MS2000激光粒度分析仪在沉积物分析中的应用   总被引：4，自引：0，他引：4  

刘秀明  李文宝  邢春颖 《实验技术与管理》2007,24(9):49-52

介绍了MS2000激光粒度分析的基本原理及结构组成,以及粒度分析前对沉积物样品进行预处理的方法,总结了近年来粒度分析方法在海洋地质学、第四纪地质学、古气候与古海洋学等研究领域的应用,并对其应用前景进行了预测。  相似文献   

微孔膜内大分子有效扩散系数的计算     

何志敏 《天津大学学报(英文版)》1995,(1)

报道一种计算分子尺寸与构型对微孔内大分子有效扩散系数影响的理论方法。基于刚性圆球分子在圆柱型孔内的扩散理论，定义分子平均投影半径和水力学球半径，分别用于估算孔内外浓度分配系数和孔内水力学拖曳力。对不同构型的大分子，使用该法计算的有效扩散系数与已发表的实验数据吻合良好。  相似文献   

Relationship between the size of pontocerebellar angle tumor and audiology     

Tang Jian-guo  Cai Yi 《浙江大学学报(A卷英文版)》2001,2(1):111-113

Objective: To study the relationship between the size of pontocerebellar angle tumor and audiology. Methods: Retrospective analysis of accoustically evoked brainstem response (ABR) waveforms and pure tone threshold in 27 subjects with tumor of pontocerebellar angle. Results: ABR wave forms and pure tone threshold were significantly affected statistically by the size of tumors, especially those tumor larger than 3 cm in diameter. Conclusion: The primary symptom of the patient was unilateral hearing loss. Early discovery of the lesion is important and ABR is a sensitive tool for early diagnose of the tumor.  相似文献   

外资在华制药企业技术战略分析     

曹莉莉  陈向东 《中国软科学》2007,(11):64-72

生物制药行业是21世纪的前瞻性行业,也是外资大力争夺创新资源的行业。本文基于1985—2005年的专利数据,主要从创新范围和创新规模两方面分析了制药行业外资技术竞争以及创新活动的特点。本文原创性地运用聚类的统计方法,定义了规模-范围矩阵(简称为双 S 矩阵),对外资技术策略的特点进行分类,进而识别各类外资的角色。本文的研究结论为行业相关政策以及企业战略的制定提供参考。  相似文献   

科研管理中瓶颈问题分析   总被引：2，自引：0，他引：2  

周耀烈  张大亮 《科研管理》2003,24(1):28-33

瓶颈问题可通过改变颈口面积和颈口秩序来解决。本文首先建立了颈口面积模型和颈口秩序模型，并用案例说明了其运用方法。该瓶颈模型还可用在经济分析、生产管理等许多问题的分析上。  相似文献   

闽中麻鸡肌纤维生长发育规律的研究     

王立克  李如兰  程云 《安徽科技学院学报》2007,21(1):6-9

选择160只闽中麻鸡在相同的环境条件饲养下,分别于0、7、14、21、28、35、42日龄各随机抽取10只宰杀,研究腿肌、胸肌、翅肌肌纤维直径的变化规律.结果表明:随着日龄的增加,不同部位肌纤维的直径均显著增加(P＜0.01);不同部位肌纤维直径在不同时期发育速度不同,肌纤维发育速度与机体发育速度相关性不明显.  相似文献   

二语习得词汇研究对高职高专英语词汇研究的启示     

金娴  吉小红 《金华职业技术学院学报》2011,11(5):27-30

词汇习得是二语学习的一个重要组成部分。国内外研究者对二语词汇习得开展了广泛和深入的研究,取得了丰硕的成果。高职高专二语习得词汇研究虽然起步较晚,但是可以借鉴国内外研究的成功经验。同时依据自身特点,开展对目标词汇量、现有词汇量和词汇学习策略的深入研究,为高职高专学生词汇习得研究奠定基础。  相似文献   

On Sample-Size Calculations for Precise Contrast Analysis in ANCOVA     

Gwowen Shieh 《Journal of Experimental Education》2019,87(2):238-259

The analysis of covariance (ANCOVA) is a useful statistical procedure that incorporates covariate features into the adjustment of treatment effects. The consequences of omitted prognostic covariates on the statistical inferences of ANCOVA are well documented in the literature. However, the corresponding influence on sample-size calculations for precise interval estimation has not been fully evaluated. This article aims to explicate the deficiency of approximate methods for ignoring the stochastic nature of covariate variables and to present exact approaches for precise interval estimation of treatment contrasts under the assumption that the covariate variables have a joint multinormal distribution. The desired precision of a confidence interval is assessed with respect to the control of expected half-width and to the assurance probability of interval half-width within a designated value. Numerical appraisals show that the suggested approaches outperform the approximate formulas for the two precision considerations.  相似文献   

Social commerce adoption using TOE framework: An empirical investigation of Saudi Arabian SMEs     

《International Journal of Information Management》2020

Social commerce is becoming an important hub for product sourcing, which helps companies to connect with customers and to gain competitive advantages. However, very little empirical research that focuses on small-and medium-sized enterprises (SMEs) has been conducted to date. This study examines factors that affect social commerce adoption by SMEs. Using the Technology-Organisation-Environment (TOE) as the theoretical framework, the researchers tested the model and related hypotheses, employing structural equation modelling. The results from a survey of 181 SMEs in Saudi Arabia indicate that trading partner pressure in the environmental context, followed by top management support in the organisational context, and perceived usefulness in the technological context, have the most significant influence on behavioural intention to use social commerce. The research contributions and conclusion as well as limitations and future research directions are presented.  相似文献   

Effects of blood flow restriction without additional exercise on strength reductions and muscular atrophy following immobilization:A systematic review     

Mikhail Santos Cerqueira  Jose Diego Sales Do Nascimento  Daniel Germano Maciel  Jean Artur Mendonca Barboza  Wouber Herickson De Brito Vieira 《运动与健康科学(英文)》2020,9(2):152-159

Purpose:To investigate whether blood flow restriction(BFR) without concomitant exercise mitigated strength reduction and atrophy of thigh muscles in subjects under immobilization for lower limbs.Methods:The following databases were searched:PubMed,CINAHL,PEDro,Web of Science,Central,and Scopus.Results:The search identified 3 eligible studies,and the total sample in the identified studies consisted of 38 participants.Isokinetic and isometric torque of the knee flexors and extensors was examined in 2 studies.Cross-sectional area of thigh muscles was evaluated in 1 study,and thigh girth was measured in 2 studies.The BFR protocol was 5 sets of 5 min of occlusion and 3 min of free flow,twice daily for approximately 2 weeks.As a whole,the included studies indicate that BFR without exercise is able to minimize strength reduction and muscular atrophy after immobilization.It is crucial to emphasize,however,that the included studies showed a high risk of bias,especially regarding allocation concealment,blinding of outcome assessment,intention-to-treat analyses,and group similarity at baseline.Conclusion:Although potentially useful,the high risk of bias presented by original stodies limits the indication of BFR without concomitant exercise as an effective countermeasure against strength reduction and atrophy mediated by immobilization.  相似文献