微生物教学中寓教于乐的几点探索

从学生日常生活的具体事例切入,寓教于学生感兴趣的事物和多彩的课外活动中,应用多媒体教学,尽可能使抽象的微生物学变得具体而有趣,从而激发学生学习的兴趣和主动性,提高教学效果和质量.     

浅谈生物概念图的教学策略

随着科学技术的发展和经济多元化,对人才结构的要求出现新的趋势,创新精神和实践能力成为衡量人才质量的最瞩目的标志。而概念图的教学方式,在很大程度上强化了学生的创新意识,是培养学生创新能力的一个具体途径。在具体的教学过程中,我是这样处理的：     

在解题中培养学生知识迁移的能力

高考越来越重视对学生能力的考查,结合几个具体的实例,从“运用化归性,将题目化繁为简,化难为易;挖掘隐含条件,重新整合,提高学生的解题能力;注重分析,培养求异精神和发散思维能力”等方面,就高中生物学教学中如何通过科学引导和灵活转换,在解题中培养学生知识迁移的能力,做了一些具体的探索.     

高中生物学新课程科学探究能力目标解析

《普通高中生物课程(实验)》对学生的科学探究能力提出了11条具体要求。对这11条具体要求的意义和内涵作了较深入的分析。     

浅谈如何提高高三生物复习课的课堂效率

本文通过具体设计一次课题活动,包括课题活动提出的背景;要达到的目标;活动实施的具体过程;以及最终学生的收获和指导教师的认识和体会。简析了如何使高三学生能系统掌握所复习的知识,提高了复习课的课堂效率,并学会对基础知识做出进一步延伸,运用所学知识解决实际问题,这样在高考中显出了较大的优越性。     

谈班级目标定位管理

目标定位管理是将学校班级的日常管理工作定位于每一个学生,通过设置工作细项,设置奖罚目标,填写《班级日志》,来定位班级的具体日常工作,用量化积分来约束学生的行为和习惯,以达到学生自我管理和学习的目的。     

浅谈生物与计算机结合的探究

生物教学与计算机结合,生物教学变得形象具体,提高学生观察力、想象力,提高学生学习兴趣,激发学生学习潜能,提高学习能力,加强学习效果。     

充分考虑学生的需求——谈“孟德尔定律”的教学思路

要提高课堂教学的有效性,需要充分考虑学生的需求.学生的需求来自学生所缺的、学生所怕的、学生所惑的3个方面.列举“孟德尔定律”一章中学生所缺、所怕、所惑的具体知识、方法和能力,分析其成因,并提供了弥补所缺、消除所怕和所惑的教学方法或策略.     

探究以实验为基础的高中化学教学设计

近些年来随着教学体制的不断调整,在具体发展过程中需要根据实际应用情况,探究切实可行的实验类型。"以实验为基础"是高中化学的基础性特征,为了强化学生对化学知识的理解,要求在具体工作中不断开展实验模式,进行教学改革,将主动权交给学生,进而激发学生的学习欲望。在本次研究中将以化学实验教学中存在的问题为研究点,结合当前教学现状,探究看具体的教学设计形式。     

高中生物有效教学探析

教学的有效性,主要是指通过教师和学生的努力,教学成果提高的显著程度。高中生物更多的是微观和抽象的,可以采用有效教学设计,使用多媒体教学方式变抽象为具体,采用以学生探究式学习方式为主体的教学模式,重视生物实验,重视生活体验的教学策略,理论联系实际解决生活中的问题,进行教学有效性评价,根据具体情况制定具体的教学方案,做到教学方法更精,教学质量更高,成绩提高更快。     

Ectogenesis and the case against the right to the death of the foetus

Ectogenesis, or the use of an artificial womb to allow a foetus to develop, will likely become a reality within a few decades, and could significantly affect the abortion debate. We first examine the implications for Judith Jarvis Thomson’s violinist analogy, which argues for a woman’s right to withdraw life support from the foetus and so terminate her pregnancy, even if the foetus is granted full moral status. We show that on Thomson’s reasoning, there is no right to the death of the foetus, and abortion is not permissible if ectogenesis is available, provided it is safe and inexpensive. This raises the question of whether there are persuasive reasons for the right to the death of the foetus that could be exercised in the context of ectogenesis. Eric Mathison and Jeremy Davis have examined several arguments for this right, doubting that it exists, while Joona Räsänen has recently criticized their reasoning. We respond to Räsänen’s analysis, concluding that his arguments are unsuccessful, and that there is no right to the death of the foetus in these circumstances.     

On the diversity of the Cladocera in the tropics

The mythical concept of an impoverished tropical cladoceran fauna is refuted. On a planetary scale, around half of the cladoceran species presently known occur exclusively in the tropics-subtropics, often with considerable restriction to particular geographical subzones. On a regional (political) scale, the situation is often unclear because of the continued fragmentary nature of studies, and because political units are not a good basis for biogeographical comparisons. At the finest level of resolution (lake-perlake comparisons), there appears to be an upper limit of c. 50 cladoceran species per individual lake. No significant difference between lakes in the temperate zone and in the tropics could be established here. Daphnia is largely absent from the tropics, but is replaced by more Sidids, Moinids, and Bosminids, such that the average cladoceran community in the limnetic zone of a tropical lake is not characterized by less species but rather by lower population densities. This, in turn, is considered a consequence of higher prevalent predation levels in the tropics.     

Tubular networks in the terminal endings of the visual receptor cells in the human,the monkey,the cat and the dog

Summary A tubular network was found in the terminal endings of the visual receptor cells in the human, the monkey (Macaca mulatta), the cat and the dog. These tubules are arranged in close groups in the vicinity of the synaptic lamellae and the invaginated dendrites. According to the form, diameter, density of the tubules and to the consistence of the network formed by them one can distinguish at these places an initial type (type I), a transitory (type II) and a vesicular one (type III). In the the type III branching, bizarre forms are frequent. The diameter of all the tubules reaches 500–600 Å, their density and walls being the same as in the synaptic vesicles.Similar networks also occur in the axons of the visual receptor cells of the monkey.

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Zusammenfassung In den Endigungen der Photorezeptorzellen von Mensch, Affe (Macaca mulatta), Katze und Hund kommen aus Tubuli bestehende Komplexe vor. Organellenartig in geschlossenen Gruppen angeordnet, liegen sie in Nähe der synaptischen Lamellen und der invaginierten Dendriten. An diesen Stellen kann man nach Form, Durchmesser, Dichte und Konsistenz der von den Tubuli gebildeten Komplexe drei Typen unterscheiden: 1. einen initialen (Typus I), 2. einen Übergangstypus (Typus II) und 3. einen vesiculären Typus (Typus III). In letzterem kommen häufig verzweigte, bizarre Formen vor. Der Durchmesser sämtlicher Tubuli erreicht 500–600 Å. Ihre Dichte und ihre Wand gleicht denen der synaptischen Vesikel.Ähnliche Komplexe fanden wir auch in den Axonen der Photorezeptorzellen vom Affen.

     

Assessing the Physiological State of the Fucoids from the Barents Sea Littoral by the End of the Polar Night

Methods of amperometry and potentiometric titration were used to follow dark respiration (DR) and apparent photosynthesis (AP) in the fucoids Ascophyllum nodosum (L.) Le Jol, Fucus vesiculosus L., and F. serratus L. from the Barents Sea littoral by the end of the 40-day-long polar night. The macroalgae were shown to manifest species-specific low rates of photosynthesis and respiration. However, in spite of their low photosynthetic status due to the effects of subzero temperature and prolonged low or zero illumination, the macroalgae have been able to restore DR and AP to the initial level already by the day 9; the ability to restore AP depended on the level of illumination. The study of the changes in the carbonate–bicarbonate system in the light and darkness demonstrated that the macroalgae grown in darkness, in contrast to those grown in twilight, could absorb bicarbonate in darkness; however, they lost this capacity after two-day-long illumination at an irradiance of 7 mol/(m² s). Bicarbonate uptake in darkness and the capacity to restore the systems of photosynthesis and respiration in fucoid cells are discussed in the context of algal energy metabolism under the polar night conditions.     

Arranging the elements of the potassium channel: the T1 domain occludes the cytoplasmic face of the channel

The voltage-gated potassium channel is currently one of the few membrane proteins where functional roles have been mapped onto specific segments of sequence. Although high-resolution structures of the transmembrane portions of three bacterial potassium channels, the tetramerization domain and the cytoplasmic ball are available, their relative spatial arrangement in mammalian channels remains a matter of ongoing debate. Cryo-electron microscopic images of the six transmembrane voltage-gated Kv channel have been reconstructed at up to 18 Å resolution, revealing that the T1 domain tetramerizes and is suspended below the transmembrane segments. However, the resolution of these images is insufficient to reveal the location of the third piece of the puzzle, the inactivating ball domain. We have used the aberrant interactions observed in a series of chimæric channels to establish that an assembled T1 domain restricts access to the cytoplasmic face of the channel, suggesting that the N-terminal ball and chain may be confined in the space between the T1 domain and the transmembrane portion of the channel.     

Feeding the vertebrate retina from the Cambrian to the Tertiary

The retina of the vertebrate eye is metabolically active and requires nutritive support. During the last 540 million years it has evolved into forms as complicated and nutritionally demanding as those found in avian or primate eyes. Diffusion from the choroid is generally able to supply the metabolic needs of thin retinae. However, when the thickness exceeds the limits of diffusion, structures are needed to supplement the vascular supply from the choroid. These supplemental nutritive devices include the choroidal gland, the falciform process and preretinal vascular plexus of fish, the conus papillaris of lizards, the pecten oculi of birds, the intraretinal vessels of mammals and a few novel systems that remain difficult to classify. These vascular systems are among the most variable features of the vertebrate eye. Here, we review classical and recent findings regarding such retinal nutrition systems, propose a three category classification for them based on histologic origins and speculate on the evolutionary forces which drove their development.     

Observations on the permeability of the choriocapillaris of the eye

Summary The choriocapillaris is a fenestrated capillary bed located posterior to the retinal pigment epithelium. It serves as the main source of supply to the photoreceptors, retinal pigment epithelium, and other cells of the outer retina. The permeability of these capillaries to intravenously injected ferritin (MW — approx. 480,000; mol. diam. 11 nm) was examined in the mouse, rabbit, and guinea pig, each of which is characterized by a different type of retinal vascularization. In all three species, the bulk of the ferritin remained in the capillary lumina, where it appeared to be blocked at the level of the diaphragmed fenestrae. Some ferritin was present in endothelial cell vacuoles. The results confirm previous work on the rat choriocapillaris and indicate that the barrier function of the choriocapillary endothelium is present even among species in which the retinal circulation differs significantly.Supported by NIH grant EY03418     

Separation of the pineal vesicle from the wall of the third ventricle during the post-hatching development of the chicken

Summary According to light- and electron-microscopic observations the pineal organ of the 3-day-old chicken consists of a prominent end vesicle and a tapering parenchymal stalk. During this stage the pineal lumen is in open communication with the third ventricle. However, in the 40-day-old chicken, which still possesses a well-developed end vesicle, the proximal portion of the pineal stalk displays regressive changes leading to local fragmentation. At this stage the pineal stalk is reduced, and the pineal lumen is missing. In 1-year-old chickens the parenchyma of the proximal portion of the stalk is further diminished, and in 3-year-old domestic fowl is completely displaced by bundles of collagenous fibers, only some nerve fibers being present. This post-hatching pineal development may reflect the sequence of changes leading from pineal sense organs to pineal glands.This work was supported by a grant-in-aid for Scientific Research from the Ministry of Education, Science and Culture of Japan