Estimating sexual dimorphism by method-of-moments

Estimating the degree of sexual dimorphism is difficult in fossil species because most specimens lack indicators of sex. We present a procedure that estimates sexual dimorphism in samples of unknown sex using method-of-moments. We assume that the distribution of a metric trait is composed of two underlying normal distributions, one for males and one for females. We use three moments around the mean of the combined-sex distribution to estimate the means and the common standard deviation of the two underlying distributions. This procedure has advantages over previous methods: it is relatively simple to use, specimens need not be assigned to sex a priori, no reference to living species analogs is required, and the method provides conservative estimates of dimorphism under a variety of conditions. The method performs best when the male and female distributions overlap minimally but also works well when overlap is substantial. Simulations indicate that this relatively simple method is more accurate and reliable than previous methods for estimating dimorphism. © 1996 Wiley-Liss, Inc.     

酶浸提取方法对士的宁产率的影响

目的：研究了纤维素酶在提取生物碱过程中的应用。方法：采用酶浸法和氯仿法两种不同的工艺提取马钱子生物总碱,高效液相色谱法（HPLC）测定了马钱子生物总碱中士的宁的含量。结果：酶浸法提取士的宁和氯仿法提取士的宁的含量分别为1．83％、1．32％;酶浸法和氯仿法提取马钱子生物总碱的产率分别为：2．85％、1．86％。     

The Method of Unweighted Means in Unbalanced Analysis of Variance

For factorial experiments with unbalanced data the method of unweighted means is an alternate method of analysis which is computationally simpler than likelihood ratio based F-tests. The quality of the null approximation to the F-distribution of the statistic for the method of unweighted means and the power of this test relative to the likelihood ratio test are discussed. Recommendations are made of when in the course of data analysis the superior operating characteristics of the likelihood ratio test may not outweigh the computational simplicity of the method of unweighted means test.     

离子通道开放状态检测法的计算机模拟研究(Ⅱ)

本文（Ⅱ）在文（Ⅰ）的基础上进一步探讨了将多指数函数检测法和连续平均开放时间检测法相结合的离子通道开放状态检测法．侧重分析了两开放状态平均开放时间的比值和同一开放状态连续出现的次数对自相关函数的影响,并给出了实施流程.本文提供的计算机模拟研究方法对研究生物医学的其它问题也有参考价值.     

"雌蕊的类型"一节的教学改进

在植物“雌蕊的类型”一节的教学实践中,我们在课堂教学中采用理论教学与实验教学同步进行的“二合一”教学方法,并在教学过程中选用典型的、合适的实验材料应用电视——显微镜成像系统对其解剖观察和讲解,这不仅活跃了课堂气氛,而且提高了学生观察和动手能力;在学生对“雌蕊一节”各概念和实验技能基本掌握的前提下,再辅以现场教学,则进一步扩展了学生的知识面,所有这些,不仅使学生更好的理解各类雌蕊的结构组成特点,而且提高了学生的综合素质。     

超氧化物歧化酶两种邻苯三酚自氧化测定活力方法的比较

在同一反应条件下,以酵母SOD为原料,对2种邻苯三酚自氧化测定SOD的方法进行了比较,实验结果表明325 nm法测定的酶活力单位与420 nm法测定的酶活力单位的比值约为2.7,考察了不同浓度邻苯三酚对SOD活力的影响。     

重组人白介素-11蛋白浓度两种测定方法比较

在基因工程蛋白药物开发研究过程中,选定恰当、准确的蛋白浓度测定方法非常重要。本文比较Lowry法和Bradford法测定重组人白介素-11蛋白浓度结果,认为选用Bradford法是可行的,但中国药典三部蛋白浓度测定方法中没有收录Bradford法,建议在中国药典三部修订时收录该方法。     

林木蒸腾耗水量测算方法的比较与应用

本文简述了林木蒸腾耗水的概念、研究价值和研究进展,从实测法和估测法的角度,综述了林木蒸腾耗水量的主要测算方法,对比了各方法的优缺点、适用性、局限性、应用现状以及适用尺度。本研究认为: 实测法可应用于多种空间尺度耗水量的测定,估测法常应用于大空间尺度蒸散量的测算。实测法是估测法的基础,因此应对实测法的测定结果进行合理的质量控制与评价,为校正估测法的估算结果提供数据基础。不管是同一大空间尺度还是不同空间尺度,实测法和估测法的结合能够提高蒸散量测算结果的准确性。提升复杂下垫面和恶劣气候环境下大空间尺度林木蒸散量的测算精度将成为未来的研究热点与难点。随着科学技术的不断进步,现有的测定装置和测算方法将被改进,精确测定林木蒸腾耗水量的新方法也将随之诞生。     

Inference from single occasion capture experiments using genetic markers

Accurate estimation of the size of animal populations is an important task in ecological science. Recent advances in the field of molecular genetics researches allow the use of genetic data to estimate the size of a population from a single capture occasion rather than repeated occasions as in the usual capture–recapture experiments. Estimating the population size using genetic data also has sometimes led to estimates that differ markedly from each other and also from classical capture–recapture estimates. Here, we develop a closed form estimator that uses genetic information to estimate the size of a population consisting of mothers and daughters, focusing on estimating the number of mothers, using data from a single sample. We demonstrate the estimator is consistent and propose a parametric bootstrap to estimate the standard errors. The estimator is evaluated in a simulation study and applied to real data. We also consider maximum likelihood in this setting and discover problems that preclude its general use.     

离子通道开放状态检测法的计算机模拟研究(I)

本文概述了离子通道马尔科夫模型的计算机模拟方法,通过对两个门控模型模拟数据的多指数函数法与本文作者提出的连续分组平均开放时间法检测结果的对比研究,探讨了新方法在检测通道开放状态时的效应和适用范围,以及有关的一些问题．本文提供的模拟研究方法对研究生物医学的其它问题也有参考价值．     

用斜面法分离厌氧微生物

描述了一种在斜面上分离厌氧微生物的方法,包括培养基、稀释细菌悬浮液的点样和菌落的挑取等。用此法长出的菌落形态清晰可见,便于分离。此法简便、易行,亦可用于观察厌氧菌的斜面培养特征和菌种保藏。     

真菌多糖水提及化学辅助提取方法研究进展

真菌多糖具有抗肿瘤、抗衰老、免疫调节等多种功效, 有较高的食、药用和商业价值。本文通过对实例的总结, 介绍热水浸提法、稀酸提取法、碱提取法、酶消化提取法等真菌多糖提取技术。通过比较阐述其优缺点、影响因素和适用范围, 为类似试验提供建议。     

Antenna modeling considerations for accurate SAR calculations in human phantoms in close proximity to GSM cellular base station antennas

International bodies such as International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Institute for Electrical and Electronic Engineering (IEEE) make provision for human exposure assessment based on SAR calculations (or measurements) and basic restrictions. In the case of base station exposure this is mostly applicable to occupational exposure scenarios in the very near field of these antennas where the conservative reference level criteria could be unnecessarily restrictive. This study presents a variety of critical aspects that need to be considered when calculating SAR in a human body close to a mobile phone base station antenna. A hybrid FEM/MoM technique is proposed as a suitable numerical method to obtain accurate results. The verification of the FEM/MoM implementation has been presented in a previous publication; the focus of this study is an investigation into the detail that must be included in a numerical model of the antenna, to accurately represent the real-world scenario. This is accomplished by comparing numerical results to measurements for a generic GSM base station antenna and appropriate, representative canonical and human phantoms. The results show that it is critical to take the disturbance effect of the human phantom (a large conductive body) on the base station antenna into account when the antenna-phantom spacing is less than 300 mm. For these small spacings, the antenna structure must be modeled in detail. The conclusion is that it is feasible to calculate, using the proposed techniques and methodology, accurate occupational compliance zones around base station antennas based on a SAR profile and basic restriction guidelines.     

Bivariate POISSON Binomial Distributions

Three bivariate generalizations of the POISSON binomial distribution are introduced. The probabilities, moments, conditional distributions and regression functions for these distributions are obtained in terms of bipartitional polynomials. Recurrences for the probabilities and moments are also given. Parameter estimators are derived using the methods of moments and zero frequencies and the three distributions are fitted to some ecological data.     

烟叶果胶质分解菌的选育

从烟叶叶面分离到产果胶酶真菌 18株 ,在此基础上 ,进行液体培养 ,测定酶活 ,得到一株酶活性较高的黄曲霉DPE - 0 0 5。对该菌株产酶培养基的碳、氮源进行正交法研究 ,正交实验的结果表明 ,影响该菌产酶活性的因素依次为A(麸皮 ) >B(乳糖 ) >C(果胶 ) >D(硫酸铵 ) ,其最佳组合为A2B3C3D1。最适产酶条件为 :麸皮 4 0 % ,果胶 0 3% ,乳糖 1 5 % ,(NH4 ) 2 SO4 0 5 % ,KH2 PO4 0 2 5 % ,MgSO4 ·7H2 O 0 0 5 % ,NaNO30 0 2 % ,FeSO4 ·7H2 O 0 0 0 1% ,起始pH 6 0 ,在 2 8℃摇床培养 7d产酶量达到最高。以玉溪B3F烟叶为材料 ,施加DPE - 0 0 5菌株所产酶液 ,在 5 0℃贮存 12h。经化学成分检测 ,结果表明 ,果胶质降低了 18 15 %。     

多元肥料效应函数模型的优化方法

本文对多元肥料效应函数模型的优化问题进行了分析,根据数学规划理论建立了对多元肥料效应函数进行优化的数学模型,给出了具体的计算方法。该方法经实践检验,效果很好。     

大豆转基因体系的研究进展

从大豆的转基因方法和受体系统两个方面概述大豆转基因体系的最新研究进展,并讨论了大豆遗传转化的主要障碍及可能的解决途径。作者认为,以根癌农杆菌介导大豆子叶节和基因枪轰击大豆未成熟子叶是较有效的大豆遗传化系统。目前,在大豆遗传转化研究中存在着大豆组织培养体系有待于进一步完善、遗传转化率较低、重复性差、大豆受体基因型单一等问题,建立新的、高效和稳定的大豆组织培养体系,提高生产上栽培大豆品种的组织培养能力,改遗传转化现有的单一基因为多基因,可能是解决上述问题的有效途径。     

扫描电镜分析牙齿釉质结构方法的讨论

通过扫描电镜对大熊猫牙齿釉质结构的三维观察与比较,结果表明:在同一枚牙齿上,不同部位的釉质切面,釉柱截面的形状、大小以及排列等,有不同的现象.因此在用上述特征描述时,应对所有要比较的样品,须精确地统一在相同的部位.本文以多次实验结果,表明了严格定位取样的重要性.     

侧孢芽孢杆菌质粒提取方法的探究

以能够降解有机磷农药的两株侧孢芽孢杆菌BL-21和BL-22为研究对象,分别采用碱裂解法、试剂盒提取法和SDS法对侧孢芽孢杆菌BL-21和BL-22的质粒进行提取,并通过凝胶电泳和紫外分光光度法对提取结果进行分析,试验结果证明,适合侧孢芽孢杆菌BL-21和BL-22的质粒提取方法是SDS裂解法,该方法提取的质粒大小为10kb,且该方法提取的结果稳定,质粒的产量和质量均符合分子生物学实验的要求。