Reliability of Chlorophyll Meter Measurements Prior to Corn Silking as Affected by the Leaf Change Problem

The normal practice of using chlorophyll meters involves measuring the youngest fully developed leaf of a corn plant (Zea mays L.) before silk emergence and then switching to the ear leaf. A discontinuity exists of chlorophyll meter measurements associated with leaf change prior to the silking stage. The lag of silk emergence within a cornfield prior to silk emergence makes it practically impossible to take chlorophyll measurements on leaves at the same growth stage. Therefore, the change in leaves being measured introduces errors when chlorophyll meters are used prior to silk emergence to diagnose nitrogen (N) deficiencies. We report results from three field studies to assess the difference in chlorophyll measurements between the uppermost fully developed leaf and the ear leaf near the time of silk emergence and identify possible problems associated with the difference when chlorophyll meters are used to estimate the need for in‐season fertilization in cornfields.     

公共选修课《丝绸学》教学实践与探索

介绍了在农业大学设置丝绸学选修课的背景及课程定位,着重阐述了课堂上如何以丝绸为载体弘扬中华传统文化,营造积极向上氛围,不失时机地对学生进行创新意识、人生价值观的正确引导、寓育于教之中的实践与探索。     

蚕丝蛋白在非绢丝领域的研究进展

介绍了蚕丝蛋白的组成,概述了蚕丝蛋白在食品、医药医疗、化妆护肤品、生物工程、环保、轻工业领域的研究进展。     

Nutrient concentration of corn as effected by poultry manure

Abstract

The elemental composition of corn was evaluated during the 1973 growing season in an experiment with various rates of poultry manure. In general, the nutrient concentration of plant tissue reflected poultry manure applications with the exception of Mg which declined and Ca, Fe and Na which appeared to be largely unaffected. The elemental concentrations in the corn tissue were not in a toxic range however, the nutrient balance was changed by poultry manure application. Sampling of corn early in the growing season can be quite valuable with respect to predicting nutrient concentration of more mature corn for Mg, Mn, B and Zn, but it leaves much to be desired for the other elements tested.     

用气相色谱—质谱法分析玉米须中化学成分的研究

用水蒸气蒸馏法提取玉米须中的挥发油,采用气相色谱—质谱(GC-MS)联用技术,鉴定出59种化合物,其中主要的化学成分有棕榈酸(17.45%)、乙酸乙酯(7.56%)、2-甲氧基-4-乙烯基苯酚(5.62%)、糠醛(4.91%)、亚油酸乙酯(3.79%)、5-甲基糠醛(2.75%)、正壬酸(2.62%)、糠醇(2.12%)、香草醛(2.01%)、苯乙醇(1.65%)、苯乙醛(1.54%)、正庚酸(1.48%)、正己酸(1.42%)、六氢金合欢基丙酮(1.32%)、正十五酸(1.29%)和月桂酸(1.02%)。     

柞蚕多丝量品种宛黄一号、宛黄二号的选育

通过多年系统选育的方法,对柞蚕遗传性较强的茧层率性状进行连续有目的地认真选择,培育出柞蚕多丝量品种宛黄一号、宛黄二号。这2个品种健康好养,抗病性、抗逆性好,千克卵收茧量平均达380 kg以上,千粒质量10 kg以上,茧层率连年达16%以上,分别比河南省柞蚕现行品种三三高出9.5%,18%,46%,目前在生产上发挥着巨大作用。     

丝素蛋白缓释微球的研究进展

微球是以高分子材料为载体包裹或吸附药物而制成的微小球状实体,粒径范围一般为1～500μm。丝素蛋白是从蚕丝中提取的天然蛋白质,具有良好的生物相容性、可降解性和理化性能,被广泛应用于手术缝合线、人工皮肤、组织工程材料、细胞培养基、药物缓释载体等。以丝素蛋白为原料制备的丝素微球,具有比表面积大、可生物降解、生物相容性好等优点,因此被广泛地研究。本文介绍了丝素蛋白缓释微球的研究现状,并对丝素微球的发展前景做出了展望。     

蚕丝的综合利用概述

简述了蚕丝在食品、生物材料、化妆品、和吸水材料方面的应用,介绍了蚕丝作为生物材料方面的研究进展。     

重组类丝状蛋白在大肠杆菌中的表达及其溶液态结构分析

利用基因重组技术表达了具有[(GVPGV)2GG(GAGAGS)3AS]n一级结构的类丝状蛋白质(BcEn),该蛋白是把源于弹性蛋白的氨基酸序列GVPGV插入到蚕丝蛋白的结晶序列GAGAGS中,以期利用该弹性片段来调控类丝状蛋白质材料高级结构的形成以及结晶程度,从而达到控制材料性能的目的。利用园二色CD光谱对BcEn在溶液状态下的结构进行了初步分析,结果显示在对BcEn具有良好溶解性的氟有机物水合六氟丙酮中,其结构的形成依赖于BcEn分子量的大小,分子量越大越易形成比较稳定的α-螺旋结构。     

蚕茧需求模型预测与分析

运用多种数学模型,对我国的蚕茧需求趋势、蚕茧供求的均衡水平以及影响蚕茧需求的因素进行预测和分析。研究结果表明：我国的蚕茧需求量有不断上升的趋势,2006～2010年蚕茧需求量将达到61～72万t;蚕茧的供求均衡理论量约为51．48万t,鲜茧收购均衡价格为1．745 1万元/t;对蚕茧需求起主要作用的因素依次是蚕茧生产量、蚕茧价格,而生丝价格的作用力最弱。