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。     

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     

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。     

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.     

Ni-Doped BiVO4 with V4+ Species and Oxygen Vacancies for Efficient Photoelectrochemical Water Splitting

Bismuth vanadate is a promising photoanode material for photoelectrochemical(PEC)water splitting,but its activity and stability need to be further improved.In this work,we synthesized Ni-doped BiVO _(4 )abundant with V ~(4+)species and oxygen defects through an in situ electrodeposition method.The effective doping can decrease the particle size of BiVO _(4 )and lead to the formation of V ~(4+)species/oxygen defects.Accordingly,the doped and defective BiVO _(4 )showed high optical absorption and rapid charge transfer,and further showed much higher PEC activity than pure BiVO _4.Specifically,5-Ni-BiVO _(4 )exhibits the highest activity in PEC water splitting,with a photocurrent of 2.39 mA/cm ~(2 )at 1.23 V versus RHE(the reversible hydrogen electrode),which is 2.5 times higher than pure BiVO _4(0.94 m A/cm ~2),and much higher incident photon-to-current efficiency(IPCE)value of 45%(while only 25%for BiVO _(4 )at ca.400 nm).This work provides an in situ method for the development of a high-performance photoanode.     

大学英语跨文化交际的教学探讨

新颁布的《大学英语课程教学要求》提出英语教学的主要内容是培养学生的语言应用能力、学习策略和跨文化交际能力。语言与文化是紧密相连的 ,学习语言必然要将语言教学与文化教学结合起来 ,加强对目的语文化的了解和学生的素质教育。本文论述了跨文化交际中的文化差异以及在英语教学中实施文化教育的必要性 ,并探讨了进行跨文化交际教学的主要方法和策略     

国家创新体系中的信息需求与信息保障

本文通过对国家创新体系中各个子系统的信息需求的讨论，阐述了信息的重要组成因素，及信息保障子系统的特点与功能。     

蜜蜂及其作用

本文从蜂产品、蜜蜂在农业中所起的作用及蜜蜂对保持生态平衡等方面阐述了蜜蜂对人类的重要作用。