In vitro antioxidant activity of phenolic-enriched extracts from Zhangping Narcissus tea cake and their inhibition on growth and metastatic capacity of 4T1 murine breast cancer cells

Phenolics, as the main bioactive compounds in tea, have been suggested to have potential in the prevention of various human diseases. However, little is known about phenolics and their bioactivity in Zhangping Narcissue tea cake which is considered the most special kind of oolong tea. To unveil its bioactivity, three phenolic-enriched extracts were obtained from Zhangping Narcissue tea cake using ethyl acetate, n-butanol, and water. Their main chemical compositions and in vitro bioactivity were analyzed by high-performance liquid chromatography (HPLC) and ultraperformance liquid chromatography-mass spectrometry (UPLC-MS). The ethyl acetate fraction (ZEF) consisted of higher content of phenolics, flavonoids, procyanidins, and catechin monomers (including epigallocatechin gallate (EGCG), epicatechin gallate (ECG), and gallocatechin gallate (GCG)) than n-butanol fraction (ZBF) and water fraction (ZWF). ZEF exhibited the strongest antioxidant capacity in vitro due to its abundant bioactive compounds. This was validated by Pearson correlation and hierarchical clustering analyses. ZEF also showed a remarkable inhibition on the growth, migration, and invasion of 4T1 murine breast cancer cells.     

中国大学生价格反应行为的基本特征

本文应用对中国13511名大学生的调查数据分析了学生价格反应行为的基本特征。结果表明，虽然接受高等教育需要承担较高的私人成本，学生的付费意愿却非常强烈，在学费上涨30％—300％五种不同幅度时，学生的高等教育需求对学费的弹性介于—0．045～—0．288之间。大学生的价格反应行为具有如下几个方面的特点：首先，学生的高等教育需求对学费及有些学生资助(如奖学金)具有灵敏的反应；其次，学生对学费及不同类型学生资助的反应不仅在性质上存在差异，而且在程度上也有所不同；第三，不同收入水平家庭学生对学费的反应是不同的；第四，学生对学费及学生资助的反应随着学生资助政策及学费的变化而变化。本文也讨论了上述结果对制订高等教育规划与财政政策的意义。     

Reduction rate of dragload and downdrag of piles by taper angles

Taper angle is one of the effective methods to reduce the dragload and downdrag of piles under the surcharge load. The model tests on the tapered pile and uniform cross-section pile embedded in sand were carried out under the surcharge load. The values of dragload and downdrag of piles versus the surcharge loads were measured. Based on the concentric cylinder shearing theory, a simplified theoretical model for calculating the dragload and downdrag of tapered piles with small taper angles under the surcharge load was proposed considering the angle effect. The correctness of the developed theoretical model was validated through comparing with the model test results obtained in this study and previous literature. Then the parametric studies of the taper angle, surcharge, strength and modulus of soil were discussed. It is shown that the tapered pile with the taper angle of 3° can reduce approximately 65% of the maximum dragload value and 30% of the downdrag value compared with a uniform cross-section pile. The value of downdrag can be decreased by approximately 50% compared with a uniform crosssection pile in the same average pile diameter.     

谈正弦定理推导中的数学探究

《普通高中数学课程标准(实验)》指出:数学探究即数学探究性课题学习,是指学生围绕某个数学问题,自主探究、学习的过程.这个过程包括:观察分析数学事实,提出有意义的数学问题,猜测、探求适当的     

朱元璋与历史教育

文章着重探讨朱元璋历史教育的相关活动:朱元璋重视历史教育的原因、进行历史教育采取的形式以及注重历史教育所产生的作用。朱元璋重视历史教育,对明初政治产生重大影响,有其积极作用;但过分注重历史教育的政治价值,也带来了消极影响。     

浅议开放教育的考试改革

开放教育的考试基本上是传统教育考试的框架,能否用现代远程教育理念去改革、创新将直接关系到开放教育的教育质量以及人才培养的目标实现。本文针对目前开放教育考试中存在的死记硬背的题型、考试形式的陈旧、方法单一等问题,提出了开放教育考试要突出考试内容的创新、题型的灵活、考试方法的科学及考试的开放性的改革理念及解放思想、更新观念、大胆探索,从改革考试形式入手,改进书面考试题型,完善、规范形成性考核,逐步试行计算机无纸化考试等具体建议,使考试进一步科学地服务于教学。     

支架立柱结构分析及损坏预防措施

通过对液压支架立柱结构进行分析,便于掌握立柱损坏的原因,及时提出损坏预防措施。     

Multi-face detection based on downsampling and modified subtractive clustering for color images

INTRODUCTION Face detection has been widely used in fields such as security, multimedia retrieval, human com-puter interaction, etc. Therefore it becomes one of the most active research areas in computer science. Re-cently, approaches to face detection include neural network (Rowley et al., 1998), boosting (Viola, 2001; Viola and Jones, 2004), template matching (Kim et al.,2000) and skin color (Cai and Goshtasby, 1999; Wang and Yuan, 2001; Soriano et al., 2003), etc. The methods of n…     

诗骚传统艺术精神的绵延——论汪曾祺的诗化抒情体小说

注重抒情的中国古代诗骚传统作为一种艺术精神影响了汪曾祺的诗化抒情体小说创作.本文从小说的结构、审美、语言以及抒情性四个方面来考察这种影响.     

高职汽车运用技术专业课程体系的创新

针对当前各类职业技术学院汽车运用技术专业课程体系改革的情况,提出建专业基础课大平台、专业技术课小模块、实验实训项目工单化的课程体系改革思路,同时在改革中加强教学文体和教材的编写,注重专业课教师素质的提高。