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排序方式: 共有64条查询结果,搜索用时 15 毫秒
41.
MJ Thompson J Toomre ER Anderson HM Antia G Berthomieu D Burtonclay SM Chitre J Christensen-Dalsgaard T Corbard M DeRosa CR Genovese DO Gough DA Haber JW Harvey F Hill R Howe SG Korzennik AG Kosovichev JW Leibacher FP Pijpers J Provost EJ Rhodes J Schou T Sekii PB Stark PR Wilson 《Science (New York, N.Y.)》1996,272(5266):1300-1305
Splitting of the sun's global oscillation frequencies by large-scale flows can be used to investigate how rotation varies with radius and latitude within the solar interior. The nearly uninterrupted observations by the Global Oscillation Network Group (GONG) yield oscillation power spectra with high duty cycles and high signal-to-noise ratios. Frequency splittings derived from GONG observations confirm that the variation of rotation rate with latitude seen at the surface carries through much of the convection zone, at the base of which is an adjustment layer leading to latitudinally independent rotation at greater depths. A distinctive shear layer just below the surface is discernible at low to mid-latitudes. 相似文献
42.
ER da Cunha CF Martins CG Silva HC Bessler SN Báo 《Reproduction in domestic animals》2014,49(5):806-812
The objective of this work was to study cellular types that did not participated in the gastrulation process, amniotic fluid cells (AFCs) and umbilical cord cells (UCCs), in conditions of long‐term culture and cryopreserved with different solutions. The AFCs and UCCs were used in a comparative study with ear fibroblast cells (EFCs) that were cultured in vitro until 20 cellular passages and cryopreserved in 10% dimethylsulphoxide (DMSO), 5% dimethyl formamide (DMF) and 7% glycerol (Gly) solutions. The cellular viability, ultrastructure, DNA fragmentation and chromosome stability were evaluated to determine the cellular type most resistant. In all cell types, it was possible to evaluate the AFCs until 15 passages and UCCs until 20 passages with different periods of cellular growth to reach the confluence phase. Solutions containing 10% DMSO ensured viability of 90.33 ± 5.58%, 90.56 ± 4.40% and 81.90 ± 3.31%, respectively for EFCs, AFCs and UCCs, being significantly more efficient and with less variation than other cryoprotectant solutions. The AFCs were more sensitive to cryopreservation and presented low viability rate at the passage 20 (17.2 ± 8.87%). There was no change in karyotype and nuclear fragmentation was low in all cellular passages studied. With the scanning electron analysis was possible the characterization of AFCs and UCCs in suspension. The three cellular types of cells presented different shapes and characteristics on the surface. The results demonstrate that bovine AFCs and UCCs can be isolated, cultured in vitro and cryopreserved in 10% DMSO, not causing damage to DNA and chromosomes. The UCCs were more resistant than AFCs in all aspects. 相似文献
43.
ER JOHNSON 《Australian veterinary journal》1996,73(6):225-232
A progeny testing system to measure beef carcase merit, the Abtech Test, has been developed. Nine carcase characteristics are measured objectively at a slaughter age of 300 days on the carcases of 12 steer progeny per sire. Five carcase characteristics were used to quantify the carcase, namely, carcase composition as submitted, carcase composition (adjusted to 20% total carcase fat), estimated lean meat yield (adjusted to 20% total carcase fat), muscle-bone ratio (adjusted to a common muscle plus bone weight), and eye muscle volume index (adjusted for total carcase muscle weight). Four carcase measurements used to describe quality were evaluated: eye muscle area at the 10th rib (adjusted for total carcase muscle weight), marbling of the eye muscle at the 10th rib (chemically determined and adjusted to 20% total carcase fat), muscle texture at the 10th rib (mean muscle bundle diameter) and fat colour (determined on intermuscular fat at the 10th rib under standard conditions).
It is proposed that this testing system could be used for the genetic improvement of beef carcases. 相似文献
It is proposed that this testing system could be used for the genetic improvement of beef carcases. 相似文献
44.
为了探索适宜的玉米黄素双棕榈酸酯(ZDP)乳液制备工艺,通过高压均质方法,采用2种天然乳化剂:大豆卵磷脂(SL)和乳清分离蛋白(WPI)和4种合成乳化剂:十聚甘油单油酸酯(PGE18)、十聚甘油单月桂酸酯(PGE12)、蔗糖酯(SE15)和吐温80(T80),以及2种不同油相:大豆油(SO)和中链甘油三酯(MCT),分别制备了ZDP乳液,研究了不同乳化剂种类和质量分数以及油相种类对ZDP乳液性质和稳定性的影响。同时,在最佳乳化剂条件下,研究了ZDP添加量对乳液性质的影响。研究结果表明:天然乳化剂乳化制备所得ZDP乳液平均粒径大,且稳定性一般。小分子合成乳化剂制得的ZDP乳液平均粒径小,但稳定性差异大。其中,PGE18为乳化剂时制备的乳液各项指标较好,且在质量分数为0.8%时乳化效果最好。MCT为油相较SO为油相制备所得乳液稳定性好。因此,选择质量分数为0.8%的PGE18为乳化剂,MCT为油相,高压均质可以制得粒径小于200 nm的ZDP乳液,且在4℃下贮藏28 d仍可保留约90%的ZDP。ZDP添加量变化在4~32 nmol/g时对ZDP乳液的粒径和电位无显著影响。 相似文献
45.
J S Kaminjolo P N Nyaga J K Omuse E R Mutiga 《American journal of veterinary research》1975,36(1):123-125
Infectious bovine rhinotracheitis-infectious pustular vulvovaginitis (IBR-IPV) viral isolates were obtained from cattle affected with epididymitis-vaginitis. Isolation of virus from the diseased animals indicated that the genital form of IBR-IPV virus infection exists in Kenya and that epididymitis-vaginitis may be associated with IBR-IPV virus. Serums prepared from cattle having the genital form of the disease did not always have detectable antibody titers. 相似文献
46.
47.
A study of parturient calf mortality in a herd of 250 Shorthorn cattle on the Southern Tablelands of New South Wales is reported. Death rates as high as 44% from heifer groups are described. There were 30 parturient deaths of which 27 were confirmed as due to maternal dystocia. Pathological changes in many of the dystocia-caused deaths were minimal, but a congested, swollen tongue was a definitive lesion. The death rate was not significantly higher in heifers mated at 14 to 16 months of age than in those mated at 20 to 22 months, but significantly more male than female calves died from maternal dystocia. As two dead calves were affected with goitre, a comparative trial using parenteral iodine was designed. Ratios of thyroid weight to calf body weight were examined for 24 of the calves where the mean was 0.52 gm/kg. Goitre was found not to be a contributing factor to the calving mortality problem. The use of a Jersey bull for heifer matings eliminated the dystocia problem. The Jersey cross allowed safe, early mating at 14 months of age. 相似文献
48.
近年来,以往不被木材加工行业和广大消费者群体接受和认可的数以百计的木制品之中的小产品——木皮,越来越受到生产和加工木材制品的企业欢迎与青睐,而且逐渐在市场上经受住了考验与洗礼。从我国东南沿海及许多大中型城市的木材制品的销售情况来看,凡是使用了木皮作为贴面的产品,都要受到市场的热捧,尤其是天然木皮产品更是待遇有加。正因为拥有了广大消费者也就是消费市场的“准入证”和“通行证”, 相似文献
49.
【目的】 研究深松结合覆膜滴灌对绿洲棉田根区土环境与根腐病发生的影响。【方法】 在新疆阿克苏地区阿瓦提县设置深松30、40和50 cm(S30、S40和S50)3种深松模式,以传统翻耕为对照(CK),研究深松对根腐病发病指数、土壤含水率、根系形态、根系活力及产量构成等影响。【结果】 与传统耕作相比,深松可有效降低耕层土壤容重,增加土壤储水能力,增加土壤扩库增容效果,病情指数的降低与土壤容重下降、土壤含水率的增加和根系活力增加具有显著的相关性。其中深松降低生育期根腐病发病指数7.0%~26.0%,以S40处理效果最佳,发病指数较传统耕作相比降低26.0%。随着深松深度的增加土壤容重依次下降,与对照相比降低2.4%~10%。深松深度与根系主要形态指标与活力具有线性相关性,与传统耕作相比根系长度增加4%~34.6%,根系表面积增加13.1%~44.8%,根系体积增加9.2%~40.6%,根系活力增加7%~42.9%。根区环境的改善促进产量增加,S40处理皮棉产量分别较CK、S30、S50增加了22.2%、15.7%和2.5%。【结论】 在新疆南疆棉区采用深松结合覆膜滴灌措施具有良好的蓄水保墒和防病增产效果,对棉花生长有利,深松40 cm处理可作为较为理想的根腐病农艺防治措施在生产中推广应用。 相似文献
50.
M. ÍHA J. KUBEKA M. VAEK J. SEA T. MRKVIKA M. PRCHALOVÁ J. MATNA M. HLADÍK M. ECH V. DRATÍK J. FROUZOVÁ E. HOHAUSOVÁ O. JAROLÍM T. JZA M. KRATOCHVÍL J. PETERKA & M. TUER 《Fisheries Management and Ecology》2009,16(2):121-129
Abstract The inshore fish community of the Římov Reservoir in the Czech Republic was evaluated over 21 years using shore seining at night. The development of the fish community was divided into two separate phases: a highly dynamic and unstable phase dominated by perch, Perca fluviatilis L., was replaced by an extremely stable cyprinid phase dominated by roach, Rutilus rutilus (L.), and bream, Abramis brama (L.). The abundance of both these species oscillated during the cyprinid phase, but with decreasing amplitude. The proportion of piscivorous fish species such as asp, Aspius aspius (L.), pike, Esox lucius L., and pikeperch, Sander lucioperca (L.), increased slightly with time but remained low. The biomass of large Cladocera was negatively correlated with fish biomass only during the perch phase. The Shannon–Weaver index of diversity increased during the fish community succession, mainly because of greater evenness amongst the species. 相似文献