从对转基因的认识谈高中学生科学素养的培养

高中化学和生物教材有多处介绍核酸、基因、转基因的知识,但通过问卷调查发现：高中学生对基因、转基因技术和转基因食品的认识模糊不清。究其原因可能是由于教学的功利性,仅关注本学科的高考,不注意学科间知识的融会贯通,不重视学科前沿知识和社会热点问题的拓展。高中化学课程中应重视“核酸”等生命化学相关内容的教学,拓展学生对转基因技术的科学认识,引导学生运用所学知识和科学方法去分析、判断转基因食品的安全性问题,着眼于培养学生的科学素养。     

"3+X"高考后特区内高中生学习化学情况调查与对策

自广东省实行“3+Ｘ”高考以后 ,高考试卷与考生的学科流向发生了极大的变化 ,给高中的教学与高考备考都带来了新的挑战与新的问题。对中学的化学学科教学 ,也产生了较大的影响。目前大学招生的热门系科一般都需要考物理与政治学科 ,而由于深圳特区内环境保护方面的原因 ,在就业问题上 ,化学方面的人才需求较少。因此 ,报考化学的学生人数较少 ,成绩优秀的学生一般也不选择学习化学。高中化学教师也在抱怨 ,化学考生素质太差 ,高三化学的教学与复习投入大产出少。教师中存在缺乏信心和无所作为的思想。为了清楚地了解高考改革后对学生学习化…     

新教材新知识教学习题设计研究

本文对新教材增加的部分知识设计了一些有利于提高学生学习能力和思维品质的习题,既可作为同步教学兴趣课使用,也可作为高考复习教学和命题方向预测参考。     

学生在化学题解答中的几种心理致误因素浅析

近几年我省高考化学科试卷质量分析反应出考生错解、误解试题的现象比较严重。我认为,这不仅是学生基础知识不牢固、不会应用所学知识解决问题这一因素的影响,学生的心理障碍对考试效果的影响也不容忽视。     

高中学生化学学习元认知水平的调查与分析

在平时教学过程中,我们比较注意研究高考要求、教材和教法,同时也注意研究学生的记忆力、注意力和想象力以及思维能力等在化学学习过程中的作用,把学生的学习过程理解为是对化学知识进行感知、记忆、理解、加工的过程。     

开设高中环境监测选修课提高中学生化学实验综合能力

高中学生面临着高考升学与提高自身综合素质两大任务。在中学化学教学中,如何使两者有效结合,是我们化学教师始终关心的一个现实问题。化学实验在化学中占有重要地位,对培养学生综合能力有着不可替代的作用。但由于许多原因(如教材的编写体系、教师队伍建设、教学条件以及高考模式等),高中化学实验一直是教学环节中一个薄弱环节,也是学生在考试中失分较严重的部分。部分学生高中毕业之后,在日常生活中不能独立运用化学实验技能解决常见问题,更谈不上自主设计实验、自主研究等较高要求了。笔者在从事高中化学教学的同时,兼任环境监测选修课的教学,在教学过程中,经常思考这个问题：能否通过选修课培养学生对化学实验的强烈兴趣,加强实验技术的掌握和应用,让学生在学习环保知识的同时,能全面提升他们的化学实验综合能力。     

一九八八年高考化学试题与中学化学教学改革

高考是为了选拔继续深造的人才,在一定程度上影响着中学教学,起着指挥作用。今年高考化学试题是一份推动中学化学教学改革的题目。它体现了教育目标的多层次要求,不仅检查知识技能也检查能力;向标准化考试过渡,对考试改革和加强实验教学起了推动作用;它摆脱了以往考试的旧模式,联系实际,灵活性大。缺点是题量过大,脱离当前教与学的实际,个别题目超纲,学生成绩可能不甚理想,区分度小些。     

中学化学教学中理论联系实际的探讨

近年来,由于教学大纲和课本的不断修订,对理论联系实际问题越来越重视。但是,学生实践知识不足的问题,仍有待进一步解决。学生知识面窄、学得过死的现象仍很普遍,高考中也反映出许多学生会背定律却不能很好地解决实际问题。而且,化学教学不仅要为高考服务,还要培养多层次的人才,所以理论联系实际的问题仍需要进一步探讨和落实。     

元素化合物复习教学的定位与设计

在以能力立意为价值取向的高考命题中,元素化合物知识成为考查化学概念与理论、化学方法与能力的载体。高考复习教学中,对元素化合物内容的科学定位是进行有效教学设计的前提,根据当前较为流行的2轮次或3轮次高考复习教学实际,第1轮次复习根据物质类别、按照通性与特性组织教学,第2轮次复习根据高考要求和高考试题特点、按照元素化合物与STS、元素化合物与氧化还原、离子反应,元素化合物与物质的制备、检验等3个专题组织教学,具体介绍复习教学设计的思路。     

把高考复习的主动权还给学生

高考前的化学总复习,是高中化学教学的最后阶段。在总复习中,教师要根据《高考化学科说明》的要求,制订和实施总复习的教学目标。通过总复习,要使学生的化学知识得到巩固和有序贮存,使学科能力得到较大提高,使心理素质更加符合高考的要求。     

HEPT类化合物的QSAR研究

为定量结构／活性相关性研究提取了量子化学参数,拓扑指数Am,分子连接性指数^mxt及疏水性常数,同时应用正交变换和最佳变量子集算法（Leaps-and-Bonds)进行了变量压缩和选择,进而实施了多元回归分析,并由此结果进行了HEPT类化合物（1－[(2-hydroxyethoxy)methyl]-6-(phenylthio)-thymine derivatives)的结构／活性关系的理论解释,进行了人工神经网络法对于该类化合物的活性预测,其结构明显好于多元回归法。     

Effect of the pH of the medium on the chemical shifts in the PMR spectra and on the distribution of the π-electron density

The dependence of the chemical shifts of the ring protons on the pH of the medium for a number of 4-hydroxyquinoline derivatives was studied by means of PMR spectroscopy. The dipolar and uncharged hydroxy forms exist in equilibrium in aqueous solutions. The effect of intramolecular hydrogen bonding on the character of the dependence of the chemical shift on the pH of the medium in the case of 3-piperidinomethyl-4-hydroxyisoquinoline was investigated. The possibility of the separate protonation of the ring nitrogen and the side-chain nitrogen in 3-piperidinomethyl-4-hydroxyisoquinoline was established. The distribution of the -electron density in 4-hydroxyisoquinoline is in good agreement with its chemical behavior.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1546–1549, November, 1971     

Effect of the pH of the medium on the chemical shifts in the PMR spectra and on the distribution of the π-electron density

The dependence of the chemical shift of the ring protons on the pH of the medium for a number of 3-hydroxyquinoline derivatives was studied by PMR spectroscopy. The regions of ionization of the molecules, which correspond to the ranges of acidic, neutral, and alkaline media, were found. In D₂O, 3-hydroxyquinoline is present only in the uncharged hydroxy form. The presence of intramolecular hydrogen bonding in 4-dimethylaminomethyl-3-hydroxyquinoline has a substantial effect on the character of the dependence of the chemical shift on the pH of the medium; the existence of separate protonation of the nitrogen atoms of the ring and the side chain of 4-dimethylaminomethyl-3-hydroxyquinoline was established. The distribution of the -electron density in the 3-hydroxyquinoline molecule is in good agreement with its chemical behavior during electrophilic substitution.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1540–1545, November, 1971.     

液滴荧光传感与计算机联用技术在微量分析中的应用

通过在LS55型荧光-磷光-发光分光光度计上加装液滴产生及调节附件,采用计算机采集与分析处理数据,成功地研制了双通道液滴光化学传感装置.利用葡聚糖凝胶对复合维生素B中不同组分的选择性吸附来达到分离与同时检测的目的,并将其用于复合维生素B药片的分析,取得了满意的结果.     

On the theory underlying the Car-Parrinello method and the role of the fictitious mass parameter

The theory underlying the Car-Parrinello extended-Lagrangian approach to ab initio molecular dynamics (CPMD) is reviewed and reexamined using "heavy" ice as a test system. It is emphasized that the adiabatic decoupling in CPMD is not a decoupling of electronic orbitals from the ions but only a decoupling of a subset of the orbital vibrational modes from the rest of the necessarily coupled system of orbitals and ions. Recent work [J. Chem. Phys. 116, 14 (2002)] has pointed out that, due to the orbital-ion coupling that remains once adiabatic decoupling has been achieved, a large value of the fictitious mass mu can lead to systematic errors in the computed forces in CPMD. These errors are further investigated in the present work with a focus on those parts of these errors that are not corrected simply by rescaling the masses of the ions. It is suggested that any comparison of the efficiencies of Born-Oppenheimer molecular dynamics (BOMD) and CPMD should be performed at a similar level of accuracy. If accuracy is judged according to the average magnitude of the systematic errors in the computed forces, the efficiency of BOMD compares more favorably to that of CPMD than previous comparisons have suggested.     

From the Micro- to the Macro-: Managing the Conservation of the Warship,Vasa

Sweden's famous warship, Vasa, sank on her maiden voyage in August 1628, and remained on the bottom of Stockholm harbour for 333 years. Raised in 1961, she became the first large-scale wooden object to be treated with polyethylene glycol (PEG). In the summer of 2000 a number of acidic salt precipitations were noticed on the surface of the ship and on wooden artefacts in the storerooms. An international research project has been established to look into the causes of this problem and suggest possible re-treatments. Meanwhile projects are underway to monitor movements in the ship, to build a better support system, and to replace the thousands of iron bolts holding the structure together, while a sophisticated new climate system has recently been installed in the museum.