نتایج جستجو برای: davanone derivatives
تعداد نتایج: 104912 فیلتر نتایج به سال:
The composition of the essential oil hydrodistilled from the aerial parts of 18 individual Artemisia herba-alba Asso. plants collected in southern Tunisia was determined by GC and GCMS analysis. The oil yield varied between 0.68% v/w and 1.93% v/w. One hundred components were identified, 21 of of which are reported for the first time in Artemisia herba-alba oil. The oil contained 10 components ...
The CoI2(PPh3)2/Zn system effectively catalyzes the [2 + 2 + 2] ene-diyne cycloaddition of 1,6-heptadiynes with allenes in a highly regio- and chemoselective fashion to yield substituted benzene derivatives in good to excellent yields.
A new strategy for Rh(I)-catalyzed [2+2+2] cycloadditions of 1,6-diynes with potassium (Z)-(2-bromovinyl)trifluoroborate as the third two-atom unit has been realized, which provides a facile entry to polysubstituented benzene derivatives.
Hexa-substituted benzene derivatives show larger two-photon cross sections than the corresponding dipolar counterparts and the largest values of delta(max) = 2000 GM and delta(max)/MW = 2.25 GM g(-1) have been obtained with a compound having C[triple bond]C and C=C bonds in the conjugation bridge.
We have successfully developed a new synthetic approach to modulate the electrostatic potentials of metallocavitands and thus their selective recognition towards substituted benzene derivatives via integrating two metal cations of different electronegativity into a self-assembled system.
abstract in first part of this project, the use of a new and biguanid-like catalyst supported on silica as a recyclable catalyst provides a new route for the synthesis of a variety of arylalkylidene rhodanine derivatives through knoevenagle reaction in at present of solvent at room temperature. rhodanine derivatives and especially arylalkylidene rhodanines have proven to be attractive compound...
We consider the task of filtering the noise from images and other types of inputs which are assumed to be piecewise continuous and piecewise monotone. We show that nonlinear diffusion of the data, a powerful filtering method, is too restrictive for such a case, leading to piecewise constant functions. We claim that the piecewise monotonicity can be enhanced by nonlinear diffusion of first parti...
Based on the local Shannon entropy concept in information theory, a new measure of aromaticity is introduced. This index, which describes the probability of electronic charge distribution between atoms in a given ring, is called Shannon aromaticity (SA). Using B3LYP method and different basis sets (6-31G**, 6-31+G** and 6-311++G**), the SA values of some five-membered heterocycles, C(4)H(4)X, a...
A new formulation of a pose refinement technique using “active” models is described. An error term derived from the detection of image derivatives close to an initial object hypothesis is linearised and solved by least squares. The method is particularly well suited to problems involving external geometrical constraints (such as the ground-plane constraint). We show that the method is able to r...
Four fundamental physical parameters of series of benzene derivatives were studied to ascertain correlations with biological activity. These included octanol/water coefficient, vapor pressure, infrared absorption (out-of-plane C-H vibration), and the pi values. Each physicochemical constant exhibited a partial correlation with biological activity suggesting that each played a role. It was presu...
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