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1.
We have examined routes for the preparation of 2-pyrrolidinone-5S-carboxaldehyde which include oxidation of 5-hydroxymethyl-2-pyrrolidinone and reduction of 5-oxoproline ethyl ester. Only the oxidation route proved satisfactory. Moffatt oxidation was most efficient but PCC oxidation gave modest yields of the desired aldehyde. 相似文献
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Despite several reported procedures for coupling alkyl halides and 5-oxoproline esters (pyroglutamate derivatives), no general method has been described. The reaction of pyroglutamate with sodium hydride, in anhydrous THF in the presence of the halide, provides this general and practical alkylation method. Alkylation under phase transfer conditions is a useful, but less general, alternative. 相似文献
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Wolfgang W. Breckner Tiberiu Trif Csaba Varga Воляфганг В. Брекнер Тибериу Триф Чаба Варга 《Analysis Mathematica》1999,25(1):15-32
RecentlyPrus-Wi?niowski [14] has proved that the continuous functions of Λ-bounded variation on [0, 1] form a set of the first category in the Banach space C[0, 1] and also in each Banach space CΓBV[0, 1] of continuous functions of Γ-bounded variation on [0, 1] provided that the sequence Γ is adequate. In the present paper these results are extended and completed by using a principle of the condensation of the singularities of a family of nonnegative functions that follows from the theorems given byBreckner [3]. It is shown that Baire category properties similar to those stated in [14] are valid for two very large classes of real-valued functions called functions of bounded λ-variation of orderp and functions of boundedmth variation of orderp, respectively. The benefit of considering these classes is that they comprise several classes of functions of bounded variation type which have occurred so far in Fourier analysis or real analysis; in particular, the functions investigated in [14]. Thus, by specializing the results derived in the present paper, they give at once Baire category information concerning a number of well-known sets of real-valued functions. 相似文献
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We report simulations concerning optical amplification in Er:Ti:LiNbO3 curved waveguides. The derivation and the evaluation of the spectral optical gain, the spectral noise figure, the amplified spontaneous emission photon number, and the signal to noise ratio are performed under the small gain approximation. The simulations show the evolution of these parameters under various pump regimes, Er concentration profiles and waveguide lengths. The results obtained are of significant interest for the design of complex, rare earth-doped integrated optics structures involving bent waveguides. 相似文献
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Electron-electron coincidence spectra of Ar-Kr clusters after photoionization have been measured. An electron with the kinetic energy range from 0 to approximately 1 eV is found in coincidence with the Ar 3s cluster photoelectron. The low kinetic energy electron can be attributed to an Ar + Kr+ + Kr+ final state which forms after electron transfer mediated decay. This autoionization mechanism results from a concerted transition involving three different atoms in a van der Waals cluster; it was predicted theoretically, but hitherto not observed. 相似文献
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Arion T Mucke M Förstel M Bradshaw AM Hergenhahn U 《The Journal of chemical physics》2011,134(7):074306
We report the occurrence of interatomic Coulombic decay (ICD) in mixed NeKr clusters. A well-defined feature ranging from 9 to 12 eV in kinetic energy is observed in coincidence with the Ne 2s photoelectrons. It derives from an ICD process, in which an initial Ne 2s vacancy is filled by a Ne 2p electron and an electron is emitted from a 4p level on a neighboring Kr atom. We have studied the dependence of the effect on photon energy, cluster composition, and cluster size. Interestingly, the ICD electron energy increases slightly and grows a shoulder on going from 2% to 5% Kr in the coexpansion process, which we interpret in terms of surface versus bulk effects. 相似文献
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Acta Mathematicae Applicatae Sinica, English Series - We present some exact integrability cases of the extended Liénard equation y″ + f(y)(y′)n + k(y)(y′)m + g(y)y′ +... 相似文献
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