Study on Injection Moulding of High Precision Aspheric Plastic Lens

With the rapid development of information and multi me dia technologies, the demand for the optical plastic aspheric elements used in o pto-electronic devices, camera, optical disc and projector lens etc. has been i ncreased rapidly in the recent years. The key technologies of fabrication of asp heric plastic lens are the design and manufacturing moulds, selection of proper injection moulding equipment, and optimization of injection moulding parameters etc. In this paper, the effect of injection pressure,...     

Research on Nanofabrication Technology of Micro-/Nano-Stereo Rapid Prototyping of PCVD

At present, the most common micro/nano-scale fabri ca tion processes include the plane silicon process based on IC technology, stereo silicon process, LIGA, quasi-LIGA based on near ultra violet deep lithography, MEMS, energy beam etching and micro/nano-machining, etc. A common problem for t hese processes is the difficulty to fabricate arbitrary form for 3-dimensional micro/nano-parts, devices or mechanisms. To develop advanced MEMS manufacturin g technology, and to achieve fabrication of true 3-dimen...     

基于DEA法的虚拟企业合作伙伴效益评价应用研究

虚拟企业合作伙伴选择是虚拟企业组建过程中的重要问题，也是一个复杂的问题。从虚拟企业合作伙伴效益评价的角度出发，在AHP(层次分析)法的基础上，给出了DEA(数据包络分析)法的C^2R模型，并结合具体企业进行了实例验证，从而证明了DEA法对于虚拟企业合作伙伴选择的科学性和有效性。     

The in vivo role of α-mannosidase IIx and its role in processing of <Emphasis Type="Italic">N</Emphasis>-glycans in spermatogenesis

The surfaces of mammalian cells are covered by a variety of carbohydrates linked to proteins and lipids. N-glycans are commonly found carbohydrates in plasma membrane proteins. The structure and biosynthetic pathway of N-glycans have been analyzed extensively. However, functional analysis of cell surface N-glycans is just under way with recent studies of targeted disruption of genes involved in N-glycan synthesis. This review briefly introduces the potential role of processing -mannosidases in N-glycan biosynthesis and recent findings derived from the -mannosidase IIx (MX) gene knockout mouse, which shows male infertility. Thus, the MX gene knockout experiment unveiled a novel function of specific N-glycan, which is N-acetylglucosamine-terminated and fucosylated triantennary structure, in the adhesion between germ cells and Sertoli cells. Analysis of the MX gene knockout mouse is a good example of a multidisciplinary approach leading to a novel discovery in the emerging field of glycobiology.Received 29 November 2002; received after revision 30 December 2002; accepted 20 January 2003     

Structural and biochemical aspects of keratan sulphate in the cornea

Keratan sulphate (KS) is the predominant glycosaminoglycan (GAG) in the cornea of the eye, where it exists in proteoglycan (PG) form. KS-PGs have long been thought to play a pivotal role in the establishment and maintenance of the array of regularly-spaced and uniformly-thin collagen fibrils which make up the corneal stroma. This characteristic arrangement of fibrils allows light to pass through the cornea. Indeed, perturbations to the synthesis of KS-PG core proteins in genetically altered mice lead to structural matrix alterations and corneal opacification. Similarly, mutations in enzymes responsible for the sulphation of KS-GAG chains are causative for the inherited human disease, macular corneal dystrophy, which is manifested clinically by progressive corneal cloudiness starting in young adulthood.     

同构于U1tu的传递模型中序数的性质

对于可测基数K,有非主K-完备的超滤∪■P(K),由此可得到ZFC的模型∪ltu以及同构于∪ltu的传递模型M.本文讨论了M中序数的一些性质,得出了如下结论:1)若f:K→Ord为函数,则Π([f])为M中序数(Π:∪ltu→M为同构映射);2)M中的基数Π(j_u(k))不为∨中的基数(j_u=∨→∪ltu为自然嵌入);3)Π与自然嵌入ju的复合Π·ju不为满射,由此可推知ju不为满射。