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排序方式: 共有2212条查询结果,搜索用时 15 毫秒
1.
Plasma Chemistry and Plasma Processing - This work reports an investigation of the discharge characteristics of atmospheric dielectric barrier discharge (DBD) plasma in terms of I-V curves and...  相似文献   
2.
The combined use of gold as transition metal catalyst and N‐heterocyclic carbene (NHC) as organic catalyst in the same solution for relay catalytic reactions was disclosed. The ynamide substrate was activated by gold catalyst to form unsaturated ketimine intermediate that subsequently reacted with the enals (via azolium enolate intermediate generated with NHC) effectively to form bicyclic lactam products with excellent diastereo‐ and enantio‐selectivities. The gold and NHC coordination and dissociation can be dynamic and tunable events, and thus allow the co‐existence of both active metal and carbene organic catalysts in appreciable concentrations, for the dual catalytic reaction to proceed.  相似文献   
3.
We report on the first examples of isolated silanol–silanolate anions, obtained by utilizing weakly coordinating phosphazenium counterions. The silanolate anions were synthesized from the recently published phosphazenium hydroxide hydrate salt with siloxanes. The silanol–silanolate anions are postulated intermediates in the hydroxide‐mediated polymerization of aryl and alkyl siloxanes. The silanolate anions are strong nucleophiles because of the weakly coordinating character of the phosphazenium cation, which is perceptible in their activity in polysiloxane depolymerization.  相似文献   
4.
Increasing the stream of recycled plastic necessitates an approach beyond the traditional recycling via melting and re‐extrusion. Various chemical recycling processes have great potential to enhance recycling rates. In this Review, a summary of the various chemical recycling routes and assessment via life‐cycle analysis is complemented by an extensive list of processes developed by companies active in chemical recycling. We show that each of the currently available processes is applicable for specific plastic waste streams. Thus, only a combination of different technologies can address the plastic waste problem. Research should focus on more realistic, more contaminated and mixed waste streams, while collection and sorting infrastructure will need to be improved, that is, by stricter regulation. This Review aims to inspire both science and innovation for the production of higher value and quality products from plastic recycling suitable for reuse or valorization to create the necessary economic and environmental push for a circular economy.  相似文献   
5.
Rotation symmetric Boolean functions are invariant under circular translation of indices. These functions have very rich cryptographic properties and have been used in different cryptosystems. Recently, Thomas Cusick proved that exponential sums of rotation symmetric Boolean functions satisfy homogeneous linear recurrences with integer coefficients. In this work, a generalization of this result is proved over any Galois field. That is, exponential sums over Galois fields of some rotation symmetric polynomials satisfy linear recurrences with integer coefficients. In the particular case of F2, an elementary method is used to obtain explicit recurrences for exponential sums of some of these functions. The concept of trapezoid Boolean function is also introduced and it is showed that the linear recurrences that exponential sums of trapezoid Boolean functions satisfy are the same as the ones satisfied by exponential sums of the corresponding rotations symmetric Boolean functions. Finally, it is proved that exponential sums of trapezoid and symmetric polynomials also satisfy linear recurrences with integer coefficients over any Galois field Fq. Moreover, the Discrete Fourier Transform matrix and some Complex Hadamard matrices appear as examples in some of our explicit formulas of these recurrences.  相似文献   
6.
In this work, tetrakis(5‐hexyn‐oxy)Fe(II) phthalocyanine was synthesised in order to perform a click reaction between the terminal alkyne groups and an azide group on a glassy carbon electrode (GCE) surface. An azide group was formed on the electrode surface following electrografting using 4‐azidobenzene diazonium tetrafluoroborate by electrochemical reduction. The Cu(I) catalyzed alkyne‐azide Huisgen cycloaddition reaction was then employed in order to react the terminal alkyne groups on the phthalocyanine with the azide groups on the GCE surface. The modified electrode was employed to catalyse the oxidation of hydrazine. The electrode showed good electrocatalytic ability towards the detection of hydrazine with a sensitivity of 15.38 µA mM?1 and a limit of detection of 1.09 µM.  相似文献   
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8.
Halogen bonding is an intermolecular interaction capable of being used to direct extended structures. Typical halogen‐bonding systems involve a noncovalent interaction between a Lewis base, such as an amine, as an acceptor and a halogen atom of a halofluorocarbon as a donor. Vapour‐phase diffusion of 1,4‐diazabicyclo[2.2.2]octane (DABCO) with 1,2‐dibromotetrafluoroethane results in crystals of the 1:1 adduct, C2Br2F4·C6H12N2, which crystallizes as an infinite one‐dimensional polymeric structure linked by intermolecular N...Br halogen bonds [2.829 (3) Å], which are 0.57 Å shorter than the sum of the van der Waals radii.  相似文献   
9.
Here we demonstrate that neat reactions of amphoteric azoles with more basic azoles give a family of finely tunable, nonstoichiometric liquids which are useful for N‐donor coordination chemistry. Reacting 4,5‐dicyanoimidazole (4,5‐DCNIm) with 1‐methylimidazole (1‐mim) gives new compounds with composition‐dependent speciation. Two crystalline compounds, a 1:1 protic salt, [H(1‐mim)][4,5‐DCNIm], and a 1:2 salt co‐crystal, [H(1‐mim)][4,5‐DCNIm]?4,5‐DCNIm, were isolated and structurally characterized, while differential scanning calorimetry revealed both suppression of crystallization and the presence of neutral and anionic species in the melt. Reactions of Cu(NO3)2?2.5 H2O, CuO, and ZnO with the neat 2:1 1‐mim/4,5‐DCNIm melt resulted in the isolation of entirely N‐donor ligated complexes of the formula M(4,5‐DCNIm)2(1‐mim)4 (M=Cu, Zn).  相似文献   
10.
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