A rapid modification of de Lautour's technique for grass leaf chromosomes

A modification of de Lautour's technique for grass leaf chromosomes is described which makes possible rapid sampling and bulk processing of grass shoot tissues for cytological examination. These tissues have a number of advantages over the root-tip tissues normally used for this purpose, of which the most important is that the supply of suitable cells in division is independent of season.     

Differences between tight and loose cultures: a 33-nation study

With data from 33 nations, we illustrate the differences between cultures that are tight (have many strong norms and a low tolerance of deviant behavior) versus loose (have weak social norms and a high tolerance of deviant behavior). Tightness-looseness is part of a complex, loosely integrated multilevel system that comprises distal ecological and historical threats (e.g., high population density, resource scarcity, a history of territorial conflict, and disease and environmental threats), broad versus narrow socialization in societal institutions (e.g., autocracy, media regulations), the strength of everyday recurring situations, and micro-level psychological affordances (e.g., prevention self-guides, high regulatory strength, need for structure). This research advances knowledge that can foster cross-cultural understanding in a world of increasing global interdependence and has implications for modeling cultural change.     

曲霉型豆豉用高产蛋白酶菌种的选育

从曲霉型阳江豆豉曲中筛选出5株菌落形态不同的曲霉(Aspergillus spp.),通过纯种发酵制备豆豉曲,测定了豆豉曲中碱性蛋白酶和中性蛋白酶的活性,从中筛选出1株蛋白酶活性较高的菌种,并对该曲霉进行ITS r DNA序列分析,发现该曲霉与Aspergillus oryzae strain P6B2(JX429926)的同源性最高,故鉴定为米曲霉(Aspergillus oryzae).以该米曲霉为出发菌株,通过紫外线诱变和硫酸二乙酯化学复合诱变处理,选育得到优良高产蛋白酶活性的突变株,其中性蛋白酶酶     

The effect of seven substituted urea herbicides on the soil microflora

Chloroxuron, diuron, fluometuron, metobromuron and monuron added to soil at 500 parts/million a.i. on a dry weight basis caused an initial stimulation of CO₂ production, followed by indications of inhibition. Nitrification was clearly inhibited, particularly by monuron and metobromuron. Metoxuron at 5 and 50 parts/million a.i. had no effect on CO₂ output and nitrification, but at 500 parts/million a.i. both were greatly reduced. Numbers of fungal propagules were temporarily lower at 50 parts/million a.i., and severely curtailed at 500 parts/million a.i. but total counts of bacterial propagules were greatly increased. Linuron had an inhibitory effect on CO₂ evolution at 500 parts/million a.i. but this varied in extent and duration; some reduction was also found at 50 parts/ million a.i. At 500 parts/million a.i. there was no effect on mineralisation of N but in soil supplemented with ammonium sulphate nitrification was reduced. Changes in microbial equilibrium occurred, but were less marked than with metoxuron. Cellulose decomposition was also reduced. Small amounts of 3,4dichloroaniline were found in linuron-treated soils, but microbial activities were not affected when 5 parts/million 3,4-dichloroaniline was added to the soil. However, at 140 parts/million microbial activities were affected adversely, but in a different pattern to that for linuron; nitrification was severely reduced, but numbers of fungal propagules were hardly affected, suggesting that the effects observed in linuron-treated soil were not due to this metabolite.     

Epithelial response to experimentally introduced intraluminal bacteria in the avian epididymal ducts

The response of the epithelial cells of the various ducts of the avian epididymis, whose function is poorly understood, to intraluminal bacteria was evaluated by the injection of an avirulent strain of Salmonella gallinarium into the RT for 24 h. Ultrastructurally, bacteria and invading mononuclear cells were present in the lumina of the RT, proximal efferent ducts (PED) and distal efferent ducts. However, only the non-ciliated (Type I) cells of the PED epithelium ingested bacteria from the lumen. Fragments of bacteria also occurred in several intercellular spaces in the epithelium of the PED. Some mononuclear cells also contained fragments of bacteria. Neither cell death in the various epithelia nor mononuclear infiltration of the periductal tissue occurred. Therefore, in addition to the established function of absorbing most of the testicular fluid entering the epididymis, the Type I cells also appear capable of recognising and removing foreign particulate matter from the epididymal through-flow in the proximal part of the epididymis.     

Untersuchungen zum Auftreten des A2-Paarungstyps beiPhytophthora infestans (Mont.) de Bary in Ostdeutschland

Zusammenfassung In Ostdeutschland sind beide Paarungstypen (A₁ und A₂) vonPhytophthora infestans (Mont.) de Bary, dem Erreger der Kraut- und Knollenf?ule der Kartoffel, vorhanden. Von 1987–1990 ist eine Zunahme des A₂-Typs in der Erregerpopulation zu verzeichnen. Die ?ltesten A₂-Isolate der Stammsammlung des Institutes sind aus dem Jahre 1981. Der Nachweis von Oosporen im Freiland gelang 1987. Die M?glichkeit der Oosporenbildung unter europ?ischen Klimabedingungen wird damit best?tigt. Durch den Einsatz des vorgestellten Blattscheibentestes l?sst sich die überprüfung des Paarungstyps vereinfachen.     

Examination of the failure behavior of wood with a short crack in the radial–longitudinal system by single-edge-notched bending test

The failure behavior of wood with a short crack was examined by conducting the single-edge-notched bending tests of a radial-longitudinal system on Agathis specimens. In the test, the mode I critical stress intensity factor was measured, and its validity was checked by the result from double cantilever beam testing method. The mode I critical stress intensity factor decreased when the crack length approached zero. With crack length correction, a constant critical stress intensity factor was obtained over a wide range of crack length including crack-free specimen.     

林业科学研究文献基础浅析

本文应用引文分析法,以《浙江林学院学报》、《林业科学》,《北京林业大学学报》、《东北林业大学学报》和《南京林业大学学报》为统计对象,分析了上述刊物1989～1990年度各期的全部汉文引用文献,从引文的文献类型、学科分类结构和时间序列3方面进行研究,初步搞清了林业科学研究文献的基本特征。