showing 36 of ~574560 from 574555 documents
Stereostructural revision of auricularic acid synthesis of 4-epi-auricularic acid
1989
Abstract Cleistanth-13,15-dien-18-oic acid (1) has been synthesised from methyl 13-keto-podocarp-8(14)-en-18-oate (3). It is demonstrated that auricularic acid is an epimer at C-4 of 1, so it must be reformulated as cleistanth-13,15-dien-19-oic acid (2).
Effect of axially bound anions on the electroreduction of tin(IV) porphyrins in tetrahydrofuran
1989
The spectroscopic characterization and electrochemistry of SnL(X)2 is presented where L is the dianion of tetra-p-tolylporphyrin or tetra-m-tolylporphyrin and X is ClO4–, Br–, Cl–, F–, or OH–. In all cases, electroreduction leads to porphyrin π anion radicals and dianions which were characterized in tetrahydrofuran by spectroelectrochemistry and e.s.r. spectroscopy. Dissociation of one ClO4– ion from SnL(ClO4)2 occurs before electroreduction of the complex but no dissociation is observed either before or after electroreduction of SnL(F)2 or SnL(OH)2. In contrast, one Br– ion dissociates after the first electron addition to SnL(Br)2 while one Cl– ion dissociates from SnL(Cl)2 after the secon…
Hématome sous-dural aigu intracrânien d'origine artérielle après rachianesthésie
1989
Resume Un cas d'hematome sous-dural intracrânien d'origine arterielle dans les suites d'une rachianesthesie est rapporte. Un homme de 67 ans est opere par voie endoscopique d'un adenome prostatique sous rachianesthesie. Les cephalees apparues au troisieme jour s'intensifient malgre un traitement etiologique et perdent leur caractere postural au cinquieme jour. Un coma brutal avec hemiplegie gauche s'installe au sixieme jour. La tomodensitometrie montre un hematome sous-dural aigu gauche, qui est immediatement evacue. L'origine arterielle est prouvee par la chirurgie. L'evolution est defavorable. La relation entre l'accident et la rachianesthesie est discutee.
A Medium Level Language for Pyramid Architectures
1989
In the paper a Parallel C Languages for pyramid architectures is described. The concept of context is introduced in order to handle concurrence between processes in massive parallel machines. Feature implementation on the PAPIA-machine are given.
Reinardt e Pirandello. Dal copione de I sei personaggi in cerca d'autore di Max Reinhardt
1989
La ricostruzione della creazione registica e interpretativa di Reinhardt sulla base dell'analisi del suo copione d I sei personaggi in cerca d'autore.
Osteocondritis disecante de la troclea humeral: a propósito de un caso
1989
Los autores presentan un caso de osteocondritis disccante de codo en un varón de 14 años de edad. El área afectada correspondía a la garganta troclcar, tratándose de una localización totalmente atípica de la que no hemos encontrado referencias en la literatura. Hacen una exposición del caso clínico y de las técnicas diagnósticas así como del proceder quirúrgico por el que se optó tras la evaluación previa. Se revisan brevemente las características de la osteocondritis disecante genéricamente, independientemente de sus posibles localizaciones y comentarios algunos aspectos que pueden influir en la localización troclcar en el codo. The authors presented one case of osteochondritls disecans of…
L'orientation, un rouage important dans la genèse des inégalités sociales à l'école
1989
National audience
Analysis of metal spinning processes by the ADINA code
1989
Abstract The ADINA code, version 84, has been employed for the analysis of sheet spinning processes. The main process parameters have been evaluated in different working conditions; namely for various geometries and constitutive laws of the material.
The Fock Bundle of a Dirac Operator and Infinite Grassmannians
1989
In the earlier chapters we have studied representations of current algebras in fermionic Fock spaces. A (fermionic) Fock space is determined by a single Dirac operator D. To set up a Fock space we need a splitting of a complex Hilbert space H to the subspaces H± corresponding to positive and negative frequencies of D. However, in an interacting quantum field theory one really should consider a bundle of Fock spaces parametrized by different Dirac operators. For example, in Yang-Mills theory any smooth vector potential defines a Dirac operator and one must consider the whole bunch of these operators and associated Fock spaces if one wants to describe the interaction of the vector potential w…
Zu einem Satz von H. Lüneburg über verallgemeinerte André-Ebenen
1989
An analysis of direct solar transmittance and atmospheric turbidity in the Mediterranean climatic belt
1989
Abstract The empirical model developed by King and Buckius for the direct transmission in clear sky is applied to hourly data of two Yugoslav locations exhibiting typical meteoclimatic characteristics common to the whole Mediterranean belt. The occurrence of “very clear”, “clear” and “very hazy” hours, after the usually accepted definitions, is determined and discussed. The degree of accuracy of the previsional model is investigated performing the comparison with the corresponding values obtained directly by energetic procedure. A general overestimate of the transmittance is experienced with notable deviations in meteorological conditions affected by the presence of dense clouds which behav…
Enthalpy of Solution of Nonionic Solutes in Organized Systems
1989
The standard enthalpies of solution of alcohols in micellar solutions of dodecyltrimethylammonium bromide were obtained by direct measurements and by enthalpies of mixing. The observed trends were analyzed with a previously reported model. From the resulting equations, the distribution constant, standard enthalpy of transfer from aqueous to the micellar phase and the standard enthalpy of solution in micellar phase can be calculated at the same time using a linear least-squares analysis. The model seems to hold well also in the case of short chain surfactants and microheterogeneities in spite of the fact that the micellization equilibrium is treated as a pseudo-phase transition.
DNA sequence and pattern of expression of the sea urchin (Paracentrotus lividus) alpha-tubulin genes.
1989
To study the molecular aspects of the regulation of transcription of a multigene family, we have isolated and sequenced cDNA and genomic clones coding for the alpha-tubulin of the sea urchin Paracentrotus lividus. Two cDNA clones, P alpha 10 and P alpha 4, contain respectively the coding information for 391 C-terminal and for 338 N-terminal amino acids of the 452 residues that constitute the complete protein. They show silent nucleotide substitutions only, suggesting that P alpha 10 and P alpha 4 represent the cloned copies of two allelic gene transcripts, which encode for two alpha-tubulin isoforms with identical amino acid sequence in the region of the overlap. The comparison of the predi…
Identités culturelles, identité européenne? / Cultural identities, European identity?
1989
Социологические и социально-психологические проблемы нововведений
1989
Сборник посвящен малоисследованным проблемам инноваций. Ученым Латвийского государственного университета представлены некоторые гипотетические разработки социологических и социально-психологических проблем нововведений.
Personības veidošanās kolektīvā
1989
Krājumā ietverti materiāli par personības veidošanos skolas un augstskolas kolektīvos. Pētīti kritēriji, kas nosaka personības izveidošanos, individuālo attīstību.
Quark Antisymmetrization Effects in Nuclear Physics
1989
We analyze the observability of quark phenomena in nuclei by studying the effects of the antisymmetrization principle at the quark level in nuclear observables. We discuss the physics associated with one body quark observables and in particular pay special attention to the so called maximal Pauli blocking scenarios. We comment about the calculation of two body quark observables showing results of the Coulomb energy for a two nucleon system with deuteron quantum numbers.
El realismo crítico-social ruso: la sociedad de exposiciones ambulantes
1989
LA SOCIEDAD DE EXPOSICIONES AMBULANTES SE FORMA EN MOSCU EN 1870, COMPUESTA POR LOS ARTISTAS QUE HABIAN RECHAZADO, POR RAZONES IDEOLOGICAS Y ESTETICAS, LAS DIRECTRICES IMPUESTAS POR LA ACADEMIA DE BELLAS ARTES DE SAN PETERSBURGO. EL IDEARIO DEL GRUPO AMBULANTE SE FUDAMENTA, SOBRE TODO, EN ASPECTOS SOCIOLOGICOS Y, POR TANTO, MAS EXTRARTISTICOS QUE ESTETICOS; POSTURA QUE SERA RETOMADA, EN LO FUNDAMENTAL, POR EL REALISMO SOCIALISTA. RECONSTRUIREMOS LA HISTORIA DEL GRUPO A TRAVES DE LA PINTURA DE GENERO Y EL PAISAJE, EVOLUCIONANDO HACIA PLANTEAMIENTOS ESTETICOS DE CARIZ INTERNACIONALISTA EN LA DECADA DE 1890.
Physikalisch bedingte Myopathien
1989
Verletzung des Muskelgewebes durch mechanische Einwirkung (Uberdehnung, Kontraktion, ausere Gewalt).
Lewis Acid-Catalyzed Stereoselection on Carbohydrate Templates
1989
The chirality and the complexing abilities of carbohydrates are utilized for chemical stereoselection in different reactions. In this sense, the carbohydrates are investigated as the chiral auxiliaries in alkylation reactions and in Michael additions of ester enolates. Furthermore, carbohydrates are demonstrated to be efficient chiral matrices in Lewis acid-catalyzed Diels-Alder reactions. They also effect stereoselection in a new synthesis of β-branched carboxylic acid derivatives. O-Acylated glycosylamines are shown to be potent chiral templates in the Strecker synthesis and in the Ugi four-component condensation to give α-amino acid derivatives in high yield and diastereoselectivity. In …
Functional Colonic Ultrasonography: Normal Findings of Colonic Motility and Follow-Up in Neuronal Intestinal Dysplasia
1989
Three types of neuronal intestinal dysplasia (type A, type B, and combination with Hirschsprung’s disease) can be distinguished. Functional assessment of the affected bowel segments can be achieved by functional colonic ultrasonography, thus providing exact parameters for further therapeutical procedure. The technique is described. Ten children with neuronal intestinal dysplasia in whom functional colonic ultrasonography was employed and results of their follow-up examinations are reported.
Un regard économique sur l'évolution de la carrière enseignante : analyse du cas français dans une perspective internationale
1989
International audience; Cette étude tente de mesurer l'attractivité de la carrière enseignante en France et de comparer la situation française avec celle qui prévaut dans les autres pays de l'OCDE. Elle distingue les aspects purement financiers des autres, en montrant notamment qu'en ce qui concerne les rémunérations, on ne peut parler de dégradation absolue au cours des deux dernières décennies et qu'on ne peut pas non plus affirmer que les enseignants sont sous-rémunérés de manière manifeste par rapport aux professions exigeant le même niveau de qualification, surtout si l'on ajuste les gains en fonction du temps de travail annuel. En revanche, si l'on considère l'ensemble de la vie activ…
Cyclosporine A + Glybenclamide. Effect on Glucose Metabolism: Preliminary Results
1989
Cyclosporine A (CsA) is an immunosuppressive drug which determines, at high dosage, glucose intolerance (1). Different drugs present a pharmacological interaction with CsA increasing or reducing its blood level (2). To investigate the role of Glybenclamide (HB419), a sulphonilureic oral antidiabetic drug of large use, on CsA glucose metabolic effect, we have administered CsA + HB419 in rats. The aim of our work is to evaluate if HB419 influences CsA blood levels and if it improves glucose tolerance.
Akadēmiskās organizācijas Konkordijas Valdemārijas Goda filistri: biogrāfijas un apceres [...Konkordijas Valdemārijas Goda filistri...]
1989
Impiego di un substrato fluorogeno per una prova rapida di conferma della colimetria in acque di mare.
1989
Conseguenze sanzionatorie dell'infedele dichiarazione dei redditi prodotti in forma associata
1989
Viene affrontata la questione relativa alla sanzionabilità dell'infedele dichiarazione dei soci di società di persone nell'ipotesi in cui il reddito di partecipazione venga rettificato a seguito dell'accertamento del reddito prodotto dalla società
El entorno del triente de Suintila de la Biblioteca Universitaria de Valencia
1989
Se intenta dar a conocer dónde, cómo y por quién fue hallado el triente de Suintila que se conserva en la Biblioteca Universitaria de Valencia. I pretend in the present work to show where, how and by who was discovered the Suintila's coin which keep in thc Library of the University of Valencia.
La física moderna en la enseñanza secundaria: una propuesta fundamentada y unos resultados
1989
Los análisis realizados sobre el aprendizaje de la Física moderna en la actual enseñanza media (Gil, Senent y Solbes 1987) muestran que los alumnos no alcanzan en general una mínima comprensión, ni siquiera cualitativa, de sus ideas y conceptos fundamentales, incurriendo en graves errores conceptuales. Tales resultados han sido atribuidos a la especial dificultad de la nueva Física, poniendo incluso en cuestión la convivencia de su introducción en los estudios secundarios (Kuhn, 1981). Intentaremos mostrar, sin embargo, que las dificultades en el aprendizaje de la Física moderna no son de naturaleza diferente a las del aprendizaje de la Física en general y que una didáctica que plantee el a…
Une illusion historiographique : justice et criminalité au 18e siècle
1989
International audience
Chlorination of p-cymene by chlorine in carbon tetrachloride: Model compounds for environmental analyses
1989
p-Cymene was chlorinated by chlorine in CCl4. The products of the chlorination were separated by distillation and purified by preparative gas chromatography. The structures of chlorocompounds were confirmed by means of their NMR and mass spectra. The distillation gave as the main compounds: (2) 2-chloro-, (4) 2,3-dichloro-, (5) 2,5-dichloro-, (6) 2,3,6-trichloro-, (7) 2,3,5,6-tetrachloro-p-cymenes and as by-products: (8) 2,5,7-trichloro-p-cymene, (9) 2,6-dichloro-1-methyl-4-(1-methylethenyl)benzene (cymenene), and (10) 2,3,6-trichloro-1-methyl-4-(1-methylethenyl)benzene (cymenene).
Cirugía de la escoliosis: evolución y Resultados
1989
Los autores, presentan una revisión de las tres series de escoliosis, intervenidas quirúrgicamente en el Servicio, en base a tres diferentes series de artrodcsis: artrodesis con barra distractora de lla:rrington, en segundo lugar con llarrington más el Dispositivo de Tracción Transversal (DTT) y por último con instrumentación Cotrcl-Dubousset (C-D). Se analizan los resultados obtenidos tras una revisión al año y a los cinco años del postopcratorio, el instrumental implantado y por último las complicaciones derivadas del mismo así como de la técnica quirúrgica. A revicw ofpatients with scoliosistreated by surgery is presented. Tbere are tbree groups of cases: Spinal fusion with Harrington In…
L'évaluation du fonctionnement du système scolaire : présentation de l'Institut de recherche sur l'économie de l'éducation
1989
International audience
Una marca de ánfora de Tubusuctu hallada en 'Sa Mesquida', Santa Ponça (Mallorca)
1989
Synthesis of various natural 8,12-elemanolides from artemisin
1989
Abstract This paper describes the chemical transformations of artemisin into various natural 8,12-elemanolides.
Le congé individuel de formation : quel impact sur le trajectoire professionnelle du salarié ?
1989
International audience
Violation of Siegert's theorem in the electro-excitation of the (1−, T = 0)-level at 7.117 MeV in 16O
1989
Abstract Cross sections are measured for the electro-excitation of the first 1−-level in 16O at extremely small momentum transfer. The model-independent interpretation with a Fourier-Bessel expansion of the transition charge density reveals an incompatibility with the life-time measurement at the photon point, i.e. a violation of Siegert's theorem.