Prevalence of intramammary infection and teat canal colonization in unbred and primigravid dairy heifers.

Teat canal keratin (n = 461) and mammary gland secretions (n = 370) were collected from 31 unbred and 85 primigravid Jersey heifers from one research and three commercial dairy herds. Of 97 heifers from which secretion samples were obtained, 96.9% had intramammary infections and 29% showed clinical symptoms. Seventy-five percent of quarters were infected. Staphylococcus aureus were isolated from 36 (37.1%) heifers and 55 (14.9%) quarters. One hundred and eight (93.1%) heifers and 326 (70.7%) quarters had teat canals colonized with mastitis pathogens. Staphylococcus aureus were isolated from teat canal keratin samples from 36 (31%) heifers and 57 (12.3%) quarters. The three most common species isolated from secretion and teat canal keratin samples were Staphylococcus chromogenes, Staphylococcus hyicus, and S. aureus. Secretions from infected (n = 240) and uninfected (n = 85) quarters had SCC of 13.6 X 10(6)/ml and 5.7 X 10(6)/ml. Macrophages were the most numerous cell type in secretions of infected and uninfected quarters. Quarters with teat canal colonization, but with no intramammary infections, exhibited higher SCC in secretion (9.3 X 10(6)/ml) than quarters without both teat canal colonizations and intramammary infections (4.9 X 10(6)/ml). Data indicated that intramammary infections and teat canal colonizations were more prevalent and SCC higher than previously realized in dairy heifers.     

燃气集团信息系统整合探讨

文章介绍了燃气信息化管理系统整合的目标、思路,并对信息系统整合的困难和整合的方式做了分析。最后对信息系统整合提出了建议。     

IS600BZa吹式比重去石机的结构特点

简述IS600BZa吹式比重去石机的结构特点，并结合设备的采购，谈了对目前国内粮机的看法。     

含中草药成分造纸法再造烟叶的制备

介绍了一种造纸法含中草药成分再造烟叶的制备工艺。该工艺应用了类似造纸的原理,将中草药与烟草混合萃取后,取其纤维制成高填充值的纸叶,萃取液经低温真空浓缩处理后浸涂到该纸叶上。该工艺扩大了中草药的用药范围,有效成分可较灵活控制,提高了中草药原料的利用率。制成的含中草药成分再造烟叶充分保留了不溶性有效药用成分,与烟香谐调,安全性好,同时具有较高的填充值,可以明显降低卷烟的制造成本。     

关注直通率提高生产过程质量保证能力

本文讲述了直通率的含义及计算方法，重点介绍了提高直通率的原则和方法。     

Design issues for the transformer in a low-voltage power supplywith high efficiency and high power density

Circuit model, design feasibility, and design tradeoffs are investigated for the transformer in 1.5-5 V power supplies with high efficiency and high power density. The transformer is constructed from a single or a matrix of pot cores and from interleaved planar windings. It has been determined theoretically and verified experimentally that such a transformer is realizable as long as the loss constraint is not severe (e.g. less than 0.5 W transformer loss per 100 W output). The primary source of loss is the winding, not the core, in 1.5 V/turn design. Measures to reduce the transformer height tend to increase transformer loss or volume