桅杆缆风绳的选择计算

通过对桅杆缆风绳的作业分析和理论推导得到了缆风绳的计算实用公式,并介绍了其计算方法的选择。     

燃料电池式乙醇传感器的研制

利用燃料电池反应原理制备乙醇传感器,可精确检测呼气中乙醇浓度,并对烟雾、汽油等典型的干扰气体具有优异的选择性.传感器电极采用价格低廉、物理化学性质稳定的磺化聚α-甲基苯乙烯制固体质子交换膜作为载体材料,降低了传感器的制造成本,并用硅酸乙酯处理质子交换膜负载二氧化硅以改善膜的亲水吸水性能.传感器采用全固态方式装配,避免了液态电化学传感器的电解液泄漏问题.传感器电极采用丝网印刷工艺制备,提高了电极尺寸的一致性、催化剂的分散度和电极的强度,改善了传感器的稳定性,提高了生产效率.     

桅柱式升降机构设计计算

根据新型库内桅柱式升降车的设计实践工作,结合该车所用升降机构的结构特点,建立了变截面4节臂倒立桅柱式升降机构的力学模型,对升降机构刚度和强度的设计计算方法进行了分析研究,对影响刚度和强度的设计参数计算公式进行了分析及推导,并结合计算实例以及相关部门的试验检测,证明了变截面4节臂倒立桅柱式升降机构模型的准确性,以及升降机构刚度、强度设计计算方法的合理性,可作为变截面升降机构强度和刚度设计计算的参考依据。     

月球车桅杆系统的展开驱动器结构设计

阐述了月球车全息摄像机转向杆装置的结构,分析了其展开驱动器在桅杆系统中的关键作用,提出了转向杆展开驱动器的设计方法。     

Proceedings of the eleventh annual meeting of the arizona society for electron microscopy and microbeam analysis held in tucson,arizona, february 7–8, 1990

The ultrastructure of the progressive testicular involution with advancing age in men is reviewed. There is no definite age at which testicular involution begins, and the onset and severity of testicular lesions are subjected to pronounced individual variations. Hormone studies also indicate great individual variations, and subtle changes in both the testis and the pituitary develop progressively with age. Testicular size, sperm quality, and numbers of all germ cell types, Sertoli cells, and Ley dig cells decrease with age. The volume occupied by the seminiferous tubules decreases, whereas that occupied by the testicular interstitium remains constant. The most frequent histological pattern of the aging testis is a mosaic of different seminiferous tubule lesions, varying from tubules with complete, although reduced, spermatogenesis, to completely sclerosed tubules. The tubules with complete spermatogenesis may show numerous morphological abnormalities in the germ cells, including multinucleation. Abnormal germ cells degenerate causing Sertoli cell vacuolation. These vacuoles correspond to dilations of the extracellular spaces resulting from the premature exfoliation of germ cells. Degenerating cells that are phagocytosed by the Sertoli cells give rise to an accumulation of lipid droplets in the Sertoli cell cytoplasm. The loss of germ cells begins with the spermatids, but progressively affects the earlier germ cell types, and tubules with maturation arrest at the level of the spermatocytes or spermatogonia are observed. The Sertoli cells show morphological abnormalities such as dedifferentiation, mitochondrial metaplasia, and multinucleation. Germ cell loss is associated with thickening of the tunica propria. When all seminiferous epithelial cells have disappeared, only an intensely collagenized tunica propria with myoid cells remains (sclerosed tubules). The Ley dig cells progressively dedifferentiate with a decrease in the quantity of both smooth endoplasmic reticulum and mitochondria, together with an accumulation of lipid droplets, crystalline inclusions, and residual bodies, and formation of multinucleate cells. The development of tubular involution with age is similar to that observed after exprimental ischemia, suggesting that vascular lesions may play an important role in age-related testicular atrophy.     

直升机桅杆上装设备动力吸振研究

文中基于动力吸振(Dynamic Vibration Absorption,DVA)技术对直升机桅杆上装设备的低频振动进行振动控制研究.采用有限元方法对悬臂梁式吸振器进行优化设计,并对其吸振性能进行仿真验证.在此基础上生产吸振试件安装在天伺馈(天线、伺服、馈线)上进行试验验证.试验结果表明,天伺馈在螺旋桨主频下的振动量级明显降低,吸振设计有效.该研究为桅杆上装设备的振动控制提供了一种新的途径.     

两级全自由叉车门架液压回路匹配设计

本文介绍了叉车两级全自由门架液压回路的设计方法,使回路组成中的各起升液压缸及管路的匹配满足叉车工作要求,并使工作液压系统具有性能稳定,结构紧凑,成本优越等特点。     

Immunogold electron microscopic localization of antigenic sites in the outer dense fiber region of rat sperm tail obtained by using antisera to two Sertoli cell secretory proteins

Polyclonal antisera raised against polypeptide components of two rat Sertoli cell secretory proteins, designated protein S70 and S45–S35 heterodimeric protein on the basis of cell origin and estimated molecular weight, were used to identify antigenic sites in (1) rat testis, () cultured Sertoli cells, (3) developing spermatids (collected from spermatogenic stage-specific seminiferous tubular segments), and (4) epididymal sperm. Indirect immunofluorescence, immunoper-oxidase, and immunogold electron microscopy (single and double labeling) were used. Immunocytochemical techniques have detected antigenic sites in (1) the cytoplasm of Sertoli cells in the intact seminiferous tubule and in culture in the form of a punctuate, granular-like pattern, and (2) the acrosome (but not the Golgi region) and tail of developing spermatids and sperm. In developing spermatids, the principal piece of the tail displays a characteristic apical-to-distal immunoreactive banding pattern that correlates both temporally and spatially with the reported multistep assembly of outer dense fibers along the axoneme. The immunoreactivity of the acrosome, connecting piece, and outer dense fibers of the sperm tail was confirmed by immunogold electron microscopy. A precise identification of the component(s) of the outer dense fiber region responsible for the antigenic homology with Sertoli cell secretory proteins is under investigation.     

High-Resolution scanning electron micrographs of freeze-cracked cells in testes from normal and irradiated rats at different stages of gonadal development

Newly developed techniques in high-resolution scanning electron microscopy (SEM) and for tissue-processing procedures have been applied to an investigation of structures of various cells in rat testes at different stages of gonadal maturation. A series of high-resolution SEM micrographs are presented which survey the surfaces of different types of testis cells during normal development, and which also illustrate ultrastructural features of some of their intracellular organelles. In addition, a series of high-resolution SEM micrographs are presented which compare the structural features of Sertoli cells in normal testes with those in germ-cell-depleted testes obtained from rats killed at varying times after having been irradiated in utero. We describe our observations on the structural properties of surfaces and intracellular organelles in Sertoli cells, Leydig cells, peritubular myoid cells, and some classes of germinal cells. We also consider the possible role of Sertoli cell apical cytoplasmic processes in lumen formation. Similarities are pointed out between the structure of germ-cell-depleted testes, resulting from irradiation in utero, and the structure of germ-cell-depleted testes in seasonal breeders during periods of involution. Finally, we discuss advantages and disadvantages of methods employed to reveal the fine structure of intracellular organelles in cells of the testis.     

塔式起重机标准节内力分析

建立了塔式起重机标准节模型,分析了在3种工况下的内力。得出的主要结论是标准节的轴向力由立柱承担．腹杆主要承担剪力和平行于塔身轴线的扭矩。     

Imaging of RNA in situ hybridization by atomic force microscopy

In this study we investigated the possibility of imaging internal cellular molecules after cytochemical detection with atomic force microscopy (AFM). To this end, rat 9G and HeLa cells were hybridized with haptenized probes for 28S ribosomal RNA, human elongation factor mRNA and cytomegalovirus immediate early antigen mRNA. The haptenized hybrids were subsequently detected with a peroxidase-labelled antibody and visualized with 3,3'-diaminobenzidine (DAB). The influence of various scanning conditions on cell morphology and visibility of the signal was investigated. In order to determine the influence of ethanol dehydration on cellular structure and visibility of the DAB precipitate, cells were kept in phosphate-buffered saline (PBS) and scanned under fluid after DAB development or dehydrated and subsequently scanned dry or submerged in PBS. Direct information on the increase in height of cellular structures because of internally precipitated DAB and the height of mock-hybridized cells was available. Results show that internal DAB precipitate can be detected by AFM, with the highest sensitivity in the case of dry cells. Although a relatively large amount of DAB had to be precipitated inside the cell before it was visible by AFM, the resolution of AFM for imaging of RNA– in situ hybridization signals was slightly better than that of conventional optical microscopy. Furthermore, it is concluded that dehydration of the cells has irreversible effects on cellular structure. Therefore, scanning under fluid of previously dehydrated samples cannot be considered as a good representation of the situation before dehydration.     

TSJ2000钻机井架风载的有限元分析

使用三维建模软件Pro／EWildfire5．o建立井架全结构模型篷导入到Workbenchl4．5中进行有限元分析,计算得出井架在满立根、无钩载的情况下,井架分别承受背面和侧面36m／s的大风时各主要构件的变形与受力情况。证明井架在该工况下各主要构件的强度刚度均满足安全使用要求。