宽温度液晶的合成

４．４’－双－（反式－对正戊基环己基）联苯（５ｃｐｐｃ５）具有熔点低，清亮点高的特点；因此，它的中介相温度很宽。本文提出一种通过三步反应合成５ｃｐｐｃ５的新路线，详细地讨论了这种液晶的合成方法以及有关影响反应的因素，并用红外、核磁、紫外、质谱等方法测定了该液晶的化学结构．研究了该化合物的热力学性质和偏光织构图。     

碳纤维微电极制作与电化学行为的研究

讨论了两种制作碳纤维微电极的方法.研究了微电极的某些电化学行为,并与宏电极的结果进行了比较.验证了在控制电流条件下边缘效应的影响.结果表明,由于传质过程的加快,在通常扫描速度下,微电极伏安技术可测得呈现稳态极化特征的伏安图形,展示了某些良好的应用前景.     

Y-Ba-Cu-O系超导体的水解性研究

高转变温度T_c的Y—Ba—Cu—O系超导体是目前最引人注目的超导材料。这种超导体在液氮沸点温度以上有稳定的零电阻温度T_o。对于不同的Y、Ba和Cu组分比,只要采用相应的烧结条件,均能制备出T_c>90K的超导样品。我们在实验中发现,此种体系超导体无论组分如何,均有明显的水解特性,最终失去超导电性。水解的最终生成物由X射线衍射测定决定。另外,利用计算机对超导体完全水解的温度-时间关系进行了模拟计算。我们以组分比Y:Ba:Cu=1:2:3均匀混料,在850℃下预烧4小时(h),然后磨碎并过筛,压制成直径16mm、厚度1.5mm的圆片,在960℃下通氧烧结9小时,得到     

EDA与电子设计教学

在EDA软件的基础上,重点介绍了仿真功能在电子设计中的应用,佐证了由传统实验教学转向现代创新性教学的重要性。     

Effect of matrix metallo-proteinase-26 (MMP-26) during embryo implantation in the mouse

Matrix metalloproteinase-26 (MMP-26, endometase and matrilysin-2), a novel member of the MMPs family, is detected not only in the placenta and uterus, but is widely expressed in malignant tumors from different sources as well as in diverse tumor cell lines. However, the function of MMP-26 in the reproductive system has never been reported. Expression of MMP-26 in mouse embryos and the function of the MMP-26 antibody during mouse embryo implantation was examined for the first time by injecting the uterine horn, immunohistochemistry,in situ hybridization, co-culture of mouse blastocysts and uterine monolayer epithelial cells, Western blot, RT-PCR, Northern blot and zymography. Our results show that there is strong expression of MMP-26 mRNA and protein in the mouse embryo. Furthermore, the MMP-26 antibody dramatically inhibited mouse embryo implantation and significantly inhibited adhesion and outgrowth of mouse blastocysts onin vitro uterine monolayer epithelial cells. At the same time, the MMP-26 antibody inhibited the expression of integrin αV mRNA and protein in a dose-dependent manner. These data suggest that MMP-26 may play a role in some of the tissue-remodeling events associated with the invasion of the endometrium by trophoblast cells and facilitate successfully embryo implantation.     

Performance and observation summary of Changchun Satellite Laser Ranging Station

This note introduces the performance and observation summary of the SLR system at Changcun Observatory, the Chinese Academy of Sciences. The performance of the SLR system has been greatly improved since August 1997. The single shot precision is improved from 5–7 cm to 1–2 cm and the normal point precision reaches 4–7 mm. The long-term stability is better than 1 cm. The amount of observation has been increased from 1000 to over 3000 passes. The whole performance of Changcun SLR system has reached the advanced level among the worldwide SLR stations.     

Sm-Nd isotope dating of hydrothermal calcites from the Xikuangshan antimony deposit,Central Hunan

The research on Samarium-Neodymium isotope systematics of hydrothermal calcites from the Xikuangshan antimony deposit, Central Hunan, places precise timing constraints on the Sb mineralization in this area. It is revealed that the Xikuangshan deposit formed during the late Jurassic-early Cretaceous Period, the early- and latestage mineralization took place at (155.5± 1.1) Ma and (124.1±3.7) Ma, respectively. The accurate age determination of mineralization is very crucial for revealing the super-enrichment mechanism of the element Sb at the Xikuangshan mine, and lays some foundations for the further understandings of its ore genesis and mineralization mechanism.     

影响新疆阜康荒漠地区红砂光合日变化因素的分析

目的 研究新疆阜康荒漠区域优势植物红砂（Reaumuria soongorica）光合及其影响因子的日变化，分析蒸腾速率、光合有效辐射、空气温度、气孔导度、相对湿度、叶面温度、胞间CO2浓度和空气CO：浓度对光合速率的影响。方法利用CI-301 CO2气体分析仪，测定光合及其影响因子的日变化，并进行相关性和多重线性回归分析。结果光合速率日变化形成典型的双峰型；蒸腾速率的日变化曲线呈双峰型；光合有效辐射、空气温度日变化和叶面温度的日变化曲线相近，在午后均呈逐步降低趋势；气孔导度与生境相对湿度的日变化为先下降，然后保持在一定的水平上；水分利用率全天递减。空气CO2浓度、空气温度、相对湿度及叶面温度和气孔导度对红砂光合速率具有显著的影响。结论红砂光合速率日变化曲线形成典型的双峰型，温度是影响红砂光合特性的重要因子之一，气孔因素则是导致其光合速率下降的决定因素。     

陕西省入境旅游市场竞争态分析

目的 为了对陕西入境旅游市场进行科学客观地分析，为政府有关部门提供决策依据。方法运用旅游系统市场竞争态模型对陕西省2002年入境旅游业客源市场和目的地市场的竞争态势进行定量计算和分析。结果①客源市场中金牛市场占40％，日本、美国、德国等市场显示出继续稳定攀升的发展特征；瘦狗市场占33％，加拿大、澳大利亚、新加坡市场已明显复苏；幼童市场占20％．泰国、菲律宾等新兴市场增长迅速；明星市场占7％，韩国市场持续增温。②目的地市场中幼童市场占60％，其中商洛地区年增长率高达50％，安康地区也高达45．1％；金牛市场占20％；明星市场占10％，西安地区一枝独秀，其市场占有率高达88．5％；瘦狗市场占10％，榆林地区弱势明显。结论2002年陕西省入境旅游客源市场表现出旺盛的增长态势，但是要实现旅游业的可持续发展，还必须进行科学的市场研究，并加强政府对旅游业发展的规划指导。     

A mathematical model for solid liquid and mass transfer coupling and numerical simulation for hydraulic fracture in rock salt

Thehydraulicfracturingtechniqueiswidelyused intheoilengineering,naturalgasexploiting,under groundheatextractingandothermineralresources mining,etc.withwelldevelopedhydraulicfracture modelsforordinaryrocks[1—3].Inthefieldofsolu tionminingofsaltdeposit,thistechniqueisusedto producefracturealongtheplanelayerofthedeposit,thustoconnecttheinjectionandtargetwells[4,5].However,duetothespecialphysicalandmechanical characteristicsofrocksalt,executinghydraulicfrac tureinrocksaltdepositisdifferentfromtha…