影响母牛受胎因素的分析

为促进山区本地牛逐渐向肉役兼用方向发展,1986～1990年在泰安市郊区房村乡利用鲁西黄牛冷冻精液进行人工授精试验。五年累计配种1746头次,情期受胎率和总受胎率分别达到57.27％和85.56％。为了探讨影响母牛受胎率的因素,进而为农村推广人工授精技术提供经验,现将冷配试验总结如下。

鲁西黄牛杂交改良本地牛的效果观察

鲁西黄牛杂交改良本地牛的效果观察张俊功，牛其军，高居明，程钦财（山东省泰安市畜牧局，２７１０００）（房村畜牧兽医站）鲁西黄牛为我国地方五大良种黄牛之一，具有体型大，肉质鲜美、遗传性稳定的特点，用其作父本，可以改良本地牛生长慢、体型小、毛色杂的缺点。因...

Effect of laser power on microstructure and mechanical properties of laser heat conduction lap welded joint between AZ31B magnesium alloy and DP780 galvanized steel

In this work, laser heat conduction lap welding(LHCLW) of AZ31B magnesium alloy sheet and DP780galvanized steel sheet was carried out by the defocused laser beam. The effects of laser power on the microstructure and mechanical properties of the joint were studied. The pros and cons of the joint were identified and evaluated by measuring the tensile shear strength, microhardness and microstructure observation. The formation mechanism of various phases at the Mg/steel interface was analyzed. The results indicated that the galvanized layer could promote the metallurgical bonding between magnesium alloy and steel by improving the diffusion ability of molten magnesium alloy at the steel interface and reacting with Mg, so as to enhance the strength of the joint. A continuous dense layered eutectic structure(α-Mg+MgZn) was formed at the interface of the joint, while MgZn_(2)and MgZn phase was formed at the weld edge zone and heat affective zone(HAZ), whereas no reaction layer was generated between the uncoated steel and magnesium alloy. A sound joint could be obtained at 2.5 kW, and the corresponding tensile shear strength reached the maximum value of 42.9 N/mm. The strength was slightly reduced at 2.6 kW due to the existence of microcracks in the eutectic reaction layer.

不同药物对鲁西黄牛超排处理后血浆中孕酮、17β-雌二醇水平的变化

以FSH、PMSG和PMSG+APMSG等3组药物对鲁西黄牛进行超排处理,开始时,P_4处于黄体期的较高水平,发情前达列最低值,发情后第2天迅速上升,采集胚胎时达到高峰。采集胚胎后,注射15—甲基PGF_(2α),P_4水平又明显下降。在超排处理的第1—8天,3组试验牛血浆中P4水平曲线趋于一致,但第10和第12天时,PMSG组P_4水平明显升高,与其他二组比较差异显著(P<0.05)。开始超排时,3组血浆中E_2水平都急骤升高,发情时达到高峰。发情排卵后E_2水平迅速下降,其中FSH和PMSG+APMSG组呈波浪式维持在较低的基础水平上,而PMSG组在第8、10、12、14天时,E_2水平显著高于其他2组。

鲁西黄牛杂交改良本地牛效果观察

鲁西黄牛为我国10大地方良种黄牛品种之一。具有体型大、肉质好,遗传性稳定的特点。利用其作父本,改良山区本地牛生长慢、体型小、毛色杂的缺点,是养牛生产的重要内容之一。我们于1986年在泰安市郊区房村乡开展了鲁西黄牛杂交改良本地牛试验,为改良本地牛提供理论依据。1

山东烟草连锁经营与供应链管理可行性分析

我国的烟草行业是一个由国家垄断经营的特殊行业,被形象的比喻为国家计划经济的最后一块砖。进入21世纪我国加入WTO后,国内卷烟市场将进一步开放,烟草行业将面临着关税减让、配额和许可证管制放松的国内环境。我国烟草行业长期处于国家专卖管理体制下,缺乏最基本的市场竞争,仅仅依靠国家烟草专卖制度保持对销售终端的掌控力,一旦烟草专卖制度取消,烟草企业对销售终端的控制力也随之消失,届时烟草行业将面临严峻的生存环境,迫切需要转型升级。山东烟草可以凭借对销售渠道的控制优势、企业的信誉优势、物流配送优势、资金优势和卷烟产品在零售终端中的核心地位优势,联合上游供应商、控制下游终端网络,打通物流体系的最后一公里,从而打造出全新的烟草现代物流体系和现代流通品牌。