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991.
992.
993.
Compounds - exist only in the cyclohemiketal form both in the solid state and in solution, in contrast with earlier assumptions on their enolic structure. 相似文献
994.
Giorgio Talenti 《Annali di Matematica Pura ed Applicata》1965,67(1):365-394
Sunto Si considerano equazioni alle derivate parziali in più variabili indipendenti, lineari e non lineari, di ordine qualsiasi;
si dimostrano teoremi di esistenza e unicità per il problema di Cauchy non caratteristico. Il metodo di questo lavoro consiste
nel ricondurre il problema di Cauchy allo studio di una trasformazione in sé di uno spazio funzionale, strettamente connesso
alle classi di Gevrey.
Questo lavoro fa parte dell'attività del gruppo di ricerca n. 23 del C.N.R. 相似文献
Summary We consider linear and non linear partial differential equations of any order, in several independént variables. We prove some existence and uniqueness theorems for the non-characteristic Cauchy problem. Our method consist in the reduction of the Cauchy problem to a study of a mapping of a function space into itself; this function space is closely related to Gevrey classes.
Questo lavoro fa parte dell'attività del gruppo di ricerca n. 23 del C.N.R. 相似文献
995.
A simple pencil and paper method to calculate the forces acting on individual atoms in a molecule, due to the electrons in the different populated molecular orbitals, has been developed within the Extended Hückel formalism. The method is applied to study the torsional stability around a single bond of some simple molecules. The results show good agreement with the experimental evidence of stable conformers. 相似文献
996.
From QCA (Quantum Cellular Automata) to Organocatalytic Reactions with Stabilized Carbenium Ions 下载免费PDF全文
Andrea Gualandi Luca Mengozzi Elisabetta Manoni Pier Giorgio Cozzi 《Chemical record (New York, N.Y.)》2016,16(3):1228-1243
What do quantum cellular automata (QCA), “on water” reactions, and SN1‐type organocatalytic transformations have in common? The link between these distant arguments is the practical access to useful intermediates and key products through the use of stabilized carbenium ions. Over 10 years, starting with a carbenium ion bearing a ferrocenyl group, to the 1,3‐benzodithiolylium carbenium ion, our group has exploited the use of these intermediates in useful and practical synthetic transformations. In particular, we have applied the use of carbenium ions to stereoselective organocatalytic alkylation reactions, showing a possible solution for the “holy grail of organocatalysis”. Examples of the use of these quite stabilized intermediates are now also considered in organometallic chemistry. On the other hand, the stable carbenium ions are also applied to tailored molecules adapted to quantum cellular automata, a new possible paradigm for computation. Carbenium ions are not a problem, they can be a/the solution!
997.
Kathrin Butzbach Federico A.O. Rasse‐Suriani M. Micaela Gonzalez Franco M. Cabrerizo Bernd Epe 《Photochemistry and photobiology》2016,92(4):611-619
Photodynamic therapy (PDT) is based on the cytotoxicity of photosensitizers in the presence of light. Increased selectivity and effectivity of the treatment is expected if a specific uptake of the photosensitizers into the target cells, often tumor cells, can be achieved. An attractive transporter for that purpose is the folic acid receptor α (FRα), which is overexpressed on the surface of many tumor cells and mediates an endocytotic uptake. Here, we describe the synthesis and photobiological characterization of polar β‐carboline derivatives as photosensitizers covalently linked to folate‐tagged albumin as the carrier system. The particles were taken up by KB (human carcinoma) cells within <90 min and then co‐localized with a lysosomal marker. FRα antibodies prevented the uptake and also the corresponding conjugate without folate was not taken up. Accordingly, a folate‐albumin‐β‐carbolinium conjugate proved to be phototoxic, while the corresponding albumin–β‐carbolinium conjugates without FA were nontoxic, both with and without irradiation. An excess of free folate as competitor for the FRα‐mediated uptake completely inhibited the photocytotoxicity. Interestingly, the albumin conjugates are devoid of photodynamic activity under cell‐free conditions, as shown for DNA as a target. Thus, phototoxicity requires cellular uptake and lysosomal degradation of the conjugates. In conclusion, albumin–folate conjugates appear to be promising vehicles for a tumor cell targeted PDT. 相似文献
998.
Vanadium K‐edge XANES in vanadium‐bearing model compounds: a full multiple scattering study 下载免费PDF全文
Federico Benzi Gabriele Giuli Stefano Della Longa Eleonora Paris 《Journal of synchrotron radiation》2016,23(4):947-952
A systematic study is presented on a set of vanadium‐bearing model compounds, representative of the most common V coordination geometries and oxidation states, analysed by means of vanadium K‐edge X‐ray absorption near‐edge spectroscopy calculations in the full multiple scattering (FMS) framework. Analysis and calibration of the free parameters of the theory under the muffin‐tin approximation (muffin‐tin overlap and interstitial potential) have been carried out by fitting the experimental spectra using the MXAN program. The analysis shows a correlation of the fit parameters with the V coordination geometry and oxidation state. By making use of this correlation it is possible to approach the study of unknown V‐bearing compounds with useful preliminary information. 相似文献
999.
Tandem palladium-catalyzed cross-coupling of alkyl, alkenyl, alkynyl, aryl, and heteroaryl 2-substituted 1,1-dibromo-1-alkenes with aryl or heteroaryl boronic acids or borate esters and dehydrobromination of the intermediate coupled products afforded internal alkynes in moderate to good yields (up to 89%). The synthesis has been carried out in a one-pot process and in a two-step sequence according to the nature of the starting 1,1-dibromoalkenes. The reported protocol is compatible with the presence in the 1,1-dibromo-1-alkene molecule of additional reactive halogen–carbon bonds, thus allowing to build up more complex alkyne derivatives. 相似文献
1000.
A protocol for the synthesis of stereodefined 1-aryl(heteroaryl) substituted 1,2-bis(2-bromopyridin-3-yl)ethenes by tandem Suzuki-Miyaura cross-coupling reactions and an example of convention into 5-phenyl-1,10-phenanthroline are described. 相似文献