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排序方式: 共有216条查询结果,搜索用时 140 毫秒
21.
Najdoski Metodija Oklevski Slobodan Stojković Goran 《Russian Journal of Applied Chemistry》2015,88(11):1896-1901
Russian Journal of Applied Chemistry - This paper presents a new method for chemical development of latent fingerprints on unfired cartridge cases and some metal surfaces. It is based on chemical... 相似文献
22.
Sustainable Synthesis of Chiral Tetrahydrofurans through the Selective Dehydration of Pentoses
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Robert W. Foster Dr. Christopher J. Tame Dr. Dejan‐Krešimir Bučar Prof. Helen C. Hailes Dr. Tom D. Sheppard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(45):15947-15950
L ‐Arabinose is an abundant resource available as a waste product of the sugar beet industry. Through use of a hydrazone‐based strategy, L ‐arabinose was selectively dehydrated to form a chiral tetrahydrofuran on a multi‐gram scale without the need for protecting groups. This approach was extended to other biomass‐derived reducing sugars and the mechanism of the key cyclization investigated. This methodology was applied to the synthesis of a range of functionalized chiral tetrahydrofurans, as well as a formal synthesis of 3R‐3‐hydroxymuscarine. 相似文献
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24.
We study the convergence of the Pre?i? type k‐step iterative method for a class of operators satisfying Pre?i? type contractive conditions on the setting of partial metric spaces. Some examples are presented to illustrate our obtained results. As applications of the presented convergence theorems, we derive global attractivity results for a class of matrix difference equations. Numerical experiments are also presented to illustrate the theoretical findings. 相似文献
25.
Boris M. Mandić Dejan M. Gođevac Ljubodrag V. Vujisić Snežana S. Trifunović Vele V. Tesević Vlatka V. Vajs Slobodan M. Milosavljević 《Chemical Papers》2011,65(1):90-92
In this paper, examination of the aerial parts of seven Senecio species from Serbia and Montenegro is reported. Phytochemical investigation of Senecio erucifolius led to the isolation and characterization of semiquinol butyl 2-(1-hydroxy-4-oxocyclohexa-2,5-dienyl)acetate (I), along with methyl 2-(1-hydroxy-4-oxocyclohexa-2,5-dienyl)acetate (jacaranone, II), and methyl 2-(4-hidroxyphenyl)acetate (III). The structure of I was established based on spectroscopic studies (1H- and 13C-NMR, IR, and CI-MS). Compound II was also isolated from S. carpathicus and S. subalpinus. The presence of jacaranone in the methanol extracts of S. wagneri, S. othonnae, and S. paludosus was confirmed by LC/ESI-TOF MS. 相似文献
26.
Dejan Brkić 《Applied Mathematics Letters》2011,24(8):1379-1383
27.
We consider the aromaticity of biphenylene and structurally related linear or angular [n]phenylenes for which the direct application of the model of conjugated circuits does not offer valid expressions for resonance energy and aromaticity. We located the cause of this problem as being due to Kekulé valence structures in which neighboring benzenoid rings are connected by two CC double bonds. By restricting the selection of Kekulé valence structures to those that contribute to Clar structures of such systems, we were able to show that linear and angular [n]phenylenes have approximately similar resonance energies, with angular [n]phenylenes being slightly more stable due to second order contributions arising from disjoint conjugated circuits. Expressions for resonance energies of [n]phenylenes up to n = 8 are listed and recursion expressions for higher n values are outlined. 相似文献
28.
Jelena Rogan Dejan Poleti Ljiljana Karanovi 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(7):m230-m233
The novel title coordination polymer, {[Cu(C8H4O4)(C10H9N3)]·H2O}n, synthesized by the slow‐diffusion method, takes the form of one‐dimensional zigzag chains built up of CuII cations linked by benzene‐1,3‐dicarboxylate (ipht) anions. An exceptional characteristic of this structure is that it belongs to a small group of metal–organic polymers where ipht is coordinated as a bridging tridentate ligand with monodentate and chelate coordination of individual carboxylate groups. The CuII cation has a highly distorted square‐pyramidal geometry formed by three O atoms from two ipht anions and two N atoms from a di‐2‐pyridylamine (dipya) ligand. The zigzag chains, which run along the b axis, further construct a three‐dimensional metal–organic framework via strong face‐to‐face π–π interactions and hydrogen bonds. A solvent water molecule is linked to the different carboxylate groups via hydrogen bonds. Thermogravimetric and differential scanning calorimetric analyses confirm the strong hydrogen bonding. 相似文献
29.
Ana Amić Zoran Marković Jasmina M. Dimitrić Marković Dejan Milenković Bono Lučić 《Molecular physics》2013,111(2):207-217
ABSTRACTParticipation of guaiacyl moiety of 3,5-dihydroxy-4-methoxybenzyl alcohol (DHMBA) in inactivation of free radicals was investigated using the DFT method. The thermodynamics of triple (3H+/3e?) free radical scavenging mechanisms was investigated. The Gibbs free energies of reactions of inactivation of selected 10 free radicals indicate DHMBA as a potent scavenger. Obtained results allow us to suggest that the contribution of guaiacyl moiety to antioxidant activity of phenolic compounds should be taken into account, what has been scarcely considered until now. 相似文献
30.
Common fixed points for maps on cone metric space 总被引:1,自引:0,他引:1
Dejan Ili? 《Journal of Mathematical Analysis and Applications》2008,341(2):876-882
The purpose of this paper is to generalize and to unify fixed point theorems of Das and Naik, ?iri?, Jungck, Huang and Zhang on complete cone metric space. 相似文献