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91.
The present paper deals with the long-time behavior of a class of nonautonomous retarded semilinear parabolic differential equations. When the time delays are small enough and the spectral gap conditions hold, the inertial manifolds of the nonautonomous retard parabolic equations are constructed by using the Lyapunov-Perron method. 相似文献
92.
1 IntroductionThispaperisdevotedtostudywhatkindofdiscreteschemesofthefollowing 2n dimen sionalHamiltoniansystemswithparameterinnormalform u=J2n H uT, H =H(u ,λ) ,(1 )whereu∈R2n,λ∈R ,H∈Ck+1(R2n×R ,R) ,k≥ 6,andJ2n =0In-In 0 ,In:unitmatrixofordernhasthepropertyofinheritinghom… 相似文献
93.
94.
当前,在医学核磁共振成象领域内,临床上广泛采用的是近似的自旋密度象、T1-和T2-加权密度象。但是,由于人体的正常组织和肿瘤之间的密度差别不大,从质子密度象很难区分人体的正常组织与肿瘤,而肿瘤与人体正常组织之间的在弛豫时间T1、T2的数值上差别较大。另外,自七十年代以来,大量关于离体(in vitro)核磁共振弛豫时间测量的文献表明,肿瘤的核磁共振弛豫时间T1,T2值具有明显的规律性,从而利用核磁共振弛豫时间成象的方法,及人体正常组织、良性及恶性肿瘤的活体(in vivo)T1,T2数值的测量,将有助于实现肿瘤识别的定量方法。 相似文献
95.
In this article, by introducing characteristic singular integral operator and associate singular integral equations (SIEs), the authors discuss the direct method of solution for a class of singular integral equations with certain analytic inputs. They obtain both the conditions of solvability and the solutions in closed form. It is noteworthy that the method is different from the classical one that is due to Lu. 相似文献
96.
Operator Matrix Forms of Positive Operators 总被引:2,自引:0,他引:2
If a 3-tuple (A:H1→H1,B:H2→H1,C:H2→H2)of operators on Hibert spaces is given,we proved that the operator ~↑A:=(↑A ↓B^*↑B ↓C) on H=H1 H2 is ≥0 is and only if A≥0,R(B)∪→R(A^1/2) and C≥B^* A^ b,where A^ is the generalized inverse of A.In general,A^ is a closed operator,but since R(B)∪→R(A^1/2,B^* A^ B is bounded yet. 相似文献
97.
Jun Xiang Ge 《International Journal of Infrared and Millimeter Waves》1994,15(10):1681-1688
In 1991, we developed a new type of quasi-optical power combiner, called a compound quasi-optical power combiner, at Ka-band. In this paper, the circuit of such a compound quasi-optical power combiner is analysed. Its equivalent circuit model is proposed. The circuit equations, the balance condition, the injection locking and the stabilized condition of the compound quasi-optical power combiner are studed by the equivalent circuit model. As an example, a compound quasi-optical power combiner which consists of two single—cavity, two—device power combiners is analysed 相似文献
98.
低功率泵浦Ti:Al2O3自锁模激光器 总被引:2,自引:0,他引:2
本文报道了低功率泵浦的Ti:Al2O3激光器实现了稳定的自锁模运转,锁模脉冲宽度为180fs。分析了激光器的结构及工作特性。 相似文献
99.
For improved mechanical and water‐swelling properties of chitosan films, a series of transparent films were prepared with dialdehyde starch as a crosslinking agent. Fourier transform infrared and X‐ray analysis results demonstrated that the formation of Schiff's base disturbed the crystallization of chitosan. The mechanical properties and water‐swelling properties of the films were significantly improved. The best values of the tensile strength and breaking elongation were 113.1 MPa and 27.0%, respectively, when the dialdehyde starch content was 5%. All the crosslinked films still retained obvious antimicrobial effects toward S. aureus and E. coli, and they showed potential for biomedical applications. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 993–997, 2003 相似文献
100.
X. Y. Yang H. C. Gao X. L. Tan H. Z. Yuan G. Z. Cheng S. Z. Mao S. Zhao L. Zhang J. Y. An J. Y. Yu Y. R. Du 《Colloid and polymer science》2004,282(3):280-286
1H chemical shift changes of sodium 4-decyl naphthalene sulfonate (SDNS) at 313 K show that its critical micellar concentration lies between 0.82 and 0.92 mmol/dm3, which is in the same range as that of the previous study at 298 K. The spin–lattice relaxation time, spin–spin relaxation time and two-dimensional nuclear Overhauser enhancement spectroscopy experiments give information about the structure of the SDNS micelle and the dynamics of the molecules in the micelle. The size of the SDNS micelle remains almost unchanged in the temperature range from 298 to 313 K as deduced by analyzing the self-diffusion coefficient. Special arrangement of the naphthyl rings of SDNS in the micelles affects the packing of these hydrophobic chains. The methylene groups of the alkyl chain nearest the naphthalene groups penetrate into the aromatic region, which results in a more tightly packed hydrophobic micellar core than that of sodium dodecyl sulfonate. 相似文献