论顿悟在高等数学教学中的诱发及培养

顿悟是指突然领悟和觉察到问题的解决办法的心理机制。顿悟理论是格式塔心理学对学习研究的最大贡献。在高等数学教学中自觉运用顿悟理论,可以诱发和培养学生的顿悟能力。首先要把握顿悟的基本原理;其次要通过创设问题情境、类比联想、数学审美、直觉猜想等方式诱发学生的顿悟;再次要通过创设独立思考空间、采用开放式教学、创设宽松和谐的课堂氛围来培养学生的顿悟。

小学生数学学习兴趣的探索与培养——小学数学教学探索与研究

“学习兴趣培养是教育的一个原则”。我们应该在小学数学教学中,把培养学生的学习兴趣作为一个重点教学内容。那么,如何在小学数学教学中,培养广大小学生学习数学的学习兴趣呢?其一,认识培养学生学习兴趣困难的原因;其二,落实开展好学习兴趣的培养的措施与方法。

松树枯梢病潜伏侵染的研究

研究表明在火炬松、湿地松、短叶松和马尾松健康梢上整年都能分离到松枯梢病菌 ,其中在火炬松上的得菌率为 15 %～ 37 7% ,且大多数月份高于 2 0 % ;湿地松上的得菌率稍低于火炬松 ,为 7 5 %～ 2 9 1% ;短叶松梢上的得菌率是 13 8%～ 5 7 1% ,月份之间的差异较大 ;马尾松得菌率最低 ,为 9 7%～ 2 2 4 % ,多数分离得菌率低于 2 0 %。健康梢的不同部位得菌率有一定差异 ,枝和新梢较高 ,芽稍低 ,叶最低。在 1年中 ,健康梢上得菌率有 3个高峰期 ,即 4～ 5月、7～ 8月和 10～ 11月 ,是潜伏侵染的的主要时期。将健康芽和梢进行诱发培养 ,10d后组织块上及周围产生松枯梢病菌的分生孢子器 ,得菌情况与常规分离相似。在当年孢子散发之前 ,对健康梢套袋隔离试验 ,发现套袋梢仍会发病 ,说明在发病的春梢中 ,有一部分是由于潜伏侵染的松枯梢病菌造成的。从而证明松枯梢病菌在火炬松、湿地松、短叶松和马尾松上普遍存在潜伏侵染。

Effect of Polysaccharides Including Elicitors on Organogenesis in Protocorm-like Body （PLB） of Cymbidium insigne in vitro

Among orchids, Cymbidiums have got a very high demand in both cut flower and pot plant trade. In the present study the effect of some polysaccharides such as chitosan and NAG （n-acetyl-glucosamine） on organogenesis in protocorm-like-bodies （PLBs） of C. insigne was studied. Synthetic phytohormones such as BA and TDZ （cytokinins） and NAA （auxin） were used for comparison. PLBs of C. insigne were explanted on modified Murashige and Skoog medium supplemented with the single addition of chitosan and NAG, and the combination of BA （benzyladenine） and NAA （1-naphthaleneacetic acid） also with the combination of NAA and TDZ （thidiazuron） among different concentrations. Combination treatments of auxin and cytokinins, the highest percentage of PLBs formation was 73% and shoot formation was 67% when cultured on the medium supplemented with 1.0 mg L1 BA without NAA. Combination treatment of NAA and TDZ, the PLBs formation was 90% and shoot formation was 60% obtained from medium supplemented with 1.0 mg Lt of NAA ＋ 0.1 mg L^-1 TDZ. Single addition of chitosan and NAG with modified MS medium was more effective for new PLBs and shoot formation. The highest percentage of PLBs formation was 87% and shoot formation was 80% obtained from the medium supplemented with 0.1 mg L^-1 chitosan. On the other hand, the PLBs formation rate reached 93% and shoot formation rate was 87% obtained from the medium supplemented with 0.01 mg L^-1 NAG. Application of polysaccharides to in vitro orchid PLBs allows developing new PLBs and shoot to form plantlet without synthetic phytohormones.

In Vitro Picloram-lnduced Somatic Embryogenesis from Leaflets of Cherry （Prunus incisa Thunb,）

Cherry regeneration via somatic embryogenesis is a powerful tool to breeding. In this way, the embryogenic capacity of Prunus incisa specie has been tested from leaves under different interactions of picloram concentrations and darkness exposures. Induction culture was achieved on MS medium supplemented with picloram concentrations at 0.5, 1 and 1.5 mg.L1 and submitted to 10, 20, 30 and 40 days of darkness. The best rate of embryogenic leaves was obtained with the interaction of 30 days darkness exposure＊ 1 mg.L^-1 picloram. According to their age, leaves were differently reacted to somatic embryogenesis; indeed, the 2nd expanded leaf from the apex was the most embryogenic one. Concerning the effect of additional auxin to picloram （1 mg·L^-1）, IAA at 0.1 mg·L^-1 and IBA at 0.1 mg·L^-1 gave significantly higher induction rates than all other concentrations, but regenerating somatic embryos showed some teratological abnormalities probably due to seconda;y embryogenesis. At the opposite, NAA at 0.5 mg·L^-1 didn＇t improve embryogenic rate but affected positively embryo development. Furthermore, embryogenesis preferentially took place on the basal part of leaf. Satisfactory rates of somatic embryogenesis are obtained but further improvement remains possible.