基于逆向工程的拖拉机造型CAD混合建模

针对国产拖拉机造型设计的特点,提出了基于逆向工程的拖拉机造型CAD混合建模方法.依据拖拉机造型三维效果图,建立了其油泥模型;采用Comet 250与AICON 3D Studio相结合的方法,基于特征进行点云数据的测量及处理,从测量数据中提取可重新进行设计的特征、约束及设计意图,在对数据进行分析的基础上,制定了建模方案...     

杂交粳稻泗优422制种特性探讨

观察了７３１Ａ、六千辛Ａ、轮回４２２、７７３０２的开花习性，并对其相互杂交的结实率进行了调查。与六千辛Ａ相比，７３１Ａ开花持续天数较短，开颖角度较小，柱头外露率低，开闭时间略长。在相同授粉条件下，７３１Ａ与轮回４２２的结实率低于六千辛Ａ与７７３０２。     

杂交玉米品种黔玉3号耐旱和耐盐能力的鉴定

分别用不同浓度的PEG-6000和NaCl溶液模拟干旱和盐胁迫,以常规玉米品种农大108为对照,从水分状况、膜伤害、光合速率、渗透势和离子吸收等生理指标对杂交玉米品种黔玉3号幼苗的耐旱和耐盐能力进行了比较和鉴定.结果表明,供试两玉米品种受胁迫后,地上部相对含水量、叶片净光合速率(Pn)和 PSⅡ最大光化学效率(Fv/Fm)都降低,叶片相对电解质渗漏率及盐胁迫下植株的Na /K 值都升高,农大108的变幅大于黔玉3号;叶片渗透势都降低,在盐胁迫下植株SRK,Na值都升高,但农大108的变幅小于黔玉3号.通过上述指标的综合评价表明,黔玉3号的耐旱、耐盐能力大于农大108.     

Bioavailability of ascorbyl phosphate calcium in hybrid catfish,Clarias macrocephalus (Gunther) × Clarias gariepinus (Burchell) feed

A 10-week feeding experiment was performed in hybrid catfish (Clarias macrocephalus (Gunther) × C. gariepinus (Burchell, 1822) with initial average weight of 1.17 g, in glass aquaria of 200-L capacity. The experiment comprised seven treatments with three replicates each. Ascorbyl phosphate calcium (APCa) was included at 30, 75, 150, 300 and 1000 mg kg⁻¹ feed and compared with one with ascorbyl polyphosphate (APP) at 36 mg kg⁻¹ feed and one without vitamin C supplementation. Fish fed APCa-supplemented feed showed better growth, feed conversion ratio, survival rate and protein utilization compared with those without such supplementation. Ascorbate concentrations in liver and head kidneys were correlated closely with dietary APCa levels. Vertebral collagen and hydroxyproline contents were significantly lower in the fish group without ascorbate supplementation. Red blood cell and white blood cell counts showed no correlation with vitamin C supplementation. Serum protein level was lowest in the group fed feed without vitamin C supplementation and this was lower than those fed feed with APCa and APP supplementation. The fish fed APCa- and APP-supplemented feed showed no difference in serum protein levels. External scorbutic symptoms and histopathological changes of gill tissue were noted in fish fed feed without APCa supplementation. The study indicates that 12.6 mg kg⁻¹ of ascorbic acid molar equivalent supplied as APCa (30 mg kg⁻¹) provided maximum growth and no gross signs as well as histological changes resulting from vitamin C deficiency.     

抗除草剂谷子杂交种长杂2号高产高效栽培技术研究

采用正交设计,对长杂2号的播期、施肥、留苗密度、种植方式4个因素的栽培技术进行了试验。结果表明,长杂2号在山西省中晚熟区取得高产的栽培方案是:最适播期5月20—25日,公顷留苗30万株左右,采用宽窄行种植方式。     

A survey of antimicrobial resistance in Escherichia coli isolated from wild sika deer (Cervus nippon) in Japan

We examined the antimicrobial susceptibility of 848 Escherichia coli isolates from 237 feces samples of wild sika deer (Cervus nippon) captured between 2016 and 2019 in 39 of the 47 prefectures of Japan. Five of the 237 wild sika deer (2.1%) carried E. coli with resistance to at least one antimicrobial, and all the resistant isolates showed resistance to tetracycline. The resistant isolates contained antimicrobial resistance genes that were similar to those in E. coli derived from humans and farm animals. Although wild sika deer are not currently likely to be a source for the transmission of antimicrobial resistance in Japan, they can potentially mediate antimicrobial resistance spread by coming into contact with humans, animals, and their surroundings.     

玉米新杂交种鲁单718的选育研究

简要介绍了玉米新杂交种鲁单718的选育背景、选育过程及品种特征特性等,对于鲁单718的成功选育提出了育种目标、选系技术与方法、杂种优势模式等方面的思路。     

杂交水稻新品种京福8优77的选育

京福8优77（京福8A／明恢77）是福建省农业科学院水稻研究所与福建亚丰种业有限公司合作选育的早籼三系杂交水稻新品种,该品种具有株型适中、穗大粒多、熟期转色好、产量高、稻瘟病抗性较好以及适应性较广等特点,2014年6月通过福建省农作物品种审定委员会审定（闽审稻2014003）。本文介绍京福8优77的选育经过、产量表现及品种特征特性。     

金枪鱼延绳钓船机电混合动力系统节油效果分析

金枪鱼延绳钓渔业是远洋渔业的重要组成部分。金枪鱼延绳钓作业过程包括航行、作业两种完全不同的工况。航行工况时要求航速较高,作业工况时要求航速较低。为了满足这两种工况,采用柴电独立运行(PTH)方式机电混合动力系统。机电混合动力系统由柴油机推进系统与电力推进系统两部分组成。高航速时使用大功率的柴油机模式,低航速时使用小功率的电力推进模式。上海远洋渔业有限公司近两年先后两批次建造了5条装备了PTH方式机电混合动力系统金枪鱼延绳钓船。根据实船测试,在作业期间,不同船型起钩阶段节油25%和8%,航行节油均达14%。通过计算分析,使用PTH方式,机电混合动力系统增加的初始投资成本可通过节油方式在4年内回收。综合节油效果显示,使用电力推进比使用柴油机推进可以节油15%~20%,达到了良好的节能减排、降低运营成本的效果。     

Piscine reovirus (PRV) in wild Atlantic salmon,Salmo salar L., and sea‐trout,Salmo trutta L., in Norway

This is the first comprehensive study on the occurrence and distribution of piscine reovirus (PRV) in Atlantic salmon, Salmo salar L., caught in Norwegian rivers. PRV is a newly discovered reovirus associated with heart and skeletal muscle inflammation (HSMI), a serious and commercially important disease affecting farmed Atlantic salmon in Norway. A cross‐sectional survey based on real‐time RT‐PCR screening of head kidney samples from wild, cultivated and escaped farmed Atlantic salmon caught from 2007 to 2009 in Norwegian rivers has been conducted. In addition, anadromous trout (sea‐trout), Salmo trutta L., caught from 2007 to 2010, and anadromous Arctic char, Salvelinus alpinus (L.), caught from 2007 to 2009, were tested. PRV was detected in Atlantic salmon from all counties included in the study and in 31 of 36 examined rivers. PRV was also detected in sea‐trout but not in anadromous Arctic char. In this study, the mean proportion of PRV positives was 13.4% in wild Atlantic salmon, 24.0% in salmon released for stock enhancement purposes and 55.2% in escaped farmed salmon. Histopathological examination of hearts from 21 PRV‐positive wild and one cultivated salmon (Ct values ranging from 17.0 to 39.8) revealed no HSMI‐related lesions. Thus, it seems that PRV is widespread in Atlantic salmon returning to Norwegian rivers, and that the virus can be present in high titres without causing lesions traditionally associated with HSMI.