高速逆流色谱分离金果榄中巴马亭

用高速逆流色谱分离金果榄中巴马亭,以氯仿∶甲醇∶0.2mol·L-1盐酸(2∶1∶1)溶剂体系,上相为固定相,下相为移动相,流速2ml·min-1,仪器转速800r·min-1,进样量100mg,2h后分离出了16.8mg巴马亭(组分Ⅱ),并经HPLC测定,组分纯度>99.6%,并由UV、IR、MS和1H NMR确定结构。     

基于CCD图像处理方法自动定焦仪的研究

实验室测透镜焦距的传统方法是由测量人员在光具座上观测、记录、数据分析和计算结果,而用肉眼观察和判别往往容易产生差错。该文提出了一种基于CCD的数字图像处理方法自动测量透镜焦距的新设计——自动定焦仪,自动聚焦系统利用图像清晰度评价函数,由单片机控制马达转动镜头至对焦清楚的位置,实现数字化测量。     

一维有限深方势阱能量本征方程的泰勒级数解和二次近似解

一维有限深方势阱能量本征方程的求解受限于超越方程,无法严格求解.本文将奇、偶宇称情况的超越方程归结为一个方程,自洽地给出两种近似解析解：一阶泰勒级数解和二次近似解.分析二者适用范围并做误差分析,发现泰勒级数解可以很好地理解能谱随量子数n平方变化的数值解(即,所谓n平方律),但在特定参数R下失效,该参数正比于势阱宽度乘以势阱高度开方.二次近似解对所有参数R都适用,能谱在大R极限下,可退化为精确求解的无限深势阱情况.对于任意参数R,二次近似波函数的保真度始终大于99.7%.     

新型2-(2-氨基噻唑-4-基)-2-(Z)-甲氧亚胺基乙酸酯类衍生物的合成及其抑菌活性

以乙酰乙酸甲(乙)酯,醛和酰氯为主要原料,合成了8个2-(2-氨基噻唑-4-基)-2-(Z)-甲氧亚胺基乙酸酯类衍生物(其中6个未见文献报道),其结构经1H NMR,IR和MS表征.初步抑菌活性测试结果表明,在给药量为200 mg·L-1时,化合物对小麦赤霉病菌和马铃薯干腐病菌有较好的抑菌活性.     

High-efficiency DBA-BOTDA with optimized SNR by multiple bandwidths pump modulation

For Brillouin optical time-domain analysis(BOTDA) based on distributed Brillouin amplification(DBA), constant Brillouin response achieved by the exponentially variable bandwidth/intensity pump modulation suffers from the much lower pumping efficiency for long-range sensing, which counterbalances the merit of DBA. In this Letter, pump modulation by multiple constant bandwidths was proposed and demonstrated. The ～98.9 km sensing with ～5 m spatial resolution and no use of optical pulse coding(OPC) was achieved by ～8 dBm Brillouin pump, which is lower by ～9 dB in theory by comparison with exponentially increased bandwidth modulation.Compared with traditional DBA-BOTDA, signal-to-noise ratio(SNR) enhancement with 4.6 dB was obtained. The flattened standard deviation(STD) of Brillouin frequency shift(BFS)(less than ～2 MHz) along the whole fiber was demonstrated.     

数学自学学习法实施途径

数学成绩的提高不仅要依靠努力,更要掌握正确的方法．中小学生及其家长都很重视数学的？自学,但却不知道怎样自学．笔者结合数学的特征,从读书模式、读书步骤、时间的安排、自我评价等方面给出了适合中小学生自学能力培养的基本途径．     

The dynamics of a memristor-based Rulkov neuron with fractional-order difference

The exploration of the memristor model in the discrete domain is a fascinating hotspot. The electromagnetic induction on neurons has also begun to be simulated by some discrete memristors. However, most of the current investigations are based on the integer-order discrete memristor, and there are relatively few studies on the form of fractional order. In this paper, a new fractional-order discrete memristor model with prominent nonlinearity is constructed based on the Caputo fractional-order difference operator. Furthermore, the dynamical behaviors of the Rulkov neuron under electromagnetic radiation are simulated by introducing the proposed discrete memristor. The integer-order and fractional-order peculiarities of the system are analyzed through the bifurcation graph, the Lyapunov exponential spectrum, and the iterative graph. The results demonstrate that the fractional-order system has more abundant dynamics than the integer one, such as hyper-chaos, multi-stable and transient chaos. In addition, the complexity of the system in the fractional form is evaluated by the means of the spectral entropy complexity algorithm and consequences show that it is affected by the order of the fractional system. The feature of fractional difference lays the foundation for further research and application of the discrete memristor and the neuron map in the future.     

电感耦合等离子体质谱法测定醋酸阿比特龙原料药中钯的残留量北大核心CSCD

0.500 0g醋酸阿比特龙原料药样品经5.0mL硝酸和1.0mL高氯酸微波消解后,加热至近干,将消解液用水定容至25mL,采用电感耦合等离子体质谱法测定其中钯的残留量。采用带有碰撞反应池的氦调谐模式,以相对丰度较高、抗干扰更强的^(105 )Pd作为同位素,以^(115)In作为内标。钯的线性范围在80.0μg·L^(-1)以内,检出限(3.3s/k)为0.020 8μg·L^(-1)。方法用于醋酸阿比特龙原料药样品的分析,测定值的相对标准偏差(n=6)为1.2%,加标回收率为94.0%~100%。     

数学教育与人文精神

数学教育的最终目的是数学本质力量的体现和人文精神的全面提升。人文精神是以人的真、善、美为价值取向，以崇高的做人品质为核心。本文从数学教育与人文精神的相互关系入手，阐述了如何在数学教育与人文精神中相互整合，相互渗透，以及如何在数学教育中培养人文精神的基本方法和原则。     

城市政务微博竞争力差异及其影响因素的时空分析——以陕西省为例

现有政务微博的研究多关注空间尺度和横断视角,缺少时间尺度和动态视角下的研究.进行时间视角下政务微博发展和建设的探究以及影响因素的分析,可以为当前竞争力提升和舆情管理能力提高等提供理论依据和实践着力点参考.基于2015—2020年陕西政务微博城市竞争力指数数据和统计年鉴面板数据,综合运用GIS技术和SPSS软件,构建了竞争力影响因素的回归方程,实证了竞争力及其影响因素的变化趋势和演变规律.结果表明:第一,陕西各市之间政务微博竞争力差距显著,空间分布不均衡.第二,2015—2020年,陕西政务微博竞争力整体呈现上升趋势,各市之间竞争力差距逐渐缩小,区域发展的协调性不断提高.第三,人口规模是2015—2020年陕西各市政务微博竞争力的主要影响因素,经济水平、教育水平和信息化基础是重要影响因素.其中,经济水平和教育水平的影响程度不断下降,人口规模和信息化基础的影响程度呈现上升趋势.