Antioxidant vitamins and chemoprevention

Free radicals play an important role in human carcinogenesis and the mechanism of their counteraction by antioxidant vitamins has been reviewed. It seems more likely that these vitamins work in concert rather than acting singly. Currently available data are compatible with the notion that these vitamins act as chemopreventives against some important cancers, e.g. carotenoids for lung cancer, ascorbic acid for salivary gland cancer, tocopherols for head and neck cancers etc. Thus, a greater consumption of fruits and vegetables should be encouraged as they are the natural sources of these chemopreventive, antioxidants along with other protective factors packaged by nature. However, much work still remains to be done to establish the role of antioxidant vitamins in carcinogenesis.     

英国图书馆学情报学研究生教育及其对我国的借鉴意义

英国的图书馆学情报学教育在经历了一系列改革之后 ,其培养目标、课程体系设置、课程内容、教学方式都发生了重大变化。对我国的借鉴意义在于 :培养方向上 ,实现培养目标的社会化和综合化 ;课程体系上 ,借鉴英国的模块化教育 ;课程内容上以信息技术贯穿整个教育始终 ,注重理论与实践的结合 ;采取多样化教学。表 1。参考文献 8。     

天门冬氨酸钾镁消除运动疲劳的作用机制

天门冬氨酸钾镁(PMA)的主要作用是加速三羧酸循环中的有氧代谢过程;消除运动中产生的氨．降低血氨浓度;消除氧自由基;提高镁的含量和Na~ ／K~ -ATP酶的活性,维持细胞膜内外离子浓度等,补充天门冬氨钾镁对抵抗疲劳产生,提高运动能力有很好的效果。本文较系统地论述了天门冬氨酸钾镁抗疲劳的生物学机制。     

新一代"环保"杨84K的扦插研究

84k杨扦插研究表明:插条浸水、封蜡、加铺地热线均有利于插条生根,80-100ppm浓度的吲哚丁酸（IBA）、大于100PPm浓度的吲哚乙酸（IAA）对插条生根率和根长有明显的促进作用,50PPmIBA和IAA一定程度上可提高插条的生根数。30-100ppm浓度的NAA则对插条的生根率、根长及生根数均有明显的促进作用。     

维生素E和硒对运动中红细胞氧化应激的影响

给大鼠腹腔内注射维生素E亚硒酸钠注射液共45天,测定红细胞抗氧化酶、膜脂质过氧化物、膜流动性、膜蛋白高分子聚合物,以期了解疲劳性运动,氧化应激和抗氧化防御体系之间的关系。研究发现VitE和Se协同作用,有效地提高了大鼠红细胞SOD,GSH-Px活性,抑制疲劳性游泳后红细胞膜MDA含量增加。     

Overt and covert use of objectives of different cognitive levels

College students provided objectives along with a study passage scored significantly lower on a multiple-choice post-test than students given the same objectives plus an overt task for the content of each objective. Scores on lower level post-test questions were significantly higher than scores on higher level questions. Students did not perform better on the post-test on content for which they had been given higher level objectives than on content for which lower level objectives were provided. This finding was not in keeping with what would be predicted from learning from text studies employing inserted study questions of different levels.     

W.K.B近似法的拓宽

本文将W.K.B近似法拓宽到缓交参量条件下的计算、类比了量子力学中的结果,并以渐变折射率光波导和平面分层介质两种模型为例作了一些有益的探讨.关键词:W.K.B.近似法,缓变参量     

EFFECTS OF DIFFERENT CONCENTRATIONS OF ANTISENSE OLIGODEOXYNUCLEOTIDES(ASODN) ON HUMAN PANCREATIC CANCER CELL LINE PaTu8988s

ＩＮＴＲＯＤＵＣＴＩＯＮＡｎｔｉｓｅｎｓｅｏｌｉｇｏｄｅｏｘｙｎｕｃｌｅｏｔｉｄｅｓ (ＡＳＯＤＮ )ｃａｎｉｎｈｉｂｉｔｔｒａｎｓｃｒｉｐｔｉｏｎａｎｄｉｎｔｅｒｆｅｒｅｗｉｔｈｓｐｅ ｃｉａｌｇｅｎｅｅｘｐｒｅｓｓｉｏｎ .ＡｆｉｘｅｄｐｏｉｎｔｏｎｔｈｅＫ ｒａｓｇｅｎｅｗｉｔｈｈｉｇｈｍｕｔａｔｉｏｎｒａｔｅｉｎｐａｎｃｒｅａｔｉｃｃａｒｃｉ ｎｏｍａｏｆｆｅｒｓａｎｉｎｔｒａｃｅｌｌｕｌａｒｔａｒｇｅｔｆｏｒｐａｎｃｒｅａｔｉｃｃａｒｃｉｎｏｍａｇｅｎｅｔｈｅｒａｐｙｗｉｔｈＡＳＯＤＮ (Ｃａｉ…     

学生成绩评价的数学建模

以课堂表现、平时作业成绩和期末闭卷考试成绩为依据,采用层次分析法构建数学模型;并对某班学生的《线性代数》成绩做了评定.结果表明,评价科学、合理.     

从超光速和3°K背景看牛爱时空观的统一

到目前为止,现代天文学观测到的超光速现象和3°K幅射背景,都被人们误认为是相对论无法解释的疑难问题。试图解释这些疑难的各种理论,都是以牛顿与爱因斯坦时空观的矛盾和对立为前提的。本文运用笔者本人在1984—1987年完成的与爱因斯坦相对论等效的牛顿修正定律,加上唯物辩证的分析,第一次把隐含在相对论之中与亚光速运动和相对惯性系相对称的、长期被人们忽视的另一半——超光速运动和绝对惯性系发掘出来了,并进一步提出了反粒子“负”质能的新解释,与牛顿万有引力定律相对称的万有斥力定律,以及河外红移、宇宙“膨胀”的新机制。