A robust DNA mechanical device controlled by hybridization topology.

Controlled mechanical movement in molecular-scale devices has been realized in a variety of systems-catenanes and rotaxanes, chiroptical molecular switches, molecular ratchets and DNA-by exploiting conformational changes triggered by changes in redox potential or temperature, reversible binding of small molecules or ions, or irradiation. The incorporation of such devices into arrays could in principle lead to complex structural states suitable for nanorobotic applications, provided that individual devices can be addressed separately. But because the triggers commonly used tend to act equally on all the devices that are present, they will need to be localized very tightly. This could be readily achieved with devices that are controlled individually by separate and device-specific reagents. A trigger mechanism that allows such specific control is the reversible binding of DNA strands, thereby 'fuelling' conformational changes in a DNA machine. Here we improve upon the initial prototype system that uses this mechanism but generates by-products, by demonstrating a robust sequence-dependent rotary DNA device operating in a four-step cycle. We show that DNA strands control and fuel our device cycle by inducing the interconversion between two robust topological motifs, paranemic crossover (PX) DNA and its topoisomer JX2 DNA, in which one strand end is rotated relative to the other by 180 degrees. We expect that a wide range of analogous yet distinct rotary devices can be created by changing the control strands and the device sequences to which they bind.     

智能通用辅助建模工具的研究与开发

本文提出了一种辅助建模过程的分级模式,并据此在Pc机上开发了一个智能通用建模工具。分级模式包括四种处理系统及五个状态,其中每种处理系统使一个状态变为相连的另一个状态。在智能通用建模工具中,问题构成系统是智能化的,其余部分是通用性的。整个工具集中了现有建模工具的主要优点,适用于广大的非计算机专家的决策人员使用。     

行星运动问题解法讨论

本文讨论了Runge—Lenz矢量的性质,利用它求解经典和狭义相对论情况下行星运动问题,并得出新的行星近日点的进动值。     

TDF对~（60）Co－γ线诱发淋巴细胞微核发生率的影响

ＴＤＦ（５，３′，５′－三羟基－７－甲氧基，二氢黄酮）能抑制~（６０）Ｃｏ－γ射线低剂量所引起的人离体外周血淋巴细胞的微核发生率，助溶剂ＤＭＳｏ无明显的抑制作用。     

海南省人群中血清α_1—抗胰蛋白酶等位基因的频率调查

本文采用 Frants 超簿层等电聚焦分析技术进行海南省1353人血清α_1—抗胰蛋白酶等位基因频率调查。结果表明该人群α_1—抗胰蛋白酶等位基因频率为 M_10.7158M_20.1981 M_30.0732,此外尚发现 MEtokyo,M-Haikow—1,M-Haikow-2,Mz,完全缺失型和未定型共6种变异类型,其总发生率占该人群1.85%。     

有挠引力量子化初探

研究了有挠时空的引力量子化问题，获得了一次型有挠引力的Ｗｈｅｅｌｅｒ－Ｄｅｗｉｔｔ方程，超空间的号差是洛仑兹的。在小超空间近似下，如果宇宙波函数是正规的，或者取无边界边界条件，都得出均匀各向同性量子宇宙以无挠方式演化的结论。     

女大学生耐力跑恐惧心理的成因与措施

分析了女大学生耐力跑教学和锻炼中出现恐惧心理的成因，提出了克服这一状况的措施和方法，为广大体育教育工作提供参考。     

Stormwater Management in Hong Kong

IntroductionStormwater management(SWM) in Hong Kong isthe responsibility of the drainage servicesdepartment (DSD) of the Governmentof the HongKong Special Administrative Region.Thedepartment is charged with the formulation ofpolicy and the design,construction,operation andmaintenance of all public stormwater drainagesystems,as well as approving private drainsthrough an administrative framework.　 The principal concern of SWM is the reductionof the risk and extent of flooding.Thus,thesuc…     

基于CAN总线的集成化六维腕力传感器的设计

提出一种基于片上系统的嵌入式集成化六维腕力传感器设计方案 ,将传感器弹性体、信号处理电路、电源系统以及总线接口电路集成在一起 ,详述了传感器设计的结构和原理 ,给出了一种规格的集成化六维力传感器实验结果 ,并与国外同类产品进行了比较