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Haddock R. John 《Applicable analysis》2013,92(4):321-330
In this paper the properties of a Liapunov function and its derivatives are combined in obtaining sufficient conditions for the boundedness and global existence of solutions of the system of differential equations x=f(t,x) (1) where f: [0,∞)XRn→ Rn is continuous. The following terms are introduced: (i) a scalar function which is mildly unbounded relative to a subset of Rn,(ii) a scalar function which is radially unbounded relative to a set, (iii) a Liapunov function with mildly negative definite derivative in a set, (iv) a Liapunov function with strongly negative definite derivative in a set, and (v) a set which is unbounded-departing with respect to system (1). As a special case the autonomous system of differential equations which corresponds to (1) is considered and the semi-invariance property of the positive limiting set of a solution is used in the results 相似文献
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Will E. Lynch Clifford W. Padgett Brandon Quillian John Haddock 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(4):298-300
The cationic pseudo‐square‐planar complex tetrakis(1‐methyl‐2,3‐dihydro‐1H‐imidazole‐2‐thione‐κS)gold(III) trichloride sesquihydrate, [Au(C4H6N2S)4]Cl3·1.5H2O, was isolated as dark‐red crystals from the reaction of chloroauric acid trihydrate (HAuCl4·3H2O) with four equivalents of methimazole in methanol. The AuIII atoms reside at the corners of the unit cell on an inversion center and are bound by the S atoms of four methimazole ligands in a planar arrangement, with S—Au—S bond angles of approximately 90°. 相似文献
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Stephen J. Krause Tim Haddock Gary E. Price P. Galen Lenhert Joseph F. O'brien Thaddeus E. Helminiak W. Wade Adams 《Journal of Polymer Science.Polymer Physics》1986,24(9):1991-2016
The structure and morphology of homopolymers and blends of rigid-rod poly(p-phenylene benzobisthiazole) (PBT) and semiflexible coil poly[2,5(6)benzimidazole] (ABPBI) were examined by wide-angle x-ray diffraction and scanning and transmission electron microscopy. When samples were processed from a solution where the total polymer concentration of 30% PBT/70% ABPBI blend was greater than a critical concentration, large-scale phase separation occurred and 0.1–4 μm ellipsoidal particles were present in a ductile matrix. The ellipsoids were chiefly composed of aggregates of well-oriented 10-nm PBT crystallites, while the matrix material was chiefly ABPBI. When the concentration was less than a critical concentration, the solution was optically homogeneous. In processing of fiber and film samples from the homogeneous solution, large-scale phase separation was inhibited by rapid coagulation in a water bath. After heat treatment, these samples were found to contain crystallites of both PBT and ABPBI with lateral dimensions of ordered regions no larger than 3 nm. The PBT homopolymer was dispersed in the matrix at the molecular level in ordered regions at a scale no larger than 3 nm, resulting in a rigid-rod molecular composite. In the rigid-rod molecular composite fiber both the molecular-level dispersion and high orientation contributed to higher values of strength and modulus compared to the properties of a phase-separated fiber. The strength and modulus of highly oriented fiber were only 25% higher than those of planar isotropically oriented film, suggesting that the level of dispersion of rod molecules is more important than orientation of the reinforcing phase in rigid-rod molecular composites. 相似文献