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181.
182.
A simple electronic measuring cup for the blind is described. It uses an array of infrared level detectors, which are immersed in the medium to be measured. When used with a standard 1-liter glass, the filling level is indicated acoustically in increments of 50 ml. 相似文献
183.
Alexandre Froda 《Annali di Matematica Pura ed Applicata》1978,44(1):185-199
Résumé L’on définit, pour ρ>0 donné, des familles de para-voisinages J(J) (§ 1) des pointsJ de l’espace euclidienE
(n),continus par rapport àJ. On étudie certaines propriétés à distance, ?.-à-d. qui rattachent les valeurs de f(P) reélle, borneé, enJ et sur J(J). L’ensemble desJ est alors relativement dense enE
(n) (§ 2). Résultats pareils en renon?ant à la continuité (§ 3). 相似文献
184.
185.
186.
H. Brunner 《BIT Numerical Mathematics》1972,12(4):468-474
Lineark-step methods (k2) with constant coefficients are derived by choosing as the second characteristic polynomial of the method a Schur polynomial whose coefficients depend on a certain set of parameters. The choice of these parameters is based on a result due to Marden concerning the location of the zeros of a class of rational functions, and it is shown that, for the (practically important) casek=2, the corresponding two-step methods are alwaysA-stable. 相似文献
187.
The effect of silica aerosils on the kinetics of the first-order nematic-isotropic (NI) phase transition is phenomenologically described in the framework of the time-dependent Landau-Ginzburg equation. A steady-state solution to the equation is presented such that the NI interface may propagate with a solitary-like wave profile under constant quenching. The results provide a plausible basis for the interpretation of the dynamical effects of quenched disorder in the liquid-crystal systems, caused by randomly interconnected porous media, such as aerosils. In the low silica aerosil ρs ( ≤0.1 g/cm^3) regime, the calculated values of the interface velocity v(T,ρs), the interface thickness κ(T,ρs), and the critical radius of a spherical nucleus of new nematic phase in a bulk isotropic environment, composed of polar molecules, such as 4-n-octyl- 4′- cyanobiphenyl and 4-n-heptyl- 4′- cyanobiphenyl shows that the effect of silica aerosils on the kinetics is reflected in a shifting of the set of temperature-dependent curves to lower temperature values.-1 相似文献
188.
[reaction: see text] Enantioselective Ir-catalyzed intramolecular allylic aminations and etherifications are described. Up to 97% ee was achieved using catalysts prepared by in situ activation of mixtures of phosphorus amidites and [Ir(COD)Cl]2. Sequential aminations of bis-allylic carbonates, involving an inter- followed by an intramolecular reaction, gave trans-N-benzyl-2,5-divinylpyrrolidine and trans-N-benzyl-2,6-divinylpiperidine with > or = 99% ee. New phosphorus amidites as well as improved conditions for intermolecular aminations are reported. 相似文献
189.
Gould C Rüster C Jungwirth T Girgis E Schott GM Giraud R Brunner K Schmidt G Molenkamp LW 《Physical review letters》2004,93(11):117203
We introduce a new class of spintronic devices in which a spin-valve-like effect results from strong spin-orbit coupling in a single ferromagnetic layer rather than from injection and detection of a spin-polarized current by two coupled ferromagnets. The effect is observed in a normal-metal-insulator-ferromagnetic-semiconductor tunneling device. This behavior is caused by the interplay of the anisotropic density of states in (Ga,Mn)As with respect to the magnetization direction and the two-step magnetization reversal process in this material. 相似文献
190.