Tube assembly built by cholesterol-based organogel

In this paper, tubular structure has been obtained by self-assembly of cholesterol derivative via sol–gel process. The tube structure and the formation mechanism have been studied and certified by scanning electron microscopy, infrared, ultraviolet-visible spectroscopy (UV–vis) and x-ray diffraction (XRD) data. It is predicated that the tube has been formed by the curl of sheet structure, and the aggregates are composed of two molecules of 1 with H aggregate in laminar structure at micro level.     

A mercury(II) ion-selective electrode based on N,N-dimethylformamide-salicylacylhydrazone as a neutral carrier.

A new PVC membrane mercury(II) ion electrode based on N,N-dimethylformamide-salicylacylhydrazone (DMFAS) as an ionophore is described, which shows excellent potentiometric response characteristics and displays a linear log[Hg(2+)] versus EMF response over a wide concentration range between 6.2 x 10(-7) and 8.0 x 10(-2) M with a Nerstian slope of 29.6 mV per decade and a detection limit of 5.0 x 10(-7) M. The response time for the electrode is less than 30 s and the electrode can be used for more than 2 months with less than a 2 mV observed divergence in a potentials. The proposed electrode exhibits very good selectivity for mercury(II) ions over many cations in a wide pH range (pH 1 - 4). The electrode was also applied to the determination of a mercury(II) ion in vegetables and in Azolla filiculoides.     

ON A MIN-MAX THEOREM

In this paper we prove a nonvariational form of a rain-max problem in [l] and give its application to a periodical problem.     

中等职业学校的物理教学方法

我国教育体制的改革,给中等职业学校的教学工作提出了新的挑战.下面就中等职业学校的物理教学方法谈几点意见: 物理教学课分为4种主要类型:实验教学,概念教学,练习教学和复习教学.1 实验教学课 物理实验是在人为控制条件下,运用仪器、设备、使物理现象反复再现,从而有目     

改性铑络合催化剂的NMR研究

合成了八种铑的络合催化剂,对它们进行了¹H及¹³C NMR测定、对谱线进行了标识,找出化学位移的一些规律性,测出了一些偶合常数,确定了它们的结构。发现一种反位效应络合产物,并非全是反位化合物而是2:1(反:顺)的位置异构体混合物。当络合配体为β双酮时,在溶液中,该配位化合物结构,特别是CH₃有一定的扭曲,CH₃在¹H及¹³C NMR中都表现出异常的行为。     

关于非线性边值问题几个存在性定理的新结果

本文运用同胚理论,研究微分方程边值问题解的存在性与唯一性,得到两个基本定理,推广了Ｂｒｏｗｎ（ｉｎＡｎｎａｌｉ．Ｍａｔ．Ｐｕｒａ．Ａｐｐｌｉ．１９７５,１０６：２０５～２１４）的结论,取消了有界性假设,并把我们的结果用于有限维的情况,考虑了非线性守恒系统在扰动情况下（Ｎｅｗｔｏｎ类运动方程）周期解的存在性与唯一性问题·把同胚用于这类问题的研究目前还是新的     

火焰原子吸收光谱法测定20型尼龙毡材料中的铁

采用空气-乙炔火焰原子吸收光谱法测定镍镉电池尼龙毡材料中的铁含量,对测定条件和干扰因素进行了综合分析。铁的浓度在0.0~5.0μg/mL内与吸光度成线性关系,相关系数为0.9998。测定尼龙毡样品铁含量的相对标准偏差不大于1.0%(n=8),标准加入回收率为97.0%~98.0%。该法适用于镍镉电池尼龙毡中铁含量的控制分析。     

N2O-C2H2火焰原子吸收光谱法测定电化学浸渍液中的钴

运用N2O-C2H2火焰原子吸收光谱法测定电化学浸渍液中的钴含量。通过试验确定了共振线、燃烧器高度、灯电流、酸性介质、火焰等实验条件。用该方法对样品中钴含量进行分析,测定结果的相对标准偏差小于1.0%(n=6),加标回收率为97.3%~98.8%。该方法适用于电化学浸渍液中钴含量的控制分析和样品系统分析。     

Effects of Light Intensity on the Growth and Lipid Accumulation of Microalga <Emphasis Type="Italic">Scenedesmus</Emphasis> sp. 11-1 Under Nitrogen Limitation

Scenedesmus spp. have been reported as potential microalgal species used for the lipid production. This study investigated the effects of light intensity (at three levels: 50, 250, and 400 μmol photons m⁻² s⁻¹) on the growth and lipid production of Scenedesmus sp. 11-1 under N-limited condition. Carotenoid to chlorophyll ratio was higher when algae 11-1 grew under 250 and 400 μmol photons m⁻² s⁻¹ than that under 50 μmol photons m⁻² s⁻¹, while protein contents was lower. Highest biomass yield (3.88 g L⁻¹), lipid content (41.1 %), and neutral lipid content (32.9 %) were achieved when algae 11-1 grew at 400 μmol photons m⁻² s⁻¹. Lipid production was slight lower at 250 μmol photons m⁻² s⁻¹ level compared to 400 μmol photons m⁻² s⁻¹. The major fatty acids in the neutral lipid of 11-1 were oleic acid (43–52 %), palmitic acid (24–27 %), and linoleic acid (7–11 %). In addition, polyunsaturated fatty acids had a positive correlation with total lipid production, and monounsaturated fatty acids had a negative one.     

双联齿轮断裂分析

机床传动系统双联直齿轮投入运行不久即发生齿面断裂事故,造成较大经济损失.传动系统所用双联齿轮未达到设计使用寿命,属于早期断裂失效.对现场收集到的断裂齿轮残块进行化学成分分析和硬度测试,对齿廓工作面及断裂形成的断口用扫描电镜进行微观观察,对齿轮残块上出现的裂纹用光学金相显微镜观察其形貌和微观特征,依据检测实验数据和结果,...