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排序方式: 共有188条查询结果,搜索用时 156 毫秒
51.
New nanoporous film thermosets were developed from polycyanurates (PCNs) obtained by polycyclotrimerization of dicyanate ester of bisphenol E in the presence of hydrolytically labile poly(ε-caprolactone) (PCL). During the synthesis of PCL-modified PCN networks, it was established that PCL was partially incorporated into the PCN structure. Porous frameworks were then derived from such PCN/PCL-based hybrid networks by selective hydrolysis of a significant part of PCL sub-chains under mild conditions. The structure and properties of the precursory networks as investigated by FTIR, solid-state 13C NMR, DSC, TGA, and pycnometry were compared to those of the resulting porous materials. Thermogravimetric analyses showed that the porous hybrid systems were characterized by thermal and thermal oxidative stabilities higher than those of their non-hydrolyzed homologues. The porosity of the resulting hydrolyzed networks was examined by SEM and DSC-thermoporometry: pore sizes ranging from 10 to 150 nm - at most - were thus determined. 相似文献
52.
Sun XL Faucher KM Houston M Grande D Chaikof EL 《Journal of the American Chemical Society》2002,124(25):7258-7259
Biotin chain-terminated glycopolymers were generated by cyanoxyl-mediated free-radical polymerization using a biotin-derivatized arylamine initiator with high conversion (75%) and low polydispersity (1.30). Streptavidin-biotinylated glycopolymer binding was verified by SDS-PAGE gel shift assay and patterned glycocalyx-mimetic surfaces successfully fabricated. 相似文献
53.
54.
Ignacio Gonzlez M. Eugenia Muoz Antonio Santamaría J. Adolfo Pomposo Hans Grande Javier Rodríguez‐Parra 《Macromolecular rapid communications》2002,23(12):659-663
An improved method, based on mechanical stirring and a controlled solvent evaporation process, is proposed to obtain PANI(CSA)0.5/m‐cresol solutions, which lead to gels with conductivities in the range 3 to 150 S/cm, preserving the elasticity associated to the gel network. Such high conductivity values have only been found for brittle films cast from PANI solutions. According to our experimental results, there is no justification for an analogy between the elastic modulus and the conductivity of physical networks. 相似文献
55.
We consider some Nikol'skij-type inequalities, thus inequalities between different metrics of a function, for almost periodic
trigonometric polynomials. Some basic methods of probability theory are applied to prove the existence of the distribution
function for an almost periodic function in the sense of Besicovitch. Finally, the Maximal function of Hardy and Littlewood
is considered and maximal inequalities on Besicovitch spaces are proved.
Received: 23 July 1998 / Revised version: 8 March 1999 相似文献
56.
Kristian Piscicchia Johann Marton Sergio Bartalucci Massimiliano Bazzi Sergio Bertolucci Mario Bragadireanu Michael Cargnelli Alberto Clozza Raffaele Del Grande Luca De Paolis Carlo Fiorini Carlo Guaraldo Mihail Iliescu Matthias Laubenstein Marco Miliucci Edoardo Milotti Fabrizio Napolitano Andreas Pichler Alessandro Scordo Hexi Shi Diana Laura Sirghi Florin Sirghi Laura Sperandio Oton Vazquez Doce Johann Zmeskal Catalina Curceanu 《Entropy (Basel, Switzerland)》2020,22(11)
The VIP collaboration is performing high sensitivity tests of the Pauli Exclusion Principle for electrons in the extremely low cosmic background environment of the underground Gran Sasso National Laboratory INFN (Italy). In particular, the VIP-2 Open Systems experiment was conceived to put strong constraints on those Pauli Exclusion Principle violation models which respect the so-called Messiah–Greenberg superselection rule. The experimental technique consists of introducing a direct current in a copper conductor, and searching for the X-rays emission coming from a forbidden atomic transition from the L shell to the K shell of copper when the K shell is already occupied by two electrons. The analysis of the first three months of collected data (in 2018) is presented. The obtained result represents the best bound on the Pauli Exclusion Principle violation probability which fulfills the Messiah–Greenberg rule. 相似文献
57.
Alan Cesar Pilon Marcelo Del Grande Maíra R. S. Silvrio Ricardo R. Silva Lorena C. Albernaz Paulo Czar Vieira Joo Luis Callegari Lopes Laila S. Espindola Norberto Peporine Lopes 《Molecules (Basel, Switzerland)》2022,27(5)
Dengue is a neglected disease, present mainly in tropical countries, with more than 5.2 million cases reported in 2019. Vector control remains the most effective protective measure against dengue and other arboviruses. Synthetic insecticides based on organophosphates, pyrethroids, carbamates, neonicotinoids and oxadiazines are unattractive due to their high degree of toxicity to humans, animals and the environment. Conversely, natural-product-based larvicides/insecticides, such as essential oils, present high efficiency, low environmental toxicity and can be easily scaled up for industrial processes. However, essential oils are highly complex and require modern analytical and computational approaches to streamline the identification of bioactive substances. This study combined the GC-MS spectral similarity network approach with larvicidal assays as a new strategy for the discovery of potential bioactive substances in complex biological samples, enabling the systematic and simultaneous annotation of substances in 20 essential oils through LC50 larvicidal assays. This strategy allowed rapid intuitive discovery of distribution patterns between families and metabolic classes in clusters, and the prediction of larvicidal properties of acyclic monoterpene derivatives, including citral, neral, citronellal and citronellol, and their acetate forms (LC50 < 50 µg/mL). 相似文献
58.
Alexander M. Vasil'tsov Al'bina I. Mikhaleva Nadezhda V. Zorina Olga V. Petrova Konstantin B. Petrushenko Cristina Pozo-Gonzalo Hans-Jürgen Grande 《Tetrahedron》2005,61(32):7756-7762
4,4′-Bis[2-(1-vinylpyrrolyl)]diphenyloxide, 4,4′-bis(2-pyrrolyl)diphenylsulfide, 4-(2-pyrrolyl)-4′-[2-(1-vinylpyrrolyl)]diphenylsulfide and 4,4′-bis[2-(1-vinylpyrrolyl)]diphenylsulfide have been synthesized in a one-pot procedure from oximes of corresponding diacetylphenylenoxide and -sulfide through their reaction with acetylene in the MOH-DMSO systems (M=Li, K) at 80-130 °C under pressure of 10-15 atm, thus illustrating applicability and general character of the reaction of synthesis of diverse dipyrrole-phenylene assemblies and their N-vinyl derivatives. Two of the pipyrroles are promising for creating new conducting polymers with sulfur and oxygen atoms in the conjugation chain and for the study of the influence of the diphenyleneheteroatom moiety on conductivity of final polymer products. For the dipyrroles with the diphenyleneheteroatom moieties and 1,4-phenylene spacer the luminescence characteristics were determined. 相似文献
59.
Investigation of the Proton-Spin-Lattice Relaxation in the Smectic-C and Nematic Phases of Long Chain Homologues of PAA Results of comparing measurements of the temperature-, frequency and angular dependences of the spin-lattice relaxation times in the Zeeman and dipolar spin systems, T1 and T1D, for some long chain homologues of PAA are presented. In particular the temperature dependence of these time constants in the nematic phase is compared with that in the smectic-C phase. 相似文献
60.
Orientation of Nematic Phases in Magnetic Fields We discuss two methods to measure the reorientation times τ0r of the director in nematic phases of liquid crystals in an external magnetic field. Both methods give the same results; advantages and disadvantages are considered. It appears that the relation resulting from continuum theory tan Φ ∞e?t/τ0r is fulfilled (Φ twist angle). In the appendix we discuss optimum conditions for the pulse method. 相似文献