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201.
Xiao Zhang Eric J. Watson Conor A. Dullaghan Sergiu M. Gorun Dwight A. Sweigart 《Angewandte Chemie (International ed. in English)》1999,38(15):2206-2208
Stable unsaturated heterocycles such as benzofuran are difficult to remove from petroleum by conventional catalytic hydrotreating. However, in a model system, coordination of Mn(CO)3+ to the aromatic ring of benzofuran activates the C−O bond towards insertion of [Pt(PPh3)2] [Eq. (1)]. The insertion is preceded by precoordination to the furan C=C bond; thus, the 2,3-dihydro analogue of 1 , which lacks this double bond, does not undergo insertion of the Pt moiety. 相似文献
202.
Ana Arauzo Elena Bartolom Javier Luzn Pablo J. Alonso Angelica Vlad Maria Cazacu Mirela F. Zaltariov Sergiu Shova Juan Bartolom Constantin Turta 《Molecules (Basel, Switzerland)》2021,26(18)
We present the magnetic properties of the metal-organic framework {[CoCxAPy]·2.15 H2O}n (Cx = bis(carboxypropyl)tetramethyldisiloxane; APy = 4,4′-azopyridine) (1) that builds up from the stacking of 2D coordination polymers. The 2D-coordination polymer in the bc plane is formed by the adjacent bonding of [CoCxAPy] 1D two-leg ladders with Co dimer rungs, running parallel to the c-axis. The crystal packing of 2D layers shows the presence of infinite channels running along the c crystallographic axis, which accommodate the disordered solvate molecules. The Co(II) is six-coordinated in a distorted octahedral geometry, where the equatorial plane is occupied by four carboxylate oxygen atoms. Two nitrogen atoms from APy ligands are coordinated in apical positions. The single-ion magnetic anisotropy has been determined by low temperature EPR and magnetization measurements on an isostructural compound {[Zn0.8Co0.2CxAPy]·1.5 CH3OH}n (2). The results show that the Co(II) ion has orthorhombic anisotropy with the hard-axis direction in the C2V main axis, lying the easy axis in the distorted octahedron equatorial plane, as predicted by the ab initio calculations of the g-tensor. Magnetic and heat capacity properties at very low temperatures are rationalized within a S* = 1/2 magnetic dimer model with anisotropic antiferromagnetic interaction. The magnetic dimer exhibits slow relaxation of the magnetization (SMM) below 6 K in applied field, with a τlf ≈ 2 s direct process at low frequencies, and an Orbach process at higher frequencies with U/kB = 6.7 ± 0.5 K. This compound represents a singular SMM MOF built-up of Co-dimers with an anisotropic exchange interaction. 相似文献
203.
Almost global solutions are constructed to three-dimensional, quadratically nonlinear wave equations. The proof relies on generalized energy estimates and a new decay estimate. The method applies to equations that are only classically invariant, such as the nonlinear system of hyperelasticity. © 1996 John Wiley & Sons, Inc. 相似文献
204.
Bahrin Lucian G. Clima Lilia Shova Sergiu Rosca Irina Cojocaru Corneliu Bejan Dana Sardaru Monica C. Marangoci Narcisa Lozan Vasile Rotaru Alexandru 《Research on Chemical Intermediates》2019,45(2):453-469
Research on Chemical Intermediates - Tetrazole- and nitrile-containing bimesitylene derivatives with potential use in coordination chemistry were synthesized and characterized, and their structural... 相似文献
205.
Stoian Sergiu Alexandru Gabor Augusta Raluca Albu Ana-Maria Nicolae Cristian Andi Raditoiu Valentin Panaitescu Denis Mihaela 《Journal of Thermal Analysis and Calorimetry》2019,138(4):2469-2480
Journal of Thermal Analysis and Calorimetry - Polypropylene (PP) is a versatile polymer, with a wide range of applications, from household appliances to packaging and automotive components.... 相似文献
206.
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208.
We prove that an equational class of Hilbert algebras cannot be defined by a single equation. In particular Hilbert algebras
and implication algebras are not one-based. Also, we use a seminal theorem of Alfred Tarski in equational logic to characterize
the set of cardinalities of all finite irredundant bases of the varieties of Hilbert algebras, implication algebras and commutative
BCK algebras: all these varieties can be defined by independent bases of n elements, for each n > 1.
相似文献
209.
Mihai Anastasiei Sergiu I. Vacaru 《International Journal of Theoretical Physics》2010,49(8):1788-1804
We study stationary configurations mimicking nonholonomic locally anisotropic black rings (for instance, with ellipsoidal
polarizations and/or imbedded into solitonic backgrounds) in three/six dimensional pseudo-Finsler/Riemannian spacetimes. In
the asymptotically flat limit, for holonomic configurations, a subclass of such spacetimes contains the set of five dimensional
black ring solutions with regular rotating event horizon. For corresponding parameterizations, the metrics and connections
define Finsler–Einstein geometries modeled on tangent bundles, or on nonholonomic (pseudo) Riemannian manifolds. In general,
there are vacuum nonholonomic gravitational configurations which can not be generated in the limit of zero cosmological constant. 相似文献
210.
I do not agree with the authors of papers arXiv:0806.2184 and arXiv:0901.1023v1 (published in [Zhe Chang, Xin Li, Phys. Lett. B 668 (2008) 453] and [Zhe Chang, Xin Li, Phys. Lett. B 676 (2009) 173], respectively). They consider that “In Finsler manifold, there exists a unique linear connection – the Chern connection … It is torsion freeness and metric compatibility …”. There are well-known results (for example, presented in monographs by H. Rund and R. Miron and M. Anastasiei) that in Finsler geometry there exist an infinite number of linear connections defined by the same metric structure and that the Chern and Berwald connections are not metric compatible. For instance, the Chern's one (being with zero torsion and “weak” compatibility on the base manifold of tangent bundle) is not generally compatible with the metric structure on total space. This results in a number of additional difficulties and sophistication in definition of Finsler spinors and Dirac operators and in additional problems with further generalizations for quantum gravity and noncommutative/string/brane/gauge theories. I conclude that standard physics theories can be generalized naturally by gravitational and matter field equations for the Cartan and/or any other Finsler metric compatible connections. This allows us to construct more realistic models of Finsler spacetimes, anisotropic field interactions and cosmology. 相似文献