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1.
鲫鱼(或其他硬骨鱼)。联系水中生活条件研究它的外部构造和内部构造。生殖。各种鱼类对於不同生活条件的适应:肉食的鱼和“温和的”鱼,水上层的鱼和水底的鱼。软骨鱼和硬鳞鱼的特徵。软骨鱼有更原始的构造,在地球上的出现也较早。我国的鱼类财富和捕鱼业情况。苏联的捕鱼业。我国养鱼业的发展。苏联先进的养鱼业(镜鲤鱼的养殖)。演示:养在缸中的活鱼,鱼的浸制标本和挂图。  相似文献   

2.
人体解剖生理学的内容和任务。伟大的生理学者巴甫洛夫的传记。 1.有机体是一个统一的整体(5;2) 人体的细胞结构。动物细胞的构造。细胞的化学成分。动物细胞和植物细胞的异同点。细胞和周围环境间的新陈代谢。细胞的增殖。勒柏辛斯卡娅关於细胞产生於非细胞形态的生活物质的学说。  相似文献   

3.
补体系统功能方面的研究近年来非常活跃。本文主要介绍以下几方面的一些新进展:1.补体膜攻击机制。2.生物膜的组成和补体的活化。3.补体活化通路中的活性小片段。4.补体对巨噬细胞的作用。5.补体受体。 6.C_(1q)。7.补体和心血管疾患。8.补体活化的调节。  相似文献   

4.
变异与进化     
变异是生物进化的起步。生物进化的另一个重要内容是选择。生物进化的结果是产生出形形色色的生物类型及其对环境的各种适应。不言而喻,没有变异,就没有进化。种内变异已知遗传物质(主要是DNA)能准确地复制自己,这有助于我们了解生物的遗传。但是,遗传总不是绝对的。这是说,同一种生物之间总有些变异。一般说,后代是亲代的复制品或拷贝。从大处讲,无疑这是对的。可是这拷贝总不会是完全的。因此,我们能够认识我们的朋友。已知人的指纹没有两个人是完全相同的。从一个指纹就经常可以鉴別那是谁  相似文献   

5.
塔里木河流域下游地区植物有30科80属122种。以双子叶植物类群占优势,其中多年生草本植物在塔里木河流域下游植物中占多数。显示了物种形成是年轻的进化类型。生态类型以旱生植物为主。占总种数的52%,这足长期适应比较干旱的自然环境的结果。该区系的温带成分占优势。地中海成分也占有一定地位。这些区系成分的植物都是干旱区荒漠植物的代表。区系地理反映了物种演化过程的历史气候、地质变化动态。查清塔里木河流域下游植物资源的数量和分布区的变迁,为该地区的植物资源保护提供科学依据。  相似文献   

6.
(一)植物月份准备材料8月 洋葱鳞茎。番茄、苹果或沙果、西瓜等果实。菜豆、玉米、小麦、棉花、苹果、柿、水稻、高粱的种子。小麦粉。单子叶植物和双子叶植物的根及变态根。水培荞麦和番茄。培养金鱼藻和黑藻。采集和制作葫芦科、菊科植物标本9月 萝卜种子。准备南瓜茎、玉米茎(浸制)。采集和制作各种花、果实和种子标本10月 胡萝卜的圆锥根、马铃薯的块茎。1一3年生杨树、极、木横枝茎。蚕豆叶片。准备水稻、凤仙花的茎。采集丁香和杨树的茎芽。种小麦和蚕豆11月 莲的根状茎,葡萄茎的扦插。果树(苹果、梨、桃)芽接材料2月整理装订植物学十…  相似文献   

7.
黑脊倒刺鲃精巢结构和精子发生的研究   总被引:9,自引:0,他引:9  
用光学显微镜和电子显微镜研究了黑脊倒刺鲃精巢的组织结构和精子发生过程。精巢属于小叶型,由精小叶、小叶间质、壶腹腔和输出管构成。精小叶由各期生精细胞和支持细胞构成。除初级精原细胞以外的各期生精细胞和支持细胞组成了精小囊。每一精小囊中的生精细胞发育同步。成熟的精子从精小囊中释放出来,进入小叶腔中。在精巢的腹侧,小叶腔与壶腹腔连接。在壶腹腔的外侧,有一条与壶腹腔平行的输出管。壶腹腔与输出管相通。在壶腹腔和输出管中都充满精子。精巢的后端与贮精囊相连。贮精囊中充满形状不规则的腔隙。腔隙中有精子分布。输出管从精巢延伸出来,进入贮精囊中,位于贮精囊的一侧。左右两个贮精囊通向一条共同的输精管。输精管上皮具有分泌功能。精子发生在精小叶中进行。精子发生经历了初级精原细胞、次级精原细胞、初级精母细胞、次级精母细胞和精子细胞阶段。精子细胞经过精子形成过程,形成精子。  相似文献   

8.
应用光学显微镜对白毛新木姜子的胚胎学特征进行了研究,首次在非寄生性樟科植物中发现了细胞型胚乳。对樟科8属进行了胚胎学特征的比较。花药四室,药室壁的发育属于"基本型",周原质团型绒毡层。小孢子母细胞连续型分裂。等四面体型四分体。二细胞成熟花粉,无孔沟。雌孢原多个,一般仅一个能继续发育。蓼型胚囊。助细胞具丝状器。反足细胞宿存。大孢子母细胞和合子具极性。宿存的一个助细胞具有吸器功能。细胞型胚乳,胚胎发育属于柳叶菜型的三叶变型。种皮源于外珠被,内表皮细胞壁螺旋状加厚。胚胎学特征表明,新木姜子属与木姜子属有密切的亲缘关系。较多的双胚囊异常现象,支持樟科与Monimiaceae具有紧密关系的推测。胚胎学特征不支持将无根藤属独立为科的观点。  相似文献   

9.
紫杉醇(Taxol)是美国化学家M。E。Wall和M。C。Wani首先从短叶红豆杉(Taxusbrevifolia)的茎皮中分离到,并同化学教授AndrewT。Mcphail于1971年确定了结构。1979年,美国爱因斯坦医学院的SusanB。Horwitz等发现Taxol的独一无二的抗癌机理。此后,Taxol的研究真正掀起了热潮。在Taxol研究中,目前美国还有法国在世界处领先地位。  相似文献   

10.
本届会议拟于1989年12月召开。会议内容交流我国在生物膜的物理、化学和生物学方面取得的最新成果并探讨我国生物膜的发展。会议形式大公报告(特邀)。专题讨论。初步拟分下列专题: (1)生物膜的结构。(2)生物膜与能量转换。(3)离子及小分子的跨膜运送。(4)离子通道。(5)蛋白质的跨膜运送。(6)生物膜与信息传递(CAMP系统,肌醇磷脂系统)。(7)受体。  相似文献   

11.
Steady-state analysis is performed on the kinetic model for the switch complex of the flagellar motor of Halobacterium salinarum (Nutsch et al. [16]). The existence and uniqueness of a positive steady-state of the system is established and it is demonstrated why the steady-state is centered around the competent phase, a state of the motor in which it is able to respond to light stimuli. It is also demonstrated why the steady-state shifts to the refractory phase when the steady-state value of the response regulator CheYP increases. This work is one aspect of modeling in systems biology wherein the mathematical properties of a model are established.  相似文献   

12.
13.
在模式动物中的研究表明,寿限延长与氧化胁迫耐受能力密切有关;在模式植物拟南芥中也发现晚花突变体具有更强的抗氧化胁迫能力,但迄今为止未见有关拟南芥寿限延长突变体的研究报道。本文建立了用氧化剂甲基紫精筛选寿限延长突变体的方法,并对用该方法从经快中子诱变的拟南芥Columbia生态型M_2代群体中筛选获得的突变体SFNA-9-4进行分析,发现该突变体的抗氧化胁迫能力和寿限均显著增加。由此说明,用该方法筛选拟南芥寿限延长突变体是可行的。  相似文献   

14.
昆虫种群系统的研究概述   总被引:23,自引:0,他引:23  
庞雄飞  梁广文 《生态学报》1990,10(4):373-378
  相似文献   

15.
A spatial version of the predator–prey model with Holling III functional response, which includes some important factors such as external periodic forces, noise, and diffusion processes is investigated. For the model only with diffusion, it exhibits spiral waves in the two-dimensional space. However, combined with noise, it has the feature of chaotic patterns. Moreover, the oscillations become more obvious when the noise intensity is increased. Furthermore, the spatially extended system with external periodic forces and noise exhibits a resonant pattern and frequency-locking phenomena. These results may help us to understand the effects arising from the undeniable susceptibility to random fluctuations in the real ecosystems.  相似文献   

16.
A method of estimating effectiveness factor for immobilized whole cells is developed by considering microbial cells as microspheres containing enzyme activity dispersed in the gel phase of the support matrix. The proper model equations describing the system are solved and the corresponding effectiveness factors calculated for various bead sizes, and numbers and activities of cells. The cell wall resistance (permeability) is found to be one of most important variables in the system. The model is applied in predicting the experimental data of other investigators.  相似文献   

17.
A quantitative model has been developed for processes in the bacteriophage lambda that control the switchover from lysogenic to lytic modes of growth. These processes include the interactions of cI repressor and cro proteins at the three DNA sites of the right operator, OR, the binding of RNA polymerase at promoters PR and PRM, the synthesis of cI repressor and cro proteins, and the degradative action of recA during induction of lysis. The model is comprised of two major physical-chemical components: a statistical thermodynamic theory for relative probabilities of the various molecular configurations of the control system; and a kinetic model for the coupling of these probabilities to functional events, including synthesis of regulatory proteins cI and cro. Using independently evaluated interaction constants and rate parameters, the model was found capable of predicting essential physiological characteristics of the system over an extended time. Sufficiency of the model to predict known physiological properties lends credence to the physical-chemical assumptions used in its construction. Several major physiological characteristics were found to arise as "system properties" through the non-linear, time-dependent, feedback-modulated combinations of molecular interactions prescribed by the model. These include: maintenance of the lysogenic state in the absence of recA-mediated cI repressor degradation; induction of lysis and the phenomenon of subinduction; and autogenous negative control of cro. We have used the model to determine the roles, within the composite system, of several key molecular processes previously characterized by studies in vitro. These include: co-operativity in cI repressor binding to DNA; interactions between repressors and RNA polymerase (positive control); and the monomer-dimer association of cI repressor molecules. A major role of cI repressor co-operativity is found to be that of guaranteeing stability of the lysogenic state against minor changes in cI repressor levels within the cell. The role of positive control seems to be that of providing for a peaked, rather than monotonic, dependence of PRM activity on cI repressor level, while permitting PR activity to be a step function. The model correlates an immense body of studies in vivo and in vitro, and it makes testable predictions about molecular phenomena as well as physiological characteristics of bacteriophage lambda. The approach developed in this study can be extended to include more features of the lambda system and to treat other systems of gene regulation.  相似文献   

18.
A system of cuticular nomenclature based on the strata observed in Enoplia is proposed. Nematode cuticle is divided into four fundamental strata: epicuticle, exocuticle, mesocuticle, and endocuticle. Application of this system allows the correlation of complementary strata throughout Nemata. The major taxonomic categories within Nemata are differentiated on the basis of their cuticular strata as compared with the Enoplia model cuticle.  相似文献   

19.
On the basis of the currently accepted model for the cell membrane structure, a physico-chemical model for mediated transport is developed and solved for the case of polar non-electrolyte migration through the cell membrane. The model considers the interstitial space defined by the transport protein subunits to be the migration pathway for polar solutes. A Langmuir-type adsorption equilibrium is assumed at the interfaces and a multicomponent diffusion mechanism of solute and water is postulated within the migration pathway, where the polar residues of the transport protein represent another component of the system. Membrane selectivity is governed by the adsorption constants, which are shown to affect strongly the kinetics of transport. Isosmotic transport and the volume change of the cell are important features incorporated in the model, which is shown to fulfill the peculiar properties of facilitated diffusion systems. It is concluded that the same type of pathway can be used for the transport of other polar solutes through existing or induced hydrophilic channels, for which a similar approach is suggested.  相似文献   

20.
本文研究了笔者与马知恩教授所提出的一类具有年龄结构的种群发展模型,该模型较完满地解决了古典的Shape-Lotka方程所存在的忽略了孵化期的问题。文中对非线性系统解的适定性、种群发展的有界性和平衡分布作了讨论,利用算子半群理论研究了解的渐近性态,并考虑了一类特殊模型;对结果给予了生物解释。  相似文献   

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