向量场是科学和工程中的重要概念，描述物理过程中的方向信息和状态的变化趋势。
Vector field is important conception in science and engineering, which describes directional information of physical procedure and developing trends of states.
本标准主要描述了乱翻滚式测试仪，对纺织品材料抗起球性能和有关织物表面变化趋势的评价。
This test method covers the resistance to the formation of pills and other related surface changes on textile fabrics using the random tumble pilling tester.
方法应用描述性统计方法分析生育率、初婚初育年龄、婚育间隔、生育间隔和出生性别比及其变化趋势。
Methods The statistical description of fertility rate, age at first marriage, age at first birth, interval between marriage and first birth, birth interval.
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