结缕草组织培养及转化因子的初步研究

以破除休眠的结缕草种子为试材，对其愈伤组织的诱导、分化及农杆菌介导转化的关键因子作了探索，结果表明：结缕草种子愈伤组织的诱导以含2，4-D 1mg/L NAA 3mg/L 6-BA0．2mg/L、分化以KT 3mg/L 6-BA 3．5mg/L NAA 0．1mg/L、生根培养以含0．2mg/L NAA的MS培养基效果最佳。通过瞬间表达的研究表明，以继代培养2周的愈伤组织为材料，农杆菌介导感染10min进行转化为佳。     

论辩证思维方法在日语教学中的运用

日语学习越来越受到重视和青睐,关于日语教学方法也有众多好的观点。本文将辩证思维的基本形式和基本方法辩证思维运用到教学活动中,在教学中渗透辩证思维方法,以辩证 思维活跃教学内容,在改革教学方式、改善教学效果、提高学生的语言运用能力进行探讨, 以期提高教学质量。     

冬枣日本龟蜡蚧的空间分布型及抽样技术研究初报

本文利用Taylor幂法则和Iwao回归法对日本龟蜡蚧Japanese wax scale的空间分布型进行了测定，结果表明日本龟蜡蚧在田间呈聚集分布，且符合负二项分布，经计算k值为2．2227。其种群聚集主要是由昆虫本身行为和环境因素中任一因子引起。应用Iwao的抽样模型建立了日本龟蜡蚧的田问理论抽样数公式：N=(1／D)^2(1．1218／M 0．2744)。并利用负二项分布零频率与均数的理论曲线公式建立了估计该种群平均密度的零频率模型：X=2．2227(Po^-0.4499-1)。     

Plant Nutrition in the Roman empire

This article presents various techniques for plant nutrition in the ancient world, namely ancient Rome. It discusses the attempts of Roman farmers to ameliorate their soil by ways of spreading manure, green manuring, and applying mineral fertilizers and other materials thought of as improving the soil. The relevant information is taken mainly from Roman literary texts that pose their own difficulties to the reader being, above all, highly stylized products of art rather than practical handbooks. Such information can nevertheless be contrasted with recent observations on the effectiveness of these methods. It is shown that ancient knowledge contributed considerably to developing a remarkably successful—if somewhat flawed with respect to scientific details—strategy of improving annual yields and thus supporting the Roman urban culture and demographic stability, with a general level of nutrition reached in Europe and North America only after World War II.     

Topographic variation of soil nitrogen mineralization and microbial biomass in Japanese cedar (Cryptomeria japonica D. Don) stands at Myougodani watershed,Toyama, Japan

The spatial variability of nitrogen (N) mineralization, nitrification, and microbial biomass was investigated using surface soils from various topographic positions at a relatively small watershed with Japanese cedar (Crgptomeria japonica D. Don) plantations. The watershed topography was characterized using a topographic index derived from GIS analysis. The topographic index reasonably reflected the spatial variability of the soil water conditions, total soil carbon (C) and N contents, and exchangeable base concentrations. However, this index was not significantly correlated with the spatial variability of net N mineralization and microbial biomass. Topographic index and soil properties (total soil C and N contents, C / N ratio, exchangeable base concentrations, and clay content) were subjected to principal component analysis to eliminate multiple-collinearity among the variables, and express the variables as new orthogonal variables. Principal component analysis showed that the soil properties could be divided into two groups: PC1 (soil nutrient pools) and PC2 (soil clay content). The topographic index was closely correlated with PC1 and not significantly correlated with PC2. Regression of PC scores on net N mineralization and microbial biomass indicated the relatively high contribution of PC2 to the variability in N mineralization and microbial biomass. This result suggested that not only topographic factors but also the clay content exerted an important influence on the spatial pattern of N mineralization and microbial biomass within a watershed with single species forests.     

Alleviation of cadmium phytotoxicity by magnesium in Japanese mustard spinach

Abstract

To clarify the mechanism of Magnesium (Mg) in alleviating cadmium (Cd) phytotoxicity, Japanese mustard spinach (Brassica rapa L. var. pervirdis) was grown for 10 days after treatment in hydroponics in a growth chamber under natural light. The treatments were: (1) nutrient solution alone (Control), (2) 10 mmol L^?1 Mg (High-Mg), (3) 2.5 µmol L^?1 Cd (Cd-toxic), (4) 2.5 µmol L^?1 Cd plus 10 mmol L^?1 Mg (Mg-alleviated). The Cd-toxic treatment showed substantial growth retardation and chlorosis of young leaves, such symptoms were not observed in Mg-alleviated plants. Magnesium-alleviated plants showed higher shoot growth, more than twofold, and decreased shoot Cd concentration, approximately 40%, compared with Cd-toxic plants. This increase in shoot growth and simultaneous decrease in shoot Cd concentration may explain the alleviation of Cd toxicity with Mg in Japanese mustard spinach. In Cd-toxic plants, concentrations of K in shoots and Zn in both shoots and roots increased compared with the other three treatments. Concentrations and accumulations of Fe and Mn in shoots decreased significantly in the Cd-treated (Cd-toxic and Mg-alleviated) plants compared with the control and High-Mg plants. Thus, the application of high amounts of Mg in the nutrient solution can alleviate Cd toxicity in plants.     

American Wine Society

This article describes the digitization of the Alabama Agricultural Experiment Station publications. This collection forms part of the United States Agricultural Information Network (USAIN) National Preservation Program for Agricultural Literature and the State and Local Literature Preservation Projects that are similar in scope to Cornell's Core Historic Literature of Agriculture digital collection. These are nationwide projects that seek to preserve scholarly literature in agriculture. Project planning and implementation is described, followed by a discussion of the potential usefulness of this collection and ways of promoting its use to various user groups.     

Saving the Elusive Past for the Future: A Case Study in Collaboration of Veterinary Libraries

ABSTRACT

This article presents a collaborative project undertaken by a group of veterinary librarians as an attempt to deal with the problematic nature of grey literature. It provides the historical context of grey literature in veterinary medicine, noting its importance in preserving the history of the veterinary profession in the United States. It also surveys veterinary grey literature and discusses the challenges of dealing with this type of material. Emphasizing the common problems presented to the veterinary library community, the paper then reports on the cooperative efforts of the group, describing the development of a mission, core values, and an action plan.     

Audiogram measurement based on the auditory brainstem response for juvenile Japanese sand lance <Emphasis Type="Italic">Ammodytes personatus</Emphasis>

In this study, the auditory thresholds for juvenile Japanese sand lance Ammodytes personatus were measured based on its auditory brainstem response (ABR). The amplitude of the ABR waveforms to a sound stimulus were larger than that of the electric background noise caused by general brainwaves and myogenic signals after the averaging procedure. Japanese sand lance responded to low frequency sounds between 128 Hz and 512 Hz with a sound pressure level of 115–125 dB. As the test frequency decreased, so did the auditory threshold level, and the level was about 116 dB at 128 Hz and 181 Hz. These results indicate that Japanese sand lance can detect low frequency sound but are less sensitive than other fish species. These high thresholds are probably caused by the lack of a swim bladder.