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71.
Employing hot tungsten filament to thermal dissociate molecular hydrogen,we generated gas phase atomic hydrogen under ultra-high vacuum(UHV)conditions and investigated its interaction with Pt(111) surface.Thermal desorption spectroscopy(TDS)results demonstrate that adsorption of molecular hy- drogen on Pt(111)forms surface Had species whereas adsorption of atomic hydrogen forms not only surface Had species but also bulk Had species.Bulk Had species is more thermal-unstable than surface Had species on Pt(111),suggesting that bulk Had species is more energetic.This kind of weakly- adsorbed bulk Had species might be the active hydrogen species in the Pt-catalyzed hydrogenation reactions. 相似文献
72.
Cheng-guang Bao 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1992,22(3):557-561
A model where three electrons move in the surface of a sphere is used to simulate the2 S e states of three (valuence) electron atoms with all three electrons at the same shell. A non-co-plane structure and a number of co-plane structures (triangle, straigh rod, and sharp wedge) together with associated modes of motions have been found. It is found that the symmetry has decisive effects on the structure of quantum states. Besides, in the case that the number of the spin-up electrons does not equal to that of the spin-down electrons, the up and down electrons may play different role in constituting the internal motions. 相似文献
73.
研究了非晶硅膜改性的弹性玻璃毛细管交联OV-1701中等极性固定相色谱柱。在适当温度下,采用过氧化二异丙苯(DCUP)游离基引发交联OV-1701固定液,成功地制备了交联OV-1701柱,该柱具有柱效高、惰性好、耐溶剂、抗腐蚀和耐高温等性能,是一种新型高性能的中等极性交联柱。 相似文献
74.
The mechanism of charge-induced high spin is studied in pi-conjugated molecules by means of a model-Hamiltonian approach. Intersite Coulomb interactions are taken into account in a pi-conjugated moiety, which is coupled with two localized spins through exchange interactions. We clarify spin alignment in neutral and oxidized states by exact numerical calculations including all the correlation effects. In thianthrene-based molecules, one-electron oxidation induces strong ferromagnetic correlation between the localized spins irrespective of the spin alignment in the neutral state. The localized spins are coupled to the delocalized hole spin ferromagnetically, leading to a high-spin state in the oxidized molecule. Our calculations on structural dependence and effective exchange interaction are consistent with the recent experiment of thianthrene bis(nitronyl nitroxide). By comparing the thianthrene-based molecule with the anthracene-based one, we clarify the role of superexchange interactions via the sulfur atoms. 相似文献
75.
本文提出了低温蒸干和炭化制样X-射线荧光分析甜饮料中16种微量元素的方法,试样在电热板上经低温蒸干,于马旨炉中300℃炭化30min,在液压样品成形机上压制成样片进行测定,所测元素不需用任何基体校正,由微机从校正曲线查得含量,榈分析结果与ICP-AES和AAS法相吻合。 相似文献
76.
Allylic and propargyl bromides react smoothly with diorganyl diselenides in aqueous media to give allylic and propargyl selenides in moderate to good yields. The reaction need not be carried out in inert atmosphere. The speed is quicker than the same reactions in organic media. 相似文献
77.
John A. Rogers Zhenan Bao 《Journal of polymer science. Part A, Polymer chemistry》2002,40(20):3327-3334
Plastic electronic materials and high‐resolution printing methods may be important technologies for new classes of consumer electronic devices that are lightweight, mechanically flexible and bendable, and that can cover large areas at low cost. This article summarizes some of our recent work in this area. It focuses on the materials and patterning techniques that we used to produce plastic active‐matrix backplane circuits for a type of paperlike display. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3327–3334, 2002 相似文献
78.
Qing LI Hui LI Bin SU Xiang Bao MENG Meng Shen CAI Zhong Jun LI* Department of Chemical Biology School of Pharmaceutical Sciences National Research Laboratory of Natural Biomimetic Drugs Peking University Beijing 《中国化学快报》2002,13(4):303-305
Our previous paper1,2reported the results of selective synthesis of mannose type glycosides and their dimers in our attempt to synthesize derivatives of N-acetyllacto- samine, which could have potential activity of anti-metastasis3. Further studies on the glycosylation of the accepters exploiting glycosyl nitrate instead of the acetate as donor showed interesting chemoselectivity between the two kinds of donor, namely, the glucose type and the mannose type. The reactivity difference of the t… 相似文献
79.
Carbon nanotubes used for constructing biosensor was described for the first time. Single-wall carbon nanotubes (SWNTs) functionalized with carboxylic acid groups were used to immobilize glucose oxidase forming a glucose biosensor. The biosensor response can be determined by amperometric method at a low applied potential (0.40V). 相似文献
80.
Wang M Wang BM Shi L Tu YQ Fan CA Wang SH Hu XD Zhang SY 《Chemical communications (Cambridge, England)》2005,(44):5580-5582
A quinine/Selectfluor combination inducing rearrangement reaction of allylic alcohols was discovered, which involved a moderate yield with good enantioselective construction of alpha-quaternary carbon center and beta-fluoro aldehyde under base condition. 相似文献