对于平面应力情况下Ⅰ型裂纹尖端区域主应力符号问题的探讨

在迄今为止的断裂力学中,往往习惯于把σ_3=0作为平面应力的标志。这样的规定意味着,在平面应力情况下的裂纹尖端区域没有一个主应力可能为负值。然而在我用光弹性贴片法研究裂纹尖端区域应力、应变场的实验中,却得到了一些与这种观点相反的 ...     

A nonenzyme glucose sensor based on Cu/Ni/CMWCNTs nanocompositesEI北大核心CSCD

Copper-nickel bimetallic nanoparticles decorated on carboxylated multi-walled carbon nanotubes （Cu/Ni/CMWCNTs）were prepared by using a simple one-pot solvothermal method,which was then employed to construct a highly sensitive non-enzymatic glucose sensor. The modified electrode showed high sensitivity and stability in glucose detection,which was mainly attributed to the synergistic effect of the compact copper-nickel nanocomposite and carboxylated multi-walled carbon nanotubes that possessing high specific surface area to increase the number of active sites and to improve the electrocatalytic activity of the modified electrode. The phase structure and morphology of the material were characterized by X-ray diffraction and scanning electron microscope; the electrochemical performance of the sensor was studied by cyclic voltammetry and chronoamperometry. The sensor had a sensitivity of 1949.1 μµA·L/（mmol·cm2）for glucose detection in the linear range of 1.0-8000 μµmol/L at a potential of 0.55 V,and the detection limit was 0.2 μµmol/L. The sensor was also applied to measure the concentration of glucose in serum samples. The developed nanocomposites sensor has the potential prospect to monitor blood glucose. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

中空纤维液相微萃取-高效液相色谱法检测药品生产企业废水中痕量的β-受体阻断剂

建立中空纤维液相微萃取-高效液相色谱法(HF-LPME-HPLC)用于监测药品生产企业排放废水中痕量的β-受体阻断剂。采用HF-LPME技术对废水中痕量的β-受体阻断剂萃取、纯化和富集,以正辛醇为萃取溶剂、萃取时间为60 min、转速为800 r/min、温度60℃。在优化的萃取条件下,美托洛尔,氧烯洛尔,贝凡洛尔的富集倍数分别为139,195,280倍,最低检测限(S/N=3)为0.064,0.048,0.032 ng/m L,日内精密度(RSD)为1.7%,1.2%,1.0%。3种药物在浓度测定范围内线性良好。     

一种硫同位素标准样品的研制

自然界中硫同位素~(32)S和~(34)S丰度的涨落,其计量部用国际标准样品(简称标样)CDT(Canyon Diablo troilite,(石员)铁硫,FeS)为基准。1962年国际硫同位素有关会议确认其同位素比R_(32/34)=22.220。所有硫矿物样品同     

激光驱动器能源系统实验平台测控系统的研究

 为了提高激光驱动器能源系统运行的稳定性、可靠性、安全性,研制了一套能源系统实验平台的测控系统。该测控系统采用RS-232串行通讯、多线程程序设计来完成并行处理,具有较强的抗干扰能力,可远距离的进行自动控制、数据采集,并能及时的进行数据处理和分析,显示报表并打印。该项研究的结果为大型激光装置的相关系统设计提供了依据。     

THE STABILITY OF STATIONARY SOLUTION FOR OUTFLOW PROBLEM ON THE NAVIER-STOKES-POISSON SYSTEM

In this article, we are concerned with the stability of stationary solution for outflow problem on the Navier-Stokes-Poisson system. We obtain the unique existence and the asymptotic stability of stationary solution. Moreover, the convergence rate of solution towards stationary solution is obtained. Precisely, if an initial perturbation decays with the algebraic or the exponential rate in space, the solution converges to the corresponding stationary solution as time tends to infinity with the algebraic or the exponential rate in time. The proof is based on the weighted energy method by taking into account the effect of the self-consistent electric field on the viscous compressible fluid.     

基于激发态分子内质子转移(ESIPT)原理的反应型荧光探针研究进展

基于激发态分子内质子转移(ESIPT)原理的反应型荧光探针,因其具有高选择性、高灵敏度及大的斯托克斯位移等优点而被广泛关注.以检测目标物的属性归类,就近十年ESIPT反应型荧光探针进行综述,阐述其检测识别机制,并对此类荧光探针应用中存在的问题及发展方向进行评述.     

可变形儒可夫斯基翼型非定常气动力的研究

对于翼面变形法向运动速度远小于来流速度的儒可夫斯基机翼,将解析解和离散涡方法相结合计算变形机翼的流场及非定常气动力,较详细地分析了变形机翼升力系数的准定常计算方法的误差来源,并给出修正方法.计算结果显示脱落涡尾迹对升力系数和机翼绕流环量的影响很小,变形机翼升力系数准定常计算方法的误差丰要来源于流体非定常运动引起的虚拟质量力,该非定常附加升力仅与当前时刻飞行姿态及翼犁形状和变形速率有关,与具体的变形历史过程无关,变形机翼的升力近似等于准定常计算结果叠加上相应的虚拟质量力.     

e~+e~-湮灭成两喷注中的末态强子快度分布和B■关联

本文在文献[1]给出的模型中,进一步赋给夸克简单的四动量分布,通过Monte-Carlo计算,不但得到了与实验符合得很好的轻夸克喷注事例末态强子快度分布等,还给出了与实验基本一致的末态重子反重子之间的快度和角度关联.     

无机化学五十年来的进展

无机化学是以现代科学理论和先进实验技术,研究无机物质的合成、结构、性能和反应。天然资源的开发利用、科学技术对合成新型材料的迫切要求,尤其是四十年代以来原子能、计算机、航天与通讯技术的兴起,在很大程度上推动了无机化学的不断发展;而学科间的相互渗透,特别是现代物理学、数学、生物学、地质学以及化学的其他分支学科,为无机化学提供了新的边缘生长条件。由于无机物质包括全部元素