关于植物群丛划分的探讨

在传统的植物群落分类系统中,群丛是植物群落分类的基本单位.从群丛分类的必要性出发,综述了传统植物群落分类系统中对群丛的定义及其划分方法,即在群丛的划分中主要依据群落中不同层片的优势种或特征种;但是在利用传统植物群落分类方法划分群丛时也存在一些不确定性因素,主要表现在确定群丛的特征种(组)时需要人为确定;同时,论述了当前植物群落数量分类的研究现状,分析了利用双向指示种分析法(TWINSPAN)、主成分分析(PCA)等数量分类方法划分群丛时存在的一些问题,主要表现在数量分类结果与传统分类单位的对应关系不能达到协调一致,无法判断是否划分到了群丛的水平.最后提出了群丛划分方法的展望:数量方法是基础,特征种(组)是及其数量特征是关键.     

数量性状主要基因随机效应的分析

数量性状主基因在不同环境或遗传背景中表现随机效应。本文提出数量性状基因随机效应分析的试验设计和统计模型,以及对基因的分离比、平均效应和随机方差进行假设测验的方法．所述方法可用于借助标记基因对数量性状基因效应作类似分析．     

中国乌头属属下等级数量分类的初步研究

本文取中国乌头属50种(含变种)植物,选取形态学性状46个、化学性状8个、组织学性状5个、生态学性状1个,运用数量分类方法,对该属进行属下等级的分类研究。根据数学分析结果,确定了树系图中变种、种、系、亚属的分级界线,并在聚类分析的基础上,进一步探讨了各等级类群的划分。     

入侵性害虫——苹果绵蚜田间种群数量的调查方法

2007年6月中旬到10底在山东省莱阳市对苹果绵蚜Eriosoma lanigerum(Hausmann)的田间发生数量进行调查研究。在田间定点调查5株苹果树上苹果绵蚜虫落数量和虫落面积,并在其它苹果树上随机选择20个虫落,计数每个虫落中苹果绵蚜的活体数,从而计算单位面积虫落中苹果绵蚜的平均数量。分析指出,以计算法求得的虫落中苹果绵蚜的实际数量为指标,既考虑了苹果绵蚜虫落的数量和大小,也考虑了单位面积虫落中苹果绵蚜活体数,并且把被苹果绵蚜蚜小蜂寄生的僵蚜排除在外,能较客观地反映出田间实际情况,是一种比较准确的表示苹果绵蚜田间数量的方法。     

荔枝蝽-寄生蜂系统数量变动模型与应用

研究荔枝蝽－寄生蜂系统的数量变动规律,得到一个差分－积分方程组及求解的递推公式,指出了公式中参数的确定方法。推导出荔枝蝽－寄生蜂系统长期演变的特性,用模型证明了人工放蜂防治荔枝蝽的优越性及滥用农药的不良后果,给出了人工放蜂的最佳次数,最佳时刻及合适的放蜂量的计算公式,导出的结论与实验结果相符。     

几种数量综述方法的介绍与比较

综述是科学研究中的一种重要方法,数量综述较传统的叙述性综述有许多优多,文章介绍并比较了目前在科学研究中比较流行的几数量综述方法.     

黑龙江省赤狐年数量趋势波动的初步分析

本文根据毛皮收购数据对赤狐在黑龙江省13年(1971～1983)的年数量趋势波动做了分析。以全省数据分析时,此期间赤狐数量趋势共有4个波动周期,平均间隔为3年,变异系数为23.57％;继而以该省八个地区联合周期分析共得26个周期,平均间隔为3.42年,变异系数为39.78％。两次分析皆表明:赤狐数量趋势的波动为随机波动,波动中赤狐种群的密度制约因素影响不明显。     

植物数量性状基因定位研究概述

植物重要的性状多为数量性状。长期以来,人类一直寻求解释植物数量性状的遗传规律以便对其进行遗传操纵。现代分子生物技术的发展为植物数量性状基因的定位、分离等研究提供了条件。本文从数量性状基因座(QTL)作图群体类型及其特点,QTL定位方法,植物QTL研究现状,以及QTL精细定位、克隆、利用等方面进行了综述,并对今后植物QTL研究进行了展望。     

标记基因型中QTL基因型条件概率分布

随着分子数量遗传学的发展,人们提出了很多统计模型用于QTL定位分析。在这些模型中,首先得确定QTL在标记基因型中的条件概率分布,然后利用适当的统计方法对QTL在基因组中所处的位置进行估计。本文讨论了常见作图群体（如F2和回交群体）中在给定标记基因型下QTL的条件概率分布,提出了用Mathematics软件推导QTL基因型条件概率分布的方法。用该方法能够快速地、准确地推导出比较复杂的标记基因型中QTL基因型的条件概率分布。     

“探究培养液中酵母菌种群数量的动态变化”实验研究

针对浙科版教材和人教版教材内容差异,讨论了“探究培养液中酵母菌种群数量的动态变化”实验中关于菌种来源、培养基选择、检测方法以及对照设计的问题,对其中关键问题进行了实验,分析了不同方案在实验中的优劣。     

Calculation of the heat of growth of Escherichia coli K-12 on succinic acid

Using data from the literature, a method is adopted for determining the empirical composition and the unit carbon formula for dried Escherichia coli K-12 cells by summing the quantities of C, H, O, N, P, and S in each of the major classes of macromolecular substances comprising the cellular biomass. With these data and the molar growth yield of cells on succinic acid, equations are written representing the anabolism and catabolism of E. coli K-12 on this quantity of substrate. The enthalpy change accompanying catabolism can be calculated directly using standard enthalpies of formation because there is no term representing cellular substance. The enthalpy change accompanying anabolism is calculated to be very small or zero using microcalorimetric and other data from which the enthalpy of formation of a unit quantity of living cellular substance can be obtained. This indicates that the net enthalpy change accompanying the growth process (anabolism plus catabolism) is the same as that calculated for catabolism alone, in agreement with the same conclusion by several investigators using direct microcalorimetry. The method described here of determining the unit carbon formula and the quantity of ash remaining after cellular combustion is compared to that conventionally used in which cellular P and S is considered either to be negligible or to be a part of the ash. It is concluded that equations representing anabolism and the growth process can be written more accurately using the presently described method, leading to more accurate thermodynamic calculations.     

Determination of proteins in infant formula by high-performance liquid chromatography-electrospray tandem mass spectrometry

To determine the protein content of formula, gel electrophoresis was performed on the infant formula samples and the entire protein patterns were analyzed by nano-high performance liquid chromatography-electrospray tandem mass spectrometry (nano-HPLC/ESI/MS/MS). From the commercial infant formula profiled in this study, a total of 154 peptides, corresponding to 31 unique proteins were identified by nano-HPLC/ESI/MS/MS. Each of the identified peptides was reconfirmed by a strict integrated approach using tandem mass spectra. This protein profiling method using gel electrophoresis coupled with nano-HPLC/ESI/MS/MS and manual evaluation is a sensitive and accurate method for protein identification as well as a powerful tool for monitoring various types of food products.     

乌头须根总生物碱提取工艺的考察

目的:考察乌头须根中总生物碱的最佳提取工艺条件。方法:酸碱滴定法测定乌头须根中总生物碱含量,以总生物碱提取率为指标,采用L9(3)~4正交实验法筛选乌头须根总生物碱的最佳提取工艺。结果:乌头须根总生物碱含量为1.094%,影响提取的主次因素为:乙醇浓度>提取次数>提取时间>乙醇用量;优选得到的最佳提取工艺为A_3B_1C_3D_3,即以8倍量80%的乙醇提取3次,每次1.5小时。结论:乌头须根总生物碱含量较高,提取工艺条件稳定、经济、可行。     

Estimation of heats of combustion of biomass from elemental analysis using available electron concepts

The method of Thornton and Dulong's formula for estimating heats of combustion are compared in this work. Heats of combustion predicted by Thornton's method for renewable resources such as wood, straw, and municipal solid wastes are considerably closer to experimentally measured values compared to values predicted by Dulong's formula. Thornton's method states that the heat of combustion is directly proportional to the quantity of oxygen consumed in the combustion process. A method which utilizes the weight fraction carbon on a dry basis and the reluctance degree to predict the heat of combustion of renewable resources is presented.     

High-throughput determination of identity, purity, and quantity of combinatorial library members using LC/MS/UV/ELSD

We have used a high-throughput LC/MS/UV/ELSD method to rapidly determine the absolute quantity and purity of 42 organic compounds from seven lead discovery libraries. A general calibration curve generated from a different set of 42 compounds with seven different scaffolds was used in this analysis. We have also studied 33 organic compounds with different molecular weight (MW) by LC/MS/UV/ELSD to investigate the effect of MW on ELSD response and the accuracy for purity and quantity measurement using UV(214) and ELSD. A general ELSD calibration curve from these compounds was also generated to quantify 42 library compounds. Purity measurement by ELSD underestimates the amounts of impurities due to a reduced ELSD response from smaller molecular weight impurities often produced in library synthesis. Absolute quantity determination by ELSD is more accurate (RSD 28%) than that by UV(214) (48%) using a calibration curve generated from the same set of compounds with diverse MWs. Error assessment for the measurement of absolute quantity of a class of commercial compounds and a class of representing reference compounds from seven diverse lead discovery libraries shows that structurally related compounds should be used to generate calibration curves to sustain smaller deviation.     

Determination of the affinity of high- and low-affinity antibodies, which are in a mixture, using ELISA and the method of non-linear regression

It was shown that application of the method of non-linear regression for the solution of the equation, which relates the fraction of free antibodies in a mixture and antigen concentrations, allows to determine the affinity constants for two antibodies in a mixture. Such method is easier and more accurate than the suggested by us earlier method, which use the numerical solution of the appropriate four equations, that describe the relations between the experimental data obtained by ELISA, competing antigen concentration, and values of antibody affinity. In addition, the proposed method allows using much less quantity of experimental measurements without diminishing of the accuracy for the affinity constants evaluations.     

Studies on the rates of water use of dwarf wheat and their relationship with potential values based on the climatological approach

Summary Field studies were conducted to assess the field evapotranspiration of dwarf wheat under semi-arid conditions of Hissar (India), and to compare the same with the values obtained by various formulae using meteorological parameters. First irrigation to the crop was given three weeks after sowing and subsequent irrigations when about 50% of the available soil moisture was depleted from the root zone. Measured quantity of water was applied according to the soil moisture deficit in the root zone.The daily rate of water use by wheat was quite low during the early part of the growth (about 2 mm per day). It increased gradually up to ear emergence and grain development (about 5 mm per day) and declined towards maturity. Potential evapotranspiration calculated by Thornthwaite formula was most unreliable for estimating evapotranspiration. Evaporation from the U.S. open pan evaporimeter gave quite closer values to the actual rates, except during maturity. Ramdas values did not show much closeness with the actual water use rates. Penman's formula gave values quite closer to the field water use rates. Consumptive use calculated by Blaney-Criddle method did not give appropriate estimate during January and February, but it exhibited much closeness during December and March. re]19750305     

Determination of the quantity of acetyl CoA carboxylase by [14C]methyl avidin binding

Conditions are described under which monomeric [14C]methyl avidin binds to SDS-denatured biotin enzymes and remains bound through polyacrylamide gel electrophoresis. The location of radioactive proteins on the dried gel was determined by fluorography and their identity was established by subunit molecular weight. The relative quantity of bound radioactive avidin, stoichiometrically equivalent to the molar quantity of biotin protein, can be determined by scanning the fluorograph with a soft laser densitometer. To determine the absolute quantity of biotin protein, the radioactive areas of the dried gel were cut out, resolubilized, and assayed for radioactivity. Since the specific radioactivity of the [14C]methyl avidin was known, the quantity of avidin bound and therefore the quantity of biotin enzyme could be calculated. The method is illustrated by the analysis of purified acetyl CoA carboxylase and is applied to the analysis of biotin enzymes in isolated rat liver mitochondria.     

Successful long-term cryopreservation of neonatal rat islet tissue

Neonatal rat pancreatic tissue was frozen to -196 degrees C using Me2SO as a cryoprotectant and a slow freezing rate to -70 degrees C followed by immersion in liquid nitrogen. Rapid thawing was used. Viability was demonstrated by successful transplantation to streptozotocin-induced diabetic recipients. Long-term preservation, up to 4 weeks, did not demonstrably affect viability. Cryopreservation techniques may afford a method for providing a diabetic recipient the opportunity to receive a large quantity of pooled islet tissue from well-matched donors.     

Determination of Urease Activity in Biological Purification Systems

Summary This paper deals with the standardisation of a suitable method to determine urease activity in bottom deposits of sewage stabilisation ponds and activated sludge units.Standard conditions were established; pH, incubation time, sample quantity, temperature, and the results are presented graphically.As the method is not dependent on ammonia distillation under vacuo, it is therefore suitable for serial analysis.Results from tests using this method can be used to determine the urea degrading efficiency of purification systems like stabilisation ponds and activated sludge systems treating urea containing effluents.