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采用二段三循环法对38Cr Mo Al A料筒螺杆进行表面氮化改性处理,经35h渗氮处理后,渗氮层深度超过0.55mm,表面硬度大于HV900,表面氮化脆度为一级。该结果表明二段三循环法可以比常规的二段渗氮法减少时间40%左右。 相似文献
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当前,我国的情报服务主要是文献服务,它是科研工作获取情报信息的重要途径和赖以发展的重要条件。没有文献服务,科学研究势必成为无米之炊。因此,努力开展多种形式并有成效的文献工作,对科研提供有保证的情报信息,便是研究单位情报部门的核心工作。开展文献服务,必须依据科研工作的实际需要和用户的具体情况,不失时机地提供适用情报。这种重视针对性和时效性的服务,是研究所文献服务的特征之一。下面,结合我们的实践,谈谈专业情报部门文献服务工作的几个方面。一、编辑出版近期专业文献通报近期专业文献通报,是一种强调时间性和专业性的文献题录通报,是一种以新近入藏的各类文献为基础,以本单位的专业设置 相似文献
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In order to study the effect of different preceding crops on soil fertility in tobacco growing areas, 166 soil samples were collected from Pingqiao tobacco growing area for nutrient determination. The analysis results show that: ① The overall soil pH value is at an appropriate level (5.5~7.0), the degree of soil acidification in the corn preceding crop is generally high, and the pH value in the peanut preceding crop is mostly at an appropriate level. ② The overall soil organic matter is at a suitable but low level. 83.33% of the soil organic matter content in the previous crop of tobacco leaves is at an appropriate level, while most of the soil organic matter content in the other previous crops is at a low level. It is necessary to supplement organic fertilizer in a timely manner. ③The alkaline nitrogen content in the soil of different previous crops exceeds 100mg/kg, which is above the average level. The application amount of nitrogen fertilizer should be controlled.④The soil available phosphorus content is relatively high in the previous crop of rice, while the rest are at an appropriate level, but the coefficient of variation is relatively large. ⑤The average content of soil available potassium is at an appropriate level, and the proportion of soil available potassium content in the previous crop of peanuts is the highest at an appropriate level, at 83.64%. ⑥The chloride ion content in the soil of the tobacco planting area is at the average level except for the previous crop of rice, but overall, the proportion of chloride ion content is relatively high. Therefore, comprehensive fertilization should be timely regulated s to regulate the proportion of chloride ions during the planting process.⑦Targeted fertilization suggestions were proposed for different previous tobacco fields. 相似文献
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正现阶段,在我国养猪产业的养殖规模在不断扩大,猪肉在肉类市场当中占据着十分重要的地位,不论是从消费量还是猪肉的产量来看,猪肉在市场当中都发挥着不可替代的作用。因此,猪群的健康养殖就显得极为重要,目前广大养殖户养猪的过程中常常会遇到猪群爆发大面积的疫病,造成巨大的经济损失和猪肉质量的下降,给社会的发展带来不安定因素。猪群主要疫病的治疗和防控工作对于生猪的健康生长、猪肉质量的提升都具有十分重要的作用,能够确保猪肉的养殖经济效益。本 相似文献
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