不同时间草地火烧后群落地上生物量结构的变化

不同时间草地火烧后,群落地上生物量结构发生不同程度的变化,最明显的是火烧地各层没有立枯体组分,未烧地立枯体随季节推迟逐渐转向下层．火烧地茎矮化,各层段叶生物量皆高于未烧地,未烧地各层段茎叶比例高于火烧地．火烧地的光线通透系数高于未烧地．     

江苏省海滩植被演替的研究

江苏省海滩植被可分为滨海盐土植被、盐沼植被及海滩沙生植被三个基本类型。本文论述了这些植被类型的演替规律。滨海盐土植被与盐沼植被的演替,外因于土壤盐分含量递减与有机质含量的递增;海滩沙生植被的演替,外因于土壤沙颗粒大小及其相应的土壤含水量的变化,所以海滩植被演替为外因动态演替。     

国人颅骨颈动脉管外口及其周围某些结构的形态观察与测量

本文对国人颅骨133例,266个颈动脉管外口形状大小进行了观察与测量。结果表明:颈动脉管外口形状不一。可区分为圆形、卵圆形和南瓜子仁形三种,其中以圆形者为数最多。颈动脉管外口长宽径和距颈静脉窝及锥体尖端之间距离两侧不等,并具有地区性差异。鼓小管下口在个别颅骨缺如。颈静脉窝之大小深浅不一,其中以右侧较大而深者为最多。     

无外源激素条件下液体和固体培养基对黄瓜子叶培养器官分化的不同影响

在固体ＭＳ基本培养基上,黄瓜子叶能形成约０．８％的直接花芽,其分化高峰约为４５天左右,而在液体ＭＳ基本培养基上,黄瓜子叶花芽分化率为８％,其分化高峰期约在３０天左右．实验结果表明：液体培养基对黄瓜子叶花芽及根的分化效果明显好于固体培养基,而对于营养芽的分化固体培养基好于液培养基,花芽分化与子叶衰老存在着较密切的关系。     

我国植被水土保持功能研究进展

 我国植被水土保持功能的研究可以概括为以下3个主要方面：1)植被水土保持功能的对比研究： 通过实地对比观测植被覆盖地与对照地（裸地、农耕地等）的径流量、土壤侵蚀量等,研究植被的减水减沙效益。研究表明,天然植被具有强大的水土保持功能,并呈现出林>灌>草的规律;人工植被水土保持功能的发挥则受到多种因素的影响,呈现出较复杂的情况。2)植被保持水土的机理研究：雨滴击溅和径流冲刷是水土流失的动力,通过分析植被削减降雨和径流动能的过程,来揭示植被水土保持功能的内在机理。研究表明,植被外在的水土保持功能是其内部各个垂直层     

Seasonal dynamics of Callibaetis willineri (Ephemeroptera, Baetidae) associated with Eichhornia azurea (Pontedericeae) in Guaraná Lake of the Upper Paraná River, Brazil

The micro-anatomy of the cephalon is described in the troglobic asellotan isopod Craseriella anops from the Nohoch Nah Chich anchialine cave system in southeast Mexico. The cephalon is entirely covered by cuticular scales bordered by marginal spines. The anterior end of the cephalon is bordered by a carina that is wider medially. The isopod is eyeless. The distal seventh portion of the cephalon is characterized by the presence of two sutures and six setae. A suture is found on each side of the distal margin of the cephalon.Each suture is bordered by microtrichs. Two simple setae with a sensory hair, articulated on the base by a socket, are found one on each side of each of the sutures. Two additional setae, similar in shape and size, occur medially on the cephalon. A terminal pore is absent on the sensory hairs of all setae. These setae are suggested to be mechanoreceptors that provide directional sensitivity and enhance the sensibility of turbulent motion, viscosity and changes of hydrostatic pressure.     

长江口九段沙植物群落研究

长江口九段沙属于发育早期的河口沙洲,植被完全保持着自然演替的早期状况。对九段沙湿地高等植物群落的结构特点及演替特征进行研究。研究结果表明：九段沙湿地植被分布几乎覆盖整个沙岛,生物量丰富。高等植物中多克隆植物,植物群落结构简单,生物多样性低,植被具原生性,群落演替的早期原生特征明显,演替过程在没有引种互花米草之前人为干扰少,互花米草的引种加速了九段沙湿地植被的陆地化演替进程。最后提出保护和开发利用九段沙植被的适应原则。     

A probabilistic method for calculating the energy of hydrophobic interactions

A theoretical approach is developed for estimating the hydrophobic interaction energy on the molecular level. The underlying idea of the model is the fundamental relationship between the probability of the appearance of a solvent-excluded volume in fluid water as a result of density fluctuations, on one hand, and the free energy of primitive hydrophobic solutes, on the other. This probability is estimated basing on an information theory model in combination with experimental data on the distribution density and radial distribution function. The free energy of hydrophobic interactions is determined for a complex that consists of several hard spheres. The critical number of particles in the complex is estimated.     

夏季绿洲生态环境对荒漠背景地表能量过程的扰动

利用观测试验资料,对比分析了夏季典型晴天敦煌绿洲与周围荒漠戈壁背景地表过程的差异,揭示了绿洲生态系统对干旱区荒漠背景地表过程的扰动特征。结果表明:绿洲地表净辐射日平均要高出周围荒漠戈壁背景60 W/m2以上,约占绿洲净辐射的1/4以上。对绿洲高出的净辐射贡献最大的是绿洲相对低的地表长波辐射,其次是较高的太阳总辐射。而绿洲相对较低的大气长波辐射对高出的净辐射有较大的负贡献,特别是地表反射辐射也有很小的负贡献。绿洲高出的地表净辐射主要贡献于加强潜热和地热流量,还有一部分被绿洲地表能量不平衡差额所占,它实际上可能由一般地表热量平衡所不考虑的垂直热量平流来输送。而绿洲明显低于荒漠背景的感热通量则节省了一部分净辐射能量。     

围栏禁牧对羊草草原和大针茅草原蝗虫丰富度的影响

报道了围栏封育后羊草草原和大针茅草原蝗虫丰富度的变化,比较了蝗虫在羊 草草原和大针茅草原的发生特点．结果表明,以毛足棒角蝗为主导种的大针茅草原蝗虫生 物量是以小翅雏蝗为主导种的羊草草原蝗虫生物量的４～５倍;围栏封育后,羊草草原蝗 虫的生物量增加 ２４％,而大针茅蝗虫的生物量略有减少;围栏措施改变蝗虫的结构组成, 使毛足棒角蝗、鼓翅皱膝蝗、宽须蚁蝗、亚洲小车蝗等旱生和中旱生的地栖或兼栖偏地栖 种类的发生减少,条纹鸣蝗、小翅雏蝗、红腹牧草蝗等中生的植栖或兼栖偏植栖种类增加, 短星翅蝗及狭翅雏蝗的生物量在大针茅草原增加而在羊草草原减少．     

Effect of lysophosphatidylcholine on the radiation-induced lipid peroxidation in liposomes

The effect of lysophosphatidylcholine (LPC) on the lipid peroxidation process (LPO) in liposomes of rat liver phosphatidylcholine initiated by irradiation of 137Cs source was studied. The formation of diene conjugates (DC) is shown to increase dramatically on incorporation of more than 10% LPC into liposomes. The dependence of DC proportion on the irradiation dose is practically linear in the range of 0 to 5 kGy. The DC concentration in the liposomes without LPC grows at least to dose of 3.3 kGy and is unchanged on further irradiation. The malonic dialdehide accumulation follows the similar dependence. The LPC effect is neutralized by the incorporation of cholesterol into liposomes. The product of free radical fragmentation of LPC, palmitoxyacetone, practically has no influence on the DC concentration. The reasons of LPC effect on the irradiation initiated LPO in liposomes is discussed.     

芦芽山自然保护区旅游开发与植被环境关系——旅游影响系数及指标分析

采用旅游影响系数对芦芽山自然保护区旅游开发与植被环境的关系进行了继续探讨。结果表明：(1)6个旅游影响因子之间的正负相关性均很好地体现了旅游活动对各因子影响的规律性,同时也说明了旅游影响因子的选择与确定以及对其赋值的正确性。它们与自然地理因子、人文地理因子的相关性说明了它们作为评价指标的可行性,同时也说明旅游活动是景区管理的主要对象。(2)根据旅游影响系数评价分级可知,整个自然保护区管理水平呈良级和中等水平,某些地段已出现危机感。其中,冰口凹和山顶附近是人为活动影响最强烈、质量管理最差的地段。评价分级的结果较好地反映了芦芽山旅游开发现状,与实际状况大致吻合,说明这一方法是可行的。(3)评价指标之间的相关性表明,距游径的水平距离愈远,敏感水平愈低,景观重要值愈大,物种多样性信息指数愈大或者稳定,旅游影响系数愈小。     

Complex formation of 70-kDa heat shock protein with acidic glycolipids and phospholipids

A new property of a heat-inducible heat shock protein (Hsp) 70.1 that it forms a complex with acidic lipids was first demonstrated. Based on the behaviors of the complexes on the native PAGE, the acidic lipid/Hsp70.1 complexes are categorized into two groups. The first group is the sulfatide-induced large-sized complex, which stays on the gel top on the native PAGE. Only the N-terminal ATPase domain is responsible for the complex formation. The second group is the ganglioside-induced complex, which is diffused in the resolution gel on the native PAGE. Both the N-terminal ATPase and the C-terminal peptide-binding domains are involved in the complex formation. No complex is formed by neutral glyco- and phospholipids. The complex formation with the acidic glyco- and phospholipids implicates the various functions of Hsp70 on the membrane surfaces.     

海南竹类的地理分布及区系特征

通过对海南岛竹类区系地理成分进行统计、分析和对其分布、与邻近地区竹类区系关系的探讨,其区系特征归纳如下:1.拥有丰富的特有成分。2.区系的热带性质明显。3.分布上差异显著。4.区系原始、古老。5.与毗邻的广东竹类区系联系较多。     

Calcium binding of troponin C. I. A potentiometric titration study.

Structural changes of troponin C on calcium binding were studied by hydrogen ion titration, circular dichroism, and fluorescence measurements. The potentiometric titration curves in the carboxyl region are shifted towards lower pH with calcium binding. The intrinsic pK of the carboxyl groups at the calcium binding sites decreases by 0.8 pK unit on calcium binding; on the other hand, magnesium ions have little effect on the intrinsic pK of the carboxyl groups. The intrinsic pK of the imidazole group is not affected by calcium binding. The value of w, an electrostatic interaction factor, is identical for calcium-free and calcium-bound troponin C and is about half of the value calculated assuming a compact sphere. The results of difference titration on the calcium binding indicate that the pH of troponin C solution increases on addition of CaCl2 up to 2 mol of Ca2+ per mol of troponin C and then decreases on further addition of CaCl2. The pH increase is depressed in the presence of MgCl2, in the low pH region, or at high ionic strength. The pH increase is also observed on addition of MgCl2. The ellipticity at 222 nm was measured under the same conditions as the difference titration measurements, and the relation between the pH change and the conformational change of troponin C on calcium binding is discussed based on the results obtained. The number of calcium binding sites and the binding constants estimated by analysis of these difference titration curves were in agreement with the results of Potter and Gergely (22). No magnesium binding site was observed. The tyrosine fluorescence measurements indicated that the binding site near tyrosine-109 is one of the high affinity sites.     

Functional morphology and ultrastructure of mouthparts in unfed water mite larvae Piona carnea (Koch, 1836) (Acariformes: Pionidae)

Mouthparts of unfed larvae Piona carnea (Koch, 1836) (Acariformes: Pionidae) were studied on whole-mount preparations, semi-thin sections and with TEM and SEM methods. The mouth apparatus is incorporated within the pseudotagma, gnathosoma, composed of the infracapitulum and of the chelicerae resting on the roof of the latter. The gnathosoma inclines to the long axis of the body and is inserted at its base into the idiosoma by the circumcapitular fold. The basal cheliceral segments are long and fused. An anterior projection, the proposed fused fixed digits, protrudes from the distal end of the basal cheliceral segment forward between the movable digits. The movable digits are always found in protruded position, strongly curved upward and show a groove on their inner sides. The ventral wall of the infracapitulum is made of the mentum posterior and the malapophyses anterior to the palp articulation. The malapophyses are squeezed between the large palps and envelope the distal portion of the chelicerae from the sides. The ventral portion of the fused malapophyses are provided with a characteristic ventral cuticular fork of unknown function. Each malapophysis terminates by a flexible lateral lip provided by several rigid jags looking posterad. The palps face downward and backward, and bear on the tibia the large curved palpal claws turned laterad. The palp femur bears on the ventral aspect a characteristic wide spade-like projection provided with its own muscles originating on the dorsal wall of the femur. The labrum is a thick cuticular arrow-like structure protruding forward into the preoral cavity, whereas the cervix is a thin weakly sclerotized plate. The particular labral valve projects forward from the dorsal basis of the labrum into the preoral cavity. The labrum and the cervix are provided by their own small labral and cervical muscles originating on the cervical apodemes. The pharynx is totally separated from the ventral wall of the infracapitulum and is devoid of ventral dilators. The dorsal pharyngeal dilators originate on the thick and sclerotized capitular apodeme and, posteriorly, on the paired cuticular branches, capitular apodemes, which end freely in the body cavity and are combined with the common salivary duct. The short sigmoid pieces serve for origin of the levator muscles of the chelicerae. Retraction of the gnathosoma and the chelicerae is mediated by several sets of muscles originating on the dorsal plate.     

高压静电场对离子溶液中过氧化氢酶的作用研究

研究了 KBr、磷酸缓冲液、Na Cl对高压静电场对过氧化氢酶作用的影响。结果表明 :浓度在 0 .0 2 m mol/L～ 0 .0 5 m mol/L的低浓度的无机离子对高压静电场对过氧化氢酶的作用影响很小。浓度在 0 .1mmol/L～0 .4 0 m mol/L的无机离子对高压静电压对过氧化氢酶的活力影响较大 ,过氧化氢酶在 3× 10 3V /cm的电场作用下活力只会升高。而对照出现先下降后上升的现象。浓度高于 0 .80 m mol/L时 ,无机离子可以保护过氧化氢酶不受高压静电场的影响。无机离子的这种效应可能是无机离子在高压静电场的作用下 ,产生反抗电场降低了高压静电场的强度所致。     

Bayesian multilevel modelling of compositional data for simultaneous inferences on Allele compositions and inbreeding coefficients

Sample data from a number of sub-populations are often investigated in order to integrate the findings of different research studies on a particular area. In case of compositional samples, like the allele frequencies collected at a single locus in different surveys, the data are independent multinomial vectors. Each multinomial distribution depends on a specific probability vector, that is, the unknown relative composition of the sub-population. A Bayesian hierarchy approach is proposed here to model the variability of the sub-composition vectors around a common mean with possibly different scales. The common mean can be seen as the relative composition of the aggregated population. Scale parameters are well known in Biology as the Wright's inbreeding coefficients. The method presented here extends some previous work by assuming less prior knowledge on the subject and constraints on the model. A relatively simple Monte Carlo algorithm is described to perform joint inferences on general and local compositions and inbreeding coefficients. The method is applied on two case studies. The first one is based on DNA samples from ten Italian regions at the loci TH01 and FES, obtained from a database currently used for forensic identification, in which inbreeding assessments can be crucial. The second application is based on a set of colour-blind sample rates in North-East Indian populations collected by Choudhury (1994). The Author found some controversial results from the classical test for comparing proportions. A clearer picture, instead, is obtained by the current Bayesian approach.     

生物素-亲和素微模式表面的制备与细胞定位

细胞在模式化表面的定位培养对于组织工程,生物传感器技术和细胞生物学基础研究具有重要意义。研究基于软光刻技术的生物素－亲和素微模式表面快速制备方法,并用所制备的模式进行了牛主动脉血管内皮细胞的定位培养。表明该技术可在细胞尺度上有效地控制细胞生长的空间位置。