首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   15篇
  免费   0篇
  国内免费   1篇
化学   15篇
物理学   1篇
  2022年   1篇
  2013年   3篇
  2012年   1篇
  2008年   1篇
  2006年   1篇
  2005年   1篇
  2003年   3篇
  2000年   2篇
  1999年   1篇
  1997年   1篇
  1992年   1篇
排序方式: 共有16条查询结果,搜索用时 46 毫秒
1.
The dehydration and dehydroxylation of the smectites, beidellite and montmorillonite (dioctahedral) and saponite and laponite (trioctahedral), were investigated by ETA, DTA, TG and X-ray diffractions. There are differences between the behaviors of di- and trioctahedral clays which are due to the differences in the ability of the exchangeable cations to migrate into hexagonal holes of the SiO4 network and due to the fact that the dehydroxylation and recrystallization of dehydroxylated trioctahedral smectites occur simultaneously, whereas there is a temperature gap of about 300°C between the dehydroxylation and the recrystallization of dioctahedral smectites.Dedicated to Dr. Robert Mackenzie on the occasion of his 75th birthdayThe authors wish to thank Laporte Industries, Inc. UK for the laponite sample.This research was supported under Project No. C12-219, Grant No. HRN5544 G002069, U.S.-IsraelCooperative Development Research Program, Office of the Science Advisor, U.S. Agency for International Development.  相似文献   
2.
A robust synthetic method for 2-alkylamino-6-carboxy-5,7-diarylcyclopenteno[1,2-b]pyridines via acylamination at the alpha position of the functionalized pyridine system has been developed. The key step in this method was achieved by treatment of the corresponding pyridine N-oxides with 2.5 equiv of imidoyl chlorides in the presence of triethylamine, thus producing the desired 2-acylaminopyridines in good yields (74-96%).  相似文献   
3.
Emanation Thermal Analysis (ETA) was used to characterize microstructure changes of hydrous ruthenia and hydrous ruthenia-titania as precursors for preparation of RuO2 and (RuO2)0.9-(TiO2)0.l by heating in the temperature range of 20–600°C in argon. A good agreement was found between ETA, TG and DTA results, X-ray diffraction patterns and surface area measurements of intermediate products of the thermal treatment. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
4.
《Analytical letters》2012,45(5):1341-1354
Abstract

Twelve procedures of sample pretreatment for manganese determination in blood serum were tested in comparable instrumental conditions. the best results were obtained by dilution of serum with diluted nitric acid, which leads to formation of an internal matrix modifier composed of calcium and phosphoric acid. Other procedures may also give satisfactory results, but then as standards aqueous albumin solutions should be used.  相似文献   
5.
6.
7.
物理习题教学是中学物理教学的重要环节,能够帮助学生提高运用物理知识解决实际问题的能力.基于ETA物理认知模型,针对理论物理认知题型、实验物理认知到理论物理认知题型和应用物理认知题型3类题型的习题特点,总结出每类题型具体的应对策略.在习题教学过程中教师需要强化学生的物理基本知识和理论,帮助学生做好从实践到构建物理模型的过渡,引导学生做好理论与实际生活联系,为提升习题教学的有效性提供参考.  相似文献   
8.
Emanation thermal analysis (ETA) was used to characterize microstructure changes during heating of Mg–Al–CO3 layered double hydroxide (LDH) in the temperature range of 293–1473 K. It was confirmed by ETA that the formation of an intermediate phase with grafted CO32– anions in the hydroxide layers took place in the temperature range of 508–523 K and the formation of Mg–Al mixed oxide (MO) occurred in the range 623–773 K. The small peak of the emanation rate at 603 K indicated the degradation of the layered structure and the broad peak in the range of 1073–1273 K characterized the onset of the separation of the decomposition products of MO into MgO and Mg2Al4O7. The ETA results revealed that dehydration of the product with grafted CO32– anions occurred at lower temperatures than that of the initial Mg–Al–CO3 LDH.  相似文献   
9.
Extended topochemical atom (ETA) indices developed by our group have been extensively applied in our previous reports for toxicity and ecotoxicity modelling in the field of quantitative structure–activity relationships (QSARs). In the present study these indices have been further explored by defining additional novel parameters to model n-octanol–water partition coefficient (two data sets; n?=?168 and 139), water solubility (n?=?193), molar refractivity (n?=?166), and aromatic substituent constants π, MR, σ m, and σ p (n?=?99). All the models developed in the present study have undergone rigorous internal and external validation tests and the models have high statistical significance and prediction potential. In terms of Q 2 and r 2 values the models developed for the datasets of whole molecules are better than those previously reported, with topochemically arrived unique (TAU) indices on the same datasets of chemicals. An attempt has also been made to develop models using non-ETA topological and information indices. Interestingly, ETA and non-ETA models have been found to have similar predictive capacity.  相似文献   
10.
It was found by DTA and TG that [Phenyl2I][Ag(CN)2] in the solid state is chemically stable on heating in argon up to 160°C. During heating to higher temperatures it decomposes, forming volatile products such as [Phenyl]I, [Phenyl]NC and (CN)2 [1]. After heating the sample to 500°C metallic silver resulted. The volatile and intermediate solid products were analysed by IR-spectroscopy.It was found by means of DTA and ETA that an isophase reversible transition takes place when the sample is heated and cooled, not higher than 100°C. At heating higher than 100°C the sample melts (melting pointT m=135°C). The enthalpy melting was determined by means of DSC (H=–28 kJ·mol–1).By means of ETA the disorder degree of the final decomposition product was estimated. The value of the activation energy of radon diffusion in the temperature range 720°–500°C equals 32.6 kJ·mol–1.Dedicated to Prof. I. N. Bekman Moscow State University at the occasion of his 50th birthday  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号