谈元素周期律和元素周期表的教学   总被引：1，自引：0，他引：1  

姚家元 《玉溪师范学院学报》1997,(6)

元素周期律和元素周期表是高中化学第一册第五章三、四两节(必修)的内容,此内容,笔者认为;不但是本册书及本章的一个重点,难点,也是整个中学化学的重点及难点,是中学化学学习的必不可少的基本内容之一;对学生来说,它不仅是必须掌握的化学基本规律,而且是学习笔研究化学学科的重要工具,故有人说:“学好元素周期律和元素周期表,是学好化学的灯塔.”教材把元素周期律和元素周期表放在学生已学了惰性气体,卤素、氧族,碱金属等几个元素族及一些重要化合物知识,并初步掌握有关原子结构及原子核外电子排布知识后面,是为了使学生在学元素周期律及元素周期表之前,掌握一些关于元素及其化合物性质规律性变化的感性知识,在此基础上,笔者认为:引导学生探索元素的性质和原子结构的关系,揭示元素周期律的实质掌握元素周期表的结构及应用,是十分及时和必要的.在进行卤素族教学时,笔者充分利用原子核外电子排布的知识,引导学生画出所有卤素元素原子的核外电子排布的结构示意简图.  相似文献   

问路     

江西元 《小朋友》2003,(2)

mnnjm我迷踟了，小朋友这是什么地方？这是我的肩膀问路@江西元  相似文献   

好奇的安安     

叶家元 《小朋友》2002,(9)

安安听说有一种名叫(鱼安)(鱼康)的鱼,会在水里“钓”鱼。他按捺不住好奇心,想知道(鱼安)(鱼康)鱼究竟是怎样钓鱼的,可他又不谙水性,就去找爷爷。安安走到小河边,看见爷爷正背靠着河岸上的桉树,兴趣盎然地钓鱼呢!安安问:“爷爷,爷爷,你能钓一  相似文献   

浅议结构后浇带在寒冷地区施工中的应用     

王积香  于同元 《黑龙江科技信息》2001,(1):F010-F010

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改善实验尝试创新     

宋建陵  魏学元 《中学生数理化》2003,(11):9-10

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教师管教问题的法律分析     

姜国平 《当代教育论坛》2006,(11):89-90

为了有效地向学生传授知识，健全学生的人格，培养学生自制、守纪的品质，提高判断是非的能力，需要教师对学生进行适当的管教。管教作为教师的一项职业权力，涉及到一系列法律问题，笔者就这个问题进行如下分析。  相似文献   

谈人力资源与经济持续发展     

潘日鸣  张若元 《科技．人才．市场》2000,(6):34-35

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非线性视角下中国碳排放的影响因素与区域差异分析     

姜国刚  顾婷婷  赵杨 《软科学》2016,(7):53-57

针对我国各地碳排放量不均衡现象,对中国1999~2013年30个省份碳排放进行度量。在STIRPAT模型基础上,采用面板门限回归估计对碳排放影响因素进行考察,分析经济增长因素对碳排放量的非线性影响。结果发现:GDP水平变量为门限变量时存在单门限效应,将模型划分为高低两个区制;GDP增长速度变量为门限变量时存在双门限效应,将模型划分为高、中、低3个区制。在高GDP水平区制和中、低GDP增速区制下,EKC存在拐点。根据估计结果将中国碳排放情况划分为6个象限,对各地区进行划分,并对碳排放区域差异的形成原因进行了解释。  相似文献   

铃兰族(广义)花粉形态与叶表皮特征的研究     

马黎明  洪德元 《中国科学院研究生院学报》1990,28(3):228-236

对铃兰族(广义)7个属分别作了花粉(17种)扫描电镜观察和叶表皮(12种)的光学显微镜和 扫描电镜观察。花粉可分为8个类型。在狭义的铃兰族的4个属内，花粉全为远极单槽，舟状。它们 的外壁除夏须草属外，都具细孔。夏须草属的花粉外壁则为细皱。  Hutchinson(1934)的蜘蛛抱蛋族 花粉形态变异很大，其中开口箭属和万年青属的花粉为远极单槽，舟形，外壁具穿孔或网纹，而蜘蛛抱 蛋属的花粉则为球状，无萌发孔。其间的显著差异支持Nakai为前两个属建立万年青族(Rohdeae)。 表1归纳了7个属的花粉形态；图1是我们对铃兰族(广义)花粉形态演化的见解。叶表皮观察表明，气 孔器为无规则型，上表皮角质层主要为条纹加厚，或均匀加厚，而铃兰属的角质层秕糠状加厚。7个属的叶表皮特征归纳于表2。  相似文献   

芍药属的研究(1)——国产几个野生种核型的报道   总被引：1，自引：0，他引：1  

洪德元  张志宪  朱相云 《中国科学院研究生院学报》1988,26(1):33-43

In the present paper 8 species with 15 populations of the genus Paeonia L. (if P. papaveracea and P. japonica are recognised as species) were collected from Sichuan, Shaanxi and Hebei provinces (see the Appendix for detail of the materials).  The micrographs of their somatic metaphase (also Mii in the case of P.veitchii) are shown in Plates 1-4, the karyo- type formulae, ranges of chromosome length and classification of karyotypes according to Steb- bins (1971) are shown in Table 5: the idiograms in Figs. 1-2, and the parameters of chromo- somes in Table 1-4.  The essential points are mentioned as follows:        (1)   Chromosomes of the various species in the section Modan have so far been examined and they are all diploid, the two species in the section Onaepia are also diploid, and thus tetraploids exist only in the section Paeonia.        (2)  Chromosomes in the genus Paeonia are relatively stable except for the differentiation of ploidy.  The karyotypes (Table 1-4) show no differences among different taxa in Sect. Modan and the same can also be said about the taxa in Sect. Paeonia (Table 1).  Not only are the karyotypes very similar, but also among the members within  either section have the same parameters of chromosomes, and, differences, if occur, are not statistically significant. Between the two sections, however, the situation is different. The arm ratios of the first pairs of chromosomes in Sect. Modan are 1.53, 1.52 and 1.48 (Table 1), but those in Sect. Paeonia are 1.12-1.28 (Table 2-4), 95% confidence limits are 1.46-1.60 for the section Modan and 1.07-1.28 (1.21-1.35 only for PB85078) for the section Paeonia, not overlapping, which indi- cates that the two sections have differentiated in respect of the first pairs of chromosomes.        (3)The population PB85024, which belongs to the P. obovata complex, has a karyotype of 2B (stebbins, 1971), which is a new one in the genus Paeonia. This karyotype is a stable one, for several individuals in the population are uniform in this respect, which shows that Steb- bins’ (1971) generalization that all the species in Paeonia have 2A does not hold true.        (4)  Three populations of P. obovata complex studied in this work from Sichuan and Shaanxi are all tetraploids, and one from Hebei is a diploid.  From the present work and the previcus reports, the materials from Japan and Korea, no matter whether flowers are pink or white, are diploids, those from Heilongjiang Province (with both pink and white flowers) (Liu Ming-yuan, personal communication) and from Heibei Province (with pink flowers) in China are also diploids, the one from Sakhalin (pink flowers) is tetraploid, those from Priamur of the Soviet Union are a tetraploid (with white flowers) and a diploid (with pink flowers), and those from Shaanxi (the Qinling Range) and western Sichuan (with both pink and white flowers) are all tetraploids.  As far as we have now known, ploidy in this parti- cular complex is correlated with the geographical distribution: diploids are found in the cen- tral part, tetraploids occur in the northern limits, and in the south  letraploids are the only cytotype.      (5)  The materials of P. mairei from western Sichuan and Shaanxi (the Qinling Range) are found all to be tetraploids, which shows that two cytotypes, diploid and tetraploid, exist in this  species,  but the geographical distribution pattern of these two cytotypes is to be revealed in the future investigation.  相似文献