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921.
Akio Yasuhara Junko Shindo Hiroyasu Ito Tsuguo Mizoguchi Keiichiro Fuwa 《Analytica chimica acta》1985
The library search system described identifies a single component or two components in the unknown pure or mixture mass spectra by comparing them with a large data base of reference spectra. A preliminary search is based on the spectral interpretation and the main search is based on the probability of peak appearance. The performance of this system was tested on 254 pure spectra and 88 mixture spectra. The percentages of successful search by using the NIH/EPA/MSDC data base were 75% for the pure spectra, and 63% for both the first and second components in mixture spectra. The percentages of successful search improved to 94% for the first components of the mixture spectra and 77% for both first and second components of the mixture spectra, when conditions for measurement of reference spectra were the same as those for the unknown spectra. 相似文献
922.
Yamabe H Mizuno A Kusama H Iwasawa N 《Journal of the American Chemical Society》2005,127(10):3248-3249
A highly useful method for the construction of cyclopentanone derivatives fused with aromatic ring based on hydrorhodation-1,4-rhodium migration sequence is achieved. Treatment of 1-aryl-prop-2-yn-1-ols, which are easily accessible via an addition of acetylides to the corresponding aryl aldehydes, with a catalytic amount of [Rh(cod)2]2(BF4) and P(p-tolyl)3 in the presence of a base gives cyclopentanone derivatives in moderate to good yield. 相似文献
923.
Kato Y Niiyama K Jona H Okada S Akao A Hiraga S Tsuchiya Y Tomimoto K Mase T 《Chemical & pharmaceutical bulletin》2002,50(8):1066-1072
An asymmetric synthesis of a selective endothelin A receptor antagonist 1b is described. Asymmetric conjugate addition of aryllithium derived from 18 to the chiral oxazoline 17 followed by hydrolysis afforded 15 in 96% ee via purification as (S)-(-)-1-phenylethylamine salt. Pd(OAc)(2)/dppf (1,1'-bis(diphenylphosphino)ferrocene) catalyzed carbonylation followed by chemoselective addition of aryllithium derived from 23 which gave ketone 24. Diastereoselective reduction of the ketone with catecholborane followed by concomitant activation of the resulting alcohol and cyclization gave the late intermediate 26. Introduction of amino moiety on the pyridine ring by imidoyl rearrangement followed by deprotection and purification by crystallization furnished the enantiomerically pure target molecule 1b in 8% overall yield from 16. 相似文献
924.
Obata M Tanihara N Nakai M Harada M Akimoto S Yamazaki I Ichimura A Kinoshita I Mikuriya M Hoshino M Yano S 《Dalton transactions (Cambridge, England : 2003)》2004,(20):3283-3287
The novel (mu-alkoxo)bis(mu-carboxylato)diruthenium complex K[Ru(2)(dhpta)(mu-O(2)C-p-ZnTPP)(2)] 3 was prepared by simple ligand substitution reaction. Strong antiferromagnetic interaction between two Ru(III) ions of 3 was observed with a coupling constant of -425 approximately -404 cm(-1). The cyclic voltammogram of 3 can be explained in terms of superposition of those of ZnTPP-p-CO(2)H and K[Ru(2)(dhpta)(mu-O(2)CPh)(2)] 2, indicating no significant electrochemical interaction. The large conproportionation constant estimated from the reduction potentials for Ru(III)Ru(III) and Ru(II)Ru(III) indicates great stability of the mixed-valence state. The mixed-valence species [Ru(II)Ru(III)(dhpta)(mu-O(2)C-p-ZnTPP)(2)](2-) 4 was prepared by controlled potential electrolysis. The electronic absorption spectrum of 4 was quite similar to that of [Ru(II)Ru(III)(dhpta)(mu-O(2)CCH(3))(2)](2-) which is a typical Class II complex. The fluorescence from the S(2) state of the ZnTPP unit of 3 was significantly (78%) quenched. The electron transfer from the ZnTPP unit to Ru(III) ions in 3 is a plausible mechanism, even though energy transfer could not be ruled out completely. The free energy change for electron transfer, Delta G(CS), was estimated to be ca.-1.1 eV, which is similar to typical values for the reorganization energy lambda in polar solvents. Hence, the electron transfer scheme is situated almost at the top of the Marcus parabola, enabling ultrafast electron transfer. 相似文献
925.
Yoshihiro Murakami Akio KurodaKazuhiko Osoda Shintaro Nishimura 《Tetrahedron letters》2003,44(4):641-644
The present study describes a rapid synthesis method for labeled [11C]FK506 for positron emission tomography (PET). A one-pot reaction from [11C]CH3I, involving a Wittig reaction as the key carboncarbon bond formation was developed. The chemical process was accomplished using a designed, fully automated synthetic apparatus, and an injectable solution of [11C]FK506 was obtained in only 34 min from [11C]CH3I. The decay-corrected radiochemical yield based on [11C]CH3I was 11.9%, and the specific activity was 39.8 GBq/μmol. 相似文献
926.
Here, we report a highly effective and chemoselective method of preparing substituted indoles from (E)-2-nitropyrrolidinostyrenes via hydrogenation in the presence of a rhodium catalyst doped by additives such as Ni(NO3)2·6H2O, Fe(OAc)2 or Co(acac)3. These hydrogenation conditions may also be applied to other substrates. Aromatic nitro compounds and olefins can be selectively reduced in the presence of aromatic benzyl ethers, aromatic halides and aromatic aldehydes. 相似文献
927.
Shinji Azuma Kenji Hayashi Akio Kudô 《Annals of the Institute of Statistical Mathematics》1984,36(1):475-479
Summary Given two sets of sizek, {α
1...,α
k} and {β
1...,β
k} there arek! possible combinations of these two
, and suppose there is apriori given a number corresponding to the partnership (α
1,β
j}. The average of the numbers corresponding to
is a random variable, and this paper presents the first five moments of the average, and an application in the study of an
isolated human population is demonstrated. 相似文献
928.
Summary The thermodynamic interaction parameters for linear polyethylene-n-alkanes were investigated with n-C6H14, n-C7H16, n-C8H18, n-C18H38, and n-C32H66 as diluents, by determining the melting temperatures of polyethylene in its mixtures with n-alkanes. It follows that, with increasing the number of carbon atom in n-alkanes, the entropy parameter
1 increases, the enthalpy parameter
1 remains approximately equal to zero, and the free energy parameter
1 decreases and approaches to zero. The change of the interaction parameters with the number of carbon atom in n-alkanes were discussed byPrigogine's theory.
Zusammenfassung Die thermodynamischen Wechselwirkungsparameter für das System lineares PolyÄthylen/n-Alkane wurden durch die Schmelzpunktsmessungen von PolyÄthylen in den Mischungen mit n-Alkanen bestimmt. Die als Verdünnungsmittel verwandten n-Alkane waren n-C6H14, n-C7H16, n-C8H18, n-C18H38 und n-C32H66. Es wurde gefunden, da\ mit steigender Zahl der Kohlenstoffatome in den n-Alkanen der Entropieparameter 1 zunimmt, wÄhrend der Enthalpieparameter 1 annÄhernd Null bleibt. Der Parameter der freien Energie 1 nimmt ab und nÄhert sich Null. Die VerÄnderung der Wechselwirkungsparameter von der Zahl des Kohlenstoffatome in den n-Alkanen wurden nach der Prigogineschen Theorie diskutiert.相似文献
929.
The boson peak is a broad peak found in the low-frequency region of inelastic neutron and Raman scattering spectra in many glassy materials, including biopolymers below approximately 200 K. Here, we give a novel insight into the origins of the protein boson peak, which may also be valid for materials other than proteins. Molecular simulation reveals that the structured water molecules around a protein molecule increase the number of local minima in the protein energy landscape, which plays a key role in the origin of the boson peak. The peak appears when the protein dynamics are trapped within a local energy minimum at cryogenic temperatures. This trapping causes very low frequency collective motions to shift to higher frequencies. We demonstrate that the characteristic frequency of such systems shifts higher as the temperature decreases also in model one-dimensional energy surfaces with multiple minima. 相似文献
930.
Murakami R Takata Y Ohta A Takiue T Aratono M 《Journal of colloid and interface science》2004,270(2):262-269
The thermodynamic equations for examining aggregate formation in an oil phase and adsorption at the oil/water interface of a nonionic solute were derived. The total differentials of chemical potentials of species and the oil/water interfacial tension were expressed as functions of temperature, pressure, and the total concentration of solute in the oil phase after explicit consideration of aggregate formation. The partial derivatives of the chemical potentials and the interfacial tension with respect to the independent variables were found to provide the thermodynamic quantities of aggregate formation and adsorption from oil phase to the interface by introducing the concept of an ideally dilute associated solution. These equations were applied to the cyclohexane solution of oleyl alcohol/water system, and the adsorption and aggregate formation was examined. 相似文献