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排序方式: 共有4613条查询结果,搜索用时 234 毫秒
981.
Nerea Ruiz del Árbol Carlos Sánchez-Sánchez Gonzalo Otero-Irurueta José I. Martínez Pedro L. de Andrés Ana C. Gómez-Herrero Pablo Merino Marten Piantek David Serrate Paolo Lacovig Silvano Lizzit José Alemán Gary J. Ellis María F. López José A. Martín-Gago 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(51):23420-23427
On-surface synthesis is emerging as a highly rational bottom-up methodology for the synthesis of molecular structures that are unattainable or complex to obtain by wet chemistry. Here, oligomers of meta-polyaniline, a known ferromagnetic polymer, were synthesized from para-aminophenol building-blocks via an unexpected and highly specific on-surface formal 1,4 Michael-type addition at the meta position, driven by the reduction of the aminophenol molecule. We rationalize this dehydrogenation and coupling reaction mechanism with a combination of in situ scanning tunneling and non-contact atomic force microscopies, high-resolution synchrotron-based X-ray photoemission spectroscopy and first-principles calculations. This study demonstrates the capability of surfaces to selectively modify local molecular conditions to redirect well-established synthetic routes, such as Michael coupling, towards the rational synthesis of new covalent nanostructures. 相似文献
982.
Davide Balestri Paolo P. Mazzeo Claudia Carraro Nicola Demitri Paolo Pelagatti Alessia Bacchi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(48):17503-17511
The crystalline sponge method (CSM) is primarily used for structural determination by single‐crystal X‐ray diffraction of a single analyte encapsulated inside a porous MOF. As the host–guest systems often show severe disorder, reliable crystallographic determination is demanding; thus the dynamics of the guest entering and the formation of nanoconfined molecular aggregates has not been in the spotlight. Now, the concept is investigated of the CSM for monitoring the structural evolution of nanoconfined supramolecular aggregates of eugenol guests with displacement of DMF inside the cavities of the flexible MOF, PUM168. The interpretation of the electron density provides a series of unique detailed snapshots depicting the supramolecular guest aggregation, thus showing the tight interplay between the host flexible skeleton and the molecular guests through the DMF‐to‐eugenol exchange process. 相似文献
983.
Rosario Caltabiano Rocco De Pasquale Eliana Piombino Giorgia Campo Ferdinando Nicoletti Eugenio Cavalli Katia Mangano Paolo Fagone 《Molecules (Basel, Switzerland)》2021,26(1)
Discoid Lupus Erythematosus (DLE) is a chronic cutaneous disease of unknown etiology and of immunoinflammatory origin that is characterized by inflammatory plaques and may lead to disfiguring scarring and skin atrophy. Current treatments are limited, with a large proportion of patients either poorly or not responsive, which makes DLE an unmet medical need. Macrophage migration inhibitory factor (MIF) is the prototype of a pleiotropic family of cytokine that also includes the recently discovered homologue D-dopachrome tautomerase (DDT) or MIF2. MIF and DDT/MIF-2 exert several biological properties, primarily, but not exclusively of a proinflammatory nature. MIF and DDT have been suggested to play a key role in the pathogenesis of several autoimmune diseases, such as multiple sclerosis and type 1 diabetes, as well as in the development and progression of certain forms of cancers. In the present study, we have performed an immunohistochemistry analysis for the evaluation of MIF in DLE lesions and normal skin. We found high levels of MIF in the basal layer of the epidermis as well as in the cutaneous appendage (eccrine glands and sebocytes) of normal skin. In DLE lesions, we observed a significant negative correlation between the expression of MIF and the severity of inflammation. In addition, we performed an analysis of MIF and DDT expression levels in the skin of DLE patients in a publicly available microarray dataset. Interestingly, while these in silico data only evidenced a trend toward reduced levels of MIF, they demonstrated a significant pattern of expression and correlation of DDT with inflammatory infiltrates in DLE skins. Overall, our data support a protective role for endogenous MIF and possibly DDT in the regulation of homeostasis and inflammation in the skin and open up novel avenues for the treatment of DLE. 相似文献
984.
Andrew J. Carrod Francesco Graglia Dr. Louise Male Dr. Cécile Le Duff Peter Simpson Dr. Mohamed Elsherif Dr. Zubair Ahmed Dr. Haider Butt Guang-Xi Xu Prof. Kenneth Kam-Wing Lo Dr. Paolo Bertoncello Prof. Zoe Pikramenou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(4):e202103541
Dual detection systems are of interest for rapid, accurate data collection in sensing systems and in vitro testing. We introduce an IrIII complex with a boronic acid receptor site attached to the 2-phenylpyridine ligand as an ideal probe with photo- and electrochemical signals that is sensitive to monosaccharide binding in aqueous solution. The complex displays orange luminescence at 618 nm, which is reduced by 70 and 40 % upon binding of fructose and glucose, respectively. The electro-chemiluminescent signal of the complex also shows a direct response to monosaccharide binding. The IrIII complex shows the same response upon incorporation into hydrogel matrices as in solution, thus demonstrating the potential of its integration into a device, as a nontoxic, simple-to-use tool to observe sugar binding over physiologically relevant pH ranges and saccharide concentrations. Moreover, the complex's luminescence is responsive to monosaccharide presence in cancer cells. 相似文献
985.
Valeriia Zaremska Jiajun Tan Prof. Sierin Lim Prof. Wolfgang Knoll Prof. Paolo Pelosi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(40):8720-8724
Enzymes, receptors, and carrier proteins discriminate between enantiomers of natural and synthetic chemicals. Whereas the structural details of this phenomenon have been investigated in enzymes and receptors, much less is known for carrier proteins of hydrophobic ligands, particularly concerning the contribution of asymmetric centers in the side chains of amino acids to chirally selective binding. Working with a pig odorant-binding protein, we have found that the replacement of either one or both isoleucine residues in the binding pocket by leucines abolishes discrimination of menthol and carvone enantiomers. The results indicate that isoleucines are crucial for chiral discrimination of hydrophobic ligands, and that asymmetry in the side chain may be as important as the overall asymmetry of the protein. The results provide suggestions and guidelines for improving chiral selectivity of binding proteins and enzymes, with consequent applications in the production of enantiomerically pure drugs. 相似文献
986.
987.
Maria Giovanna Chini Daniele Urbani Paolo Dambruoso Raffaele Riccio Giuseppe Bifulco 《Magnetic resonance in chemistry : MRC》2020,58(6):566-575
We report the structural dependency of long range scalar J-coupling constant across four bonds as function of the dihedral angles Φ1 and Φ3. The calculated homonuclear coupling constants 4J(H,H), obtained at a density functional theory level, were measured between C(1)─X(2) and X(2)─C(3) bonds in three-term models, where C, N, O, and S were systematically used as the second atom of the alkyl structures ( 1 - 4 ). The 4J(H,H) calculated values, tabulated for variation of 30° for both Φ1 and Φ3, have disclosed an unexpected detectable coupling constant (4J(H,H) ≥ 1 Hz) across heteroatoms, useful to provide valuable structural information. A 2-methyl-1,3-dithiane sulfide ( 5 ) was used as a case study to prove the applicability and reliability of the calculated values to real issues. The 4J(H,H) values obtained at density functional theory for the system 4 have reproduced with good accuracy an unexpected experimental 4J(H2ax-H4ax) = 1.01 Hz of sulfide molecule ( 5 ), suggesting these calculated coupling constant values as a new powerful tool for the organic synthesis and stereochemical analysis. 相似文献
988.
Paolo Podio-Guidugli 《Annali di Matematica Pura ed Applicata》1997,172(1):103-124
An invariance argument is presented that yields the constitutive splitting of the total energy into an internal and a kinetic part, as well as a representation of the latter and the inertial forces in terms of one and the same mass tensor.Dedicated to Professor Walter Noll on the occasion of his retirement from teaching. 相似文献
989.
Paolo Secchi 《Archive for Rational Mechanics and Analysis》1996,134(2):155-197
We consider the initial-boundary-value problem for quasi-linear symmetric hyperbolic systems with characteristic boundary of constant multiplicity. We show the well-posedness in Hadamard's sense (i.e., existence, uniqueness and continuous dependence of solutions on the data) of regular solutions in suitable functions spaces which take into account the loss of regularity in the normal direction to the characteristic boundary. 相似文献
990.
The linear non-autonomous evolution equation , with the initial datum u(0) = x, in the space C([0, T], E), where E is a Banach space and {A(t)} is a family of infinitesimal generators of bounded analytic semigroups is considered; the domains D(A(t)) are supposed constant in t and possibly not dense in E. Maximal regularity of the strict and classical solutions, i.e., regularity of u′ and A(·)u(·) with values in the interpolation spaces DA(0)(θ, ∞) and DA(0)(θ) between D(A(0)) and E, is studied. A characterization of such spaces in a concrete case is also given. 相似文献