共查询到20条相似文献,搜索用时 62 毫秒
1.
2.
焦建华 《太原师范学院学报(自然科学版)》2004,3(2):77-78
强碱弱酸盐水溶液显碱性,强酸弱碱盐水溶液显酸性.按照常规,只有这两种类型的盐溶液之间才能相互促进水解,发生较为完全的反应.文章通过一个实验的设计及实施,直观验证了某些强碱弱酸盐溶液之间也可发生反应,为研究物质间发生化学反应提供了新思路。 相似文献
3.
研究了以固态高锰酸钾、固态强碱性阴离子交换树脂(Cl型)和液态溶剂(甲苯或苯)为体系的三相氧化体系.实验结果表明强碱性阴离子交换树脂具备三相体系的催化剂作用,能使醇顺利地转化为相应的羰基化合物,并获得了最佳反应条件. 相似文献
4.
《九年义务教育三年制初级中学化学教师教学用书》中提出的制取甲烷的方法操作麻烦,成功率低,况且“本实验由于熔融强碱对玻璃的侵蚀以及反应混合物在冷却后结块,经常导致试管炸裂.”我们又实验了改进的方法,产气效果虽好,但由于强碱的侵蚀,试管仍然炸裂.为此,我们不用氢氧化钠,直接用醋酸钠在催化剂的作用下加热分解制甲烷,克服了上述诸多弊端.现总结于下,请同仁赐教.1实验过程取无水醋酸钠4g,氧化铁2g,均匀混合,装人中号试管中,墩实,试管口稍微向下倾斜,固定在铁架台上加热.加热部位由试管底部往前移,防止药品熔化… 相似文献
5.
以天然樟脑为手性源,在强碱作用下与甲基硒溴顺利反应得到exo型为主的硒醚产物,再经还原及与不饱和的烯丙基溴反应合成了新型结构的手性硒盐,该手性硒盐在强碱作用下能够形成硒叶立德,将其应用于手性环丙的不对称合成研究,实验结果表明具有很好的非对映选择性和对映选择性. 相似文献
6.
7.
以氟化钾浸渍的氧化铝为固体强碱,在相转移催化条件下由乙酰丙酮和1,2二溴乙烷通过烷基化反应合成了1,1二乙酰基环丙烷.实验表明使用相转移催化剂可以提高产率.本文中,笔者探讨了该反应的机理. 相似文献
8.
以大孔强碱树脂为母体树脂,用硫酸进行磺化反应,合成两性树脂.考察了硫酸浓度,反应时间,反应温度对树脂吸附量的影响,找出了较好的合成条件,在此条件下合成的两性树脂显示了较好的硬水软化能力和热水再生性能. 相似文献
9.
蔡邦宏 《佛山科学技术学院学报(自然科学版)》1999,(1)
从水的离子积和粘度的文献数据出发,得到不同温度下水的极限摩尔电导、电导率及无限稀强酸强碱的中和焓。结果表明:温度从0℃升高到100℃,无限稀强酸强碱的中和焓将从-61.0kJmol-1变化到-42.0kJmol-1。 相似文献
10.
11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness. 相似文献
12.
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly. 相似文献
13.
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well. 相似文献
14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation. 相似文献
15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。 相似文献
16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death. 相似文献
17.
Miao Maosheng 《华南师范大学学报(自然科学版)》2014,(6)
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula- 相似文献
18.
Yang Weitao 《华南师范大学学报(自然科学版)》2014,46(6):137-138
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re- 相似文献
19.
Bernard Kirtman 《华南师范大学学报(自然科学版)》2014,(6)
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that 相似文献
20.
《上海师范大学学报(自然科学版)》2014,(5):550
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with 相似文献