陇西盆地段黄河发育时代问题的新认识

根据陇西盆地的两个次级盆地阶地即兰州盆地最高级黄河阶地和陇西盆地黄河一级支流大夏河最高级阶地的磁性地层学研究表明,二者的形成时代大致相同,约为１．６ＭａＢ．Ｐ．左右,也即此时黄河才开始在这两个盆地中出现．这一结果修订了黄河在陇西盆地中出现的最早时间．完整的黄河阶地系列实际上是第四纪期间青藏高原阶段性隆升的忠实记录．     

不同产地两面针根药材中微量元素的含量测定

应用电感耦合等离子体-原子发射光谱法(ICP-AES)和原子荧光光谱法(AFS)对广西12个不同产地两面针根的19种微量元素进行分析测定,该方法通过硝酸-高氯酸消解体系,有效彻底地消解样品中的有机物;而对于易挥发元素汞、硒,则通过控制样品的消解量、消解温度和消解时间,从而达到最佳的消解效果。该方法简单、高效、试剂用量少、结果准确,加标回收率为90.12%—104.14%,精密度均小于3%。结果表明,不同产地中药两面针根的微量元素含量有异,Na、Mg、K、Ca、Zn、Mn几种人体必需微量元素在不同产地两面针根的含量丰富,重金属元素Cr、As未检出,12个产地的Hg和11个产地的Pb均符合药用和出口标准,但Cd含量均超过药用和出口标准。此结果为研究两面针药材微量元素和药效相关性提供有效的数据,为两面针规范化种植基地选择及临床安全用药提供科学实验依据。     

Low–energy photodisintegration of 9Be and α+α+n→9Be +γ reactions at astrophysical conditions

A semi–microscopic model for the low–energy photodisintegration of the ⁹Be nucleus is constructed, and the experimental data are analyzed with its help. The older radioactive isotope data are supported by this analysis. The theoretical photodisintegration cross section is derived. The astrophysical rates for the reaction α+α+n→⁹Be+γ and the reverse photodisintegration of ⁹Be are calculated. The new reaction rate for α+α+n→⁹Be+γ is compared with previous estimations. Received: 19 January 1998     

The study of the cultivation of chinese hamster ovary and bowes cell lines with poly(organophosphazene) membranes

Sixteen poly(organophosphazenes) were prepared by reaction between polydichlorophosphazene (NPCl2)n and nucleophilic reagents such as phenoxides and amino compounds. Adhesive and colony formation percent were investigated using V-79 Chinese hamster cells on poly(organophosphazene) films. It was found that [NP(OC6H5)2-x(NHBu-n)x]n (x = 0.2, 1.8) gave the best percent adhesiveness. This value was similar to that of Falcon. On the other hand, [NP(OC6H5)-(NHBu-n)]n film showed best colony percent formation. This was of a higher value than that of Falcon. The [NP(OC6H5)2]n properties were poor for cultivation of useful Bowes and chinese hamster ovary cell lines in comparison with Cytodex III.     

Superoxide generator using polyaniline catalyst

A superoxide generator using a polyaniline catalyst was prepared. This apparatus was able to generate superoxide as 2.5 ppm of hydrogen peroxide concentration at an applied reduction current of −0.2 mA and at −0.25 V versus the saturated calomel electrode. Sterilizing of S. aureus and P. aeruginosa was confirmed by a cultivation test after 30 min of superoxide generation.     

学用并重,教研融合——胶体与界面化学研究生课程的改革实践

在研究生基础理论课程学习中,存在所学知识僵化,不能运用于科研实践中;与科研活动脱节,对科学研究的支持作用不明显等情况。因此,我们以胶体与界面化学课程为例,通过课堂讲授与启发式讨论的精确配合、理论知识的学与用并重、基础理论与前沿研究的良好衔接以及挖掘经典理论发展中的科研历程等措施,使学生有能力灵活运用所学理论知识解决实际科研中的问题,避免理论课程与实验室科研活动脱节,培养从实验结果中抽象模型、演绎理论、批判性解读现有结果等科研能力,启蒙其科学思维,为研究工作打下基础。     

应用化学专业新生研讨课教学实践

针对中学传统应试教育与大学创新教育的矛盾,西北农林科技大学应用化学专业开设新生研讨课,加强培养学生创新意识与创新能力以及学术探索和批判精神。教学内容包括专业介绍以及应用化学学科的9个学术领域,教学方式以小班讨论为主。本文探讨了该课程的教学模式、教学内容、考核方式以及教学效果,为相关专业开设新生研讨课提供了新思路。     

计算机实验室与应用型创新人才培养探讨

计算机实验室承担大学生在计算机上做实验的基础课、专业课、选修课和学科竞赛等各专业实验教学任务。通过对实验室在高校创新人才培养中存在问题和重要性进行分析,以计算机实验室为例研究了实验室与应用型创新人才培养之间的关系,以培养大学生计算机的综合应用能力和创新能力为目标的开放、互联、共享计算机实验室对应用性创新人才培养发挥了重要作用。     

协同创新引领下地方高校化工类专业校企合作模式构建与实践

概括了以往高校和企业合作的主要模式,分析了各模式的优势和劣势。探讨了通过校企多方深度融合,构筑协同创新中心引领下的新型校企合作模式的必要性。并以湖南理工学院化工类专业为例,介绍了我校在协同创新引领下开展校企合作的经验与效果,对今后的相关改革具有一定的借鉴意义。     

Electro-hydraulic tillage depth control system for rotary implements mounted on agricultural tractor Design and response experiments of control system

A tillage depth control system for rotary implements mounted on an agricultural tractor was designed and constructed to improve accuracy of tillage depth. The control system was composed of five main units: (1) a detecting unit to measure the tilting angle (position) of the lift arm, the pitching angle of the tractor and heights of sensors from ground surface, (2) a controlling unit, (3) a hydraulic unit to operate a three-point hitch linkage by a lift arm cylinder, (4) a three-point hitch linkage and rotary implements, and (5) a setting unit to put the reference tillage depth and a dead zone into the control circuit. The tillage depth was controlled by an on/off operation of a solenoid valve, of which time was proportional to the controlling time. Experiments to evaluate the response characteristics of the control system were conducted under various engine speeds, i.e. various flow rates of hydraulic oil, various tillage depths and some input frequencies. The results of the response experiments of the control system are discussed in this paper.