Showing papers by "Bulgarian Academy of Sciences published in 1971"
145 citations
TL;DR: A mathematical model of the proposed mechanism gives a satisfactory explanation of the various features of the process of cytodifferentiation such as the requirement for mitotic divisions, the induction phenomena, etc and suggest implications of the model for understanding other biological phenomena, such as carcinogenesis and the emergence of new organic forms for natural selection.
100 citations
TL;DR: In this article, the system olefin-NiO has been investigated by means of a thermodesorption technique and the energy of activation of desorption and the heats of adsorption of some olefins have been determined.
59 citations
TL;DR: In this article, the authors investigated the surface melting of negative crystals (inclusions) in diphenyl and found that the critical temperatures of transition were determined for different crystal surfaces.
50 citations
TL;DR: It is found that the “saccadic suppression” is not saccadic but merely depends on the motion of the entire visual pattern on the retina.
43 citations
TL;DR: In this article, a statistical calculation of the piezoelectric corrections for the main dielectric constants of a nematic liquid crystal is presented, and the dependence of these coefficients on the degree of order of the nematic phase is elucidated.
39 citations
TL;DR: In this paper, the high field kinetics of the oxide film growth on passive iron appears inconsistent with current assumptions for a high electronic conductivity of this film, and the electronic conduction of the film formed in a neutral sulphate-free solution was studied through the electrochemical behaviour of the Fe(CN) 6 4− /Fe(CN 6 3− redox couple on the passive iron electrode.
37 citations
TL;DR: In this article, the electronic spectra of a number of diethyldithiocarbamate complexes of elements with closed-shell configurations have been recorded in different solvents and the observed transitions are discussed in terms of solvent shift and valence orbital energy differences.
35 citations
TL;DR: In this paper, the reflection of argon ions with an energy of 50 to 500 eV from a copper single crystal is simulated on a digital computer, and three models are used to describe the interaction of the projectiles with the crystal: 1. The ion interacts in each moment only with the nearest crystal atom, 2. the ion interacts with all atoms of some micro-crystallite whose atoms are assumed to be free, and 3.
Abstract: The reflection of argon ions with an energy of 50 to 500 eV from a copper single crystal is simulated on a digital computer. Three models are used to describe the interaction of the projectiles with the crystal: 1. the ion interacts in each moment only with the nearest crystal atom, 2. the ion interacts with all atoms of some microcrystallite whose atoms are assumed to be free, 3. the ion interacts with a microcrystallite of bound lattice atoms. For the Ar+–Cu and Cu–Cu interaction we use the Born-Mayer potential. A comparison of the results on the spatial and energy distributions of the ions in the different models is made.
[Russian Text Ignored].
33 citations
TL;DR: In this article, the screening effect of the surface diffusion of adatoms towards the growing nuclei on the kinetics of heterogeneous nucleation is studied, and a solution of the problem treating the time dependence of the number of nuclei is suggested for the case of sufficiently high substrate temperatures.
31 citations
TL;DR: This paper has followed the same line of approach to fill the existing gap in the amino acids sequence at position 17-3 1 in the molecule of Black Sea dolphin myoglobin and served as a practical test of the amino acid sequenator built in this laboratory according to Edman’s model.
TL;DR: In this paper, thin-layer chromatography on silica gel is proposed as a method for assigning the relative configurations of diastereomeric pairs of compounds of the above type.
TL;DR: In this paper, the solution spectra of the tellurium(II) and (IV) complexes of Te(dtc)2 and (4) have been recorded, and Spectral evidence suggests that both the dtc ligands are unidentate, and that two of the DTC ligands of Te-dtc4 are bidentate.
TL;DR: In this article, the IR spectra of the AR of some aromatic dinitriles and mononitriles, and their 15N substituted derivatives, obtained electrochemically or by reacting them with an alkali metal, were investigated.
TL;DR: In this article, negative crystals in diphenyl were used as a model in the investigation of the equilibrium form and it was found that the basal pinacoid {001, the prism {110} and the pinacoidal {20 1 } belong to the equilibrium.
TL;DR: It is suggested that the changes described are the result of increased thyrotropin stimulation.
TL;DR: In this paper, the theory of electron emission in dielectrics is further extended in order to include insulators with arbitrary band structure, and formal expressions for the total energy distribution of the emitted electrons and for the current density are derived.
Abstract: The previously proposed theory of electron emission in dielectrics, based on the quasi-free electron model, is further extended in order to include insulators with arbitrary band structure. Using a generalized formula for the transition probability, formal expressions for the total energy distribution of the emitted electrons and for the current density are derived. A rather general band structure of the insulator is proposed which permits to express explicitly the temperature and field dependence of the energy distribution and of the current for all possible emission conditions using appropriate barrier shape approximations.
Die fruher vorgeschlagene, auf dem quasifreien Elektronenmodell basierende Theorie der Elektronenemission in Dielektrika wird erweitert, um Isolatoren mit beliebiger Bandstruktur zu erfassen. Unter Benutzung einer verallgemeinerten Formel fur die Ubergangswahrscheinlichkeit werden formale Ausdrucke fur die totale Energieverteilung der emittierten Elektronen und fur die Stromdichte abgeleitet. Es wird eine ziemlich allgemeine Bandstruktur des Isolators vorgeschlagen, die Temperatur- und Feldabhangigkeit der Energieverteilung und des Stromes fur alle moglichen Emissionsbedingungen explizit auszudrucken erlaubt, indem geeignete Naherungen fur die Barrierenform benutzt werden.
TL;DR: The NMR spectra of the erythro and threo forms of the esters PhCH a XCH b (Ph)COOC 2 H 5, where X = OH, NH 2, NHPh, and NHCONH 2 have been investigated in CDCl 3, DMSO-d 6, benzene and pyridine solutions as discussed by the authors.
TL;DR: In this article, the influence of pyridine on the EPR spectra of some copper-II dithiocarbamate and Dithiophosphate complexes has been studied.
TL;DR: In this paper, the cross-sections in the range of four momentum transfer squared from 0.003 to 0.120 (GeV c) 2 were measured at 30, 50 and 70 GeV by using a thin polyethilene target in the internal proton beam of the Serpukhov accelerator.
TL;DR: An epigenetic mechanism of neoplastic transformation is proposed which is initiated by affecting the metabolic circuits controlling the synthesis of nonhistone chromatin proteins (deblocking proteins) which explains the properties of neplastic cells and the process of carcinogenesis.
Abstract: Analysis of literature data and computer experiments with mathematical models lead to the conclusion that the molecular mechanisms of cytodifferentiation and of carcinogenesis are the same. Thus an epigenetic mechanism of neoplastic transformation is proposed which is initiated by affecting the metabolic circuits controlling the synthesis of nonhistone chromatin proteins (deblocking proteins). The process is stochastic and mitosis dependent. This epigenetic mechanism explains the properties of neoplastic cells and the process of carcinogenesis.
TL;DR: Evidence is presented that rRNA fragments produced by heating originate mainly from old rRNA, suggesting that old and newly synthesized cytoplasmic rRNA behave differently as far as hidden breaks are concerned.
TL;DR: In this article, a piezoelectric correction of the dielectric constant is discussed, which explains qualitatively why the average DCE of the nematic phase fails to coincide with the experimentally observed isotropic DCE.
TL;DR: In this paper, material soluble in chloroform has been extracted from bright bituminous coals of two different ranks 1) following preheating to the temperatures of maximal plasticity; 2) after treatment with sodium in liquid ammonia; 3) by fractionating the pyridine extracts; 4) after preliminary acetylation with acetic anhydride in the presence of Pyridine.
TL;DR: In this article, a biogenetic relationship between paraffins, olefins, secondary alcohols and ketones in rose flower wax was suggested, compared with those by other authors.
TL;DR: The rotational barriers about the CN bond of eight m- and p-substituted N, N-dimethyl cinnamamides have been determined by the iterative total line shape NMR method.
Abstract: The rotational barriers about the CN bond of eight m- and p-substituted N, N-dimethyl cinnamamides have been determined by the iterative total line shape NMR method. The ΔG values have been correlated with the substituent constants σ, σn and σ+. By comparison of the results with literature data, some conclusions about the accuracy of the barrier determination as well as the transmittance of polar effects in conjugated amides have been drawn.
TL;DR: Though the genetic structure of the morphologic characters of female Haemonchus has been distinguished, the taxonomic value of these characters has yet to be determined.
TL;DR: In this article, the electronic structures of the two planar rotational isomers of furfural are discussed, and it is shown that definite differences should be observed between the properties of the possible retainers.
TL;DR: The stability constants of the complexes, at mole ratios 1 : 1, are determined by a modification of the method of successive dilution as discussed by the authors, which depends on the electron donating capacity of the complex forming units, with the increase of this capacity they increase for the low molecular complexes and decrease for the corresponding polymer complexes.
Abstract: The complex formation in chloroform solution of tetracyanoethylene with the polymers: polyphenyl methacrylate, poly-2-naphthyl methacrylate, and polyvinyl carbazole and the corresponding monomers and saturated monomer analogs is investigated.
The stability constants of the complexes, at mole ratios 1 : 1, are determined by a modification of the method of successive dilution. The values of these constants are greater for the polymers than for the corresponding monomers and monomer analogs. The extinction coefficients of the complexes increase in the transition from polymer to monomer.
The stability constants depend on the electron donating capacity of the complex forming units. With the increase of this capacity they increase for the low molecular complexes and decrease for the corresponding polymer complexes.
Die Komplexbildung von Tetracyanoathylen in Chloroform mit den Polymeren Polyphenylmethacrylat, Polynaphthyl-(2)-methacrylat und Polyvinylcarbazol sowie mit den entsprechenden Monomeren und gesattigten Monomeranalogen wurde untersucht.
Mit Hilfe des modifizierten Verfahrens der aufeinanderfolgenden Verdunnung wurden die Stabilitatskonstanten der Komplexe beim Molverhaltnis 1 : 1 bestimmt. Die Polymeren weisen grosere Werte fur diese Konstanten auf als die Monomeren und die gesattigten Monomeranaloga. Die Extinktionskoeffizienten der Komplexe steigen beim Ubergang vom Polymeren zum Monomeren an.
Die Stabilitatskonstanten sind auch von dem Elektronendonatorvermogen der komplexbildenden Glieder abhangig; sie nehmen mit ansteigendem Elektronendonatorvermogen bei den niedermolekularen Komplexen zu und bei den entsprechenden Polymerkomplexen ab.