Unilateral failure of development of mandibular premolars and molars in an Eastern Grey kangaroo (Macropus giganteus) and its effects on molar progression

An adult male Eastern Grey kangaroo from a wildlife reserve near Melbourne was submitted for necropsy examination and was discovered to have abnormal dentition. There was no evidence that any premolars or molars had ever been present on the right mandible, whilst the incisors were normal. The age of the kangaroo was estimated to be 1 year 9 months using the right maxillary molars and 2 years 4 months old using the contralateral side, presumably due to the asymmetry of the dental arcades. 'Lumpy jaw', a common periodontal disease of kangaroos, from which Bacteroides sp was cultured, was present on the base of the vertical ramus of the left mandible. Complete unilateral absence of premolar and molar teeth in the mandible of a kangaroo has not been described. This condition affected molar progression in both sets of maxillary molars.     

MgO/MgCl2物质的量比对镁水泥基稻草板性能的影响

镁水泥基稻草板是以氯氧镁水泥为胶凝相,稻草为增强相的一种新型建筑材料．通过试验研究MgO／MgCl2物质的量比对镁水泥基稻草板静曲强度、软化系数和开始吸潮返卤时间的影响规律,并对试验结果进行分析讨论．结果表明：当n（MgO）：n（MgCl2）为7时,材料的机械性能和耐水性均为最佳,此时水化产物以518相为主．     

江西地区人群第3磨牙融合根根管系统形态学研究

目的：了解第3磨牙融合根根管系统的形态结构。方法：采用透明标本法对来源于江西地区人群的81例策3磨牙融合根的根管系统进行观察。结果：(1)策3磨牙根变异较多，常呈融合根，以单根融合量多，(2)第3磨牙融合根的根管以多口、多孔类多见．其中上颌占69．8％，下颌占39．5％；(3)C形根管在下颌策3磨牙发生率为21．1％，而在上颌策3磨牙无C形根管发生。结论：第3磨牙融合根根管系统复杂，多、多孔类根管出现率较高。     

植物在高温胁迫下的生理研究进展

高温是影响当前农业生产的主要的不利环境因子之一。根据高温胁迫下植物的生理机制研究进展,本文综述了植物在高温逆境下其生物膜的稳定性,氧化物和抗氧化系之间的平衡、胺的代谢、光合作用、热激蛋白的变化情况和其耐热性的机制,以及植物体内信号物质脱落酸(ABA),钙离子(Ca2 ),水杨酸(SA),茉莉酸(JA)对高温胁迫的响应。高温胁迫可以诱导内源脱落酸(ABA),钙离子(Ca2 ),水杨酸(SA),茉莉酸(JA)含量的增加,同时对应的几种外源的信号物质也可以提高植物的抗性。最后就今后这方面研究方向提出了思考。     

SPAC水分热力学函数及幼苗各叶位水分状况

1986～1987年在土壤-植物-大气连续系统(SPAC)中测定了土壤、小麦和玉米、大气的需水指标并计算了热力学函数。结果表明:SPAC中土壤水的偏摩尔自由能>植物水的偏摩尔自由能>大气水的偏摩尔自由能。大气水偏摩尔焓>土壤水偏摩尔焓>植物水偏摩尔焓。大气水的偏摩尔熵>土壤水的偏摩尔熵>植物水的偏摩尔熵。随着温度的升高,土壤水势、玉米小麦叶水势均升高,而大气水势降低。在SPAC中,玉米、小麦幼苗各叶位水势均表现为从基部向上依次增高的现象。     

一种弱电解质溶液无限稀释摩尔电导率的方法

依据Kohlrausch离子独立运动定律的基本原理,采用经典的电化学实验方法,测定强电解质溶液的无限稀释摩尔电导率,间接求出弱电解质溶液的无限稀释摩尔电导率。从而设计出一种测定弱电解质溶液无限稀释摩尔电导率的实验方法,应用于物理化学实验教学。该实验方法简便,结果准确。     

α-Amylase inhibitor in local Himalyan collections of Colocasia: Isolation, purification, characterization and selectivity towards α-amylases from various sources

The α-amylase inhibitor from corms of Colocasia collected from Bhota village of Hamirpur district, Himachal Pradesh was purified to 17.21 folds with 61.61% recovery using ammonium sulfate precipitation, gel filtration chromatography (sephadex G-200) and ion exchange chromatography (DEAE-sephadex). A single band of the purified inhibitor was obtained by Native-PAGE. SDS-PAGE revealed the purified inhibitor to be a monomer with molecular weight of 13,900 daltons. The nature of inhibition was found to be of non-competitive type as determined by Lineweaver-Burk plot and a K_i value of 0.54 nmole was obtained by Dixon’s plot. The inhibitor was found to be heat stable and retained 81.50% activity at 70 °C temperature. Inhibitor was found to have pH optima of 6.9. The purified inhibitor was found to have inhibitory activity against α-amylases extracted from the larvae of Callosobruchus chinensis, Tribolium castaneum, Corcyra cephalonica and midgut α-amylase of Spodoptera littoralis. 100% larval mortality of C. cephalonica was observed when fed on wheat flour mixed with 0.0036% (w/w) of purified inhibitor. Purified α-amylase inhibitor was found to inhibit the activity of human salivary α-amylase. It also had inhibitory activity against potato α-amylases and reduced sugar content in treated potato slices. The purified inhibitor was found to be a glycoprotein. In the present study, the ability of the inhibitor to inhibit insect amylases highlights its possible role in pest resistance and post harvest decay of crop plants. Inhibitory activity of α-amylase inhibitor against mammalian amylases could suggest its potential in treatment of diabetes and cure of nutritional problems, which result in obesity.     

摩尔吸光系数与惰性电解质的离子强度效应

研究了摩尔吸光系数和支持电解质离子强度之间的关系，通过对BacИЛbeB公式的等量经验方程的验证和应用，证实该研究可用于测定热力学摩尔吸光系数。     

金衢盆地的土壤铝状况及其对棉花生长的影响

选用浙江省金衢盆地８个具代表性和不同熟化程度的土样，研究了土壤的ｐＨ及不同浸提方法测得的铝含量与铝饱和度之间的关系，有机质对浸提铝含量的影响及土壤铝对棉花生长的影响。结果表明：不同方法浸提的铝含量和铝饱和度一般是随土壤ｐＨ的降低而增加，但重要原因之一还是有机质的影响，试验中，加柠檬酸可增加水浸提铝浓度，其增加值又随ｐＨ下降而增加。用不同方法浸提的土壤铝含量顺序不同。新垦、贫瘠的土壤上，铝对棉花生长的中毒影响与溶液中铝摩尔活度一致。生产上用０．０１ｍｏｌ·Ｌ￣（－１）ＣａＣｌ＿２的土壤浸提液铝浓度作棉花铝中毒的土壤诊断指标较好，临界浓度为０．１８ｍｇ·Ｌ￣（－１）。