秦川牛保种情况的分析(续) Ⅱ、群体留种方式与世代间隔

根据陕西省秦川牛场秦川牛保种群30多年的记录统计,分析了该群体的世代间隔与留种方式。结果表明,该群体平均世代间隔为6.9年,采取的是对保种不利的合并留种,导致各种家系后代供量方差增大,尤其是公牛的女儿供量方差高达77.39,比平均女儿供量(5.84头)高13倍。不同始祖个体在后裔群中的血统分布也极不均匀。若能改进留种方式或设法降低选择强度,则可大大提高保种效果。     

运用手机媒体创新新生代农民工思想政治教育论略

我国新生代农民工已成为农民工的主体,但这一特殊群体的思想政治教育是我国当前思想政治教育中最为薄弱的环节之一。手机媒体的兴起与发展,使其成为对新生代农民工进行思想政治教育的重要载体和新平台。运用手机媒体创新新生代农民工思想政治教育有着诸多的优势。要在坚持思想问题和实际问题并重、教育和服务并行、"扬长"与"避短"并举原则的基础上,把握思想政治教育的"向度"、"力度"、"温度"、"尺度",不断探索运用手机媒体创新新生代农民工思想政治教育的路径。     

The generation identification and process of digenesis of Korean pine forest

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Life cycle of Caligus rogercresseyi, (Copepoda: Caligidae) parasite of Chilean reared salmonids

Caligus rogercresseyi, [Contrib. Zool. 69 (2000) 137] is the only caligid known to affect the salmon industry in Southern Chile. Economic losses due to reduced fish quality, cost of chemical treatment and outbreaks of other diseases such as the Piscirickettsiosis occur. The life cycle of C. rogercresseyi is described in rainbow trout reared in seawater tanks from observations made under natural conditions of light and temperature between January 1997 and April 1998. Fish were infected with laboratory-cultured larvae obtained from ovigerous females. Rainbow trout were periodically slaughtered for parasite collection and identification. C. rogercresseyi life cycle includes the following stages: two nauplius, one copepodid, four chalimus and the adult. No preadult stage was observed. Timing of the different stages of development was directly dependent on water temperature. The maturation of the eggs or the time for a complete life cycle took place at 45 days in July at 10.3 °C, 31–32 days in April at 12.4 and 12.8 °C, respectively, and at 26 days in November at 15.2 °C. In January, at 16.7 °C, only the appearance of first eggs were observed at 18 days. A simple degree–day (dd) model is proposed for each developmental stage between 4 and 17 °C, where the development rate is a linear function of the average temperature of water. Using this degree–day model, the proportion of fourth stage chalimus was maximum at 172 dd of effective temperature, adult males at 193 degree–days, adult females at 208 dd. The minimum temperature threshold is at 4.2 °C where there is no development of the parasite. The appearance of first eggs occurred at 231 dd and the first pigmented eggs at 277 dd. The temperature-independent degree–days value allowed to predict the timing of C. rogercresseyi life cycle at any temperature within the evaluated range.     

热带玉米光周期敏感相关性状的遗传分析

 采用 6个世代平均值分析方法 ,对抽雄期、散粉期、吐丝期、株高、穗位高等光周期敏感的相关性状进行了遗传比较研究。结果表明 ,钝感×钝感组合 5个性状加性基因效应的贡献占总遗传变异的 11.3%～ 5 3.6 % ,显性效应贡献占 36 .0 %～ 78.6 % ,上位性效应占 5 .5 %～ 2 7.0 % ,说明显性效应大于加性效应 ,上位性效应普遍存在 ;而钝感×敏感组合 5个性状的加性基因效应的贡献为 6 6 .9%～ 84 .5 % ,显性贡献为 11.6 %～ 30 .7% ,上位性贡献为 1.4 %～ 5 .2 % ,说明加性效应占主导地位 ,显性和上位性效应作用显著降低 ,但不同钝感×敏感的敏感组合之间存在一定差异。温带遗传成分在钝感×敏感杂种后代中所占的比重 ,对减弱光周期敏感反应具有一定的剂量效应。含有 2 5 %热带成分的BC1敏感性状最弱 ,利用价值较大。     

论藏族林卡的造园精神与艺术特征

藏族林卡是藏民族创造的园林类型,在青藏高原自然地理环境和藏文化滋生下形成,具有独特的民族造园精神和艺术特点。从藏族林卡生成的自然和社会环境出发,对其造园精神作了系统论述,阐释了藏族林卡的艺术特征,以获取对藏族林卡和中国传统园林体系更加完整而深刻的认识。     

植物细胞内ROS的种类及其产生部位

文中对植物细胞内活性氧(ROS)的种类进行了介绍,并综述了细胞内ROS的产生途径.     

景观文化的创新研究

解析了景观文化的概念,从景观文化创新的角度,对景观文化的生成规律和创新进行创造性解析论证,认为景观文化的创新应该围绕"虚景观文化",侧重于观念形态。基于马克思主义唯物辩证法的特征,指出景观文化的生成规律。分析了景观文化创新发展的阻碍因素,强调了景观文化创新对城市规划及构建具有地域特色的景观文化网络具有现实意义。     

塞北兔品系选育初探

根据塞北兔品种特征及其毛色分离现象,组建0世代品系基础群,采用闭锁群体继代选育法进行品系选育。经过5个世代连续选育,塞北兔各品系毛色纯合度逐渐提高,同时各品系的生长发育性状和繁殖性状无显著变化,使原塞北兔种兔群逐渐形成了遗传稳定的野灰色、白色、红黄色3种被毛颜色的群体。