查询词典 sampling

Methods Seventy-five stu-dents were recruited based on cluster sampling for this study.

目的 探讨健康教育对护理本科生艾滋病知识和态度的影响。

Methods A questionnaire investigation was carried out among pupils, parents and teachers by cluster sampling.

采用整群抽样对学生和家长教师进行问卷调查。

A structured questionnaire was administered to 1091 students who were selected by cluster sampling.

以问卷调查法针对33所原住民国小1250名学童为对象，有效问卷1091份。

Methods 1118 students in 4 senior high schools in Dongcheng District of Beijing were sampled by random cluster sampling.

方法采用整群随机抽样的方法，抽取北京市东城区4所中学的高中一、二、三年级各2个班，共1118名学生，用中学生心理健康诊断测验量表进行测评。

AVO analysis is suggested for solving to solve the difficulty in identification of thin alternating layers in exploration of oilfields. It can improve the current method that has no thickness variable in the formula of reflective and is limited by sampling rates in calculation of the coefficient in the time of domain. Using the relationship of stress and displacement on two interfaces, this paper derives the spectrum of reflective coefficient for any incidence angle and thiekness of thim layer based on the equation of seismic wave propagation in the frequency domain.

针对油气田开发中薄互层认识难的问题，提出从AVO分析解决困难，克服现有方法在反射系数公式中无厚度变量、时间域计算反射系数谱受采样率限制的不足，运用两个界面间位移与应力关系，从频率域地震波传播方程推导了任意入射角和薄层厚度下的反射系数谱。

What is the sampling distribution of a regression coefficient?

分别回答什么是回归系数，什么是回归系数的样本分布？

A high performance digital IF radar receiver which uses IF echo and COHO joint process algorithm, field sampling, field processing and remote transmission is introduced. Its performance can meet the requirements of modern high performance radar system.

采用中频回波和中频相参信号联合相干处理，现场采样，现场处理，远程传输的体系结构实现了高性能数字中频雷达接收机，其性能可以满足现代高性能雷达系统的需要。

The chromosome preparation procedures with wheat coleoptile cells as sampling objects were preliminarily established.

初步建立起以小麦胚芽鞘为取样对象的体细胞染色体制片方法。

In this sampling, Beijing Lao Cai Chen Food Co., Ltd. of sesame have been detected coliform bacteria exceeded.

在本次抽查中，北京市老才臣食品有限公司的芝麻酱被检测出大肠菌群超标。

This thesis has mainly contributed two results in theory: one is that the covariance matrix is not positive definitive if the number of sampling is least than the number of variables, the other is that the covariance matrix of discrete sample is positive definitive if and only if the sum of every random column vector of data matrix is non I-linear combination.

本论文在理论上，主要得出两个新的结果：ⅰ抽样调查中，若样本的个数少于变量的个数则样本协方差矩阵恒为非正定；ⅱ离散型样本协方差矩阵正定的充要条件是样本资料阵的各随机列向量是非I-线性组合。

A carrier gas such as nitrogen is directed through line 20 and valve 22 to connect with line 26 and mix with the gas sample.

如氮气之类的载体通过管线20和阀22引入，与管线26相通，与气体样品混合。

But for the most part, knaves and parasites had the command of his fortune

然而支配他的家产的大多是恶棍和寄生虫。