showing 36 of ~574560 from 574555 documents
Solution properties of polyelectrolytes—V. Viscometric study of mixed polyanions in pure water
1990
Abstract A viscometric study of sodium polystyrene sulphonate (NaPSS) and sodium poly( l -glutamate) (NaPLG) in salt-free water has been carried out as a function of the total concentration, cm, and the concentration of one polyelectrolyte at fixed concentration of the other. The influences of the molecular weight and concentration are considered in order to establish the degree of compatibility. For the first time, an equation is proposed to define the reduced viscosity of the NaPSS + NaPLG mixture in water. The viscometric interaction parameter, Bm, taking into account the electrostatic and thermodynamic interactions between both polyions, is defined as a geometrical mean of the contribut…
Theoretical Design of Organic Metals Based on the Phthalocyanine Macrocycle
1990
Phthalocyanine molecular crystals and cofacially linked polymers are well documented as low-dimensional materials that may attain high electrical conductivities. Air-stable conductivities on the order of 1 to 1000 S/cm after partial oxidation by iodine have been reported.1–3 These conductivity studies indicate that the electrical conductivity has very little dependence on the identity of the atom complexed in the cavity, but is strongly dependent on the orientation and spacing of the phthalocyanine rings. A columnar stacking with minimum spacing leads to a maximum interaction between π-molecular orbitals on adjacent rings and promotes the highest conductivity. More effective π-interactions …
Grundzüge der Atom- und Molekülphysik
1990
Jeder heise Stoff sendet elektromagnetische Strahlen aus, durch deren spektrale Zerlegung (Abschn. 7.3.8) man sein Emissionsspektrum erhalt. Dieses hat auser im sichtbaren Bereich auch Beitrage sowohl im IR- als auch im UV-Gebiet. Gluhende feste und flussige Korper und ebenso sehr stark verdichtete heise Gase senden ein sog. kontinuierliches Spektrum aus (Abschn. 7.5.3).
Meniscectomía por Cirugía Artroscópica
1990
El propósito de este trabajo es presentar la experiencia y valoración estadística de 83 artroscopias de rodilla realizadas por los autores, durante el año 1988, describiendo la patología hallada, la técnica empleada, complicaciones per y postoperatorias así como la estancia media hospitalaria de estos pacientes. With this work, the authors showed their experience and statistic evaluation of 83 arthroscopies of the knee in 1988, describing the pathological findings, technical procedure used, complications during and after the arthroscopy as well as the average stay of these patients in the hospital.
Aproximació al règim senyorial, repartiment i usos del sol als dominis de la Casa de Medinaceli al Pais Valencià: Balanç provisional de les cartes-po…
1990
EN COMPARACION CON LA SITUACION ANTERIOR A LA EXPULSION DE LOS MORISCOS, EL REGIMEN SEÑORIAL DEFINIDO POR LAS CARTAS-PUEBLAS PRESENTA, EN GENERAL, UN BALANCE POSITIVO PARA LOS REPOBLADORES; ADEMAS, SI SE CONSIDERA LA NECESIDAD NOBILIARIA DE CONCEDER CONCORDIAS SIEMPRE FAVORABLES A LOS ENFITEUTAS (O, INCLUSO, DE REDACTAR OTRAS CAPITULACIONES), SE COMPRENDE LA EXISTENCIA DE UNA NOTABLE DINAMICA NEGOCIADORA IMPUESTA POR LA CAPACIDAD DE RESISTENCIA. CABE DESTACAR, POR OTRA PARTE, EL PREDOMINIO ABSOLUTO DE LA ENFITEUSIS EN LA ESTRUCTURA QUE ADOPTARA EL REPARTO Y USOS DEL TERRAZGO DURANTE EL ANTIGUO REGIMEN, ASI COMO EL HECHO DE QUE LA DIFERENCIACION SOCIAL EN LA COMPOSICION DE COMUNIDAD RURAL SE…
Insular variation in central MediterraneanCrociduraWagler, 1832 (Mammalia, Soricidae)
1990
Morphometric variation of Crocidura mandible in Sicily and surrounding islands (Egadi archipelago, Ustica, Pantelleria and Gozo) was analyzed by principal component and canonical variate analyses in order to integrate recent chromosomal and biochemical observations. Specimens of C. suaveolens and C. leucodon from mainland Italy and of C. russula from Sardinia were used as reference in this analysis. The biometry of the only taxon of shrews living in Sicily is significantly different from the three reference samples. This result, coupled with a recently discovered new karyotype, provides strong evidence for a new Eurasian species, for which the name C. sicula Miller 1901, was chosen. Crocidu…
How to pay for the debt — Coping with the Third World's crisis
1990
The Brady Plan is the first official proposal to give priority to a tangible reduction in the debtor countries' debt service burden and is thus a milestone along the path towards overcoming the international debt crisis. However, the instruments foreseen in the Plan virtually invite criticism and scepticism. What are the main inadequacies of the Brady Plan? How can the international debt strategy be developed further and made more effective?
Die ärztliche Aufklärung — Eine Gratwanderung zwischen juristischem Muß und ärztlichem Tun?
1990
Die arztliche Aufklarung — mit den Worten Karl Jaspers — zeichnet sich aus durch die Verantwortung fur die Richtigkeit der Aussage und fur die Wirkung auf den Kranken [7]. Die Problematik dieses sowohl von Juristen als auch von Arzten anerkannten Anspruchs wird besonders deutlich, wenn die Krankheit selbst dem sog. „verstandigen Patienten“ als abstrakte juristische Konstruktion die innere Verarbeitung des Aufklarungsgesprachs versperrt.
Sociología del desenvolupament i límits ecològics
1990
La interpretació convencional del canvi social contemporani depèn de la sociologia del desenvolupament o modernització, la qual és, en gran manera, un corol·lari de la teoria econòmica del creixement. Les crítiques al creixement fetes pels economistes ecològics (Georgescu-Roegen, Daly i altres) tenen, en conseqüència, diverses implicacions per a la sociologia del canvi social. L'article conté una exploració preliminar d'algunes d'aquestes implicacions. S'hi il·lustra la dependècia entre teoria del canvi social i creixement econòmic en referència a les tesis de transició a la societat postindustrial de Bell. La possibilitat de generalitzar el model de societat de les actuals zones industrial…
El Marte imprudente de Velázquez
1990
SE DA UNA NUEVA LECTURA DEL ENIGMATICO CUADRO DE VELAZQUEZ DEDICADO A MARTE. EL LIENZO SE CONECTA CON LA EMBLEMATICA. EL ESTUDIO ENRIQUECE LAS INTERPRETACINES DE LA OBRA. CENTRADAS EN EL YELMO DORADO, CON EL ANALISIS DE UN ELEMENTO HASTA AHORA DESCUIDADO: LA SERPIENTE SE ENCUENTRA EN LA PARTE SUPERIOR DEL YELMO. SE INTERPRETA LA OBRA COMO UNA REPRESENTACION DE MARTE PRUDENTE QUE EL PINTOR ASOCIA A FELIPE IV, COMO ADVERTENCIA A SU DESCUIDO EN LOS ASUNTOS DE GUERRA. (A.B.C./ L.A.G.)
Oocyte Quality According to Protocols for Controlled Ovarian Hyperstimulation and Patients’ Age
1990
In in vitro fertilization (IVF) and embryo transfer (ET), the induction of multiple follicular growth represents the first and necessary step for the efficient performance of the technique.
El Principi de Le Chatelier i la seua abusiva aplicació en la didàctica de l' equilibri químic
1990
Explotación de recursos geológicos en la periferia valenciana: Camp de Túria y Hoya de Buñol-Chiva
1990
En este artículo se pretende estudiar la influencia que ejerce el área metropolitana de Valencia (AMV) sobre el espacio contiguo occidental (las comarcas del Camp de Turia y la Hoya de Buñol-Chiva) en un aspecto determinado: la explotación de los recursos geológicos de este espacio. Para ello el estudio se centrara en primer lugar en las condiciones litológicas del área en cuestión. Seguidamente, definiremos la evolución de este sector desde finales del siglo XVIII. Y, finalmente, estudiaremos la situación actual. Para ello nos basaremos en la localización de los yacimientos y su evolución, así como en la titularidad de las distintas explotaciones y en los principales destinos del volumen e…
La trashumancia ibérico-valenciana en la Edad Moderna
1990
La trashumancia de rebaños desde las altas sierras de Albarracín, Gúdar y Javalambre hasta las llanuras litorales valencianas es un hecho poco conocido a pesar de la gran importancia que ha tenido para mantener durante siglos la alta productividad de nuestra agricultura y para explicar relaciones de migración y dependencia que llegan a nuestros días.
Präoperative Lokalisationsdiagnostik beim organischen Hyperinsulinismus — sinnvoll oder überflüssig —
1990
Im eigenen Krankengut (n = 43) hatte die perkutane Sonographie eine Sensitivitat von 61,9%, das Angio-CT von 73,3%, die Angiographie von 66,6% und die PTP von 76,9%. Intraoperativ waren 95,2% der Geschwulste palpabel und die intraoperative Sonographie hatte eine Sensitivitat von 81,2%. In der BRD werden laut Umfrage mit Ausnahme einer Klinik immer eine Sonographie und eine Computertomographie und in 83,8% eine Angiographie gefordert. Eine praoperative Lokalisationsdiagnostik ist beim organischen Hyperinsulinismus nicht zwingend notwendig, sie hat jedoch nach wie vor ihre Bedeutung.
The Mechanism of Action of Carbonic Anhydrase
1990
A survey of the structure-function relationship in the enzyme carbonic anhydrase is presented. The coordination number around the metal ion in derivatives inhibited with some anions is stressed as well as the role of the cavity in determining the coordination number. Inferences on the enzyme-substrate interactions are presented.
Fluorimetric determination of 1-naphthol and mixtures of carbaryl and 1-naphthol in micellar media
1990
The interaction of 1-naphthol with different types of anionic, cationic and non-ionic surfactants has been studied spectrofluorimetrically in order to obtain a sensitivity enhancement in the determination of this compound. At neutral pH, cetyl trimethyl ammonium bromide (CTAB) provides a 2-fold sensitivity enhancement of 1-naphthol and exhibits a weak interaction with carbaryl. In strong alkaline medium carbaryl is hydrolyzed to 1-naphthol and in the presence of CTAB micells, a 5-fold sensitivity enhancement and a limit of detection of 0.2 μg·ml−1 with a 101±3% percentage of recovery is obtained. These facts permit the development of an accurate method for the fluorimetric analysis of 1-nap…
Calculation of voltammetric peaks by the transformed Heyrovsky-Ilkovi? equation
1990
Calculating real polarographic or voltammetric peaks is rather difficult. A new possibility to compute such peaks is the use of the transformed Heyrovsky-Ilkovic equation. The calculation allows to simulate polarograms or voltammograms by computer. Furthermore, it is possible to smooth voltammetric peaks without loss of peak height or separation of overlapping peaks.
On-line microwave oven digestion flame atomic absorption analysis of solid samples
1990
Abstract A manifold has been developed for on-line microwave oven digestion and flame atomic absorption spectrometric (FAAS) determination of metallic elements in solid samples. The use of a closed flow system permits sample treatment before analysis by FAAS, the direct injection of slurries avoids a filtration step and the interconnection of two conventional rotary injection valves allows the rapid introduction of samples and standards. The determination of lead in sewage sludge was employed as a test system for the proposed on-line sample digestion manifold. The procedure has a limit of detection of 0.2 μg Pb g−1.
Investigations of the Microstructure of Lipid Interface Films
1990
The phase behaviour of phospholipid monolayers at electrolyte/gas interfaces is studied by fluorescence microscopy. At the LE/LC phase transition, phase separation leads to a Wigner-type lattice structure. The observations are quantified using digital image processing. The results show that the phase transition comprises three different regimes.
PROTONIUM: The Mainz Cascade Model
1990
Recent experiments at LEAR have studied extensively the properties of antiprotonic hydrogen, often also called protonium.
A Precise Determination of the Number of Families With Light Neutrinos and of the Z Boson Partial Widths
1990
Title : The socialization at work in the federal universe, the determining element of the social regulation of the sports organization. Contribution to the social politics of the sport service of Nice city Abstract : This study postulates the existence of certain specific cultural determinism in the social regulation of the sports organization. It leans on a work of inquiry which concerns 148 agents of the municipal service of the sports of the Nice city. The investigation puts in evidence a causal report between the type of trajectory of professional insertion of the municipal agents and their level of support in the manager politics of the organization. The agents, whose bibliographic rou…
Els malnoms d'Atzeneta
1990
Els malnoms d'Atzeneta
L'aide à la décision à l'échelon local ou régional
1990
International audience
Abduction saccades in unilateral internuclear ophthalmoplegia
1990
Horizontal eye movements were investigated in 60 consecutive patients with unilateral internuclear ophthalmoplegia utilizing direct current electrooculography. In nine patients additional conjugated slowing of ipsiversive saccades indicated the diagnosis of a one-and-a-half syndrome. Slowing of abduction saccades was bilateral in two patients and unilateral in 20 (ipsilateral to the MLF lesion in 17 patients and contralateral in three). Slowing of abduction saccades was attributed to impaired inhibition of the tonic resting activity of the antagonistic medial rectus muscle. On the eye contralateral to the lesion 70% of the patients had abduction nystagmus and 66.7% hy permetric abduction sa…
Un intento de autonomía universitaria: el fracaso de la reforma Silió de 1919
1990
La reforma de 1919 del ministro César Silió por decreto, no llegó a implantarse, aunque se redactaron y aprobaron los estatutos de loa universidades. Fue el primer intento de su autonomía.
Valence electronic structure of polystyrenes with different tacticities : how to go (or not to go) too far ? A joint theoretical and experimental app…
1990
Abstract Monochromadzed Al-K α XPS spectra from iso- and syndiotacdc polystyrenes are analyzed with the help of theoretical band structures and densities of states produced from a valence effective Hamiltonian (VEH) computation scheme. A discussion of the correlations found between the experimental and theoretical results points out to the potentialities but also to the limits of both methods.
Triply factorized groups
1990
Transport- und Regelprozesse
1990
Die Funktionen der Zellen und Gewebe — Stoffwechsel, Reproduktion, Wachstum, Regeneration, Kontraktion, Sekretion und Erregbarkeit — erfordern einen standigen Transport von Stoffen und Flussigkeiten innerhalb des Organismus. Sauerstoff und Nahrstoffe mussen laufend den Zellen zugefuhrt, Kohlendioxid und andere Stoffwechselendprodukte an die Umgebung abgegeben werden. Voraussetzung fur den kontrollierten Ablauf der Stoffwechsel- und Erregungsprozesse sind ferner bestimmte Ionenkonzentrationen innerhalb der Zellen, die durch spezifische Transportsysteme der Zellmembran aufrechterhalten werden. In Abhangigkeit von der Flussigkeitsaufnahme und -ausscheidung vollzieht sich schlieslich der Flussi…
Thury
1990
Formation et insertion des apprentis de niveau V, quelle relation rétablir ?
1990
International audience
Walsh function analysis of 2-D generalized continuous systems
1990
The importance of the generalized or singular 2D continuous systems are demonstrated by showing their use in the solution of partial differential equations in two variables. A technique is presented for solving these systems in terms of Walsh functions. The method replaces the solution of a two-variable partial differential equation with the solution of a linear algebraic generalized 2D Sylvester equation. An efficient technique for the recursive solution of the latter equation is offered. All the results apply also in the usual Roesser 2D state-space case. >
Katheter und Drainagen
1990
Die Endotrachealintubation hat sehr haufig eine Tubusfehlposition zur Folge. Daher ist eine rontgenologische Positionskontrolle des Endotrachealtubus nach jeder Intubation unbedingt notwendig. Jede Rotation und Flexion des Kopfes fuhrt zu einer Verschiebung des Tubus bis zu maximal 1,5 cm.
Arterial O2-Partial Pressure at Positve Endexpiratory Pressure in Hyperoxia for Verification of Patent Foramen Ovale?
1990
As a rule, during anaesthesia a time dependent increase in pulmonary shunting occurs even in states of normal lung function. Therefore positive end-expiratory pressure ventilation (PEEP) is often used to decrease intrapulmonary right/left shunting (RL shunt) and thus to increase arterial O2 partial pressure (paO2) without increasing the inspiratory oxygen fraction.
Gender differences in social and test anxiety
1990
Abstract Some cognitive and performance correlates of ‘worry’ and ‘emotionality’ components of test-anxiety were studied with particular reference to gender differences. An Italian adaptation of the Worry-Emotionality (W-E) Scale was administered to a sample of 99 high-school students, together with other scales devised to assess ‘Fear of negative evaluation’ and the subjects' perception of the real, ideal and social aspects of the Self. The Grade Point Average was taken as outcome measure of academic performance. The results show that in the male subjects, Worry correlates, as expected, with poor self-image and with negative academic performance; more complex correlations are found in fema…
Early Pan-African evolution of the basement around Elat, Israel,and the Sinai Peninsula revealed by single-zircon evaporation dating, and implication…
1990
We report 2<r7Pb/206Pb single-zircon evaporation ages for early Pan-African rocks from southern Israel and the northeastern Sinai Peninsula, the northernmost extension of the Arabian-Nubian shield. The oldest rocks are metamorphic schists of presumed island-arc derivation; detrital zircons date the source terrain at ca. 800-820 Ma. A major phase of tonalite-trondhjemite plutonism occurred at ca. 760-780 Ma; more evolved granitic rocks were emplaced at about 745 Ma. A metagabbro-met adiorite complex reflects the youngest igneous phase at ca. 640 Ma. We Find no evidence for pre-Pan-African crust, and our data document important crust-forming events that correlate with similar episodes elsewhe…