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排序方式: 共有68条查询结果,搜索用时 15 毫秒
1.
Broussy S Bernardes-Génisson V Gornitzka H Bernadou J Meunier B 《Organic & biomolecular chemistry》2005,3(4):666-669
An ortho-metallation-electrophilic substitution sequence was employed as a key step to build the 4-benzoylpyridine framework. It was found that 4-benzoylpyridine-3-carboxamide and an N-pyridyl alkylated derivative both exist in a unique cyclized hemiamidal structure, not in the usually expected keto-amide open form. These structures represent fragment models of the Isoniazid-NAD adducts involved in the mechanism of action of the antituberculous drug Isoniazid. 相似文献
2.
Vania Sordoni 《Journal d'Analyse Mathématique》2013,121(1):383-399
We study the Gevrey singularities of solutions of microhyperbolic equations using exponential weighted estimates in the phase space. In particular, we recover some known results on the propagation of Gevrey regularity in an elementary way, using microlocal exponential estimates. 相似文献
3.
Jonas Strh Laura Ruiz Arana Philipp Polzin Irma Vania Eliani Patric Lindenberg Niclas Heidenreich Csar dos Santos Cunha Sebastian Leubner Huayna Terraschke 《无机化学与普通化学杂志》2019,645(5):537-543
Despite the strong technological importance of lanthanide complexes, their formation processes are rarely investigated. This work is dedicated to determining the influence of synthesis parameters on the formation of [Ce(bipy)2(NO3)3] as well as Ce3+‐ and Tb3+‐substituted [La(bipy)2(NO3)3] (bipy = 2,2′‐bipyridine) complexes. To this end, we performed in situ luminescence measurements, synchrotron‐based X‐ray diffraction (XRD) analysis, infrared spectroscopy (IR), and measured pH value and/or ion conductivity during their synthesis process under real reaction conditions. For the [Ce(bipy)2(NO3)3] complex, the in situ luminescence measurements initially presented a broad emission band at 490 nm, assigned to the 5d→4f Ce3+ ions within the ethanolic solvation shell. Upon the addition of bipy, a red shift to 700 nm was observed. This shift was attributed to the changes in the environment of the Ce3+ ions, indicating their desolvation and incorporation into the [Ce(bipy)2(NO3)3] complex. The induction time was reduced from 8 to 3.5 min, by increasing the reactant concentration by threefold. In contrast, [La(bipy)2(NO3)3] crystallized within days instead of minutes, unless influenced by high Ce3+ and Tb3+ concentrations. Monitoring and controlling the influence of the reaction parameters on the structure of emissive complexes is important for the development of rational synthesis approaches and optimization of their structure‐related properties like luminescence. 相似文献
4.
Julio C.M. Ximenes Glauber C. Melo Vania M.M. Melo Josué Mendes Filho Antonio G. Souza Filho 《Journal of Physics and Chemistry of Solids》2012,73(2):232-236
In this paper we report the optical studies of single wall carbon nanotubes dispersed in biomaterials. We have obtained very stable suspensions of SWNTs, which allowed us to get good photoluminescence signal from the individually dispersed nanotubes. These new hybrid systems may find some applications in bionanocomposites with photoluminescence properties and in biosensors. Furthermore, the dispersion of carbon nanotubes in these biocompatible materials is important for evaluating the toxicity of either isolated or lightly bundled single wall carbon nanotubes. 相似文献
5.
This paper introduces a method for the identification of the position and the depth of a transverse crack in a rotor system, by using vibration measurements. As it is reported in literature and from field experience, a transverse crack modifies the dynamic behaviour of the rotor, generating in a horizontal axis shaft periodical vibrations with 1x, 2x and 3x rev. components. A model-based diagnostic approach and a least-squares identification method in the frequency domain are used for the crack localisation along the rotor. The crack depth is calculated by comparing the static bending moment, due to the rotor weight and to the bearing alignment conditions, to the identified 'equivalent' periodical bending moment, which simulates the crack. Finally, the validation of the proposed method is carried out statically and dynamically by means of experimental results obtained on a test-rig. 相似文献
6.
We construct a general reduction scheme for the study of the quantum propagator of molecular Schrödinger operators with smooth potentials. This reduction is made up to infinitely (resp. exponentially) small error terms with respect to the inverse square root of the mass of the nuclei, depending on the C∞ (resp. analytic) smoothness of the interactions. Then we apply this result to the case when an electronic level is isolated from the rest of the spectrum of the electronic Hamiltonian. To cite this article: A. Martinez, V. Sordoni, C. R. Acad. Sci. Paris, Ser. I 334 (2002) 185–188. 相似文献
7.
Paola D. D. S. Maia Diego dos Santos Baio Hayandra F. Nanini Victor Paulo F. da Silva Lissa Bantim Frambach Iuri Matheus Cabral Beatriz Pêgo Beatriz E. Ribeiro Mauro Srgio Gonalves Pavo Vania M. F. Paschoalin Heitor S. P. de Souza Anna Paola T. R. Pierucci 《Molecules (Basel, Switzerland)》2022,27(4)
Phenolic compounds (PCs) present in foods are associated with a decreased risk of developing inflammatory diseases. The aim of this study was to extract and characterize PCs from craft beer powder and evaluate their potential benefits in an experimental model of inflammatory bowel disease (IBD). PCs were extracted and quantified from pure beer samples. BALB/c mice received either the beer phenolic extract (BPE) or beer powder fortified with phenolic extract (BPFPE) of PCs daily for 20 days by gavage. Colon samples were collected for histopathological and immunohistochemical analyses. Dextran sodium sulfate (DSS)-induced mice lost more weight, had reduced colon length, and developed more inflammatory changes compared with DSS-induced mice treated with either BPE or BPFPE. In addition, in DSS-induced mice, the densities of CD4- and CD11b-positive cells, apoptotic rates, and activation of NF-κB and p-ERK1/2 MAPK intracellular signaling pathways were higher in those treated with BPE and BPFPE than in those not treated. Pretreatment with the phenolic extract and BPFPE remarkably attenuated DSS-induced colitis. The protective effect of PCs supports further investigation and development of therapies for human IBD. 相似文献
8.
In the present work, a method was developed and optimized aiming at the determination of anatoxin-a in environmental water samples. The method is based on the direct derivatization of the analyte by adding hexylchloroformate in the alkalinized sample (pH = 9.0). The derivatized anatoxin-a was extracted by a solid-phase microextraction (SPME) procedure, submersing a PDMS fiber in an amber vial for 20 min under magnetic stirring. GC-MS was used to identify and quantify the analyte in the SIM mode. Norcocaine was used as internal standard. The following ions were chosen for SIM analyses (quantification ions in italics): anatoxin-a: 191, 164, 293 and norcocaine: 195, 136, 168. The calibration curve showed linearity in the range of 2.5-200 ng/mL and the LOD was 2 ng/mL. This method of SPME and GC-MS analysis can be readily utilized to monitor anatoxin-a for water quality control. 相似文献
9.
Let T=α
0
I+α
1
D+⋅⋅⋅+α
n
D
n
, where D is the differentiation operator and
a0 1 0\alpha_{0}\not=0
, and let f be a square-free polynomial with large minimum root separation. We prove that the roots of Tf are close to the roots of f translated by −α
1/α
0. 相似文献