热力学键合研究——蛋白聚合/蛋白活性对蛋白质吸着水蒸汽作用的实际影响

一、导言食品水分吸着等温线具有非常实用的重要意义,并一直是各种热力学和数学研究解决的课题.一般情况下,在食品蛋白质和其他系统里可以观察到S形或Ⅱ巨型水分吸着等温线.相对水蒸汽压力或“水分活性”(α_w=P/P_0),和水湿含量M之间的关系往往用方程式来表示,这些方程式可以用来进行数据的线性回归分析.一个显著的例外就是5参数型/水蒸汽吸着等温线的非线性回归分析,这就是 D＇Arcy和Wait(1970,1981)就食品蛋白和其它系统引入的.D＇Arcy和Watt(1970,1981)的模型包括把单个水分子结合为两个不同位置的类型:强和弱.此外,水分活性α_w高时,该模型假设多分子层水分的某一“偏差”结合到大分子表面.随着水湿含量由低到高的增加,这一等位结合模型进一步假设所有类型(包括多分子层类型)的结合区位置,同时被不同程度地占满.这样,根据这一模型,即使α_w处于很低的情况下多分子层水就会小量出现.D＇Arcy和Watt模型确实是一个等位结合型,有关论据在附录里给出,在该附录当中,D＇Arcy和Watt理论吸附等温线的一个完整求导是以水结合方程式给出的.其后模型里所包括的隐含假设和近似数也通过该求导公式在附录中给出.如前所述,由于多分子层假设,D＇Arcy和Watt模型在αw≥0.93高的情况下,不能很好适于实验吸着等温线     

Estimating Combining Ability of 4x-2x Crosses in Cultivated Potatoes

Progenies derived from crosses between Solarium tuberosum and 2n pollen-Producing diploid hybrids, exhibit obvious hybrid vigor. The 2n pollen-producing clone can act as a bridge in crossing S. tuberosum and S. andigena with S. phureja. Populations from 4x-2x crosses show more unifomity and less segregation compared with that of 4x-4x crosses. The parent-offspring correlation for the traits, starch content and tuber number, is significant at 0.01 level. The regrssion equations are Y (mp-F1)=1.0 1.2x and Y (mp - F1) = 5.3 0.8x, respectively. The 2n pollen-producing clones play an impotant role in increasing tuber stach content. Estimates of the combining ability for the main yield components indicate that additive effect prodominatcs for such trais as plot yield, tuber weight per plant and starch content, whereas both additive and non-additive effects lay equal stress on mean tuber weight and non-additive effect is important for tuber number. In general, non-additive effect appears to be important in     

Assessment of Negative Training on the Use of Cubicle Beds by Heifers

40 in-calf heifers were observed to examine the effect of timbers placing in passage area on their use of cubicle beds. Prior to the experiment preliminary observation was taken on these 40 heifers and they were divided into two even groups (cubicle user(or control) group versus cubicle refusal (or experimental) group by whether they properly used the cubicle beds or not. The timbers were placed in passage and feeding areas for the cubicle refusal group to force the animls to lie in the cubicle beds. The results of this experiment showed that feeding behaviour was unaffected by the presence of the timbers, but lying acitvity was about 8% higher for the experimental group, which led to a mean of almost 2 hours longer lying time over 24 h. After the timbers were removed, there was a significant decline in lying by the experimental group. The diurnal pattern of lying behaviour in cubicles indicated that the major effect on lying activity exerted by the presence of the timbers was seen during midnight to 10:00 a     

美国核果类果树线虫的治理策略

美国各地核果树上发生的主要线虫有根结绒虫、剑线虫、痕线虫及轮线虫,所用控制措施包括植树前杀线剂处理、应用抗病砧木、轮作及卫生预防措施.     

柑桔园微喷灌之益处

美国佛罗里达州柑桔园使用微喷灌的历史并不悠久。70年代初,一些栽培者和研究人员开始了微喷灌的试验,直到70代末至80年代初,因生产技术的改进,才有了微喷灌优点的详尽记载。《灌溉》杂志(Trulio,1969～1989)报道,佛州微喷灌作物的面积1974年仅为2400英亩,1980年扩大到15400英亩,     

选择玉米制种基地时应注意的几个问题

1.选择隔离安全的地方 生产玉米杂交种要求制种基地周围700米以内不能种植其它玉米.隔离安全,这是选择基地的首要条件.在实践中还应注意,不能为凑够基地面积数,而把那些接近隔离安全的地方也确定为基地.     

乳αS1-酪蛋白基因型和日粮粗蛋白质浓度对奶山羊泌乳及N、Ca和P利用的影响

以24只产羔2周的奶山羊为试验动物进行预试验,研究乳中αS1-酪蛋白(αS1-CN)基因型(纯合基因型:A／A和F／F各12只)对产乳量和乳成分的影响。预试验结束后,试验主要研究乳中αS1-CN的基因型和日粮粗蛋白质浓度对产乳量、乳成分及N、Ca、P利用的影响。以日粮粗蛋白质浓度(分别占DM13.2％、16.8％和19.8％)和试验期(3-6周,8-11     

鸵鸟大肠杆菌病的诊治

禽大肠杆菌病(Colibacillosis)是由埃希氏大肠杆菌(E．coli)的某些致病菌所引起的多种禽病的总称。其中比较危害严重的有大肠杆菌性败血症、肠炎、脐带炎、全眼球炎、气囊炎，大肠杆菌性肉芽肿和关节炎等病型。其特征为败血症和剧烈腹泻，导致严重脱水。本病可引起幼禽大量死亡或发育不良。     

苏联造林学理论与实践的现状和前景(摘编)

今年5月戈尔巴乔夫访华揭开了中苏两国关系史上新的一页,恢复了两国各方面的正常关系。9月5日列宁格勒林学院院长奥涅金教授和造林教研室主任、苏联著名造林学家列契柯教授对我校的访问则恢复了两校中断近30年的校际关系,并签署了新的合作协议,为两国林学界关系的全面发展打下了基础。两位苏联专家在访问我校期间分别做了学术报告。30年来,苏联的林业工作在理论和实践上已有了很大的发展,而我们对此所知甚少。为此,现将列契柯教授4个专题报告中的前2个记录稿摘要编写如下,供读者参考。报告的总题目是编者自已加的。     

Close-to-nature Design and Management：Developing Effective and Harmonious Urban Forest in China

In the pastfew years, with speedilydeveloping of socialeconomy and continuously speeding up of urbanizationprogress in China, the problems of the ecologicalenvironment in urban area, such as air pollution, heat-island effect, dangers of wind and sand, and shortageof water resources, etc., have gradually been gravenessand become the focus issue concerned by citizens also.It has become the common understanding of mostcitizensthat ahealthy,secureand comfortableecologicalenvironment of human settl…