沙冬青叶肉细胞中液泡膜内陷特征的电镜观察

沙冬青(Ammopiptanthus mongolicus)是我国温带荒漠地区特有的常绿灌木,是国家重点保护的植物。它既能防风固沙,又能结瘤固氮,又可入药。对于沙冬青的生理生态和解剖学特征已有报道,但对其叶肉细胞中液泡膜内陷特征尚未见到报道。根据我们的研究观察,发现沙冬青叶肉细胞液泡膜的内陷特征主要表现在如下两个方面:一、液泡膜首先向内膨起,形成小泡,由小到大,并反复折叠,形成大的膜状结构。这种膜状结构彼此差异很大,有的只有一层膜,其膜所包围的空间中很少有可见成分,有的体积较大,形状复杂,膜层之间有一些泡状或     

不同抗冷级别的棉苗在低温处理后叶片细胞超微结构的变化

本实验以分属早熟和晚熟两类不同抗冷级别的３个棉花品种为材料，将其幼苗经４℃低温处理１２ｈ，用透电子显微镜观察叶片细胞超微结构的变化。结果表明：低温处理后早熟品种的叶绿体和液泡没有明显的变化；而晚熟品种的叶绿体则发生变形重叠，液泡浓度加大，且出现了多层膜状结构。说明细胞结构的稳定性与棉花品种的抗冷性密切相关。     

眼Bruch膜超微结构

眼Ｂｒｕｃｈ膜超微结构刘贵生武会珍赵玉珍雷建章（河北医科大学电镜实验中心，石家庄０５００１７）Ｂｒｕｃｈ膜（玻璃膜，布鲁赫膜，Ｂｒｕｃｈ＇ｓｍｅｍｂｒａｎｅ）是指位于脉络膜毛细血管层与视网膜视部色素上皮间薄薄的一层膜状结构而言，因首由Ｂｒｕｃｈ描述，...     

小麦叶肉细胞的电镜观察

本文运用透志镜常规榈制备技术，观察小麦叶肉细胞的超微结构。发现在小麦叶肉细胞中，存在向液泡中伸入的多层膜结构及无膜晶体结构等特殊结构。     

家兔三叉神经节的超微结构——冷冻复型透射电镜观察

本文应用冷冻复型电镜技术研究了家兔三叉神经节的膜结构。观察到节细胞核有大量密布的核孔,其形态在核膜的不同劈裂面上表现不一。经测算1μm～2,平均核孔数为38个,核孔直径为76nm,占核表面积的17.24 ％。胞质内细胞器膜结构的立体感很强。雪旺细胞核上有散布的核孔,1μm～2上有核孔14个,胞质内有线粒体、RER、小泡等结构。有髓神经纤维的不同断面立体构筑很清晰;观察到在大的同心圆板层中夹杂有小的旋涡样板层结构;相邻板层间有圆形空隙。轴索中微丝微管清晰,轴索膜有的向轴浆内陷入。髓鞘板层上的膜内微粒,PF面较EF面者为多。研究结果为该神经节的超微结构提供了新的资料。     

杨树冬芽过冷却机理的超微结构研究

本文对夏季生长季节杨树项芽和寒冬中冬芽基部组织进行了电子显微镜观察。证明了夏季杨树顶芽基部组织细胞的液泡大，且透亮，没有观察到明显的内含物。冬芽基部组织细胞具有许多小液泡，液泡内含有大量的高电子致密的内含物，寒冬中这些物质在液泡中的积累，推测可能是形成过冷却的物质基础。     

杨树冬芽过冷机理的超微结构研究

本文对夏季生长率季节杨树项芽和寒冬中冬芽基部组成进行了电子显微镜研究，证明了夏季杨树顶芽基部组织细胞的液泡大，且透亮，没有观察到明显的内含物，冬芽部组织细胞具有许多小液泡，液泡内含有大量的高电子致密的内含物，寒冬中这些物质在液泡中积累，推测可能是形成过冷却的物质基础。     

Dubin Johnson综合征的肝细胞超微结构观察

采用肝穿刺的方法,利用透射电镜对Dubin Johnson综合征(结合型高胆红素血症)患者进行了肝细胞超微结构的电镜观察。观察结果：电镜下可见到肝细胞内及毛细胆管周围有大量的外有单层膜包绕的色素颗粒,颗粒大小不均匀;其内容物有三种形态,即电子密度较高且均匀的颗粒,电子密度略低的颗粒及电子密度不均匀的内含有小脂滴样物质的颗粒;毛细胆管扩张,腔内微绒毛减少,管壁增厚;粗面内质网及滑面内质网明显扩张成许多小囊泡,使得肝细胞成筛孔状,肝细胞间有胶原纤维增生,肝细胞间隙增宽,并有微绒毛出现。其结果有助于临床的诊断。     

大豆种子萌发过程中子叶细胞超微结构和ATP酶活性动态研究

采用磷酸铅沉淀的电镜细胞化学方法，研究大豆种子萌发过程中，子叶细胞超微结构变化与ATP酶活性的消长。子叶细胞的ATP酶活性主要定位在质膜。在种子萌发的0-3天，子叶细胞贮存蛋白质和油脂大量急剧降解，并快速转运到胚，质膜ATP酶活性较高。萌发的6-9天，子叶细胞内含物大部分消解，蛋白体膜相互融合形成大液泡，原质体开始有稀疏的片层结构，ATP酶活性渐弱至无。萌发第12天，原质体的片层堆叠成基粒，子叶细胞转为同化器官，制造养分，质膜再度呈现较强的ATP酶活性。子叶细胞质膜ATP酶活性反应子叶细胞生理代谢状态。     

杨树花粉内生殖细胞的发育和雄性生殖单位的形成

已经证明,在具双细胞的杨树花粉内,会形成营养核包围生殖细胞结构形式的雄性生殖单位,这是双细胞花粉粒中观察到雄性生殖单位的唯一例证。本工作利用透射电子显微镜,对杨树花粉内雄性生殖单位的形成过程进行了研究,结果发现,这一形成过程经历了三个阶段:(1)生殖细胞贴壁阶段。第一次证实生殖细胞与营养细胞之间的弧形壁具三层结构,中间的纤丝层和两侧的电子透明区,分别与花粉内壁和外壁内层相连。(2)生殖细胞离壁阶段。包围生殖细胞的营养细胞质膜内陷,产生大量液泡。由于液泡具溶酶体的功能,弧形壁内纤丝层溶失。进入了营养细胞内的生殖细胞,周围仍具狭窄的电子透明区,     

北方四种卫矛属常绿阔叶植物叶肉细胞超微结构在冬季的适应性变化

以北京地区生长的4种常绿阔叶植物北海道黄杨（Euonymus japonicus cv.＇CuZhi＇）、大叶黄杨（E.japonicus Thunb.）、金心黄杨（E.japonicus cv.aureo-pictus）和扶芳藤[E.fortunei（Turcz.）hand.-Mazz]为材料,研究其叶肉细胞超微结构在冬季应答低温胁迫的适应性变化。结果表明：在冬季北海道黄杨、大叶黄杨和金心黄杨叶肉细胞的叶绿体结构相对完整,其中的嗜锇颗粒增多,淀粉粒消失;叶绿体周围的线粒体数量显著增多,且结构完整、内嵴明显;细胞质中有同心圆状排列的多层膜结构出现。扶芳藤在初冬时叶肉细胞中的叶绿体有些肿胀,内膜系统稀疏,淀粉粒消失;随着气温进一步的降低,叶绿体出现解体,这些特征表明扶芳藤的抗寒性弱于其它3种常绿阔叶植物。     

Optimization technique for linearly polarized radial-line slot-array antennas using the multiple sweep method of moments

This paper presents an effective full-wave procedure to optimize linearly polarized radial-line slot-array antennas. The procedure is based on a recursive method for solving large matrix equations known as the multiple sweep method of moments. As a result of this paper, new design suggestions have been introduced which greatly contribute to the performance improvement of this type of antennas. These elements are the arrangement of the slots in concentric ellipses instead of circles and a slight but crucial modification on the usual collocation of the reflection-canceling slots.     

混合排列柱状薄层中的向列相液晶指向矢分布的研究

利用向列相液晶弹性理论,研究了混合排列柱状薄层中的向列相液晶指向矢的分布。向列相液晶被限定在两个同心圆柱构成的薄层中,在内外表面施加强锚定及弱锚定边界条件,锚定易取向方向取径向和轴向(垂直柱轴及平行柱轴)的边界条件,得到了四种混合排列柱状薄层模型RsZw、ZwRs、RwZs、ZsRw。基于Frank弹性自由能和Rapini-Papoular近似的表面能,研究了不同锚定强度、不同内半径及不同弹性常数值的指向矢分布,计算机模拟得出指向矢取向的曲线图。由于柱对称性、锚定强度、薄层厚度以及弹性各向异性共同竞争的影响,这四种模型的指向矢分布有着很大的不同。     

Yellow pigment granules in hornets: their origin and development

The present article discusses the yellow pigment in the cuticle of the Oriental hornet Vespa orientalis (Vespinae, Hymenoptera). This insect possesses, both in its gaster region and its head plates, yellow pigment granules that are located underneath the upper layers of the cuticle. All other regions of its body are endowed with a colour ranging from brown to black. As for the yellow granules, some occur within cells while others bud off from the cells inside tubular extensions that interpenetrate the cuticular layers and create accumulations of pigment. Whichever the case, the yellow granules invariably are approximately 0.5 microm in diameter and arranged in three longitudinally extending concentric cylinders, with the innermost cylinder comprising a string that interconnects between the various granules. Our paper discusses the physical properties of these yellow granules and their possible role in everyday hornet life.     

视觉测量中圆形标记点的高精度定位

为了消除透视变换过程中产生的圆心偏差,基于交 比不变和配极对应原理,提出了一种利用同心圆目标精确定 位圆心在图像中的真实投影点的方法。首先介绍相关的理论基础,然后详细介绍了算法 的实现步骤,最后通过仿真和真 实图像实验验证算法的正确性以及影响圆心定位精度的因素。实验结果表明,本文算法可以 稳定、准确地获取圆形目标的真 实投影点,且投影点的定位精度要优于0.2pixel,相较椭圆拟合法 具有明显的精度优势;同时,本文算法仅包含简单的线性运 算,因此具有较高地运算效率。由于本文算法对摄像机和同心圆的物理参数无任何要求,因 此具有应用广泛的特点。     

被子植物胚性细胞及嫁接愈伤组织中的环状片层

在荠菜的胚细胞和胚柄细胞中，以及番茄／番茄和苋菜／番茄的嫁接隔离层附近愈伤组织细胞中，发现环状片层。环状片层有同心圆环状片层，非同心圆环状片层和复合同心圆环状片层三种形态，环状片层来源内质网，在植物中的存在具有普遍性，对其功能进行了讨论。     

Scanning electron microscopy and energy-dispersive X-ray microanalysis studies of afibrillar cementum and cementicle-like structures in human teeth

We examined afibrillar cementum (AFC) and cementicle-like structures (CLS) in human teeth by scanning electron microscopy and energy-dispersive X-ray microanalysis. The AFC showed a spur- or island-, plate- and mass-like structure with appositional laminations, while large masses in the enamel fissures enclosed CLS showing concentric appositional rings. Such AFC was observed in enamel fissures, an abnormal enamel pit, dens invaginatus and root furcations with enamel droplets, as well as on the cervical enamel surfaces, where ameloblasts are differentiated at the later or last stage of enamel formation. Cementicle-like structures were occasionally found independent from AFC and some CLS contained epithelial cell-like or ameloblast-like remnants in the core, surrounded by a few or many concentric rings. In addition, cementicles (CEC) in the root furcations also contained the remnants of Malassez's epithelial-rest cells surrounded by a few concentric rings. In some areas, AFC was mixed with enamel structures. These results show that the organic material in some parts of AFC and CLS may be derived from epithelial cells similar to that of CEC. Calcification values of AFC and CLS were significantly higher than that of fibrillar cementum, and the minute crystals are probably apatite.     

Square and Hexagonal Columnar Liquid Crystals Confined in Square and Triangular Pores

Columnar liquid crystals confined in cylindrical pores are known to orient perpendicular to the pore axis, although for potential nanoelectronic applications they would need to be aligned axially. The X‐ray diffraction study reveals that while in all three compounds examined, the columns arrange in concentric circles in circular pores, axial alignment is indeed achieved for the hexagonal phase of a discotic hexa‐peri‐hexabenzocoronene in “triangular pores,” and for the square phase of a T‐shaped amphiphile in “square pores.” For the third compound, a carbazole dendron with very soft hexagonal columns, a new three‐circle configuration is observed by atomic force microscopy (AFM) in triangular pores. The complex structure of domain walls in columnar liquid crystals is thus seen for the first time on the level of individual columns. A simple estimation of free energies confirms that it is the distortion of polygonal columnar lattice that prevents axial orientation in circular pores. The model also explains the appearance of the three‐circle arrangement of soft columns.     

‘麦香’桃叶片变色期色素含量及超微结构的变化

本文以桃的栽培品种‘麦香’（Prunus persica‘mai xiang’）为试材,在8月中旬其叶片由绿变紫红时,对其不同叶位的叶片色素含量进行了测定;以叶色维持绿色不变的品种‘照手姬’桃（Prunus persica‘terutehime’）为对照,并观察了这2个品种的叶片细胞超微结构。结果表明：当花色苷与总叶绿素、类胡萝卜含量的比值约为1∶3.86∶0.43时叶片开始转为淡紫色;当三者含量的比值达到1∶1.70∶0.18时,‘麦香’的整个叶片转变为紫色;当三者的比值大于1∶1.35∶0.16时,叶片的紫色加深变为紫红色。超微结构研究发现,‘麦香’的顶端嫩叶与‘照手姬’的存在显著差异,‘照手姬’桃叶绿体基粒片层清晰,而此时‘麦香’叶绿体基粒片层已表现出明显的松散,线粒体膜有降解现象,而且在上表皮细胞和栅栏组织的液泡中已存在不明物质,这种幼龄期表现的衰老迹象,可能是‘麦香’桃的早熟性决定的。在基部叶片的超微结构中,两品种都出现了相似的衰老现象,即叶绿体片层结构严重扭曲并出现解体现象、嗜锇颗粒增多变大、线粒体外膜解体,内嵴混乱。此外’麦香’叶片中还显示出特有的结构：栅栏组织细胞的液泡和上表皮细胞出现大量絮状或粒状的黑色物质。本实验结果表明,‘麦香’桃叶片的成色取决于花色苷和总叶绿素的比例,‘麦香’桃在变色期合成花色苷,然后可能运输到栅栏组织的液泡和上表皮细胞,使叶片呈现紫红色。     

An investigation of concentric ring antennas with low sidelobes

An analysis is made of circular antenna arrays with diameters being 2 to9lambda(the minimum inner circle diameter being0.4lambda) containing 3 to 18 concentric circles. For the purpose of computation of the array factor the elements of the array are assumed to be isotropic radiators. The elements of each circle have equal current amplitudes and are phased so that the contributions of all the elements add in phase in the direction of the main beam. The Chebyshev radiation pattern function is approximated by a truncated Fourier-Bessel series, from which the current amplitude of each circle is obtained. From these current amplitudes a method for computing the current amplitude to excite a new distribution of fewer circles is shown. Also, an empirical method is given for improving the sidelobe level of the radiation pattern by adding an element to the center of the array. A number of circles in the array sufficient to avoid pattern deterioration is found to be the integer nearest to5d/4lambdafor -20 and -30 dB sidelobe level and4d/3lambdafor -40 dB, wheredis the diameter of the array. This represents a large reduction in the number of circles needed over the Fourier-Bessel series representation in the case of large antennas. Experimental verification of the computed pattern is made for an array of two concentric circles with diameters of0.8lambdaand1.6at a frequency of 90 Mc/s. The elements of the array were vertical monopoles.