变系数函数方程解的振动准则

本文建立了一类变系数非线性函数方程一切解振动的几个充分条件,并且给出了它们在差分方程中的若干应用。本文的结果改进和推广了近期文献的某些结果。     

侧基带有L-苯丙氨酸的手性两亲嵌段共聚物的合成及其自组装行为

N3-苯丙氨酸与嵌段共聚物聚乙二醇-b-聚炔丙基缩水甘油(MPEO-b-PGPE)发生"click"反应,合成了具有光学活性的两亲嵌段共聚物聚乙二醇-B-聚L-苯丙氨酸三唑基缩水甘油(MPEO-b-PGTP),用1H-NMR和元素分析对其结构和组成进行表征.并对其自组装行为进行研究,滴体积法测定MPEO-b-PGTP溶...     

第2次数学危机的影响和启示

17世纪笛卡尔、费尔马在研究运动和切线时,引进坐标系和变数,创立了解析几何,这为微积分的诞生开辟了道路.恩格斯把对数的发明、解析几何的创立和微积分的建立,并称为17世纪的三大成就.他说:“在一切理论成就中,未必再有象17世纪下半叶微积分的发明那样,被看作是人类精神的最高     

基于相似度准则的试验装备采购风险评估模型

试验装备采购风险的决策问题具有复杂性、模糊性和群决策性.分析采购风险评估问题的层次结构,设计专家权重的有效算法,构建基于相似度的风险评估群决策模型并通过实例分析结果证明了方法的合理性和有效性.     

Synthesis and Crystal Structure of 3-（2,4-Dichlorophenyl）- 4-dydroxy-5-cyclohexanyl-△3-dihydrofuran-2-one

The title compound 3-（2,4-dichlorophenyl）-4-dydroxy-3-（2,4-dichlorophenyl）-4- dydroxy-5-cyclohexanyl-A3-dihydrofuran-2-one 5 has been synthesized by the cyclization of methyl O-（2,4-dichlorophenyl-acetyl）-1-hydroxycyclo-hexane-carboxylate 4, and its crystal structure was determined by single-crystal X-ray diffraction. The crystal belongs to the triclinic system, space group Pi with a = 6.8192（3）, b = 10.5053（5）, c = 10.5811（5）A,α = 71.681（10）, β = 78.905（12）, γ = 81.036（12）°, C15H14C1203, Mr = 313.18, V= 702.44（6）A3, Z = 2, De= 1.481 g/cm^3, F（000） = 324,μ = 0.465 mm^-1, S = 1.006, the final R = 0.0331 and wR = 0.1363 for 2505 observed reflections with I 〉 2σ（I） and 183 variable parameters. The crystal analysis shows that the cyclohexene unit of the title compound has a quasi-chair conformation, and a one-dimensional chain structure is formed via the intermolecular hydrogen bond O（1）-H（101）…O（2）.     

超高效液相色谱–串联质谱法同时测定化妆品中7种双酚类化合物及其衍生物

建立同时快速测定化妆品中7种双酚类化合物及其衍生物的超高效液相色谱–串联质谱方法.水剂化妆品采用正己烷–乙酸乙酯(体积比为1:1)溶液超声提取;粉类、膏霜乳液类、凝胶类化妆品采用乙酸乙酯超声提取,提取液经氮吹浓缩后用甲醇–水(体积比为1:1)溶液定容,用Waters XSelect HSS T3(100 mm×2.1μ...     

光纤光栅负荷传感器在港口门机上的应用

港口门式起重机的光纤布喇格光栅负荷传感器将钢索张力转变为对测力传感器的正压力,测力元件采用等应变梁结构,使固定在上下表面的光栅同时受到拉力和压力,以两光栅反射波长位移量的叠加表示钢索受到的载荷。该装置提高了测量灵敏度和线性度,而且抵消了环境温度的干扰。标定数据表明,光纤光栅负荷传感器的误差只有0．70／60,大大优于电应变片3％的精度指标要求。     

Responsive mechanism of three novel hypochlorous acid fluorescent probes and solvent effect on their sensing performance

Optical properties and responsive mechanisms of three newly synthesized fluorescent probes for hypochlorous acid(HOCl) are investigated by employing time-dependent density functional theory. The computational results show that the absorption and emission properties of these probes change obviously when they react with hypochlorous acid. It is found that the probe FHZ has the best performance according to the probing behavior. Moreover, the responsive mechanisms of the probes are studied by analyzing the distributions of molecular orbitals and charge transfer, which are shown as the photoninduced electron transfer(PET) for FHZ and the intramolecular charge transfer(ICT) for the other two probes. Specially,solvent effect on optical properties of the probe FHZ before and after reaction is studied within the polarizable continuum model(PCM). It is shown that performance of the probe depends crucially on the solvent polarity. Our computational results agree well with the experimental measurement, and provide information for design of efficient two-photon fluorescent probes.     

122~125Sn中子谱因子的实验研究

多个Sn同位素位于慢速中子俘获（s-）过程路径上,其中子谱因子可用于计算ASn（n,γ） A+1Sn直接辐射俘获的天体物理反应率,并可研究Sn同位素对s-过程核合成的贡献。本工作在中国原子能科学研究院HI-13串列加速器Q3D磁谱仪上,对实验室系下8°~66°范围内的122,124Sn（d,p）和（p,d）单中子转移反应角分布进行了测量。利用DWBA理论计算了转移反应角分布,并提取了122-125Sn的基态以及123,125Sn第一激发态的中子谱因子。其中,122Sn和124Sn的基态中子谱因子是首次从实验上获得。由于本工作成功鉴别开了123,125Sn的基态和第一激发态的效应,因此给出的谱因子比前人的结果更可信。Several Tin isotopes are on the path of slow neutron capture (s-) process, and the direct components of (n, γ) reactions can be derived from their neutron spectroscopic factors. In the present work, the angular distributions of 122,124Sn(p, d) and (d, p) reactions are obtained using the high-precision Q3D magnetic spectrograph in Beijing HI-13 tandem accelerator in China Institute of Atomic Energy. The distorted-wave Born approximation (DWBA) calculations are performed to extract the neutron spectroscopic factors of the ground state of 122-125Sn and the first excited state of 123,125Sn. The neutron spectroscopic factors of the ground state of 122Sn and 124Sn are firstly obtained in this work. As the events of the ground state and first excited state of 123,125Sn can be distinguished clearly by our experiment, the neutron spectroscopic factories of 123,125Sn are more reliable.     

DAMPE-PSD探测单元模块大动态范围读出方案的实验验证

暗物质粒子探测卫星（Dark Matter Particle Explorer,DAMPE）的塑闪阵列探测器（Plastic Scintillator Detector,PSD）需要实现高能e/γ粒子的鉴别功能以及对Z=1~20的宇宙线重离子的电荷测量功能。它使用光电倍增管作为读出器件,并从打拿极5和打拿极8同时引出信号来增大读出动态范围。基于该设计方案的探测单元模块在兰州重离子加速器冷却储存环（HIRFL-CSR）上的外靶终端（ETF）进行了束流测试实验。实验得到了PSD单元条在中能轻核区（Z≤8）的能量响应,并证明了单元条的衰减长度与入射粒子种类无关。通过将实验结果外推至高能重核区,同时结合衰减长度、入射角度和能量涨落等因素,可以估算出PSD探测单元模块输出信号幅度的动态范围。结果显示,该范围在PSD前端电子学模块的线性工作区间内,从而验证了PSD大动态范围读出方案设计的合理性。The Plastic Scintillator Detector (PSD) of DArk Matter Particle Explorer (DAMPE) aims for high energy e/γ identification and charge measurement for cosmic-ray ions from Z=1~20. It adopts photomultiplier tube as the readout device and extracts signals from both dynode5 and dynode8 to enlarge the readout dynamic range. A beam test on a PSD detector unit based this design has been carried out at the External Target Facility (ETF) terminal of the Cooling Storage Ring of Heavy Ion Research Facility in Lanzhou (HIRFL-CSR). The detector response to light nuclei (Z≤8) at the medium energy scale was extracted and the attenuation length was proved to be irrelevant with the impinging nuclei species. By extrapolating the result to heavy nuclei at the high energy scale and taking into account light attenuation, energy fluctuation and imping angle, the dynamic range of the output signal of PSD detector unit was estimated. The range is well within the linear range of the front-end electronics of PSD, thus verifies the large dynamic range readout design of PSD.