders for use in future in situ conservation activities. Semen was collected by electro-ejaculation from three captive Punjab Urial rams. Suitable ejaculates of individual animals were pooled and divided into three aliquots for dilution with the experimental extenders (Tris–citric acid, skim milk and sodium citrate) at 37 °C. Extended semen was cooled from 37 °C to 5 °C in 2 h, and stored for three days at 5 °C. Sperm motility (%), viability (%; live/dead), acrosome integrity (%) and plasma membrane integrity (%) were assessed on days 1, 2 and 3 of storage. On day 1, sperm motility, viability as well as acrosome and plasma membrane integrity were similar (p > 0.05) in all three experimental extenders. On day 2, sperm motility, viability, acrosome and plasma membrane integrity were higher (p < 0.05) in Tris–citric acid extender compared to sodium citrate based extender. On day 3 of storage, the values of motility, viability and acrosome integrity were higher (p < 0.05) in Tris–citric acid extender than in skim milk and sodium citrate based extenders. In conclusion, Tris–citric acid extender appears to be a better option compared with skim milk and sodium citrate extenders for liquid storage of Punjab Urial semen.  相似文献   

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Résumé Les recherches combinées qualitatives et quantitatives indiquent chez la Brebis, et contrairement aux résultats acquis chez la Vache, que la parturition n'est pas accompagnée d'une décharge plus ou moins intense de calcitonine. La Brebis parturiente ne montre aucune variation significative de la calcémie et de la phosphatémie; sa thyroïde renferme des taux de calcitonine analogues à ceux rencontrés chez des brebis taries, non gestantes. Dans les mêmes conditions, l'examen au microscope électronique des cellules C permet encore de rendre compte d'activités de synthèse, de sécrétion et d'excrétion tout à fait normales.
Qualitative and quantitative studies of C-cell activity in the parturient ewe (Ovis aries L.)
Summary A combination of qualitative and quantitative studies show that there is not an abrupt release of calcitonin at the time of parturition in the ewe; these results differ from those obtained by several authors in the parturient cow. At lambing time, ewes are neither hypocalcemic nor hypophosphatemic; thyroidal calcitonin content is similar in parturient and in dry non-pregnant ewes. In electron microscopic studies, synthesis and release of calcitonin from C-cells in ewes, slaughtered in the hours just after lambing, appear to be as usual. These results are discussed with regard to the syndrome of parturient paresis in ruminants.
Avec la collaboration technique de Mme S. Vernerey.  相似文献   

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Boron is an essential nutrient for plants, but it is toxic in excess. Transgenic rice plants expressing an Arabidopsis thaliana borate efflux transporter gene, AtBOR4, at a low level exhibited increased tolerance to excess boron. Those lines with high levels of expression exhibited reduced growth. These findings suggest a potential of the borate transporter BOR4 for the generation of high-boron tolerant rice.  相似文献   

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A hemoglobin C chain has been detected in anemic Moufflon and in anemic Barbary sheep. Results of limited structural studies suggest that these C chains are closely related to the C chains which are produced in the domestic sheep and goat during experimental anemia and rather different from the C chain of certain nonanemic Barbary sheep. The structural variability among the chains of some nonanemic Caprini species is greater than that observed for the C chains of the same animals.This research was supported in part by United States Public Health Service Research grant HE-05168.  相似文献   

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第三节祖国在防治疾病上的伟大成就这节课是在学生已掌握了传染病的基本知識的基础上来进行講授的,首先在教材里提出以血吸虫病、天花、瘧疾、黑热病、痳疯等传染病說明了新旧社会的对比;同时也说明了社会主义社会制度的优越性。我們的党和政府对于人民健康的关怀是无微不至的,并且对于各种疾病的积极防治工作加强了党的领导,及时提出了一系列的方針、政策和措施;建立了专业防治机构,培养了专业干部;結合生产发动了广大羣众来参加防治。因此在防治各种传染病的工作中取得了很大的成績。  相似文献   

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第五节大脑皮层的机能——高级神經活动本节是本章也是本書的高峯,是把过去学习过有关反射作用的知識进行总結和提高,使学生能从理論上理解神经对人的意义——保持內部各器官的协調,同外界环境的统一。  相似文献   

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Hall(1977)首次在新西兰的土壤中发现GlomusinjtequensHall。Ames和Schneider(979)在美国的加利福尼亚再次发现了这个种。他们认为该种与无梗囊霉(Acauloryora)有相似之处,抱子都是从泡囊发育而成,但无梗囊霉的抱于是在产抱囊的侧面形成,而该种的抱子则是在产抱囊柄的内部发育而成的。为此,Ames和Schneider(197)为这个种建立起一个新属——内养囊霉属(Entrophospora),把这个种改名为稀有内养囊霉Entrophoworam斤equens(HallAmesetSchnelder。SChellGk和Spain(1984)报道了这个属的另一个种哥伦比亚内养囊霉(Entro…  相似文献   

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Abstract

The molecular structure of poly (dT)·poly (dA)·poly (dT) has been determined and refined using the continuous x-ray intensity data on layer lines in the diffraction pattern obtained from an oriented fiber of the DNA. The final R-value for the preferred structure is 0.29 significantly lower than that for plausible alternatives. The molecule forms a 12-fold right- handed triple-helix of pitch 38.4 Å and each base triplet is stabilized by a set of four Crick-Watson-Hoogsteen hydrogen bonds. The deoxyribose rings in all the three strands have C2′-endo conformations. The grooveless cylindrical shape of the triple-helix is consistent with the lack of lateral organization in the fiber.  相似文献   

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Obituary

Robert (Robin) Hill (1899–1991)  相似文献   

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TheZhoukoudian(Choukoutien)Site(英汉对照)TheZhoukoudianSite,famous“home”ofPekingMan,liesapproximately50kilometressouthwestofthePe...  相似文献   

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X-ray diffraction analyses of fibers of polydeoxyadenylic acid · polydeoxythymidylic acid show that this molecule exists as a 10-fold double-helix with axial rise per nucleotide h = 3.24 to 3.29 A?. The structure is very similar to B-DNA (h = 3.37 A?) in having C3-exo furanose rings and base-pairs positioned centrally on the helix axis, but distinctive enough to have two packing modes, neither of which has been observed for B-DNA. Although the triple-stranded poly(dT) · poly(dA) · poly(dT) also has a large value of h(3.26 Å), each of the chains is a 12-fold helix of the A-genus with C3-endo furanose rings and bases displaced several Angstrom units from the helix axis.  相似文献   

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(S)-(?)-Vertinolide 1 was synthesized via the tetronic acid derivative 6 from (S)-(?)-tetrahydro-2-methyl-5-oxo-2-furancarboxylic acid 3. (±)-Vertinolide was also synthesized from (±)-3.  相似文献   

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