立柱式无土栽培

立柱式无土栽培就是将圆柱体竖立于地面。在圆柱表面种植植物,变传统的平面栽培为立体栽培。这种栽培法能大幅度提高单位平面上的种植量和收获量。单位平面上的种植量与立柱数量和立柱表面积成正比,但柱的数量不是越多越好,柱表面也不是越大越好。植物生长需要光照,植物采光情况是影响植物产品数量和质量的主要因素。如果设置合理的立柱密度,又根据植物品种特性定植适当株数,就能够在光资源不变的情况下,达到土地资源利用少,植物产品收获量高,经济效益好的目的。下面结合我们近几年的工作,对立柱式无土栽培作一简要介绍。     

开管式循环和闭管式循环的对比观察

动物的循环系统有开管式循环和闭管式循环２种,开管式循环的血液经心脏、大血管流出后,进入器官间或组织间隙,血液与其细胞直接接触。闭管式循环的血液始终在血管中流动,血液与其细胞不直接接触。为了让学生更好地理解这部分知识,可让学生对比观察活青蛙的闭管式循环...     

问题式与情境式对比中的主线教学审视

从"腐乳的制作"一节的同课异构教学活动出发,对比了问题式主线教学与情境式主线教学二者的教学方法与效果。从新课导入、制作原理、实验设计、操作注意事项4个方面进行了教学评价,并在教学反思中重新审视主线教学的实施关键。     

花卉柱式无土栽培

于玻璃温室内的160 m2面积上,以干湿交替型盆钵组装起高200 cm, 直径15 cm的立柱77根,然后组成立柱“树林”并种花,25个科的共53种草花用同一营养系统管理,生长都良好,立柱“树林”象是花的“森林”,显示了良好的生态关系。在此基础上挑选不同种盆花组成不同情趣的家庭阳台花柱。阳台花柱具若干优点：新型盆钵具良好的水、气、肥协调关系,适合多种花卉生长;柱高任选,便手提携带;柱体能环绕中轴旋转使植物受光均匀;花柱底部是具中岛结构式底盆,起蓄水和稳定作用,还便于多根立柱串联扩大栽培量;有人工和自动浇灌两种系统,省工省时且干净卫生。     

花卉柱式无土栽培

于玻璃温室内的 1 60m2 面积上 ,以干湿交替型盆钵组装起高 2 0 0cm ,直径 1 5cm的立柱 77根 ,然后组成立柱“树林”并种花 ,2 5个科的共 53种草花用同一营养系统管理 ,生长都良好 ,立柱“树林”象是花的“森林” ,显示了良好的生态关系。在此基础上挑选不同种盆花组成不同情趣的家庭阳台花柱。阳台花柱具若干优点 :新型盆钵具良好的水、气、肥协调关系 ,适合多种花卉生长 ;柱高任选 ,便手提携带 ;柱体能环绕中轴旋转使植物受光均匀 ;花柱底部是具中岛结构式底盆 ,起蓄水和稳定作用 ,还便于多根立柱串联扩大栽培量 ;有人工和自动浇灌两种系统 ,省工省时且干净卫生。     

问题式教学与方法式教学在微生物学教学中的应用

微生物学是工科院校生物技术专业的专业基础课,又是一门在工业上应用非常广泛的学科。针对工科院校学生需要较强的动手能力,根据微生物学的内容特点,对理论教学的改革进行了探讨,提出了问题式和综合式教学方法,取得了较好的教学效果。     

人类的椎骨式、牙式、乳头式、指(趾)式证实了人猿同祖

通过对人类的椎骨式、牙式、乳头式、指（趾）式的阐述，进一步说明这些结构是生物进化过程中形成，是“人猿同祖”的有力证据。     

蝌蚪唇齿式的表述

蝌蚪的唇齿式在研究蝌蚪的生物学特性和生物多样性中具有重要的作用,本文比较详细介绍了目前国内外5种蝌蚪唇齿式表达方式,并比较了它们的优缺点.     

阻抗式测容积法

所谓的阻抗式测容积法是指在身体任何部位通以适当的交流电,依电流的方向、形式取得体内情报,作为诊断或监护使用的技术。阻抗法的应用有各种方式,但都是使用两对电极,,一对是通电电极(Ⅰ—Ⅰ),一对是探测电极(E—E)。一般在Ⅰ—Ⅰ间通以50～100KHz,0.1～1mA的电流,再依E—E间呈现电位的波幅和波形的变化,而测得体内容积     

Potassium channels in cell cycle and cell proliferation

Normal cell-cycle progression is a crucial task for every multicellular organism, as it determines body size and shape, tissue renewal and senescence, and is also crucial for reproduction. On the other hand, dysregulation of the cell-cycle progression leading to uncontrolled cell proliferation is the hallmark of cancer. Therefore, it is not surprising that it is a tightly regulated process, with multifaceted and very complex control mechanisms. It is now well established that one of those mechanisms relies on ion channels, and in many cases specifically on potassium channels. Here, we summarize the possible mechanisms underlying the importance of potassium channels in cell-cycle control and briefly review some of the identified channels that illustrate the multiple ways in which this group of proteins can influence cell proliferation and modulate cell-cycle progression.     

Interspecific cell markers and cell lineage in birds

A cell marking technique based on the structural differences existing between the interphase nucleus in two closely related species of birds, the chick and the Japanese quail, is described. In all embryonic and adult cell types of the quail, a large mass of heterochromatin is associated with the nucleolus making quail and chick cells easy to identify at the single cell level after application of any DNA-specific staining procedure and also at the electron microscope level. This method has been largely used to construct chimeras in ovo and to study dynamic processes such as cell migrations or cell lineage segregation during ontogeny. Recently monoclonal antibodies specific for either quail or chick antigenic determinants (for example, class II MHC antigens) have been prepared, increasing the interest of the quail-chick chimera system as an experimental model.     

Asymmetric cell division and cell fate in plants

A variety of approaches has recently been employed to investigate how sister cells adopt distinct fates following asymmetric divisions during plant development. Surgical and drug studies have been used to analyze asymmetric divisions during both early embryogenesis in brown algae and pollen development in tobacco. Genetic screens have been used to identify genes in Arabidopsis thaliana that are required for specific asymmetric cell divisions during pollen and root development. These studies indicate that cell polarity and division orientation are closely tied to the process of cell fate specification, and suggest that differential inheritance of determinants and positional information may both be involved in the specification of cell fates following asymmetric cell division.     

Connexins and their channels in cell growth and cell death

Direct communication between cells, mediated by gap junctions, is nowadays considered as an indispensable mechanism in the maintenance of cellular homeostasis. In fact, gap junctional intercellular communication is actively involved in virtually all aspects of the cellular life cycle, ranging from cell growth to cell death. For a long time, it was believed that this was merely a result of the capacity of gap junctions to control the direct intercellular exchange of essential cellular messengers. However, recent data show that the picture is more complicated than initially thought, as structural precursors of gap junctions, connexins and gap junction hemichannels, can affect the cellular homeostatic balance independently of gap junctional intercellular communication. In this paper, we summarize the current knowledge concerning the roles of connexins and their channels in the control of cellular homeostasis, with the emphasis on cell growth and cell death. We also briefly discuss the role of gap junctional intercellular communication in carcinogenesis and the potential use of connexins as tools for cancer therapy.     

T cell receptor-mediated DNA fragmentation and cell death in T cell hybridomas

Activation of Ag-specific T cell hybridomas with a high density of immobilized anti-CD3 antibody resulted in not only secretion of IL-2 but also cell death of up to 60 to 80% in selected hybridomas after 14 h. Similar results were obtained with V beta 8+ T cell hybridomas stimulated with cross-linked F23.1 antibody. In these activated hybridomas, we found that DNA was fragmented into 180- to 200-bp multiples. DNA fragmentation was not observed when T cells were maintained after killing with anti-Thy-1 plus C or with heat treatment at 45 degrees C, nor when T cells were incubated with fixed anti-CD4 antibody. Furthermore, fragmentation was detectable at 6 h after incubation when almost all of the cells were still viable as evaluated by trypan blue dye exclusion test. Cell death was prevented by addition of EGTA, cycloheximide, actinomycin D, and zinc, suggesting that the induction of cell death requires Ca2+ influx, newly synthesized protein(s), and involvement of endonuclease.     

Glycoproteins and lectins in cell adhesion and cell recognition processes

Summary The discovery of endogenous lectins having specific and high affinity for the carbohydrate portions of glycoproteins has opened up new directions in the field of cell adhesion and cell recognition. Two endogenous lectins, termed as CSL and R1, initially isolated from the rat cerebellum and having a wide distribution in mammalian tissues, have been shown to participate in essential mechanisms of cell adhesion. The membrane-bound lectin R1 seems to be involved in transient recognition between neuronal cells, followed by elimination of the glycoprotein ligands at the surface of the recognized cell. In contrast, CSL is a molecule involved in adhesion between various normal or transformed cells since it participates in the formation of tight junctions. The glycoprotein ligands recognized with higher affinity by these two lectins seem to possess a special structure which defines a sub-class of oncofetal HNK-1 glycans. The over-expression of the glycoprotein ligands of these lectins in most transformed cells provides new tools for understanding the underlying mechanism of malignant transformation as well as the generation of signals through cell adhesion.