新型双磨盘式磨粉机系统的研发

把剪切式粉碎原理应用到磨粉机系统中,并配备了相应的磨粉工艺系统,使DG系列双磨盘式磨粉机具有独特的两组动、静盘式机构及间隙调整机构.结构设计紧凑,生产效率高,维护保养简单.在热敏性粉体加工、非铁(污染)材料粉体和粘性物体磨粉等行业应用广泛.     

山东省乡村旅游动能系统测度与地域类型研究

乡村旅游作为多产融合的绿色产业,在推进新旧动能转换重大工程建设中发挥着重要作用。以2018年山东省17地市为研究对象,从需求侧、供给侧和结构转换3个维度构建乡村旅游动能系统指标体系,采用因子分析法对山东省乡村动能系统进行测度,并借助聚类分析方法将乡村旅游动能系统划分为三种地域类型,在此基础上针对不同的地域类型提出相应的动能系统提升策略。     

金属光电效应逸出功简要分析

大学物理教材中对光电效应下的定义不准确,对光电子是否有最大初动能存在两派观点,通过对金属逸出功的分析,表明光电子存在最大初动能。     

Kinematic analysis of the drag flick in field hockey

Attaining high speed of the stick head and consequently of the ball is essential for successful performance of the drag flick in field hockey, but the coordination pattern used to maximise stick head speed is unknown. The kinematics of the drag flick was studied in ten elite hockey players who performed twenty shots each towards a target located 1.5 m high. A 150 Hz active marker motion analysis system was used, alongside two force plates to detect foot touchdown. Angular velocity and contribution to stick endpoint speed of upper body joints were analysed. Repeated measures ANOVA was used to compare timing of onset and peak angular velocities between joints. Participants used a kinematic pattern that was close to a proximal-to-distal sequence. Trunk axial rotation and lateral rotation towards the target, right wrist flexion and left wrist extension were the main contributors to stick endpoint speed. Coaches should emphasise trunk rotations and wrist flexion and extension movements for maximising stick head speed. Given the high level of the participants in this study, the coordination of joints motions, as reported here, can serve as a guideline for drag flick training.     

一类质点组动能定理的推导方法

给出了质点组动能定理，不同于一般教材的一种推导方法，并对两种方法进行了比较。     

稀土复合固体超强酸SO_4~(2-)/TiO_2/Ce~(4+)催化合成乙酸环己酯及动力学研究

研究了以稀土复合固体超强酸SO42-/TiO2/Ce4+为催化剂合成乙酸环己酯的反应,在反应温度分别为100℃、110℃、120℃下,测出酯化反应的动力学参数,建立了动力学方程,并与无催化剂作用下合成乙酸环己酯反应的活化能及动力学方程进行了比较.实验结果表明,该催化酯化反应的优化合成条件是:乙酸用量为0.262 1mol时,醇酸摩尔比为1.5:1,催化剂用量为1.0g,带水剂环己烷的加入量为12mL.稀土复合固体超强酸SO42-/TiO2/Ce4+可使反应的活化能明显降低,是合成乙酸环己酯的有效催化剂.     

Production of a monoclonal antibody against oxytetracycline and its application for oxytetracycline residue detection in shrimp简

A novel monoclonal antibody (MAb) against oxytetracycline (OTC) was generated and characterized. The MAb was used in the development of an enzyme-linked immunosorbant assay (ELISA)-based detection system. An OTC-bovine serum albumin (BSA) conjugate was prepared and used in the immunization of mice. A conventional somatic cell fusion technique was used to generate MAb-secreting hybridomas denoted 2–4F, 7–3G, and 11–11A. An indirect competitive ELISA (icELISA) was applied to measure the sensitivity and specificity of each MAb in terms of its 50% inhibitory concentration (IC50) and percentage of cross-reactivity, respectively. MAb 2–4F exhibited the highest sensitivity, with an IC₅₀ of 7.01 ng/ml. This MAb showed strong cross-reactivity to rolitetracycline, but no cross-reactivity to other unrelated antibiotics. When MAb 2–4F was used to detect OTC from shrimp samples, the recoveries were in the range of 82%–118% for an intra-assay and 96%–113% for an inter-assay. The coefficients of variation of the assays were 3.9%–13.9% and 5.5%–14.9%, respectively.     

阻抑甲基橙褪色催化动力学光度法测定痕量钴(Ⅱ)

在稀HNO4介质中,Co(Ⅱ)对高碘酸钾氧化甲基橙褪色反应具有阻抑作用,且阻抑反应的强弱与加入Co(Ⅱ)离子浓度成正比,由此建立了阻抑甲基橙褪色催化动力学光度法测定痕量Co(Ⅱ)的新光度分析方法。研究了最佳实验条件,吸光度为502nm处,阻抑反应吸光度(A)与非阻抑反应吸光度(A0)的差值△A与钴(Ⅱ)质量浓度在0.003-1.0μg/25 mL范围内有良好的线性关系,检出限为1.0981×10-10g/mL。测定了动力学参数,反应为准一级反应,表观活化能为63.24 kJ/mol,在80℃下反应的表观速率常数为6.70×10-4/s。该方法可用于药用VB12针剂中痕量Co(Ⅱ)测定,回收率在97~102%之间,符合痕量分析要求。     

钙镁离子对胶原自组装的影响

采用紫外光度法和扫描电镜研究了钙、镁离子对胶原自组装的影响.胶原自组装的动力学曲线呈阶梯形变化的规律,钙离子延缓胶原自组装的时间,自组装时间随胶原浓度、钙离子浓度的增大而延长,低浓度镁离子可遏制胶原-磷酸钙的生物矿化动力学曲线上的负峰.分析了自组装过程中钙镁离子与胶原的作用机制.     

Hip and upper extremity kinematics in youth baseball pitchers

The purpose of this study was to examine the relationship between dynamic hip rotational range of motion and upper extremity kinematics during baseball pitching. Thirty-one youth baseball pitchers (10.87 ± 0.92 years; 150.03 ± 5.48 cm; 44.83 ± 8.04 kg) participated. A strong correlation was found between stance hip rotation and scapular upward rotation at maximum shoulder external rotation (r = 0.531, P = 0.002) and at ball release (r = 0.536, P = 0.002). No statistically significant correlations were found between dynamic hip rotational range of motion and passive hip range of motion. Hip range of motion deficits can constrain pelvis rotation and limit energy generation in the lower extremities. Shoulder pathomechanics can then develop as greater responsibility is placed on the shoulder to generate the energy lost from the proximal segments, increasing risk of upper extremity injury. Additionally, it appears that passive seated measurements of hip range of motion may not accurately reflect the dynamic range of motion of the hips through the progression of the pitch cycle.