班级作为“初级群体”的理论探讨

班级作为“初级群体”的理论探讨张巍谢维和北京师范大学教育系长期以来，无论是教育实践工作者还是教育理论工作者一直视班级为一种社会组织，由此，建立并健全了一整套班级组织的互动模式，支持班级组织的正常、有序地运转。然而，班级模式维护的有序是否是有效的呢？即...     

解决流动人口子女教育问题促进教育改革和社会发展

决流动人口子女教育问题促进教育改革和社会发展北京师大副校长教授谢维和流动人口子女的教育，是一个具有普遍性的世界性课题。它既是当前教育与社会的一个“问题”，同时又是社会发展、教育改革甚至是经济建设的一个契机。首先，流动人口子女的教育，与整个社会主义市场...     

高师函授学员思想政治工作浅议

高师函授教育是我院师资培训的重要一翼,函授教育的质量如何,直接关系到我院师资培训的总体质量及我院的声誉.加强高师函授学员的思想政治工作,不仅在端正函授教育的办学方向,全面提高函授教育质量方面占有极其重要的地位,而且是关系加强社会主义精神文明建设和提高我们民族素质的大事。本文拟就这个问题谈一些浅显的看法。     

a second, a third…

我们知道,冠词的用法有这样一条规则:序数词前面用定冠词the。是不是绝对如此,再无其他用法了呢?当然不是,请看中学英语课本中出现的四个句子: (1)He cast his net a second time, and drew in an old basket full of sand. He cast it a third time, and drew in a lot of stones. (JBⅤ, P. 128) (2)"Congratulations!" said Gessler, sneering. "Now tell me why you took a second arrow!"(SBⅠ, P. 282)     

国际科学课程教学方法研究的新世纪图景

科学课程对于学生理解科学的本质、提高公民科学素养具有重要作用。选取Web of Science数据库2000-2016年4127篇有关科学课程教学方法的论文,运用文献计量学和科学知识图谱的方法,对国际科学课程教学法的研究现状进行统计与可视化分析。研究表明,新世纪以来,科学课程教学方法研究的热点主要围绕概念教学,研究前沿主要围绕科学论证、有意义评价以及学生合作。美国在科学课程研究方面具有绝对的强势地位,而中国尚未形成足够的国际学术影响力。     

当好幕后指挥

当好幕后指挥■濮阳市实验小学和艳红要想使队员成为队活动的主人，辅导员必须更新观念，明确任务。在活动中，辅导员是导演，而不是演员；是主导，而不是主体。具体到工作中，则要尊重队员的意愿，相信队员的能力，摒弃大小活动一手包揽，甚至限制束缚的做法。开展活动时...     

满腔热情为教师服务──浅谈山区校长的管理艺术

现在，学校管理的手段、万法、艺术之说可谓琳琅满目。但当好教师的勤务员，为教师服务才是山区校长进行学校管理最行之有效的方法。校长是一所学校的领导者。什么是领导呢？小平同志说过：“领导就是服务。”就学校领导而言，就是要全心全意地为教师服务，少说空话，多办实事，山区工作条件和生活环境都非常艰苦，要想充分调动教师工作的积极性，主动性和创造性，要尽可能地为他们创造必要的工作条件和生活条件。我们要求教师具备无私奉献精神，但教师也是常人，他也需要人所需要的一切。美国心理学家马斯洛认为：一个正常人，如果同时缺乏…     

芍药属的研究(1)——国产几个野生种核型的报道

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.     

浙江产7种菝葜的染色体研究

本文报道浙江产菝葜属smilax 7个种的染色体数目和核型。S．nipponica有两种核型，2n＝   26和2n=32，均为3B型，但后一种细胞型的雄株的第一对染色体大小不等，可能为性染色体；S.   riparia 2n=30，属3B型；S．siebodii n＝16；S. china有两个染色体数目，2n＝96 和n＝15；   S. davidiana 2n=32，属3B型，对减数分裂MI的观察发现n＝16；S．glabra 2n=32，亦属3B   型：S. nervo-marginata var．liukiuensis 2n=32，属3C型。讨论了种间在核型上的差异、属的基数、   核型演化趋势和性染色体等问题。     

菌根

在悬崖削壁的石缝里,会像封面所画的那样长出苍劲古茂的大树:在贫瘠的泥炭沼泽地上,会出现大片森林。这几乎是普遍的现象。我们知道,石缝里是缺乏可溶性养分,尤其是缺乏可溶性含氮盐类的。在不分解的泥炭里也是一样,养分被固定在有机物质里,不能被植物直接利用。树木为什么能在这样恶劣的环境里正常生长?还有,现在世界上的许多大草原里,是看不到树木的。在草原上