比塔派克斯的根尖诱导效果

目的　探讨比塔派克斯在根尖诱导术中的诱导效果 .方法　选择根尖尚未形成的年轻恒牙牙髓炎或根尖周炎共 112个患牙 (患者 97例 ) .随机分为两组 ,实验组 6 4个牙用比塔派克斯糊剂诱导根尖成形 ,对照组 4 8个牙用氢氧化钙糊剂诱导根尖成形 .结果　实验组根尖诱导效果优于对照组 ,两组间有显著性差异 (P <0 .0 5 ) .结论　比塔派克斯糊剂比氢氧化钙糊剂具有更好的根尖诱导作用     

我国海水制盐业废渣处理利用现状

介绍了盐石膏的理化性质,综述了我国海盐工业废渣盐石膏在水泥、石膏建材等建筑领域以及对盐石膏的深加工等方面的综合利用研究现状,并指出利用盐石膏制备硫酸钙晶须具有广阔的发展前景。     

应用全谱直读光谱仪测定原油中铁和钙元素的含量

提出了利用电感耦合等离子发射光谱ICP -AES法测定原油中铁、钙元素含量的方法 ,考察了雾化压力、RF功率等对被测元素分析线强度的影响 ,确定了仪器的最佳使用条件。试验表明 ,该方法简便、快速、精密度和准确度均令人满意 ,能满足实际应用的要求     

Calcium release from frog sarcoplasmic reticulum by an imidazolyl reagent

Summary Calcium is released from the isolated heavy sarcoplasmic reticulum (SR) of frog skeletal muscle upon application of 0.1–1 mM diethylpyrocarbonate (DEP, an imidazolyl reagent). The Ca-ATPase activity of SR was suppressed by 20% in the presence of 1 mM DEP. More than 1 mM of free magnesium ion or 5 M ruthenium red eliminated the effect of DEP on calcium release but not on Ca-ATPase activity. A plausible site of DEP action is on the calcium channel.     

Effect of feeding cereal-legume diets to rats on in vitro absorption of45Ca

Summary The in vitro absorption of calcium from the duodenum was significantly less in a group of rats fed on a wheat diet than in a group fed a wheat and Bengal gram (7030) diet.     

Effect of calcium ions on the secondary structures of photosystemⅡ and its relations with photoinhibition

Calcium ions play an important role in the oxygen_evolving process of photosystem Ⅱ as demonstrated in many experiments. The changes of the secondary structures of PS Ⅱ induced by the depletion of Ca 2+ were reported. The results indicated that the removal of Ca 2+ led to the transition of α helix to turns and sheet structures. While Ca 2+ was re_added to the media, only the structures changed to turns could be recovered. The protein conformational changes of PS Ⅱ during the donor side photoinhibition induced by the depletion of Ca 2+ were also studied. This showed that the protein conformational changes differed between the control and Ca 2+ _depleted samples in a short period of illumination (within 10 min). However, the changes became similar when the illumination time was increased.     

用强碱性阴离子交换树脂从碳酸盐溶液中回收铀的研究 2.U(Ⅵ)在溶液相与树脂相的化学状态

在过量碳酸盐存在的Ｕ（Ⅵ）溶液中,Ｕ（Ⅵ）的化学状态与溶液的ｐＨ值有关,当ｐＨ＞８时,Ｕ（Ⅵ）以［ＵＯ２（ＣＯ３）３］４－离子存在．吸附于树脂相的Ｕ（Ⅵ）的化学状态也与供吸附的料液的ｐＨ值有关,当ｐＨ＞９时,Ｕ（Ⅵ）才完全以［ＵＯ２（ＣＯ３）３］４－吸附于树脂相．当ｐＨ在６．５～８．０范围时,Ｕ（Ⅵ）在溶液中还可能以［ＵＯ２（ＣＯ３）２］２－或Ｈｎ［ＵＯ２（ＣＯ３）３］ｎ－４形式存在,而Ｕ（Ⅵ）以［ＵＯ２（ＣＯ３）２］２－形式吸附于树脂相的可能性很小,它主要以Ｕ２Ｏ２－７的形式吸附于树脂相．     

非晶Fe77.5Si8.5B14合金晶化动力学的非等温方法研究

利用非等温差示扫描热分析法(DSC)研究了非晶Fe77.5Si8.5B14合金的晶化动力学.不同升温速率的DSC曲线表明非晶Fe77.5Si8.5B14合金的晶化过程为两步晶化.通过对不同升温速率的DSC曲线的分析,计算了两个析晶峰的晶化表观激活能E1(388.2 kJ·mol-1)和E2(339.0 kJ·mol-1),以及两个析晶峰的Avrami指数n1(1.7)和n2(3.3).根据动力学参数分析了非晶Fe77.5Si8.5B14合金的析晶机理晶化峰1的成核类型为均匀成核,晶粒生长为扩散控制的一维生长和二维生长;晶化峰2为整体析晶,晶粒生长以界面控制的二维生长和三维生长为主.最后结合表观激活能计算了两个析晶反应的频率因子ν1(4.05×1025)和ν2(1.14×1021).     

柴达木盆地西部第三系碳酸盐岩层的古生物特征

柴达木盆地西部第三系的碳酸盐岩层中发现有藻类、介形虫、有孔虫、腹足类、多毛类等化石.除藻类外各种生物的数量都比较少.生物具有个体小,壳体构造简单,多样性低等特点.所有生物都属于广盐性生物.根据该区古生物特征分析和与其它地区的对比,认为当时该区生物生长于内陆半咸化湖至咸化湖环境,而不是海相或海陆过渡相环境.参11.     

超重力场中微细晶须碳酸钙结晶过程及产品稳定性研究

在旋转填充床转子高速旋转产生的超重力场中，以MgCl12或H3PO4为晶形控制剂合成微细晶须碳酸钙，通过反应过程中pH值的变化以及针状晶种存在与否两种情形下晶体形貌的演变对结晶过程进行了研究，同时对产品粒子的稳定性进行了初步探讨．结果表明，无晶种存在时，微细晶须碳酸钙晶形的形成需要经历不规则外形-类纺锤形-晶须状-微细晶须状4个阶段；有晶种存在时，产品粒子倾向于在其表面或周围成核，最终所有粒子短轴与长径比趋向均匀；微细晶须碳酸钙粒子在陈化及干燥情形下表现出良好的稳定性．