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951.
Javad?AzizianEmail author Ali R.?Karimi Hamedeh?Arefrad Ali A.?Mohammadi Mohammad R.?Mohammadizadeh 《Monatshefte für Chemie / Chemical Monthly》2004,135(6):729-733
Summary. We report on the addition of dialkyl acetylenedicarboxylate to 1-alkylisatins or tryptanthrine in the presence of triphenylphosphine which leads to highly functionalised novel unsaturated -spirolactones. 相似文献
952.
Ákos Császár 《Journal of Mathematical Analysis and Applications》2004,297(2):490-494
The paper presents a formula for the γ-interior of a set under special conditions for , more general than those in the previous paper [Acta Math. Hungar. 80 (1998) 89-93]. There are also some applications. 相似文献
953.
Michael Růžička 《Applications of Mathematics》2004,49(6):565-609
Many electrorheological fluids are suspensions consisting of solid particles and a carrier oil. If such a suspension is exposed to a strong electric field the effective viscosity increases dramatically. In this paper we first derive a model which captures this behaviour. For the resulting system of equations we then prove local in time existence of strong solutions for large data. For these solutions we finally derive error estimates for a fully implicit time-discretization. 相似文献
954.
The microsurface adsorption–spectral correction (MSASC) technique has been applied to investigate the interaction of alkali blue 6B (AB6B) with cetyltrimethylammonium bromide (CTAB). The aggregation of AB6B on CTAB obeys the Langmuir isothermal adsorption. The aggregate was characterized by MSASC. For the monomer aggregate AB6B2CTAB formed, its binding constant is calculated to be K = 3.01·105 and its molar absorptivity to be 2.45·106 liters·cm–1 at = 690 nm. The adsorption has been used to carry out quantitative detection of cationic surfactant in samples. 相似文献
955.
《Tetrahedron》2003,59(3):295-301
The rigid 6-oxobicyclo[3.1.0]hexane scaffold, characteristic of the natural antibiotic neplanocin C (3), was used to build prototypes of conformationally locked deoxynucleosides in the North hemisphere of the pseudorotational cycle. The purine analogues 6 and 7 are conformationally equivalent to carbocyclic nucleosides built with the bicyclo[3.1.0]hexane template. The pyrimidine nucleosides were unstable and underwent a facile intramolecular epoxide ring-opening reaction leading to heterocycle 22. Only the deoxyguanosine analogue 7 showed antiviral activity against EBV. 相似文献
956.
O.I. Kalchenko A.V. Solovyov S.A. Cherenok N.F. Starodub V.I. Kalchenko 《Journal of inclusion phenomena and macrocyclic chemistry》2003,45(1-2):19-25
In capillary electrophoresis using poly(vinyl sulfate), added to sample solutionsand running buffers, the signal of Rhoda-mine 6G (R6G) is shaped like a squarewave. When -, -, or -cyclodextrin (-, -,or -CD) has further been added to the running buffers as well as samplesolutions, the intensity of the square-wave type signal of R6G has been enhanced,accompanied by narrowing of the signal width. The migration time of the risingedge of the square-wave type signal has been very slightly delayed by the additionof CD. These findings exhibit the formation of inclusion complexes of R6G withCDs. From the analyses of the variations in signal width with the concentration ofCD, the equilibrium constants for the formation of the 1:1 inclusion complexes ofR6G with -, -, and -CDs have been evaluated to be 245,210, and 302 M-1, respectively, although the equilibrium constants could not be estimated using a conventional procedure based on electrophoretic mobility, inwhich poly(vinyl sulfate) was not added. The values of the equilibrium constants for- and -CDs are comparable to those obtained from the absorbancechanges in spectrophotometry, whereas the value for -CD is about four timesgreater than that obtained from the absorbance change. 相似文献
957.
Ishmuratov G. Yu. Yakovleva M. P. Galyautdinova A. V. Muslukhov R. R. Tolstikov G. A. 《Russian Chemical Bulletin》2003,52(3):740-744
A new procedure was developed for the synthesis of racemic analogs of 1,5-dimethyl-branched insect pheromones based on monoalkylation of ethyl acetoacetate with 1-acetoxy-5-bromo-3-methylpentane produced upon decyclization of 4-methyltetrahydropyran. 相似文献
958.
Zhizhiashvili studied questions associated with the approximation properties of Cesàro means of trigonometric Fourier series for functions of two variables in the spaces H. It is proved here that the corresponding estimate cannot be improved for p = 1 or p = . 相似文献
959.
We develop a notion of an n-fold monoidal category and show that it corresponds in a precise way to the notion of an n-fold loop space. Specifically, the group completion of the nerve of such a category is an n-fold loop space, and free n-fold monoidal categories give rise to a finite simplicial operad of the same homotopy type as the classical little cubes operad used to parametrize the higher H-space structure of an n-fold loop space. We also show directly that this operad has the same homotopy type as the n-th Smith filtration of the Barratt-Eccles operad and the n-th filtration of Berger's complete graph operad. Moreover, this operad contains an equivalent preoperad which gives rise to Milgram's small model for when n=2 and is very closely related to Milgram's model of for n>2. 相似文献
960.
V. F. Murzina 《Algebra and Logic》2003,42(3):181-191
A modal logic associated with the
-spaces introduced by Ershov is examined. We construct a modal calculus that is complete w.r.t. the class of all strictly linearly ordered
-frames, and the class of all strictly linearly ordered
-frames. 相似文献