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排序方式: 共有313条查询结果,搜索用时 15 毫秒
41.
On the finitistic dimension conjecture for artinian rings 总被引:1,自引:0,他引:1
42.
Michael J. Fuller E.Bright Wilson Walther Caminati 《Journal of Molecular Spectroscopy》1982,96(1):131-145
The rotational spectra of two conformations of 3-chloro-propanol were observed for the four possible and isotopic species. For both conformations the oxygen atom is gauche with respect to the C2C3 bond and the hydroxyl hydrogen is trans with respect to the C2C1 bond. In one conformation (T) the chlorine is trans with respect to C1C2 and it is gauche in the other form (G). The ground state of the G form is about 0.7 kcal/mole more stable than that of the T form. A discussion is given about the failure to observe the H bond species. The most likely reason is the too close approach of Cl and O in this hypothetical configuration. The quadrupole coupling constants were obtained for the G form. The rotational spectra of five excited states of the T form and of one excited state of the G species were measured. Partial r0 and rs structures are given. 相似文献
43.
Using a transmission line theory, expressions for the propagation constant and characteristic impedance of a borehole antenna
are derived. Both air-filled and fluid-filled holes are considered. The required modal equation is solved by a rapidly convergent
iterative method. Some data for the input impedance and effective dipole moment for the terminated line are then provided.
It appears that the presence of conducting fluid in the hole will not seriously impair the effectiveness of the radiating
structure, but the voltage gradients in the insulation will be increased markedly. 相似文献
44.
We present a comparison of IR absorption spectra for heavy metal flouride glass processed either in a HF or H2O atmosphere. The similarities are remarkable for the 2.9-μm absorption features, which precisely coincide in peak wave length, line shape, and line width for both treatment methods. A discussion and an analysis of these findings are given. 相似文献
45.
C.R. Fuller 《Journal of sound and vibration》1984,93(3):341-351
The radiation of sound from a flanged duct system containing various hard-walled pressure sources and a finite length of non-uniformly lined duct is considered. Reflection coefficients, transmission losses and the directivity of the radiated field are evaluated. Direct comparisons between the results for the non-uniformly lined ducts, a uniformly lined duct and a hard-walled duct are made for fixed values of admittance, liner length and source distributions. Several interesting wave scattering characteristics which relate to the design of aircraft turbofan inlet liners are uncovered. 相似文献
46.
We show Regge-pole dominance in a representative heavy-ion DWBA calculation and display various pole manifestations in both calculated elastic and transfer quantities. 相似文献
47.
Pickering emulsions with controllable stability 总被引:1,自引:0,他引:1
We prepare solid-stabilized emulsions using paramagnetic particles at an oil/water interface that can undergo macroscopic phase separation upon application of an external magnetic field. A critical field strength is found for which emulsion droplets begin to translate into the continuous-phase fluid. At higher fields, the emulsions destabilize, leading to a fully phase-separated system. This effect is reversible, and long-term stability can be recovered by remixing the components with mechanical agitation. 相似文献
48.
Fuller AM Leigh DA Lusby PJ Slawin AM Walker DB 《Journal of the American Chemical Society》2005,127(36):12612-12619
We report the synthesis of a [2]catenate using a square planar palladium(II) template, together with two isomers of the interlocked structure: a single tetradentate macrocycle that adopts a "figure of eight" conformation to encapsulate the metal and a complex in which the two macrocycles of the catenane are not interlocked. The three isomers can each be selectively formed depending on how the building blocks are assembled and cyclized. Olefin metathesis of both building blocks while they are attached to the metal gives the single large macrocycle in 77% yield. Cyclizing the monodentate unit prior to attaching both ligands to the metal gives the [2]catenate in 78% yield. Preforming the tridentate macrocycle produces a complex in two atropisomeric forms-threaded and nonthreaded-in a 2:3 ratio, which do not interconvert in dichloromethane at room temperature over 7 days. RCM of the nonthreaded atropisomer affords the complex with two noninterlocked macrocyclic ligands; RCM of the threaded atropisomer generates the topologically isomeric [2]catenate. Heating the acyclic atropisomers in acetonitrile provides a mechanism for their interconversion via ligand exchange, allowing the threaded:nonthreaded ratio to be varied from 2:3 to 8:1. All three fully ring-closed complexes were characterized unambiguously by 1H NMR spectroscopy and X-ray crystallography. As far as we are aware, this is the first time such a set of three formal topological and constitutional isomers has been described. 相似文献
49.
E.L. Fuller 《Advances in colloid and interface science》1981,14(4):285-286
50.