公牛精子在四种介质中的品质变化     

王根林  于朝梅 《黑龙江动物繁殖》1994,(1)

６头荷斯坦成年公牛，每头采集３次精液，分别利用精子穿透试验和姬姆萨染色法，评定精子在发情母牛子宫颈粘液、ＶＢ１２、稀释液和解冻液等四种介质中的泳动速度、顶体完整车、畸形率以及精子有效存活时间的变化。结果表明，精子泳动速度在不同介质中的差异极显著，在宫颈粘液中显著高于其它介质，在ＶＢ１２中最低；不同介质中精子顶体完整率的差异不明显；畸形率在ＴＢ１２中显著低于解冻液；精子有效存活时间在稀释液和解冻液中显著高于ＶＢ１２中。不同公牛在四种介质中的反应亦有一定差异。  相似文献   

水稻白叶枯病菌胞外多糖的病理学研究     

蒋士君  陈寊 《湖南农业大学学报(自然科学版)》1992,(1)

测试了12个致病力不同的Xanthomonas oryzae Pv.oryzae 菌株,其EPS产生能力受培养周期和可利用糖的影响。多糖只有1个级分,不含蛋白成分,分子最小于2×10~6道尔顿。其非专化性毒性包括堵塞植物幼苗切条导管而致萎,导致被注有EPS的植物组织变裼坏死;诱使植细物胞电解质渗漏。此外,弱致病力菌株的FPS具有诱导品种对白枯病的抗性能力。初步认为,白叶枯病菌EPS可能与症状形成有关,并参与寄主一病菌相互作用过程中对水稻外源凝集素的识别,但EPS可能只是病菌致病力的构成之一。  相似文献   

Effect of Recovery Medium on the Isolation of Campylobacter Jejuni Before and After Heat Treatment     

Marja-Liisa Hnninen 《Acta veterinaria Scandinavica》1982,23(3):416

The effect of various concentrations of polymyxin B and Colistin in Skirrow’s or Butzler’s type media, respectively, on the recovery rate of 13 strains of G. jejuni before and after heat treatment was studied. Prior to heating, a Butz-ler’s type medium containing 40 I.U. per ml Colistin was inhibitory for certain strains of C. jejuni. After heating at 48° G for 30 min, media containing 2.5 I.U. per ml polymyxin B or 10 I.U. per ml Colistin were not inhibitory for heat-injured cells. When the concentrations of polymyxin B were increased to 5.0 I.U. per ml or those of Colistin to 20 or 40 I.U. per ml in the selective media, the means of the differences of log cell counts between non-selective Brucella blood agar and the selective media was statistically significant (P < 0.05). The mean D-value of G. jejuni strains in Brucella broth at 48° G was 18.4±5.4 min.  相似文献   

Mycoplasma bovis infections in cattle     

Maunsell FP  Woolums AR  Francoz D  Rosenbusch RF  Step DL  Wilson DJ  Janzen ED 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2011,25(4):772-783

Mycoplasma bovis is a pathogen causing respiratory disease, otitis media, arthritis, mastitis, and a variety of other diseases in cattle worldwide. It is increasingly recognized by the veterinary and livestock communities as having an important impact on the health, welfare, and productivity of dairy and beef cattle. M. bovis diseases can be difficult to diagnose and control because of inconsistent disease expression and response to treatments and vaccines, and large gaps in our understanding of the epidemiology and pathophysiology of these diseases. There are limited data on which to base evidence-based decisions for treatment and control, and the literature contains differing clinical biases and opinions. This document is intended for veterinarians dealing with cattle and is focused on the cattle production systems of North America. The goal of the consensus statement panel was to encourage an evidence-based approach to M. bovis problems. The scientific literature was critically reviewed, including peer-reviewed journal articles and reviews obtained by database searches using the terms "Mycoplasma bovis" or "mycoplasma + cattle." Where other data were lacking, conference proceedings were reviewed as a source of expert opinion.  相似文献   

农业机械虚拟现实设计——基于数字媒体技术及人机工程学     

张建敏  张达敏  陈静  易从琴  冉寒伟 《农机化研究》2011,33(12)

在传统的农业机械产品设计中,手绘设计不够精确和真实,同时设计进度缓慢,返工和修改工作量大,而基于数字媒体技术及人机工程学的虚拟现实设计具有高效、快捷、直观、网络化和资源易于共享等特点。设计师们通常使用CAD和3DS MAX进行虚拟现实设计,用CAD对零部件截面进行建模,用3DS MAX进行零件及外型建模、产品效果图、虚拟装配和机构运动动画仿真,形成全新概念的具有信息化、自动化、智能化和敏捷化等特点的现代虚拟现实设计技术。  相似文献   

Long-term deer exclusion in yew-wood and oakwood habitats in southwest Ireland: Changes in ground flora and species diversity     

Philip M. Perrin  Fraser J.G. MitchellDaniel L. Kelly 《Forest Ecology and Management》2011,262(12):2328-2337

Changes in ground flora were monitored over a 32-year period in deer exclosures in a yew-wood and a neighbouring oakwood in Killarney National Park, southwest Ireland; both woods are Annex I habitats under the European Habitats Directive. Comparison was made with unfenced plots adjacent to each of the exclosures. During the period of the study, both woods were heavily grazed by introduced sika deer (Cervus nippon). In the yew-wood exclosures, total ground flora cover increased markedly during the period of deer exclusion, the main species to increase in abundance being Rubus fruticosus agg. and Hedera helix. Herbaceous species increased initially in frequency but subsequently declined; herbaceous species had higher total cover in unfenced plots than in fenced plots at the end of the study. In the oakwood, Luzula sylvatica and Vaccinium myrtillus expanded their cover in one exclosure with cover in ferns declining, but in other exclosures where dense holly thickets developed, it was instead R. fruticosus and H. helix that became more abundant within the fences than outside. Overall, long-term fencing has caused a shift from vegetation characterised by woodland specialist to woodland generalist species and there are indications of a long-term decline in diversity. We conclude that chronic heavy grazing in these woodlands has strongly influenced the overall abundance and composition of the ground flora, but that complete exclusion of grazing is also undesirable due to potential declines in diversity of woodland specialists.  相似文献   

不同种源南方红豆杉幼林生长和紫杉醇含量的研究   总被引：6，自引：2，他引：4       下载免费PDF全文

张蕊  周志春  余能健  骆文坚  冯建国  金国庆 《林业科学研究》2011,24(1):56-62

利用在福建明溪和浙江龙泉农田庇荫设施栽培的24个种源的2年生南方红豆杉种源试验林,研究幼林收获期生长、分枝、生物收获量和枝叶紫杉醇含量的种源差异和地理变异模式,并综合选育出一批药用优良种源。结果表明:南方红豆杉幼树树高、当年抽梢长、地径、冠幅、最长侧枝长、当年侧枝数、侧枝总数和鲜枝叶紫杉醇含量等在种源间差异显著,不存在明显的地理变异模式。来自气候温暖但年降水量较少地区的种源生长快、分枝多、树冠浓密。与生长和分枝性状不同,产地年均温低、≥10 ℃积温小的种源其鲜枝叶紫杉醇含量较高,产地年降水量对种源鲜枝叶紫杉醇含量影响较小。南方红豆杉生长和分枝性状不仅存在显著的种源效应,而且存在明显的地点效应和种源×地点互作,栽植地水热资源丰富及适宜栽植密度可显著促进植株的树高和分枝生长及生物收获量的提高。种源生长和分枝性状间呈显著的正相关,而种源鲜枝叶紫杉醇含量与生长、分枝性状和生物收获量则不显著负相关或不显著正相关,有利于生物收获量大、紫杉醇含量高的优良种源选择。依据鲜枝叶紫杉醇含量和产量筛选出安徽黄山、福建柘荣、湖南桑植、贵州黎平、云南石屏5个药用优良种源,其单株鲜枝叶紫杉醇产量大于种源总体平均值的17.65%-25.77%,鲜枝叶紫杉醇含量皆在97 mg·kg^-1以上。  相似文献   

不同覆盖基质粒径对草花种子出苗质量的影响     

陈莉  盛利  吴稚斐  刘晓娣  曲修永 《山东林业科技》2011,41(5):50-52

草花在园林景观利用的地位越来越来高,草花生产育苗技术是关键环节。蛭石且有可靠的理化性质,是作为草花种子发芽的上好覆盖材料,不同粒径的蛭石对草花的发芽生长有直观影响。试验表明：三级蛭石比二级蛭石作为覆盖基质对柳穿鱼和福禄考种子发芽率有提高,柳穿鱼和福禄考种苗根长、根重有提高。  相似文献   

须弥红豆杉育苗基质的筛选试验     

杨文忠  赵丽芳  杨斌  王卫斌  余子哈  杨根林 《西部林业科学》2011,40(1)

在滇西北须弥红豆杉的主要天然分布区丽江市,结合生产实践中广泛使用的几种育苗基质,开展了腐殖土、腐殖土+圃地土、圃地土、泥炭基质4种育苗基质对须弥红豆杉实生容器苗生长影响的试验.苗木培育586天后对其成苗率、全株长度、苗高、根系长度及1～3级根数目等生长指标进行统计分析,结果表明:腐殖土+圃地土的育苗效果最佳,单独使用腐殖土作为育苗基质的效果最差;证明了传统认为的泥炭基质、腐殖土育苗效果最好、圃地土效果最差的观念并不正确.研究结果对滇西北地区开展须弥红豆杉壮苗培育具有实际应用价值,对其他地区的红豆杉苗木生产有参考意义.  相似文献   

不同栽培基质对'西伯利亚'百合生长的影响     

李云飞  朱莉  孙奂明  隗公臣 《北方园艺》2011,(6):75-76

以周径16~18 cm的‘西伯利亚’百合种球为试材,研究了不同栽培基质对百合生长的影响。结果表明:50%草炭+50%蛭石处理的植株长势最好,其次是70%草炭+20%珍珠岩+10%壤土和60%草炭+20%蛭石+20%壤土处理的,3种处理间差异不显著。50%壤土+50%牛粪处理的植株长势最差。基质成本分析表明,50%草炭+50%蛭石处理的为150元/m3,70%草炭+20%珍珠岩+10%壤土处理的为106元/m3,60%草炭+20%蛭石+20%壤土处理的为110元/m3。70%草炭+20%珍珠岩+10%壤土的混合基质成本比50%草炭+50%蛭石的混合基质成本低44元/m3,前者可以在生产中应用。  相似文献