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61.
Stefanic P Simoncic Z Breznik M Plavec J Anderluh M Addicks E Giannis A Kikelj D 《Organic & biomolecular chemistry》2004,2(10):1511-1517
The proline peptide bond was shown by 2D proton NMR studies to exist exclusively in the trans conformation in benzyl (2S)-1-[[(2S)-2-methyl-6-nitro-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl]carbonyl]-2-pyrrolidinecarboxylate [(S,S)-11], benzyl (2S)-1-[[(2S)-2-methyl-7-nitro-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl]carbonyl]-2-pyrrolidinecarboxylate [(S,S)-9], and in the corresponding 6-amino and 7-amino carboxylic acids (S,S)-3 and (S,S)-4. On the other hand, the diastereomers (R,S)-11 and (R,S)-9 containing an (R)[2-methyl-6/7-nitro-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl]carbonyl moiety, and the diastereoisomers (R,S)-3 and (R,S)-4 incorporating an (R)[6/7-amino-2-methyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl]carbonyl moiety were found to exist as equilibria of trans(63-83%) and cis(17-37%) isomers. These conformationally defined templates were applied in the construction of RGD mimetics possessing antagonistic activity at the platelet fibrinogen receptor. 相似文献
62.
On some additive mappings in rings with involution 总被引:1,自引:0,他引:1
Summary LetR be a *-ring. We study an additive mappingD: R R satisfyingD(x
2) =D(x)x
* +xD(x) for allx R.It is shown that, in caseR contains the unit element, the element 1/2, and an invertible skew-hermitian element which lies in the center ofR, then there exists ana R such thatD(x) = ax
*
– xa for allx R. IfR is a noncommutative prime real algebra, thenD is linear. In our main result we prove that a noncommutative prime ring of characteristic different from 2 is normal (i.e.xx
* =x
*
x for allx R) if and only if there exists a nonzero additive mappingD: R R satisfyingD(x
2) =D(x)x
* +xD(x) and [D(x), x] = 0 for allx R. This result is in the spirit of the well-known theorem of E. Posner, which states that the existence of a nonzero derivationD on a prime ringR, such that [D(x), x] lies in the center ofR for allx R, forcesR to be commutative. 相似文献
63.
A novel simple synthesis of 5-substituted-1,2,4-oxadiazole-3-carboxylates 5 from N-acylglycines 1 , which are transformed with DMF in the presence of phosphorus oxychloride into 2-substituted-4-dimethyl-aminomethyleneoxazol-5(4H)-ones 2 , followed by opening into 2-aroylamino-3-dimethylamino-propenoates 3 , and nitrosation to give the oximes 4 as intermediates, which cyclize spontaneously into 5-substituted-1,2,4-oxadiazole-3-carboxylates 5 . The compounds 2 can be transformed into 5 without isolation of 3 and 4 . 相似文献
64.
Anna Sopková Jozef Chomič Edita Matejěíková 《Monatshefte für Chemie / Chemical Monthly》1971,102(4):961-963
Zusammenfassung Durch Ersetzung des Cadmiums im Clathrat Cden[Ni(CN)4]·2C6H6 wurden drei Verbindungen des TypsM(en)
m[Ni(CN)4]·nC6H6 (M
2+=Ni, Cu, Zn;m=2–3;n=0.14–0.28) hergestellt und charakterisiert.
Synthesis of ethylendiamine-(metal II)-tetracyanoniccolate dibenzene clathrate compounds
Replacing cadmium ion in Cden[Ni(CN)4]·2C6H6 clathrate compound three compounds ofM(en) m[Ni(CN)4]·nC6H6 type (M 2+=Ni, Cu, Zn;m=2–3;n=0.14–0.28) were prepared and characterized.相似文献
65.
In [HOLá, Ľ.—HOLY, D.: Pointwise convergence of quasicontinuous mappings and Baire spaces, Rocky Mountain J. Math.] a complete answer is given, for a Baire space X, to the question of when the pointwise limit of a sequence of real-valued quasicontinuous functions defined on X is quasicontinuous. In [HOLá, Ľ.—HOLY, D.: Minimal USCO maps, densely continuous forms and upper semicontinuous functions, Rocky Mountain J. Math. 39 (2009), 545–562], a characterization of minimal USCO maps by quasicontinuous and subcontinuous selections is proved. Continuing
these results, we study closed and compact subsets of the space of quasicontinuous functions and minimal USCO maps equipped
with the topology of pointwise convergence. We also study conditions under which the closure of the graph of a set-valued
mapping which is the pointwise limit of a net of set-valued mappings, is a minimal USCO map. 相似文献
66.
A short, efficient synthesis of 22-hydroxyacuminatine, starting from a readily accessible hydroxy pyridone, is presented; key steps include a Heck coupling with methyl pentadienoate, a flash vacuum pyrolytic cyclization, and a Friedl?nder condensation. 相似文献
67.
Matej Bresar 《Proceedings of the American Mathematical Society》1998,126(1):181-187
Let be a unital Banach algebra. Several characterizations of continuous derivations of having only elements with finite spectrum in their ranges are obtained. In particular, if is semisimple, then such derivations map into its socle.
68.
We briefly answer the comments in Information Flow, Causality and the Classical Theory of Tachyons by Basano.Work partially supported by MPI (ex-art. 286 T.U.). 相似文献
69.
Two or more physical systems frequently interact with each other, where the independent solution of one system is impossible without a simultaneous solution of the others. An obvious coupled system is that of a dynamic fluid-structure interaction. [8] In this paper a computational analysis of the fluid-structure interaction in a mixing vessel is presented. In mixing vessels the fluid can have a significant influence on the deformation of blades during mixing, depending on speed of mixing blades and fluid viscosity. For this purpose a computational weakly coupled analysis has been performed to determine the multiphase fluid influences on the mixing vessel structure. The multiphase fluid field in the mixing vessel was first analyzed with the computational fluid dynamics (CFD) code CFX. The results in the form of pressure were then applied to the blade model, which was the analysed with the structural code MSC.visualNastran forWindows, which is based on the finite element method (FEM). (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
70.
Ladislav Moravský Peter Troška Matej Klas Marián Masár Štefan Matejčík 《等离子体物理论文集》2020,60(7):e202000014
In this work, we present the application of a fast and sensitive microanalytical method, microchip capillary electrophoresis (MCE), for the determination of NO2− and NO3− ions in deionized water treated by atmospheric pressure plasma jet (APPJ). The MCE technique consisted of an online combination of isotachophoresis with zone electrophoresis, both performed on the microchip. The argon plasma has been characterized by optical emission spectroscopy (OES) and Fourier transform infrared spectroscopy (FTIR). OES confirmed the presence of argon excited species (Ar I) emission (4p → 4s) lines, N2 emission bands (second positive system C3Πu → B3Πg), and OH band (A2∑+ → X2Π Δv = 0), as well as the presence of NO and excited NO2. The presence of NO2 molecules was also confirmed by FTIR absorption spectroscopy. The performance of the developed MCE method was evaluated for linearity, limit of detection, limit of quantitation, precision, and accuracy, and the concentration of NO2− and NO3− in the water as a function of the water treatment time was monitored. 相似文献