RESOLUTION OF RACEMIC MIXTURES OF CARBOCYCLIC ANALOGUES OF NUCLEOSIDES AND ASSIGNMENT OF THEIR ABSOLUTE CONFIGURATION

Racemic trans-6-chloro-9-[2-(hydroxymethyl)cyclopentyl]purine was resolved using HPLC with a chiral column. The absolute configurations of the enantiomers were determined by NMR studies of their (R)- and (S)-methoxy-phenylacetates.     

医院感染病原菌及耐药性监测报告

从３９０４ 例住院病人标本中分离出医院内感染病原菌７８１ 株,结合临床常用的１４ 种抗菌药物药敏试验结果进行整理分析。结果,革兰阳性球菌所占比例呈上升趋势,革兰阴性杆菌呈下降趋势。引起医院感染的主要病原菌为真菌、大肠埃希菌、克雷伯菌、肠球菌、金黄色葡萄球菌。２ 年间金黄色葡萄球菌对青霉素的耐药率已＞ ９３ ％ ,对第三代喹诺酮类的耐药率下降了１６．６６ ％ ～４０．８３ ％ 。肠球菌对万古霉素的耐药率上升了２７．５９ ％ 。克雷伯菌、沙雷菌、大肠埃希菌对头孢菌素类、第三代喹诺酮类的耐药率呈上升趋势。金黄色葡萄球菌、表皮葡萄球菌、肠杆菌属、铜绿假单胞菌对阿米卡星的耐药率呈下降趋势。     

A REAPPRAISAL OF THE USE OF MULTIDIMENSIONAL SCALING TO INVESTIGATE THE SENSORY CHARACTERISTICS OF SWEETENERS

Previous investigations of the sensory characteristics of sweeteners using a multidimensional scaling (MDS) approach, have involved sweeteners which were not matched for sweetness. Under such circumstances, part of the estimated distance between sweeteners is attributable to sweetness differences. This detracts from the value of the consequent MDS space, when the main objective is usually to investigate sensory characteristics other than sweetness. In this study, the MDS approach was applied to sweetener solutions which were matched for sweetness with 5% sucrose. The direction of any residual sweetness differences was identified by including 1,3,5 and 7% sucrose solutions, all matched to equal viscosity, in the study. From the resulting three dimensional MDS sweetener space, it was evident that Dimension 1 was almost exclusively due to sweetness differences whereas Dimensions 2 and 3 were devoid of influence from sweetness and hence represent the sweeteners with respect to their other sensory characteristics.     

THE SOLUBILITIES OF THE l-DIHALOGENATED TYROSINES IN ETHANOL-WATER MIXTURES AND CERTAIN RELATED DATA

1. The solubilities of l-tyrosine, dichloro-l-tyrosine (hydrated), dibromo-l-tyrosine (anhydrous), and diiodo-l-tyrosine in ethanol-water mixtures at 25° have been determined. 2. It was found that the solubilities of the dihalogenated substitution products of l-tyrosine are increased by addition of ethanol up to a certain concentration. Further addition of ethanol leads to a decrease in solubility. The solubility of l-tyrosine is decreased by addition of ethanol. 3. Dichloro-l-tyrosine (hydrated) was found to change to the anhydrous form when allowed to stand in the presence of ethanol. 4. The apparent heat of solution of diiodo-l-tyrosine in an ethanol-water mixture has been determined. 5. The solubility of dl-thyroxine at 30° has been determined in urea solution, ethanol, dioxan, ethylene glycol, and propylene glycol.     

辛硫磷和溴氰菊酯混剂对家蝇抗性发展的影响

以家蝇（ＭｕｓｃａｄｏｍｅｓｔｉｃａｖｉｃｉｎａＭａｃｑｕａｒｔ）为试虫,用辛硫磷溴氰菊酯单剂及不同配比的混剂进行汰选试验。所有混剂选育的家蝇抗性发展都很缓慢,而单剂抗性发展都很快。增效试验表明,辛硫磷与溴氰菊酯混配有明显增效作用,特别是对抗性品系。生化分析结果表明,对溴氰菊酯的抗性发展与酯酶的酶活升高有关。对辛硫磷抗性发展与多功能氧化酶的酶活升高和乙酰胆碱酯酶敏感性降低有关。混剂选育的家蝇其对单剂的敏感性的变化及酶系的变化,随着混剂的配比而变化     

刺猬的皮肌及其神经支配

刺猬的皮肤,包括皮肤肌和皮下脂肪,是一个质量很大的器官,平均占体重43形,最多可达57％以上。刺猬的皮肌,如果不是动物界中最发达的,也是非常发达的,尤其环状皮肌带约占体重11％(赵以炳等1958)。在功能上,刺猬的皮肌是重要的生理性体温调节器官,背面带针刺的部分有保温御寒作用,腹部有散热机能(赵以炳等1950a)。清醒的刺猬当遇到强敌或其它干扰时,常蜷缩成带剌的球。不活动的冬眠刺猬也取同样姿势,以防侵害。可以说,蜷缩是一种主动的保护性行为,这种强烈的蜷缩主要是由于环状皮肌带持续有力的收缩。尤其令人惊奇的是冬眠时的蜷缩,这是在一般生理活动明显降低的     

SELECTION OF ASSESSORS BASED ON THEIR SKILL IN IDENTIFYING BASIC TASTES IN LOW CONCENTRATION SOLUTIONS

A method for the first step in the selection of trained sensory assessors, based on their skill in identifying basic tastes in low concentration solutions, was defined and evaluated. The solutions used were: 0.4 and 0.8% sucrose; 0.03, 0.04 and 0.06% citric acid; 0.08 and 0.15% sodium chloride; 0.02 and 0.03% caffeine. Concentration ranges were found adequate. The criterion for selection was to have over 65% correct answers. Out of 226 candidates who received the test, 141 (62%) were selected. The probability of a candidate having more than a certain percentage of correct answers was calculated. The influence of the dilution water quality on the perception of basic tastes was significant; distilled water was the most adequate.     

COMPARISON OF TWO SIMPLE METHODS FOR THE MEASUREMENT OF DETECTION THRESHOLDS FOR BASIC, UMAMI AND METALLIC TASTES

Two simple methods were followed to determine detection thresholds for the taste of substances in aqueous solution. The methods applied were: a modification of the ascending method of limits and a method based on the use of scales. Detection thresholds were calculated for the four basic tastes (sweet, salty, acid, and bitterness), umami and metallic. Reference substances for each taste were sucrose, sodium chloride, citric acid, caffeine, monosodium glutamate and iron (II) sulfate heptahydrate and the results of the two methods were compared. We found that the threshold values calculated by method ASTM-679 was within the range of concentrations identified with the scales method.     

分布于日本和中国的鹅观草及其杂种的形态学和细胞学研究

本文对分布于日本的Agropyron tsukushiense (Honda) Ohwi var. transiense (Hack.) Ohwi (2n=6x=42)和分布于中国的Roegneria kamoji Ohwi (2n=6x=42)及其杂种F_1(2n=6x=42)进行了形态学及细胞学的研究,并同时探讨了亲本种的亲缘关系。总体来看,亲本材料之间在形态上虽有差异但并不十分显著。杂种F_1的形态特征介于其父、母本之间。在减数分裂过程中,亲本种和杂种F_1的染色体配对行为均十分正常。但在检查了大量的成熟花粉和穗状花序之后,发现杂种F_1有部份不育现象。上述研究结果表明A. tsukushiense var. transiens的三个染色体组与R. kamoji的三个染色体组同源。结合形态学和育性等方面的研究资料,作者认为上述两个材料仍应属于同一分类等级。但必须指出,由于长期的地理隔离,他们之间产生了一定的形态变异和生殖障碍。按照国际植物命名法规(ICBN)上述两个材料应组合为:Roegneria tsukushiensis (Honda) B. R. Lu, Yen et J. L. Yang及其变种var. transiens (Hack.) B. R. Lu, Yen et J. L. Yang comb. nov.     

植物多糖的凹形结构与生物活性关系

简述了植物多糖的生物活性与结构 ,讨论了植物多糖的生物活性与结构的关系 ,提出了凹形结构是多糖产生生物活性的基础