showing 36 of ~574560 from 574555 documents
Flow-injection spectrophotometric determination of arylamines and sulphonamides by diazotization and coupling in a micellar medium
1991
Abstract In a sodium dodecyl sulphate (SDS) micellar solution, the rate of coupling of a diazonium ion with N-(1- naphthyl)ethylenediamine (NED) increases greatly, the protonation of the resulting azo dyes takes place at higher pH values and the dyes are more soluble. These favourable features were applied to the development of a simple flow-injection spectrophotometric procedure for the determination of diazotizable substances of pharmaceutical interest. Limits of detection in the range 0.2–0.5 μg ml−1 (signal-to-noise ratio=3), with relative standard deviation of 0.7–3% (n=3) for 5 μg ml−1 standards, were obtained.
Polymerizable and polymeric zwitterionic surfactants: 2. Surface activity and aggregation behaviour in aqueous systems
1991
Abstract The surfactant properties of a series of permanently zwitterionic monomers and polymers were studied with respect to structural variations. A strong influence of the molecular geometry on solubility and aggregation behaviour was observed, in particular for the polymers. Whereas all monomers were water-soluble and true surfactants, the water solubility of the polymers was restricted to selected geometries. Water-soluble polymers showed the properties of classical polysoaps, i.e. low surface activity and solubilization power for hydrophobic solutes. In contrast, water-insoluble polymers formed stable monolayers at the air-water interface and could be deposited onto solid substrates b…
Un posible centro de documentación: las Cortes valencianas de época foral
1991
Pinturas esquemáticas del abrigo del Espolón del Zapatero (Quesa, Valencia)
1991
Clarification of the Three-Body Decay of 12C (12.71 MeV)
1991
Using β decays of a clean source of 12 N produced at the IGISOL facility, we have measured the breakup of the 12 C (12.71 MeV) state into three α particles with a segmented particle detector setup. The high quality of the data permits solving the question of the breakup mechanism of the 12.71 MeV state, a longstanding problem in few-body nuclear physics. Among existing models, a modified sequential model fits the data best, but systematic deviations indicate that a three-body description is needed. peerReviewed
Photon Scanning Tunneling Microscopy and Reflection Scanning Microscopy
1991
The Photon Scanning Tunneling Microscope (PSTM) is the photon analogue to the Electron Scanning Tunneling Microscope (ESTM). It uses the evanescent field due to the total internal reflection (TIR) of a light beam in a prism modulated by a sample attached to the prism. The exponential decay of the evanescent field is characterized by the penetration depth dp and depends on the angle of incidence θ, the wavelength and polarization of the incident beam. Changes in intensity are monitored by a probe tip scanned over the surface, and the data are processed to generate an image of the sample. Images produced by a prototype instrument are shown to have a vertical resolution of about 3 A and a late…
Bakterielle Exotoxine und ihre mögliche Relevanz für die Pathogenese des septischen Schocks
1991
Die Mehrzahl menschenpathogener Bakterien produziert Exotoxine, deren primarer Angriff auf die Plasmamembran der Zielzellen gerichtet ist. Ein Hauptmechanismus fur diese Schadigung besteht in der Bildung von Poren, welche die Membran durchlochern und zum raschen Zusammenbruch des lebensnotwendigen „milieu interieur“ der Zelle fuhren. Prototypen solcher Porenbildner sind das α-Toxin von S. aureus, die Familie der sulfhydryl-aktivierten Toxine (mit Streptolysin-O als ein Hauptvertreter) sowie die in jungster Zeit entdeckte Familie der mit dem E. coli-Hamolysin verwandten Toxine [1, 2]. Bislang wurde membranschadigenden Toxinen wenig Beachtung als moglichen Pathogenitatsfaktoren geschenkt. In …
An Urbanistic Project Based on General Systems Theory
1991
This paper intends to be an outline of the Urbanistic Development Planning of the Valencian Community in Spain to be performed during the years 1991 to 1993, The following are considered as objectives of the Planning: – Quality of Life improvement, – protection of Nature, – rational management of natural resources, – rational use of land; all based on social demand. The territory and the mechanism of intervention is considered as a system whose elements can be grouped as: – uses of land, – infrastructure, equipment, services, – objectives, – intervention and management. The Planning proposes itself to be: integral, strategic, prospective, programmed, controllable and participative, A simula…
Evaluación de la actividad electrodérmica y relación con el cuadro clínico en pacientes esquizofrénicos
1991
On Optic Aphasia and Visual Agnosia
1991
Abstract The following is a translation from a paper by Freund published in two parts almost exactly 100 years ago. It is based on a talk he gave on February 23rd, 1888 at a meeting, chaired by Wernicke, of the Society of East German Psychiatrists at Breslau. A brief report of the proceedings of the meeting appeared in the same year under the title Einige Grenzfalle zwischen Aphasie und Seelenblindheit (Some borderline cases between aphasia and agnosia) (Freund, 1888). This is presumably why the first part, published in 1889, has the heading II before its title Ueber optische Aphasie und Seelenblindheit.
Herbicidal activity of derivatives of 9-aminofluoren-9-ylphosphonic acid
1991
A series of derivatives of 9‐aminofluoren‐9‐ylphosphonic acid (phosphonic analogues of morphactins) were synthesized and screened for herbicidal activity against Lepidium sativum, Cucumis sativus and Lycopersicon esculentum. Ethyl 9‐(N‐alkylamino)fluoren‐9‐yl(phenyl)phosphinates appeared to be equipotent with glyphosate and thus may be recognized as new lead compounds for further structural modifications.
Bastiones de resistencia en Castilla-La Mancha : el caso de Villamalea
1991
El objetivo de esta ponencia es resumir la intervención que tuve en el seminario organizado por la Universidad de Castilla-La Mancha-Fundación lº de Mayo en torno al tema "Colaboración, pasividad v enfrentamiento: tres actitudes colectivas ante el Franquismo". Mi intervención va a referirse a la actitud colectiva de enfrentamientos de un pueblo campesino-Villamalea- contra la dictadura del general Franco, a lo largo de más de treinta años. Este trabajo solo pretende ofrecer una primera aproximación general con el objetivo de dar a conocer el fenómeno político de este municipio. En primer lugar quiero señalar, a forma de introducción, que la lucha y los enfrentamientos contra el franquismo e…
أزمة الجامعات الفرنكوفونية في أفريقيا جنوب الصحراء
1991
International audience; Les responsables des universités francophones en Afrique subsaharienne sont confrontés à un cruel dilemne : au fil des années, leur budget leur permet de moins en moins d'assurer un fonctionnement décent de leur établissement, d'où une baisse de la qualité des diplômés et de la recherche ; dans le même temps, un certain nombre d'études montrent que les coûts unitaires y sont trop élevés, que l'enseignement supérieur reçoit une proportion trop forte des crédits d'éducation et que la cure d'amaigrissement de leur budget doit être prolongée et accentuée. L'objectif de cet article est d'abord de confirmer, par des données, les énoncés de ces deux diagnostics apparemment …
Modificaciones fisarias en la rata tras enclavijamiento: estudio comparativo entre implantes plásticos y metálicos
1991
El presente trabajo se efectuó para estudiar las modificaciones locales inducidas por implantes que atraviesan el cartílago de crecimiento. Se utilizaron 20 ratas macho de 5 semanas de edad. A través de una incisión parapatelar externa se insertó una aguja de Kirschner en el fémur derecho y una de plástico en el izquierdo, ambas de 1 mm de diámetro, atravesando la placa fisaria distal. Cinco animales por grupo fueron sacrificados al cabo de 1,2,8 y 16 semanas. Tras denudar los fémures de partes blandas, su extremidad distal fue procesada para estudio histológico, histomorfométrico e histoquímico. Los resultados demuestran que desde la segunda semana la fisis tuvo mayor altura en los fémures…
Physiological and Structural Changes in Tobacco Leaves Treated with Cryptogein, a Proteinaceous Elicitor fromPhytophthora cryptogea
1991
Cryptogein was applied on the petiole section of excised tobacco leaves. It elicited necroses that can be correlated with histological alterations, such as rapid chloroplast breakdown and a collapse of cells leading to disorganization of the parenchyma tissue. In addition, it induced ethylene production and accumulation of capsidiol. In order to detect an early response, we analyzed the kinetics of chlorophyll fluorescence induction (...)
Notes sobre la toponímia medieval de la comarca dels Ports
1991
Notes sobre la toponímia medieval de la comarca dels Ports
Les fouilles du Mont-Beuvray : Rapport biennal 1988-1989
1991
International audience
Funkcja imidazolowa histydyny w syntezie peptydów
1991
Study of diuron in soil solution by means of a novel simple technique using glass microfibre filters
1991
International audience
Monte Carlo simulation of phase separation and clustering in the ABV model
1991
As a model for a binary alloy undergoing an unmixing phase transition, we consider a square lattice where each site can be either taken by an A atom, a B atom, or a vacancy (V), and there exists a repulsive interaction between AB nearest neighbor pairs. Starting from a random initial configuration, unmixing proceeds via random jumps of A atoms or B atoms to nearest neighbor vacant sites. In the absence of any interaction, these jumps occur at jump ratesΓ A andΓ B, respectively. For a small concentration of vacancies (c v=0.04) the dynamics of the structure factorS(k,t) and its first two momentsk 1(t),k 2 2 (t) is studied during the early stages of phase separation, for several choices of co…
Analysis of Infrared and Raman-Spectra of 116SnH4 in the 1900 cm-1 Region - Study of the 1000, 0010 Interacting States
1991
0022-2852
Iconografía de urnas cinerarias romanas en los grabados de Carlo Antonini
1991
CARLO ANTONINI, PERTENECIENTE A LA ESCUELA ROMANA, A CABALLO ENTRE LOS SIGLOS XVIII Y XIX, FUE UN DESTACADO ARQUITECTO, DIBUJANTE Y GRABADOR. EN 1821 PUBLICO UN MANUAL DE TRES VOLUMENES EN EL QUE SE PRETENDIA DAR A CONOCER LAS COLECCIONES DE VASOS ANTIGUOS DE LOS MUSEOS VATICANOS Y OTRAS GALERIAS DE ROMA. EN EL PRIMER VOLUMEN SE OCUPO DE LOS VASOS ANTIGUOS DEL MUSEO PIO-CLEMENTINO. DESCRIBE LAS PIEZAS E INCLUYE GRABADOS DE LAS MISMAS. SUS INSCRIPCIONES Y SU DECORACION PERMITEN ANALIZARLAS ICONOGRAFICAMENTE, PUDIENDO CONCLUIR QUE TODOS PRESENTAN, CON VARIANTES, TEMAS PARECIDOS RELACIONADOS CON LA INMORTALIDAD. (A.B.C./ L.A.G.)
The avian oesophageal motor function and its nervous control: some physiological, pharmacological and comparative aspects.
1991
1. This paper deals with the avian oesophageal motor function and it attempts to draw some comparative aspects between neural regulation of the avian and mammalian oesophagus. 2. Different from the mammalian oesophagus, the avian oesophagus, presents at rest electrical activity associated to spontaneous contractions. 3. Swallowing elicits peristaltic contraction, characterized by an inhibitory and an excitatory component. 4. Non-adrenergic, non-cholinergic neurons are responsible for the inhibitory component. 5. Contrarily to what observed in mammals, where the peripheral mechanism are important for the peristaltic sequence, the primary peristaltism of birds seems to be entirely mediated by…
Du duché capétien au rêve d'un royaume entre la France et l'Allemagne : la grande aventure des ducs Valois, leur rôle dans le développement de l'idée…
1991
International audience
Theoretical EHT study of oxidative coupling of methane on pure MgO and MgO doped with Li and Na
1991
Abstract On the basis of Extended Huckel Theory, empirical studies on the oxidative coupling of methane with MgO pure and MgO doped with Li and Na are presented. The results obtained from the two-dimensional energy surfaces calculated for the interaction between linear clusters of these oxides and the methane molecule show a qualitative agreement with the experimental behaviour reported for these catalysts. The calculated activation energy barriers are in accord with the relative activities of these oxides (Li/MgO > Na/ MgO > MgO) and are of the same order of magnitude as the experimentally determined activation energies.
In vitro production of anti-neutrophilocyte-cytoplasm-antibodies (ANCA) by Epstein-Barr virus-transformed B-cell lines in Wegener's granulomatosis.
1991
The frequent detection of anti-neutrophilocyte-cytoplasm-antibodies (ANCA) in patients with Wegener's granulomatosis (WG) led to the supposition that this disease might be of autoimmune nature. For some authors assume that Epstein-Barr virus (EBV) infection of human B-lymphocytes besides polyclonal activation could reveal the cryptic immune status against different autoantigens in patients with autoimmune diseases we investigated EBV-transformed B-lymphocytes from patients with Sjögren's syndrome, mixed connective tissue disease, WG and healthy blood donors. Two stable B-cell lines (Ho3, We1) could be established. Inhibition experiments showed that antibodies produced by transformed B-lymph…
Panorama actual de la filosofía analítica de la mente: funcionalismo y experiencia
1991
Este capítulo del libro Filosofía analítica hoy expone las diferentes variantes de funcionalismo en filosofía de la mente y valora su capacidad para dar cuenta de la naturaleza cualitativa de la experiencia.
Teoría del montaje cinematográfico
1991
Montaje es un término técnico que en lengua española designa lo que en inglés es editing. Sin embargo, el mismo término tiene una dimensión más amplia y ambiciosa que la estética ha empleado para referirse al arte moderno, desde las técnicas de collage hasta las amalgamas más recientes. En realidad, el concepto está íntimamente unido a una red semántica que define la modernidad: maquinismo (cadena de montaje) y fragmentación (arte de vanguardia). Así pues, el término montaje puede aplicarse al cine para definir en él lo que lo convierte en históricamente hijo de la modernidad y lo que comparte con los movimientos de vanguardia que surgen durante su infancia, sin necesariamente ponerse en re…
Methodische Voraussetzungen für die Diagnose und Verlaufskontrolle von Neuropathien
1991
Unter dem Begriff der Neuropathie versteht Dyck [5] alle Storungen, die primar das periphere Neuron schadigen. Damit werden auserst heterogene Erkrankungen des peripheren Nerven zusammengefast, wobei meist die genaue Kenntnis der Krankheitsursache fehlt und oft auch wenig uber die Pathogenese bekannt ist. Aus dieser Unkenntnis vieler wichtiger Faktoren resultieren die verschiedensten Einteilungsschemata, die sich aus einer unterschiedlichen Gewichtung klinischer, anatomischer und physiologischer Kriterien ergeben. Mit Hilfe elektrophysiologischer Methoden konnen einige funktionelle Aspekte erganzt werden, keineswegs wird dadurch aber eine genauere Wertung morphologischer oder klinischer Asp…
Hormonmangelsyndrom des unteren Harntraktes
1991
In der Postmenopause finden sich gehauft unspezifische Beschwerdebilder im Sinne einer Reizblase, bzw. eines Urethralsyndroms, evtl. in Kombination mit Inkontinenzbeschwerden. Die gemeinsame Embryologie von Urethra und Vagina, zusammen mit den in Urethra und Blasenhals nachgewiesenen Hormonrezeptoren erklart die hormonabhangigen trophischen Veranderungen im Urogenitalbereich. Die einfache Untersuchung des Urethral- und Vaginalabstriches mit Bestimmung des karyopygnotischen Indexes (KPI) last eine Beurteilung der Ostrogenwirkung zu. Bei entsprechendem Mangelsyndrom fuhrt eine kontinuierliche, uber mindestens 6 bis 8 Wochen durchgefuhrte lokale Ostrogentherapie zu einer deutlichen Tonus- bzw.…
A note on strongly Lie nilpotency
1991
In this note the authors studies strongly Lie nilpotent rings and proves that if a ringR is strongly Lie nilpotent thenR(2), the ideal generated by all commutators, is nilpotent.
Triazolopyridines. Part 11. Ylides derived from 2-Acylmethyltriazolopyridinium salts.
1991
Abstract Ylides derived from 2-acylmethyltriazolopyridinium salts (2a) -(2c) react with methyl or ethyl propiolate and with dimethyl acetylenedicarboxylate to give ylides (3a)–(3e), (6) or (7). In some cases 1:2 adducts are formed, shown to be the novel ylides (8a)–(8d); an X-ray diffraction confirms structure (8a).
Mapping of phenytoin-inducible cytochrome P450 immunoreactivity in the mouse central nervous system
1991
Abstract The distribution of phenytoin-inducible cytochrome P450 in non-treated mouse brain and spinal cord was analysed immunohistochemically using polyclonal antibodies against phenytoin-induced mouse cerebral microsomal P450. This P450 protein was proved in Ouchterlony [Volk B. et al. (1988) Neurosci. Lett. 84 , 219–224], Western blot, and immunohistochemical analyses to be reactive to the specific antibodies and an IgG fraction raised against phenobarbital-induced rat liver microsomal P450IIB1. The phenytoin-induced P450 is designated P450IIB1 * because immunologically it is comparable with P450IIB1; however, it has not yet been analysed for other characteristics of this enzyme. Immunoc…
Influence of nitrogen on accumulation of isosojagol ( a newly detected coumestan in soybean ) and associated isoflavonoids in roots and nodules of my…
1991
International audience
Antineoplastika, 17. Mitt.1): Darstellung mono- und disubstituierter 2,4-Dichlor-6-diethylamino-1,3,5-triazine
1991
Die Umsetzung von 2,4-Dichlor-6-diethylamino-1,3,5-triazin (1) mit den sekundaren Aminen 2a-g fuhrt zu den Diamino-1,3,5-triazinen 3a-g und den Melaminen 4a und 4b. Die Struktur der Endprodukte wird durch die IR-, 1H-NMR- und Massenspektren charakterisiert. Antineoplastic Agents, XVII: Mono- and Disubstituted 2,4-Dichloro-6-diethylamino-1,3,5-triazines The reactions of 2,4-dichloro-6-diethylamino-1,3,5-triazine (1) with the secondary amines 2a-g lead to the diamino-1,3,5-triazines 3a-e and the melamines 4a and 4b. The structures of the reaction products were established spectroscopically (IR, 1H-NMR, and MS).