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排序方式: 共有236条查询结果,搜索用时 31 毫秒
1.
掺杂是调控金刚石性能的一种重要手段。本文采用温度梯度法,在5.6 GPa、1 312 ℃的条件下,选用Fe3P作为磷源进行磷掺杂金刚石大单晶的合成。金刚石样品的显微光学照片表明,随着Fe3P添加比例的增加,金刚石晶体的颜色逐渐变深,包裹体数量逐渐增加,晶形由板状转变为塔状直至骸晶。金刚石晶形的变化表明Fe3P的添加使生长金刚石的V形区向右偏移,这是Fe3P改变触媒特性的缘故。红外光谱分析表明,Fe3P的添加使金刚石晶体中氮含量上升,这说明磷的进入诱使氮原子更容易进入金刚石晶格中。激光拉曼光谱测试表明,随着Fe3P添加比例的增加,所合成的掺磷金刚石的拉曼峰位变化不大,其半峰全宽(FWHM)值变大,这说明磷的进入使得金刚石晶格畸变增加。XPS测试结果显示,随着Fe3P添加比例的增加,金刚石晶体中磷相对碳的原子百分含量也会增加,这意味着添加Fe3P所合成的金刚石晶体中有磷存在。 相似文献
2.
Yang Shaoming Deng Kaiqiang Shao Shan Zhang Jian Peng Jiaxi Fang Zhili Xu Wenyuan 《Journal of Solid State Electrochemistry》2022,26(3):821-830
Journal of Solid State Electrochemistry - A molecularly imprinted photoelectrochemical (PEC) cathodic sensor was developed for the detection of bovine serum albumin (BSA). The PEC sensor was... 相似文献
3.
Wenyuan Xu Yan Wang Suying Li Yongbing Cheng Zanru Guo Lin Hu Mengyin Liao Jiaxi Peng Xi Chen Shaoming Yang 《应用有机金属化学》2021,35(1)
Dimethyldichlorosilane, one of the most consumed organosilicon monomers in the industry, can be prepared in a highly efficient and environmentally friendly synthesis method of disproportionating methylchlorosilanes. However, the internal mechanism of the reaction remains unclear. In this paper, the mechanism catalyzed by AlCl3/MIL‐53(Al) and AlCl3/MIL‐53(Al)@γ‐Al2O3 catalysts was calculated at B3LYP/6‐311++G(3df, 2pd) level by using the density functional theory (DFT). The results showed that although the two catalysts had similar active structures, the catalytic effects were significantly different. The Lewis acid center on the surface of γ‐Al2O3 in the core‐shell catalyst is complementary to the classic Lewis acid AlCl3 through the spatial superposition effect, which greatly improves the Lewis acid catalytic activity of AlCl3/MIL‐53(Al)@γ‐Al2O3. 相似文献
4.
环氧乙烷亲核开环的区域选择性规则是有机化学中典型脂肪三元杂环亲核性开环的选择性规则,具有普遍性。本文以非对称环氧乙烷的亲核性开环为核心,从开环反应过渡态稳定性的角度讨论了决定环氧乙烷亲核开环区域选择性的原因。介绍了该区域选择性规则在经过三元杂环正离子中间体的非对称烯烃亲电加成反应区域选择性教学中的应用。加强学生对不同反应的机理和选择性的联系,起到教学中融会贯通的作用,可以提高教学效率和效果。 相似文献
5.
A new strategy for the C(sp2)–H imidation and 1,2-imidofluorination of vinylsulfides has been established through simple treatment with N-fluorobis(benzenesulfonyl)imide, which acts as both oxidant and nitrogen source. For alkyl and electron-rich aryl vinylsulfides, alkyl/arylthioenamines are produced in up to 92% total yields. However, for steric and electron-deficient aryl vinylsulfides, 1,2-imidofluorination products are prepared in up to 73% yields. The chemoselectivity is controlled by the steric and electronic effects of aryl substituents. Thionium ions are proposed as key intermediates in the two reactions. 相似文献
6.
The mass spectrometric behavior of seven 2a,4-disubstituted 2,2a,3,4-tetrahydro-2-phenyl-1H-azeto[2,1-d][1,5]benzothiazepin-1-ones has been studied with the aid of mass-analyzed ion kinetic energy spectrometry and accurate mass measurements under electron impact ionization. All compounds show a tendency to eliminate a phenylketene molecule, an ethyl or benzyl radical, or a phenylketene molecule plus an SH radical. The mass spectrometric behavior of the title compounds was compared to those of 2-heteroatom-substituted analogues. 相似文献
7.
Jiaxi Guo Purnatosh Saha Junfeng Liang Mrinal Saha Brian P. Grady 《Journal of Thermal Analysis and Calorimetry》2013,113(2):467-474
Silica has been non-covalently coated on multi-walled carbon nanotubes (MWCNTs) using the sol–gel chemistry, where tetraethoxy silane (TEOS) was used to form an inorganic silica layer immediately next to surface of MWCNTs and octyl triethoxy silane was coated over the TEOS. Transmission electron microscopy (TEM) measurements show that the diameter of MWCNTs increases with increasing the number of coating layer, indicating that the silica has been coated on MWCNTs. Quantitative analysis from thermogravimetric analysis (TG) also indicates that the inorganic and organic silica has been successfully coated on MWCNTs. Further, quantitative analysis found that the amount of silica measured by TG agrees well with the increase of thickness of coated MWCNTs obtained from TEM, indicating that little or no free silica exists in the system. The thermal conductivity of epoxy/MWCNTs composite was studied and the results show that the thermal conductivity of the composite is improved by coating MWCNTs in this manner and increases with increasing the number of coatings. 相似文献
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9.
1,1‐Bis(4‐alkylthiophenyl)‐1‐alkenes were conveniently and efficiently prepared from alkyl phenyl sulfides and acyl chlorides via a tandem Friedel–Crafts acylation and alkylation in the presence of anhydrous aluminum chloride. The scope, limitation, and mechanism of the tandem reaction were also discussed. 相似文献
10.