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排序方式: 共有396条查询结果,搜索用时 31 毫秒
1.
Daniel Pa?ca 《Journal of Mathematical Analysis and Applications》2007,325(1):90-100
Some existence results are obtained for periodic solutions of nonautonomous second-order differential inclusions systems with p-Laplacian. 相似文献
2.
Mechanisms of ‘environmental decoherence’ such as surface scattering, Elliot–Yafet process and precession mechanisms, as well as their influence on the spin phase relaxation are considered and compared. It is shown that the ‘spin ballistic’ regime is possible, when the phase relaxation length for the spin part of the wave function (L(s)) is much greater than the phase relaxation length for the ‘orbital part’ (L(e)). In the presence of an additional magnetic field, the spin part of the electron's wave function (WF) acquires a phase shift due to additional spin precession about that field. If the structure length L is chosen to be L(s)>L>L(e), it is possible to ‘wash out’ the quantum interference related to the phase coherence of the ‘orbital part’ of the WF, retaining at the same time that related to the phase coherence of the spin part and, hence, to reveal corresponding conductance oscillations. 相似文献
3.
Nonlinear and chaotic oscillations of a constrained cantilevered pipe conveying fluid: A full nonlinear analysis 总被引:2,自引:0,他引:2
In this paper, the planar dynamics of a nonlinearly constrained pipe conveying fluid is examined numerically, by considering the full nonlinear equation of motions and a refined trilinear-spring model for the impact constraints—completing the circle of several studies on the subject. The effect of varying system parameters is investigated for the two-degree-of-freedom (N=2) model of the system, followed by less extensive similar investigations forN=3 and 4. Phase portraits, bifurcation diagrams, power spectra and Lyapunov exponents are presented for a selected set of system parameters, showing some rather interesting, and sometimes unexpected, results. The numerical results are compared with experimental ones obtained previously. It is found that in the parameter space that includesN, there exists a subspace wherein excellent qualitative, and reasonably good (N=2) to excellent (N=4) quantitative agreement with experiment. In the latter case, excellent agreement is not only obtained in the threshold flow velocities (u) for the key bifurcations, but the inclusion of the nonlinear terms improves agreement with experiment in terms of amplitudes of motion and by capturing features of behaviour not hitherto predicted by theory. 相似文献
4.
In the framework of path integrals we present a solution to the Schrödinger equation for a free particle confined to the half-linex > 0. A solution in question corresponds to the boundary condition (/x) (0,t)= (0,t) where is a real constant. 相似文献
5.
M. Yu. Lidak R. A. Paégle V. É. Straume D. É. Shnore Yu. P. Shvachkin 《Chemistry of Heterocyclic Compounds》1971,7(3):372-376
The synthesis of peptides which include a DL--(N1-uracilyl)--alanine (DL-willardiine) residue as an N-terminal or C-terminal group was investigated, dipeptides of DL-willardiine with glycine and L-tyrosine were obtained, and DL-willardiyl-DL-willardiine was synthesized; the latter is the simplest representative of the family of monotonic homopeptides which contain, as a repeating side substituent, a natural nucleic base capable of participation in intermolecular interactions of the complementary type.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 404–408, March, 1971. 相似文献
6.
Hexenes give large amounts of hexane and isomeric hexenes over EUROPT-1. A constant hydrocarbon coverage can be assumed in the steady-state period of the reaction; the direction of reactions of these surface species depends on the hydrogen excess and also on the structure of starting hydrocarbon.
Based on the diploma work of Mr. M. Räth and Ms. B. Brose. 相似文献
EUROPT-1 , . , . , .
Based on the diploma work of Mr. M. Räth and Ms. B. Brose. 相似文献
7.
M. K. Kilevitsa Yu. A. Maurin'sh R. A. Paégle É. É. Liepin'sh A. A. Zidermane M. Yu. Lidak 《Chemistry of Heterocyclic Compounds》1981,17(11):1120-1125
1-(5-Halo-1-uracilyl)-2, 5-di-O-acetyl--D-glucofuranurono-6,3-lactones were obtained by condensation of 2,4-bis(trimethylsilyl)-5-halouracils with 1,2,5-tri-O-acetyl--D-glucofuranurono;-6, 3-lactone. The chemical transformations of these compounds were studied. The structure of the glucuronides was proved by the IR, UV, circular dichroism, and NMR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1532–1537, November, 1981. 相似文献
8.
The novel bis(cyclohexylaminium) cyclohexylaminebis(orotate–N,O)cuprate(II) dihydrate, (C6H15N)2[Cu(C5H2N2O4)2(C6H14N)] · 2H2O, has been prepared and characterized by elemental analysis, magnetic measurements, FT-IR and UV–Vis spectroscopy, thermal analysis and X-ray diffraction. The Cu(II) complex crystallizes in the monoclinic space group P21/c. The copper atom in the five-coordinated (chaH)2[Cu(HOr–N,O)2(cha)] · 2H2O is chelated by a deprotonated pyrimidine nitrogen atom and carboxylate oxygen atom as a bis(bidentate) ligand and the cyclohexylamine ligand completes the square-pyramidal coordination. The thermal decomposition of the complex has been predicted by the help of thermal analysis (TG, DTG and DTA). 相似文献
9.
The chemical reactions and kinetics of the catalytic coupling reaction of carbon monoxide to diethyl oxalate were studied in the presence of hydrogen over a supported palladium catalyst in the gaseous phase at the typical coupling reaction conditions. The experiments were performed in a continuous flow fixed-bed reactor. The results indicated that hydrogen only reacts with ethyl nitrite to form ethanol, and kinetic studies revealed that the rate-determining step is the surface reaction of adsorbed hydrogen and the ethoxy radical (EtO-). A kinetic model is proposed and a comparison of the observed and calculated conversions showed that the rate expressions are of rather high confidence. 相似文献
10.
A solid-phase microextraction method coupled with a flame photometric detector was developed for the analysis of organophosphorus pesticides in water. Two kinds of fiber (100 mum polydimethyl siloxane (PDMS) and 85 mum polyacrylate (PA) fibers) were used and compared. Parameters that may affect the extraction, such as the duration of absorption and desorption, temperature of absorption, ionic strength, elutropic strength, and concentration of humic acid were investigated. Higher sensitivity and lower detection limits were achieved using a PA fiber than using a PDMS fiber. The detection limit is less than 0.3 mug l(-1) for most of the analytes, except for mevinphos (420 mug l(-1)). The precision is better than 9%. 相似文献