PTES专家系统知识库的构造

本文大专家系统设计方法的指导下，通过对整理、知识表示、知示获取、知识库构造等环节的描述，介绍了一个植物分类专家系统知识库的构造方法     

关于拓扑Boole格的连续性

本文摒弃了拓扑 Boole 格连续性的传统定义,建立了新的连续性定义,从而使得拓扑空间连续性的基本理论可以推广到拓扑一般 Boole 格上.     

传感器的应用与开发方向

传感器已成为当今科学技术进步的代名词,它的广泛应用和发展,标志着一个国家科学技术进步的程度。文章着重从应用的角度,阐述了传感器的重要性以及未来的发展趋向。     

集成式液压系统油路块CAPP系统开发研究

在综合分析各种ＣＡＰＰ系统应用模式的特点及实际情况的基础上，提 出了液压集成油路块ＣＡＰＰ系统－ＪＫＣＡＰＰ的应用模式：以派生型为主、 检索型为辅、交互型为补充的实用型、多层次、综合应用模式．介绍了 ＪＫＣＡＰＰ系统的功能、特点、工作原理及各功能子模块．该成果已应用于液压 系统ＣＡＤ／ＣＡＭ一体化集成软件系统．     

ZnL2Cl4的晶体结构、荧光性质及标准摩尔反应焓变

在无水乙醇中,用1-氨基-4-甲基哌嗪缩水杨醛（L）与ZnCl2合成了希夫碱配合物ZnL2Cl4,对其进行了元素分析及固体荧光袁征,并用Xn射线衍射测定了其单晶结构．结果表明,Zn^2＋与4个Cl-形成配位键,并与配体以分子间氢键形式联接成三维超分子结构．晶体属于单斜晶系,空间群为C2／c,晶胞参数α=12．0757（12）nm,b-8．9859（8）nm,c-27．435（3）nm,β=98．9450（10）°,V=2940．8（5）nm3,Z=4,F（000）=1344,Dc=1．463g／cm3,μ=1．231mm^-1．该L及ZnL2Ck均有较好的发光性质,发出蓝色荧光．298．15K下,ZnCl2和L在无水乙醇中的溶解焓及配合物液相反应生成焓分别为（7．150±0．022）,（-32．587±0．307）,（3．745±0．035）kJ／tool,热化学循环求得固相标准摩尔反应焓变为（-54．279±0．671）kJ／m01．     

改性壳聚糖吸附剂对水中低浓度汞的吸附

制备了几种改性壳聚糖吸附剂,通过优化试验确定了制备改性壳聚糖吸附剂的乙酸/壳聚糖浓度配比及固化碱液条件,并比较了不同吸附剂对Hg2+的吸附性能.以分子印迹法结合交联胺化改性法制备的Hg2+分子印迹改性壳聚糖吸附剂小球(P-C-CTS-ex(Hg0.3))对Hg2+具有最高的吸附容量,在低浓度Hg2+(CHg2+<40mg/L)溶液中,此吸附剂对Hg2+的吸附容量可达9.017 mg/g,比未改性壳聚糖(CTS)的吸附量高出1倍以上.研究还揭示了交联前Hg2+对壳聚糖分子中的活性氨基的保护功能及除Hg2+后的分子印迹作用.循环再生实验表明,P-C-CTS-ex(Hg0.3)经过8个循环以后的吸附容量保持稳定,颜色与外观等基本不变,重复使用性能稳定;而未改性CTS吸附剂经过"吸附-脱附-再生"8个循环后,球体积明显变小,颜色逐渐变黄,吸附容量不稳定.这表明本研究制备的Hg2+分子印迹改性壳聚糖吸附剂的吸附容量和再生性能均明显优于普通壳聚糖吸附剂,具有应用于含Hg废水处理的潜力.     

大尺度钢筋混凝土双向板的受拉薄膜效应分析

针对板块平衡法缺乏足尺试验验证的缺点,选取2块4.6 m×2.7 m钢筋混凝土矩形板和2块2.7 m×2.7 m钢筋混凝土方形板,进行了模拟均布荷载作用下的大挠度加载试验.试验结果表明:在形成塑性铰线时,板块平衡法中的挠度特征值计算公式对矩形板有效,对方形板则较为保守;板块平衡法中原有的最大挠度特征值计算公式对混凝土双向板较为保守.为此,对形成塑性铰线时的挠度特征值计算公式进行了修正,并提出了新的最大挠度特征值计算公式.将其应用于板块平衡法中,根据已有的混凝土板试验数据,对混凝土板的极限承载力进行了理论和试验的对比分析.结果表明,修正的板块平衡法可以准确地计算大变形下考虑受拉薄膜效应影响的极限承载力.     

ZNRF3 promotes Wnt receptor turnover in an R-spondin-sensitive manner

R-spondin proteins strongly potentiate Wnt signalling and function as stem-cell growth factors. Despite the biological and therapeutic significance, the molecular mechanism of R-spondin action remains unclear. Here we show that the cell-surface transmembrane E3 ubiquitin ligase zinc and ring finger 3 (ZNRF3) and its homologue ring finger 43 (RNF43) are negative feedback regulators of Wnt signalling. ZNRF3 is associated with the Wnt receptor complex, and inhibits Wnt signalling by promoting the turnover of frizzled and LRP6. Inhibition of ZNRF3 enhances Wnt/β-catenin signalling and disrupts Wnt/planar cell polarity signalling in vivo. Notably, R-spondin mimics ZNRF3 inhibition by increasing the membrane level of Wnt receptors. Mechanistically, R-spondin interacts with the extracellular domain of ZNRF3 and induces the association between ZNRF3 and LGR4, which results in membrane clearance of ZNRF3. These data suggest that R-spondin enhances Wnt signalling by inhibiting ZNRF3. Our study provides new mechanistic insights into the regulation of Wnt receptor turnover, and reveals ZNRF3 as a tractable target for therapeutic exploration.     

Quantum phase transition in a resonant level coupled to interacting leads

A Luttinger liquid is an interacting one-dimensional electronic system, quite distinct from the 'conventional' Fermi liquids formed by interacting electrons in two and three dimensions. Some of the most striking properties of Luttinger liquids are revealed in the process of electron tunnelling. For example, as a function of the applied bias voltage or temperature, the tunnelling current exhibits a non-trivial power-law suppression. (There is no such suppression in a conventional Fermi liquid.) Here, using a carbon nanotube connected to resistive leads, we create a system that emulates tunnelling in a Luttinger liquid, by controlling the interaction of the tunnelling electron with its environment. We further replace a single tunnelling barrier with a double-barrier, resonant-level structure and investigate resonant tunnelling between Luttinger liquids. At low temperatures, we observe perfect transparency of the resonant level embedded in the interacting environment, and the width of the resonance tends to zero. We argue that this behaviour results from many-body physics of interacting electrons, and signals the presence of a quantum phase transition. Given that many parameters, including the interaction strength, can be precisely controlled in our samples, this is an attractive model system for studying quantum critical phenomena in general, with wide-reaching implications for understanding quantum phase transitions in more complex systems, such as cold atoms and strongly correlated bulk materials.     

Re-emerging superconductivity at 48 kelvin in iron chalcogenides

Pressure has an essential role in the production and control of superconductivity in iron-based superconductors. Substitution of a large cation by a smaller rare-earth ion to simulate the pressure effect has raised the superconducting transition temperature T(c) to a record high of 55?K in these materials. In the same way as T(c) exhibits a bell-shaped curve of dependence on chemical doping, pressure-tuned T(c) typically drops monotonically after passing the optimal pressure. Here we report that in the superconducting iron chalcogenides, a second superconducting phase suddenly re-emerges above 11.5?GPa, after the T(c) drops from the first maximum of 32?K at 1?GPa. The T(c) of the re-emerging superconducting phase is considerably higher than the first maximum, reaching 48.0-48.7?K for Tl(0.6)Rb(0.4)Fe(1.67)Se(2), K(0.8)Fe(1.7)Se(2) and K(0.8)Fe(1.78)Se(2).