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991.
以十二烷基苯磺酸钠(SDBS)为模板, 采用低温固相反应法合成了硫掺杂二氧化锡(S-SnO2)纳米粉体材料, 并用XRD、XPS、SEM、UV-Vis、FTIR及HR-TEM等技术对材料进行了表征, 探讨了S掺杂SnO2纳米材料对百草枯的可见光降解性能, 分析了S掺杂效应的作用机理。结果表明, 采用固相反应法所得SnO2及S-SnO2纳米材料的禁带宽度变窄, SDBS对材料的表面结构具有一定的调控作用。S是以S(Ⅳ)和S(Ⅵ)的形式进入SnO2晶格形成Sn1-xSxO2晶体结构而不是进入SnO2晶格间隙, Sn-O-S键的弯曲振动峰介于930~980 cm-1之间。S的掺杂使SnO2纳米材料表面活性增强, 光催化降解百草枯的活性依次为SnO2 2(SDBS) 2 2(SDBS), 2 h内, S-SnO2(SDBS)样品对除草剂百草枯的光催化活性达95.2%, 其主要原因是S-SnO2(SDBS)材料表面有更多的羟基和进入SnO2晶格的S, 有利光生电荷的有效分离。 相似文献
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In this paper, we derive the asymptotic expansions of the moments of normalized partial maxima for general error distribution. A byproduct is to deduce the convergence rates of the moments of normalized maxima to the moments of the corresponding extreme value distribution. 相似文献
996.
In this paper, we study gradient solitons to the Ricci flow coupled with harmonic map heat flow. We derive new identities on solitons similar to those on gradient solitons of the Ricci flow. When the soliton is compact, we get a classification result. We also discuss the relation with quasi-Einstein manifolds. 相似文献
997.
Analysis of an aggregation‐based algebraic two‐grid method for a rotated anisotropic diffusion problem 下载免费PDF全文
A two‐grid convergence analysis based on the paper [Algebraic analysis of aggregation‐based multigrid, by A. Napov and Y. Notay, Numer. Lin. Alg. Appl. 18 (2011), pp. 539–564] is derived for various aggregation schemes applied to a finite element discretization of a rotated anisotropic diffusion equation. As expected, it is shown that the best aggregation scheme is one in which aggregates are aligned with the anisotropy. In practice, however, this is not what automatic aggregation procedures do. We suggest approaches for determining appropriate aggregates based on eigenvectors associated with small eigenvalues of a block splitting matrix or based on minimizing a quantity related to the spectral radius of the iteration matrix. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
998.
Wei Wang Xue-Mei ZhaoJing-Li Wang Xin GengJun-Fang Gong Xin-Qi Hao Mao-Ping Song 《Tetrahedron letters》2014
Primary aromatic amides can be synthesized from aldehydes and hydroxylamine hydrochloride in the presence of Cs2CO3. Various aromatic aldehydes (include some heteroaromatic aldehydes) are able to generate the corresponding aromatic amides in moderate to excellent yields. 相似文献
999.
Sheng‐Run Zheng Xi‐Ling Wen Zi‐Meng Liu Tao Xie Jing‐Bo Tan Jun Fan Shuang‐Shuang Hou Wei‐Guang Zhang 《无机化学与普通化学杂志》2014,640(10):2057-2061
Two coordination polymers (CPs), namely, [Cu(Hptz)2(Hhba)2]n ( 1 ) [Hptz = 5‐(4‐pyridyl)‐1H‐tetrazole, H2hba = 2‐hydroxybenzoic acid] and [Zn3(ptz)2(hpa)2]n ( 2 ) (H2hpa = 2‐hydroxy‐2‐phenylacetic acid), were synthesized by solvothermal reactions. Both complexes were characterized by elemental analysis, infrared spectroscopy, powder X‐ray diffraction, thermogravimetric analysis, and single‐crystal X‐ray diffraction analysis. Compound 1 exhibits a 2D (4,4) network, where each layer connects to four adjacent layers to construct a 3D supramolecular framework. Compound 2 has a 3D framework structure composed of 1D SUBs, which are formed by both carboxyl and tetrazole groups. The complexes represent two rare examples of CPs constructed from Hptz and organic carboxyl acid ligands. Complex 2 exhibits intense, red‐shifted emissions in the visible region at room temperature. 相似文献
1000.
Xin Ma Lien B. Lai Stella M. Lai Akiko Tanimoto Mark P. Foster Vicki H. Wysocki Venkat Gopalan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(43):11667-11671
We demonstrate that surface‐induced dissociation (SID) coupled with ion mobility mass spectrometry (IM‐MS) is a powerful tool for determining the stoichiometry of a multi‐subunit ribonucleoprotein (RNP) complex assembled in a solution containing Mg2+. We investigated Pyrococcus furiosus (Pfu) RNase P, an archaeal RNP that catalyzes tRNA 5′ maturation. Previous step‐wise, Mg2+‐dependent reconstitutions of Pfu RNase P with its catalytic RNA subunit and two interacting protein cofactor pairs (RPP21⋅RPP29 and POP5⋅RPP30) revealed functional RNP intermediates en route to the RNase P enzyme, but provided no information on subunit stoichiometry. Our native MS studies with the proteins showed RPP21⋅RPP29 and (POP5⋅RPP30)2 complexes, but indicated a 1:1 composition for all subunits when either one or both protein complexes bind the cognate RNA. These results highlight the utility of SID and IM‐MS in resolving conformational heterogeneity and yielding insights on RNP assembly. 相似文献