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  • Artikel: DFG Deutsche Nationallizenzen  (249)
  • 1970-1974  (249)
  • 1965-1969
  • 1955-1959
  • 1920-1924
  • 1973  (249)
  • Computational Chemistry and Molecular Modeling  (108)
  • Biochemistry and Biotechnology  (106)
  • Electron Microscopy
Datenquelle
  • Artikel: DFG Deutsche Nationallizenzen  (249)
Materialart
Erscheinungszeitraum
  • 1970-1974  (249)
  • 1965-1969
  • 1955-1959
  • 1920-1924
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 23 (1973), S. 133-140 
    ISSN: 1432-0533
    Schlagwort(e): Metachromatic Leukodystrophy ; Neuronal Inclusions ; Laminated Bodies ; Mucopolysaecharides ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The ultrastructural findings of the metachromatic granules in the anterior horn cells of the spinal cord in a case of metachromatic leukodystrophy are presented. The typical neuronal inclusions are concentrically laminated bodies of approximately 1 μ. In addition various morphological variations of the abnormal inclusions are seen side by side in the same neuron and give the impression that the highly organized laminated bodies are formed as a result of progressive deposition of membranous material upon a nidas which is initially amorphous, which then becomes granular, fibrillar or horizontally striped and finally multilaminated. Material capable of binding colloidal iron particles is demonstrated in these inclusions, and suggests the presence of mucopolysaccharides.
    Materialart: Digitale Medien
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  • 2
    ISSN: 1432-0533
    Schlagwort(e): Electron Microscopy ; Encephalomyocarditis (EMC) Virus ; Neurotrophic Viruses ; Viremia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary One hundred and eighty 12 week old Swiss mice were injected subcutaneously with 0.1 ml suspensions of the E and M variants of encephalomyocarditis (EMC) virus. Ninety-seven surviving mice were sacrificed at intervals from 24 h to 21 days following injection. The M variant group showed only mild microglial proliferation in the brain, while the E variant group displayed various alterations in the astrocytes and neurons exhibiting loss of nuclear membranes and marked changes in the mitochondria and other organelles. In addition, the neuronal cytoplasm displayed aggregates of fine electron-dense granules on the third day which increased in size during the fifth to seventh day. After 7 days, the neurons contained occasional rhomboid structures composed of rows of parallel arranged granules which were similar to those observed in the viscera after EMC virus infection.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 24 (1973), S. 62-67 
    ISSN: 1432-0533
    Schlagwort(e): Dystrophia Myotonica ; Electron Microscopy ; „Fingerprint Inclusions” in Muscle Fibres
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary „Fingerprint inclusions” were observed in numerous muscle fibres of 3 cases of dystrophia myotonica studied by electron microscopy in two different laboratories. They consist of parallel or concentric palisades of short electron dense linear elements. Identical „fingerprint inclusions” were reported in two other clinical conditions and cannot therefore be regarded as specific for a particular muscle disease. Their origin and significance remain obscure.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 26 (1973), S. 45-57 
    ISSN: 1432-0533
    Schlagwort(e): Electron Microscopy ; Extracellular Fibrils ; Neurologia ; Retina ; New Formation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Extracellular formation of microfibrils was observed in the cavities of peripheral cystoid degeneration in senile human eyes. The ultrastructure of the fibrils is described and the source of production of the fibrillar material is discussed. It originates most probably from neurological cells, within or surrounding the cysts.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 25 (1973), S. 1-13 
    ISSN: 1432-0533
    Schlagwort(e): Electron Microscopy ; Myxopapillary Ependymoma ; Basement Membrane ; Filum Terminale ; Collagen
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A fine structural study of a myxopapillary ependymoma of the filum terminale confirms and emphasizes the distinctive morphological features of this tumor. Electron basement membrane production were identified. It is suggested that they are related to the growth of ependymal tumor cells in juxtaposition to the collagen normally present in the conus medullaris and filum terminale.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 25 (1973), S. 207-219 
    ISSN: 1432-0533
    Schlagwort(e): Aujeszky's Disease ; Inoculation ; Virus Particles ; Electron Microscopy ; Neuronal Degeneration ; Demyelination ; Axoplasmic Transport
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Sixteen calves were killed at intervals during the course of the disease from 48 h onwards after subcutaneous infection with Aujeszky's disease virus. Ultrastructural changes were evident in the spinal ganglia from 84 h post-inoculation and the intercostal nerves from 96 h post-inoculation. The cytopathic changes in the spinal ganglia consisted of neuronal degeneration, neuronophagia, Schwann cell degeneration and cellular infiltration. The neuronophagic nodule was invariably contained within an intact sheath of satellite cells. Changes in the intercostal nerves were less dramatic but cellular infiltration was frequently seen and occasional Schwann cells were degenerate. In the terminal stages of the disease demyelination was rarely observed. In the ganglion virus was invariably seen in degenerating neurons and occasionally in Schwann cells and monocytes. Satellite cells were rarely infected even when ensheathing an infected neuron. Extra-cellular virus was not observed in ganglia or nerves. Schwann cells and monocytes in the nerves were occasionally infected. Virus particles were seen in the axoplasm both in the ganglion and in the entire length of the nerve. The particles in the axoplasm varied in morphology; thus unenveloped and enveloped particles, and particles in the process of acquiring an envelope were recognised. It was concluded that the neural pathway of Aujeszky's disease virus is probablyvia the axoplasm.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1432-0533
    Schlagwort(e): Tissue Culture ; Electron Microscopy ; Enzyme Histochemistry ; Sympathetic Ganglioneuroblastoma ; Medulloblastoma
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The results of combined tissue culture, ultrastructural and enzyme histochemical investigations carried out on a sympathetic ganglioneuroblastoma are reported.In vitro a vigorous sprouting of newly formed neuritic processes was observed a few days after explantation. The enzymatic reactions for acethylcholinesterase were positivein situ as well asin vitro. The tumor elements showed the ultrastructural characteristics of nerve cells with many microtubuli and filaments, plenty of ribosomes, well developed endoplasmic reticulum. Dense bodies, corresponding to neurosecretion granula (catecholamines) were also observed. Synaptic structures were missing. The results of these investigations confirm that this kind of tumor is different from so-called medulloblastoma.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 23 (1973), S. 23-31 
    ISSN: 1432-0533
    Schlagwort(e): Chronic Polymyositis ; Virus-Like Particles ; Electron Microscopy ; Paramyxovirus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Electron microscopic examination of a biopsy of skeletal muscle from a young girl with chronic polymyositis revealed the presence of sarcoplasmic and perinuclear inclusions. A large number of virus-like particles was demonstrated at the surface of muscle cells and in extracellular space. On the basis of the microscopic appearance it is suggested that the virus particles belong to one of the members of the paramyxovirus group.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 24 (1973), S. 273-286 
    ISSN: 1432-0533
    Schlagwort(e): Muscle ; Acromegaly ; Histochemistry ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Muscle biopsies from 9 acromegalics were examined by conventional histological and histochemical techniques. Six biopsies were also examined with the electron microscope. Isolated fibre necrosis or vacuolar degeneration was found in 3 biopsies and increased numbers of internal nuclei in 5 biopsies. A high glycogen content was demonstrated in many fibres in each biopsy by the PAS method and by electron microscopy. Routine enzyme histochemical techniques showed hypertrophy of type I and type II fibres in 2 subjects, hypertrophy of type I fibres only in 2 subjects, atrophy of both fibre types in 2 subjects and atrophy of type II fibres only in 4 subjects. Electron microscopy showed large amounts of lipfuscin pigment in many fibres while some fibres had large sarcolemmal nuclei with prominent nucleoli, and a prominent Golgi apparatus. Satellite cells were found in 3 biopsies. In one biopsy coiled membranous configurations thought to consist of phospholipids, and tubular aggregates thought to be derived from degenerating mitochondria were present at the periphery of a number of type II fibres. It is postulated that some of the ultrastructural changes found in muscle fibres are the result of the growth hormone-induced hypertrophic process and the increased turnover of cytoplasmic components associated with it while others reflect the atrophic process in some muscle fibres.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 24 (1973), S. 345-349 
    ISSN: 1432-0533
    Schlagwort(e): Cockayne's Syndrome ; Peripheral Nerve ; Electron Microscopy ; Demyelination
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The ultrastructure of sural nerve biopsies was studied in two sisters with Cockayne's syndrome. Both had severe physical and mental retardation and evidence of peripheral neuropathy. Striking alterations in the myelin sheath with relative preservation of the axis cylinder were noted in both. There were also electron dense bodies in the Schwann cells. These findings support the suggestion that Cockayne's syndrome may be a form of leukodystrophy.
    Materialart: Digitale Medien
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 26 (1973), S. 259-264 
    ISSN: 1432-0533
    Schlagwort(e): 6-Aminonicotinamide ; Tissue Culture of Chick Spinal Cord ; Electron Microscopy ; Neurotoxic Effects ; Glucose-6-Phosphate Dehydrogenase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Well myelinated cultures of chick embryo spinal cord were exposed to medium containing 6-aminonicotinamide in a concentration of 0.5 mmol for up to 48 h. By 24–48 h of exposure to the antivitamin, neurons showed a granulovacuolar degeneration which later led to the formation of large vacuoles in the neuronal perikarya. Myelin degeneration was also observed in this period in the form of swelling, beading and ballooning. Electron microscopy revealed moderately swollen mitochondria and dilated endoplasmic reticulum as the earliest neuronal change. Later, neurons became pyknotic and the cytoplasmic organelles disintegrated. Presynaptic endings and glial cells, however, was spared any degenerative change. Intermittent and irregular splitting of myelin lamellae were also observed along the intraperiod lines. Biochemical assay of the glucose-6-phosphate dehydrogenase activity in the experimental cultures showed that 45% of the enzyme activity was lost during the 30-h period. It is concluded that the formation of 6-aminonicotinamide analogues of NAD and NADP coenzymes leads to the impairment of the pentose phosphate pathway and the glucose turnover, and thus produces neurotoxic effects in the central nervous system.
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 26 (1973), S. 275-284 
    ISSN: 1432-0533
    Schlagwort(e): Minimata Disease ; CNS Degenerative Disorder ; Mercury Poisoning ; Focal Demyelination ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A case of suspected mercury poisoning (Minamata disease) was studied. Microscopic and ultrastructural changes in the nervous system were compared with those of a confirmed case of mercury poisoning from Minamata Bay, Japan, and those from exprimental animals intoxicated with methyl mercury. Disintegration of the granular layer, disappearance of the Purkinje cells with Bergmann's fiber proliferation and demyelination of the fiber tracts were observed in the cerebellum. Ultrastructural examination also revelad extensive proliferation of astrocytic fibers and characteristic focal demyelination and loosening of the myelin sheaths in many nerve fibers. Such pathological changes were consistent with those observed in both human cases and experimental animals poisoned by methyl mercury.
    Materialart: Digitale Medien
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  • 13
    ISSN: 1432-0533
    Schlagwort(e): Cerebral Ischaemia ; Recirculation ; Enzyme Histochemistry ; Electron Microscopy ; Dendrite Swelling ; Pinocytosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Complete cerebral ischaemia of 30 and 90 min was produced in normothermic barbiturized cats by clamping the innominate and subclavian arteries and lowering the systemic blood pressure. When the brains were adequatly recirculated after 30 min of ischaemia, electron microscopical and histochemical changes observed at the end of the circulatory arrest, were almost fully reversible. Endothelial cells of capillaries showed increased number and size of pinocytotic vesicles and numerous intraluminal flaps. ATPase activity was increased in the capillary walls and glial cells. Opposite to this, severe and irreversible ultrastructural changes were observed after 90 min of ischaemia, and all the enzyme activities studied were sharply decreased.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 23 (1973), S. 265-280 
    ISSN: 1432-0533
    Schlagwort(e): Experimental Neurinoma ; Schwannoma ; Nitrosourea ; Tumor Trausplantation ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Nervous system tumors were induced in the offspring of BD-IX (inbred) and CFE (non-inbred) rats by transplacental administration of ethylnitrosourea. Tumors of the peripheral nervous system (PNS) were obtained in approximately 80% of all animals, and tumors of the central nervous system (CNS) in 16%. Although several peripheral nerves were sites of tumor formation, the trigeminal nerve was the most frequent nerve affected. In male CFE rats, 70% of all PNS tumors affected the trigeminal nerve. The incidence of trigeminal nerve tumors in female BD-IX rats was only 33% of PNS tumors. Light and electron microscopy showed that the PNS tumors are made-up of Schwann cells, and behave like malignant tumors. The tumors began as a proliferation of recognizable Schwann cells, later they lost their basement lamina, destroyed the nerve tissue and invaded neighboring structures, but did not metastasize. Like their human counterparts, they showed “dense” and “loose” areas. In both of these, Schwann cells were recognized as the tumor cells. Trigeminal nerve tumors were transplanted fromin vitro cultured cells or directly from transplanted fresh tumor fragments to isologous rats (BD-IX). Subcutaneous. intraperitoneal and intracerebral transplants were done. The morphology and behavior of the transplanted tumors were similar to the original malignant neurinomas.
    Materialart: Digitale Medien
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  • 15
    ISSN: 1432-0533
    Schlagwort(e): Chronic Progressive Ophthalmoplegia ; Cerebellar Ataxia ; Electron Microscopy ; Enzyme Histochemistry ; Mitochondria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Electron microscopic and enzyme histochemical studies were performed on the cerebellum and the ocular and deltoid muscles from a 38 year old woman who developed bilateral ptosis at the age of nine years. Histologically the cerebellum appeared normal. The biopsies of three ocular muscles showed varying sizes of muscle fibers which were rounded and contained increased numbers of subsarcolemmal nuclei. The deltoid muscle stained by hematoxylin and eosin appeared normal, but the trichrome stain showed increased numbers of red granules within the sarcolemma corresponding ultrastructurally to increased numbers of abnormal mitochondria. These abnormal mitochondria displayed increased reaction products with LDH, NADH and SDH preparations, while the muscle gave normal reaction in phosphorylase, PAS and myosin ATP preparations. Chemical studies on the cerebellum showed normal proteolipids, glycolipids and phospholipids. Ultrastructurally, the cerebellum, the myofibers of three ocular muscles and the deltoid muscle exhibited abnormal mitochondria which showed peculiarly arranged circular cristae. They frequently contained paracrystalline structures which consisted of individual tubules arranged in a helical pattern. Frequently, the abnormal mitochondria were replaced by dense rectangular inclusions and occasionally showed complete transition to crystalline structures.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 23 (1973), S. 9-22 
    ISSN: 1432-0533
    Schlagwort(e): Earliest Ischaemic Neuronal Change ; Astrocytic Swelling ; Mitochondrial Swelling ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A combined light and electron microscope study was made of the alterations occurring in the neurones and astrocytes of the neocortex and hippocampus of rats killed immediately after intermittent exposures to nitrogen of 5 and 15 min. Blood flow in the right common carotid artery had previously been interrupted by application of an artery clasp which was removed after the exposure to nitrogen and the animals killed by perfusion-fixation with glutaraldehyde. Microvacuolation (MV), the earliest stage of anoxic-ischaemic neuronal damage, was observed in the ipsilateral neocortex and hippocampus of both groups and ischaemic cell change (ICC) bilaterally in the neocortex of animals exposed for 15 min. Ultrastructural examination showed the microvacuoles to be swollen mitochondria. Slightly dense, mildly distorted, non-vacuolated neurones were also seen in the neocortex and hippocampus. They did not exhibit the ultrastructural changes seen in MV and ICC. Swollen astrocytic processes were sometimes seen around the damaged neurones, more frequently after 15 min exposure. Slight swelling of perivascular astrocytic processes was occasionally observed while the extracullular spaces in the neuropil remained unaltered. This implies that the accumulation of fluid in oedematous grey matter is confined to the astrocytic compartment. The reversibility or otherwise of all the neuronal alterations is discussed.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 25 (1973), S. 149-160 
    ISSN: 1432-0533
    Schlagwort(e): Nutritional Encephalopathy ; Brain Edema ; Vitamin E Deficiency ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Focal lesions were induced in the cerebellum by feeding chickens a diet high in unsaturated fats and deficient in vitamin E. Ultrastructurally, the lesions consisted of central and peripheral zones. The central zone was characterized in the cortex and white matter by enlargement of the intercellular space, swelling of astrocytes, vacuolization of oligodendrocytes, ballooning of nerve fibers, degenerative changes in small blood vessels, and extravasation of plasma and blood cells. The peripheral zone was characterized by enlargement of the intercellular space in the white matter, swelling of astrocytes in the cortex, and the accumulation of dark bodies in the endothelium of small blood vessels. The results suggest that this nutritional encephalopathy is caused by alterations in the permeability of the vascular bed due to the dietary stress of unsaturated fatty acids in the absence of vitamin E.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 23 (1973), S. 326-333 
    ISSN: 1432-0533
    Schlagwort(e): Hexachlorophene Intoxication ; Cerebral Edema ; Status Spongiosus ; Electron Microscopy ; Myelinopathy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Hexachlorophene intoxication produced cerebral edema in rats and mice characterized by the accumulation of fluid within myelin sheaths. Vessels remained impermeable to Trypan Blue. The amount of water in the brains of affected mice gradually returned to normal when the animals were put back on a normal diet. Correspondingly the status spongiosus decreased in severity in recovering animals. Some axonal degeneration occurred but there was no evidence of any breakdown of myelin lipids. The similarity of this encephalopathy to that seen following intoxication with triethyltin, isonicotinic acid hydrazide and cuprizone is emphasized. The potential toxicity of hexachlorophene to human infants is discussed.
    Materialart: Digitale Medien
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  • 19
    ISSN: 1432-0533
    Schlagwort(e): Subarachnoid Hemorrhage ; Glycerol ; Phenoxybenzamine ; Cerebral Edema ; Prevention ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Twenty-four hours and one week, respectively, after subarachnoid hemorrhage (SAH) had been experimentally induced in baboons, therapeutic dosages of glycerol and/or phenoxybenzamine hydrochloride were injected intravenously. Groups of three animals were studied at various time intervals after SAH: one animal served as a control, one animal per group received phenoxybenzamine hydrochloride (PBZ), and thefinal animal received both PBZ and a 10% glycerol (in saline) injection. The animals were prepared for electron microscopy by whole body perfusion with a glutaraldehyde/phosphate fixative. Few ultrastructural abnormalities were noted in cerebral tissue in each of the animals receiving glycerol, whereas the brain tissue from the untreated animals and those which had been treated with PBZ alone showed morphological changes compatible with cerebral edema.
    Materialart: Digitale Medien
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  • 20
    ISSN: 1432-0533
    Schlagwort(e): Wilson's Hepato-lenticular Degeneration ; Primary Degeneration of Peripheral Nerve ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The sural nerve from a patient with'Wilson's hepato-lenticular degeneration was examined by electron microscopy. The myelin sheaths showed remarkable changes and the axons secondary changes, while the unmyelinated nerve fibres were intact. These findings demonstrate that pathological changes of peripheral nerves occur in Wilson's disease. The changes are considered to be primary degeneration of the myelin sheaths.
    Materialart: Digitale Medien
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 24 (1973), S. 117-127 
    ISSN: 1432-0533
    Schlagwort(e): Pinealoma ; Two-Cell Type Pattern ; Electron Microscopy ; Germinoma
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Four pinealomas of the two-cell type (atypical teratomas) were investigated by electron microscopy. They all showed the same unique histological ultrastructure. The lymphocyte-like cells did not differ ultrastructurally from lymphocytes. Many plasma cells with well-developed rough surfaced endoplasmic reticulum were also seen. The small cells and the plasma cells were considered to be derived from blood cells. A variety of the large cells in the process of differentiation were observed. They had a large and ovoid nucleus with uniform granular chromatin and contained one or more prominent nucleoli. The large cells had many dilated cytoplasmic cisternae, numerous glycogen granules of about 250–300 Å in diameter and annulate lamellae. Ultrastructurally, the pinealoma of the two-cell type resembled the seminoma of testis which is of germ cell origin. This suggests that the pinealoma may be of germ cell origin.
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 24 (1973), S. 128-152 
    ISSN: 1432-0533
    Schlagwort(e): Transneuronal Degeneration ; Olfactory Bulb ; Rabbit ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary After peripheral deafferentation of the olfactory bulb of the rabbit obtained either spontaneously by atrophic rhinitis (main bulb only) or surgically, a transneuronal degeneration is observed by light microscopy: narrowing of the outer plexiform layer (30 to 40%), decrease (40%) in mean area of the mitral cells, light texture of the periglomerular neuropil. The study by electron microscopy at survival-times of from 8 h to 6 months shows: 1. intraglomerular dendritic lesions; 2. rarefaction of thick dendrites in the outer plexiform layer; 3. reduction of Nissl bodies in mitral and tufted cells. 4. periglomerular lesions: their morphology and laminar aspect could evoke a vascular origin. The interpretation of these modifications and their relation to transneuronal atrophy are discussed. Dark mitral- or granule cells have been observed neither in the main nor in the accessory olfactory bulbs, even when complete denervation occured.
    Materialart: Digitale Medien
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 26 (1973), S. 247-251 
    ISSN: 1432-0533
    Schlagwort(e): Argyria ; Silver Deposition ; Choroid Plexus ; Silver Granules ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A 72-year-old woman developed generalized argyria after prolonged intranasal application of a colloidal silver solution. The brain parenchyma, including several infarcts, was free of silver, but the choroid plexus showed silver deposited in the basal lamina, the stroma including calcified bodies, and occasionally within a mesenchymal cell of the choroid plexus stroma. The basal lamina beneath the choroidal epithelium was most affected. The silver granules appeared solid and free of any limiting membrane.
    Materialart: Digitale Medien
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 26 (1973), S. 317-327 
    ISSN: 1432-0533
    Schlagwort(e): Peripheral Neuropathy ; Tangier Disease ; Schwann Cells ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Nerve biopsy findings are recorded for two previously reported patients with Tangier disease (hereditary high density lipoprotein deficiency). Both cases showed unusual clinical manifestations in comparison with other reported cases. The neurological disorder, symptoms from which began in the third decade, gave rise to a lower motor neuron deficit of unique distribution, which was accompanied by progressive sensory impairment limited for many years to loss of pain and temperature sensibility, ultimately involving all sensory modalities. Both biopsy specimens displayed similar features, with a gross loss of unmyelinated and myelinated axons, an extensive accumulation of lipid within Schwann cells, and excessive endoneurial collagenization. The axonal loss appeared to represent a primary axonal degeneration, there being no evidence of a demyelinating process. It is suggested that the accumulation of cholesterol within Schwann cells may be the result of a failure of cholesterol removal mechanisms or of intracellular lipid transport.
    Materialart: Digitale Medien
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  • 25
    ISSN: 1432-0533
    Schlagwort(e): Neuronal Inclusions ; Cerebrum ; Cholesterol Inhibitor ; Rat ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Intraperitoneal injections of a hypocholesterolemic drug, AY9944 produced neuronal cytoplasmic inclusions in the brain of Wistar strain of rats. The inclusions were numerous and larger in size in the younger age groups but gradually decreased in number and size after 30 days of age. Only a few small inclusions were seen in rats of 35 days of age or older, in spite of continuous injection of the drug. Inclusions gradually decreased in number after discontinuation of the drug in a relatively younger age group. Injection of the drug in adult rats produced only a few small neuronal inclusions. Ultrastructurally, concentrical lamellar structures were the predominant ones in younger age groups but other types of inclusions were seen in older animals and those receiving lesser amounts of the drug or those which were examined after discontinuation of the drug. This observation suggests that morphologically different inclusions can be formed by basically the same treatment if there is any difference in the metabolic activity of the target cell or the amounts of the drug. Biochemical analysis of the sterols revealed a consistently high level of 7-dehydrocholesterol up to 69 days of age, when AY9944 was administered continuously, despite the fact that there was a decrease in the number and size of the abnormal neuronal inclusions.
    Materialart: Digitale Medien
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 25 (1973), S. 259-270 
    ISSN: 1432-0533
    Schlagwort(e): Tuberous Sclerosis ; Electron Microscopy ; Cerebral Biopsy ; Astrocytes ; Cerebral Tumor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The electron microscopic study of a cortical biopsy from a child presenting a Tuberous Sclerosis shows the importance of the astrocytic gliosis, the existence of abnormal cells of which two types can be recognized, and the presence of giant cells. All these cells are remarkable by the abundance of the ergastoplasm, the development of the Golgi apparatus, and the presence of membrane bound dense bodies. These cells are undoubtedly of astrocytic origin and appear very similar to the cells observed in a tumour of the caudate nucleus of another child affected by the same disease. These morphological data lead to believe that the cerebral abnormalities of the Tuberous Sclerosis essentially concern the astrocytes. The main characteristic of this astrocytic lesion would be its blastomatous potentiality.
    Materialart: Digitale Medien
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 12 (1973), S. 16-29 
    ISSN: 1432-0827
    Schlagwort(e): Bone ; Cartilage ; Culture ; Glycosaminoglycans ; Sephadex ; Collagen ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Des cultures de monocouches cellulaires d'épiphyses fémorales distales d'embryons de veaux sont étudiées immédiatement après la première sub-culture, réalisée après culture primaire. L'examen au microscope optique classique montre des dépôts disséminés de matériel métachromatique: en microscopie électronique, de fines fibrilles, considérées comme des fibres de collagène, en voie de développement, ont été observées. La nature des sécrétions cellulaires a été étudiée à l'aide de précurseurs radioactifs, fractionnés sur Sephadex G200, ainsi qu'à l'aide de chromatographie par échange d'ions. La digestion enzymatique par hyaluronidase et chondroitinase AC et ABC, bactérienne et testiculaire, démontre que les cellules synthétisent 70% de glycosaminoglycanes sulfatés et 30% de glycosaminoglycanes non sulfatés. Parmi les glycosaminoglycanes, 70% sont constitués par du chondroitine-4-sulfate, 20% par du chondroitine-6-sulfate et le reste probablement par du keratane-sulfate. Les études avec des acides aminés marqués indiquent que les cellules synthétisent une protéine de poids moléculaire élevé, contenant de l'hydroxyleproline, ainsi qu'une protéine non-collagénique, mise en évidence par incorporation de tryptophane.
    Kurzfassung: Zusammenfassung Einschichtige Zellkulturen von der distalen Femurepiphyse von Kalbsembryonen wurden nach der ersten Subkultur untersucht, welche nach der Verschmelzung der primären Kulturen angesetzt wurde. Die lichtmikroskopische Untersuchung zeigte verstreute Ablagerungen von metachromatisch gefärbtem Material; bei der Elektronenmikroskopie wurden feine Fibrillen festgestellt, welche als Collagenvorstufe angesehen wurden. Nach einer Kultur von mehreren Tagen zeigte sich eine lacunäre Anordnung der Zellen. Die Beschaffenheit der Zellsekretionen wurde mittels radioaktiv markierten Verbindungen untersucht, welche auf Sephadex G200 und durch Ionenaustausch-Chromatographie fraktioniert wurden. Die enzymatische Verdauung mit bakterieller und testikulärer Hyaluronidase und Chondroitinase-AC und-ABC zeigte, daß die Zellen 70% sulfatierte und 30% nichtsulfatierte Glycosaminoglycane synthetisierten. Die sulfatierten Glycosaminoglycane enthielten 70% Chondroitin-4-Sulfat, 20% Chondroitin-6-Sulfat, und der Rest war wahrscheinlich Keratansulfat. Untersuchungen mit markierten Aminosäuren-Vorläufern deuteten darauf hin, daß die Zellen ein Hydroxyprolinhaltiges, hochmolekuläres Protein synthetisierten und dazu etwas Eiweiß, bei dem es sich auf Grund des Tryptophaneinbaues nicht um Collagen handeln kann.
    Notizen: Abstract Monolayer cell cultures from the distal femoral epiphyses of embryo calves were studied following the first subculture, which was carried out after confluence in primary culture. Light microscopic examination revealed scattered deposits of metachromatic-staining material; on electron microscopy fine fibrils considered to be developmental collagen were seen. After several days in culture lacuna-like patterns of cells were seen. The nature of the cell secretions were studied by radioactive precursors, which were fractionated on Sephadex G200 and by ion exchange chromatography. Enzyme digestion with bacterial and testicular hyaluronidase and chondroitinase-AC and-ABC revealed that the cells synthesized 70% sulphated, and 30% non-sulphated glycosaminoglycans. Of the sulphated glycosaminoglycans 70% was chondroitin-4-sulphate, 20% chondroitin-6-sulphate, and the remainder probably keratansulphate. Studies were labelled amino acid precursors suggested that the cells synthesized a high-molecular weight protein containing hydroxyproline, as well as some non-collagenous protein, shown by tryptophan incorporation
    Materialart: Digitale Medien
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 13 (1973), S. 83-92 
    ISSN: 1432-0827
    Schlagwort(e): Proteoglycan ; Collagen ; Cartilage ; Electron Microscopy ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé L'élimination de protéoglycans solubles de coupes de cartilage costal de boeuf, par extraction dans une solution de 4M d'hydrochlorure de guanidinium, permet de mettre en évidence des quantités abondantes de collagène dispersé et désagrégé dans la matrice. Les protéoglycanes, résistants à l'extraction, sont visibles sous forme de granules concentrés dans les régions périlacunaires. Les granulations plus importants des protéoglycanes semblent venir du chondrocyte. Dans la matrice, éloignée des chondrocytes, ces granules deviennent plus étroites. Un composant non granulaire “amorphe” masque les fibres de collagène, de telle sorte qu'elles sont difficilement visibles dans le cartilage intact.
    Kurzfassung: Zusammenfassung Die löslichen Proteoglycane wurden mittels Extraktion in 4 M Guanidinhydrochlorid aus Rippenknorpelschnitten des Rindes entfernt. Dies erlaubte die Sichtbarmachung von großen Mengen von verstreuten und auseinandergerissenen Collagen in der Matrix. Die Protoglycane, welche sich nicht extrahieren lassen, erscheinen als kleine, in den perilacunären Regionen konzentrierte Körnchen. Die großen Proteoglycan-Körner scheinen in den Chondrocyten zu entstehen. Sobald sie sich in die Matrix, außerhalb der Chondrocyten, verlagern, werden die Körner kleiner. Ein nicht-granulärer, „amorpher” Bestandteil verhüllt die Collagenfasern, so daß diese im intakten Knorpel nicht deutlich gesehen werden können.
    Notizen: Abstract Removal of the soluble proteoglycans from slices of bovine costal cartilage by extraction in 4 M guanidinium hydrochloride permitted the visualization of abundant amounts of dispersed and disaggregated collagen in the matrix. Proteoglycans which are resistant to extraction are seen as small granules which are concentrated in the perilacunar regions. Large proteoglycan granules appear to originate in the chondrocyte. As they come to occupy positions in the matrix distant from the chondrocyte, the granules become smaller. A non-granular, “amorphous” component masks the collagen fibers so that they cannot be readily seen in the intact cartilage.
    Materialart: Digitale Medien
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 12 (1973), S. 143-158 
    ISSN: 1432-0827
    Schlagwort(e): Amorphous ; Apatite ; Electron Microscopy ; Crystallization ; Precipitation ; Calcium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Du phosphate de calcium amorphe (ACP) sèché peut se présenter sous forme discoide ou sphérique. Les particules discoides sont plus fréquents dans les specimens d'ACP sèché, isolés immédiatement après précipitation. Les formes sphériques dominent dans les specimens sèchés provenant de suspensions plus âgés. Les particules discoides résultent de la dessication de l'échantillon. Les sphères peuvent aussi se produire pendant la dessication, mais s'observent aussi dans la solution. Les disques et les sphères ont une origine commune sous la forme d'un agrégat d'ACP hautement hydraté de morphologie inconnue. La formation d'apatite cristallin en solution est intimement associée avec l'ACP. Les premiers cristaux apparaissent à la surface des sphères amorphes et en contact avec les disques amorphes. En cas de sphères, les cristaux initiaux augmentent de taille et forment de nouveaux cristaux par nucléation secondaire jusqu'à ce que les sphères soient enrobées par l'apatite. Cependant, lorsque la transformation est totale, l'apatite ne remplit pas l'espace occupé préalablement par les sphères amorphes dissoutes. Ces observations ne confirment pas le concept d'une conversion d'un état solidein situ dans ce cas mais suggèrent une transition hétérophasique d'un processus de translocation ionique par l'intermédiaire d'une solution. La production de cristaux dans les disques amorphes suggère que l'apatite peut aussi se former directement du précurseur dans la solution.
    Kurzfassung: Zusammenfassung Getrocknetes amorphes Calciumphosphat (ACP) kann scheiben- und kugelförmig auftreten. Die scheibenförmigen Partikel herrschen in getrockneten ACP-Proben vor, welche direkt nach der Fällung isoliert wurden. Die kugeligen Formen herrschen in trockenen Proben aus älteren Suspensionen vor. Die Scheibenbildung ist ein Ergebnis des Trocknungsvorganges. Kugelige Formen können beim Trocknungsvorgang ebenfalls auftreten, sie sind aber in der nativen Suspension ebenfalls anwesend. Scheiben- und Kugelformen scheinen einen gemeinsamen Vorläufer in der Lösung zu haben, welcher ein hochhydratisiertes ACP-Aggregat unbekannter Morphologie zu sein scheint. Die Bildung von kristallinem Apatit in der Lösung steht in engem Zusammenhang mit ACP. Die ersten Kristalle erscheinen auf der Oberfläche der amorphen Kugeln und in Kontakt mit den amorphen Scheiben. Die ursprünglichen Kristalle auf den Kugeloberflächen nehmen an Größe zu und bilden durch sekundäre Nukleation weitere Kristalle, bis die Kugeln in Apatit eingehüllt werden. Wenn die Umwandlung abgeschlossen ist, füllt jedoch das Apatit den Platz nicht aus, der vorher von den aufgelösten amorphen Kugeln eingenommen wurde. Diese Beobachtungen bekräftigen die Auffassung einerin situ-Umwandlung in den festen Zustand bei dem beschriebenen Falle nicht, sondern deuten auf eine heterophasischen Übergang, welcher durch einen lösungsbedingten Ionenverschiebungs-Prozeß gefördert wird. Das Auftreten von Kristallen in den amorphen Scheiben deutet darauf hin, daß sich Apatit auch direkt aus dem Lösungsvorläufer bilden kann.
    Notizen: Abstract Dried amorphous calcium phosphate (ACP) can exist in discoidal and spheroidal forms. The disk-shaped particles are most prominent in dried ACP specimens isolated immediately following precipitation. The spherical forms become dominant in dried specimens taken from older suspensions. The disk-like morphology is a result of sample drying. Spherules can also arise during the drying step but are present in the native suspension as well. Both the disks and spherules appear to have a common solution progenitor in the form of a highly hydrated ACP aggregate of unknown morphology. The formation of crystalline apatite in solution is intimately connected with ACP. The first crystals appear on the surface of the amorphous spherules and in contact with the amorphous disks. In the case of the spherules, the initial crystals increase in size and generate additional crystals by secondary nucleation until the spherules become enveloped by apatite. However, when conversion is completed, the apatite does not fill appreciably the space previously occupied by the dissolved amorphous spherules. These observations do not support the concept of anin situ solid state conversion in this case, but indicate a heterophase transition supported by a solution-mediated ion translocation process. The occurrence of crystals in the amorphous disks suggest that apatite can also form directly from the solution progenitor.
    Materialart: Digitale Medien
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Lung 150 (1973), S. 49-59 
    ISSN: 1432-1750
    Schlagwort(e): Pigeon Breeder's Disease ; Electron Microscopy ; Pulmonary Function
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A case of the acute form of pigeon breeder's disease is presented. Electron-microscope studies show the histomorphological substrate of the foreign-body reaction and the immunological cell response caused by the inhaled pigeon material.
    Materialart: Digitale Medien
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Lung 149 (1973), S. 181-192 
    ISSN: 1432-1750
    Schlagwort(e): Hyperoxia ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die elektronenmikroskopischen Ergebnisse bei Hyperoxie und hyperbarer Oxygenation bestätigen übereinstimmend in der Frühphase an der Lunge die exsudativen Veränderungen mit Endothelschwellung und latentem interstitiellen Ödem. Durch eine deutliche Verbreiterung des Blut-Luft-Weges besteht eine Reduktion in der Diffusionskapazität. Die Störungen in der Permeabilität der Zellmembranen betreffen zunächst mehr das Capillarendothel als das Alveolarepithel. Für das Auftreten der Zellschäden ist die Höhe des Saurerstoffpartialdruckes entscheidender als die hyperbare Oxygenation. Die Einatmung von reinem Sauerstoff im Überdruck führt zusätzlich über einen Anstieg des Kohlensäurepartialdruckes im Gewebe zu einer neurochemisch ausgelösten akuten Hypertension mit Lungenödem (Wood und Perkins, 1970). Das Lungenödem bei Hyperoxie und hyperbarer Oxygenation kommt sehr wahrscheinlich auf mehreren pathogenetischen Wegen zustande. Atelektasen bei Hyperoxie sind wahrscheinlich durch die Exsudation von fibrinmonomerhaltigem Blutplasma mit nachfolgender Inaktivierung vorhandener Surfactant-Aktivitäten sowie durch die Blockade der intracellulären Synthese des Surfactant ausgelöst. Zusätzlich sind direkte Enzymschäden der Zelle nach Sauerstoffvergiftung, besonders die Wirkungen der Peroxydationen auf die Mitochondrienmembranen zu berücksichtigen (Haugaard, 1968; Podlesch, 1972; Kleinschmidt, 1972). Der Schweregrad der Diffusionsstörung ist vom O2-Partial-druck und von der Expositionsdauer abhängig. Hibernation retardiert die Sauerstofftoxizität (Huizenga, Butcher und Simmonds, 1972). Die Lungen kleinerer Laboratoriumstiere reagieren schneller und empfindlicher auf O2-Schäden als die Lungen größerer Laboratoriumstiere und als die Lunge des Menschen. Kurzfristige Intervallbeatmung von 40%igem Sauerstoff im Inspirationsgemisch ist unschädlich und ruft keine Lungenveränderungen hervor. Trifft dagegen eine länger angewandte Hyperoxie auf eine vorgeschädigte Lunge, z. B. bei Schocksyndrom, Fettembolie oder Lungentrauma, müssen sich die Schäden aggravieren und können unter dem Bild eines progressiven Atemnotsyndroms zum Tode führen. Hyperoxische Lungenschäden benötigen aufgrund der elektronenmikroskopischen Befunde mehrere Monate bis zur anatomischen Ausheilung, wobei die Wiederherstellung der Lungenfunktion der anatomischen Ausheilung vorangeht.
    Notizen: Abstract The results of electron microscope examinations during hyperoxia and hyperbaric oxygenation unanimously confirm the exudative changes in the lungs in the early stages, with endothelial swelling and latent interstitial oedema. Because of marked spreading of the blood-air paths, a reduction occurs in the diffusion capacity. Disturbances in the permeability of the cell membrane involve the capillary endothelium at first more than the alveolar epithelium. The level of the oxygen partial pressure is more decisive than hyperbaric oxygenation for the appearance of cell damage. Inspiration of pure oxygen at excess pressure also causes neurochemically induced acute hypertension with pulmonary oedema due to an increase in the partial pressure of carbon dioxide in tissues. Probably several pathogenic pathways are involved in the formation of pulmonary oedema in hyperoxia and hyperbaric oxygenation. In hyperoxia, atelectases are probably produced by the exudation of blood plasma containing fibrin monomer with subsequent inactivation of the surface activity present and by the blockade of the intracellular synthesis of surfactant. In addition, direct damage to cell enzymes after poisoning with oxygen, especially the effect of peroxidation on the mitochondrial membranes must be taken into account. The degree of severity of diffusion disturbance depends on the O2 partial pressure and on the duration of exposure. Hibernation delays the toxicity of oxygen. The lungs of smaller laboratory animals react more quickly and more sensitively to the harmful effects of O2 than the lungs of larger laboratory animals and man. Short periods of artificial respiration at intervals, with 40% oxygen in the inspiration mixture, are harmless and cause no changes in the lungs. However, if hyperoxia is used for a longer period, on a previously damaged lung, for example in shock, fat embolism or lung trauma, the damage becomes worse and may end in death resulting from progressive dyspnoea. The electron microscope findings show that in hyperoxic lung damage, several months are required for anatomical cure, the restoration of lung function preceding the anatomical cure.
    Materialart: Digitale Medien
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    European archives of psychiatry and clinical neuroscience 218 (1973), S. 79-91 
    ISSN: 1433-8491
    Schlagwort(e): Storage Disease ; Juvenile Amaurotic Idiocy ; Curvilinear Bodies ; Electron Microscopy ; Rectal Biopsy ; Speicherkrankheit ; Juvenile amaurotische Idiotie ; Curvilineäre Körper ; Elektronenmikroskopie ; Rectum Biopsie
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Bei einem Fall von juveniler amaurotischer Idiotie mit protrahiertem Verlauf (Beginn der Erkrankung mit 14 Jahren, Alter des Patienten 52 Jahre) wird über die Ultrastruktur des Speichermaterials in einer Rectumbiopsie berichtet. Das in Makrophagen der Mucosa gespeicherte Material entspricht den für die juvenile Form charakteristischen curvilineären Strukturen. Gegenüber der Kufsschen Form läßt sich der Fall ultrastrukturell durch das Fehlen der bei der Spätform beschriebenen Lipofuscin-Granula abgrenzen. Das klinische Bild spricht auch für die juvenile Form. Auffallend waren neben dem protrahierten Verlauf der verzögerte Beginn der Erkrankung sowie das späte Einsetzen der geistigen Retardierung.
    Notizen: Summary The ultrastructure of storage material in a rectal biopsy taken from a patient with juvenile amaurotic idiocy with protracted course (onset of illness: 14 years; age of patient: 52 years) is described. The material stored in macrophages of the mucosa was like the curvilinear structures characteristic of the juvenile type. It was possible to exclude Kufs' type in this case by absence of the lipofuscin granula seen in the fine structures in the adult type. The clinical picture was also consistent with the juvenile form. Apart from the protracted course, other striking features were the delayed onset of the disease and the late beginning of mental retardation.
    Materialart: Digitale Medien
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 340 (1973), S. 361-366 
    ISSN: 1432-2013
    Schlagwort(e): M. rectus abdominis ; Slow Fibres ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Out of 253 muscle fibres taken from various parts of frog rectus abdominis muscles 52 were identified electron microscopically as slow. 48 slow fibres were localized at the ventral surface and at the linea alba. No evidence was found for the existence of a fibre type with structural features different from typical twitch or slow fibres.
    Materialart: Digitale Medien
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 136 (1973), S. 19-30 
    ISSN: 1432-0878
    Schlagwort(e): Autonomic innervation ; Uterus ; Oviduct ; Adrenergic, Cholinergic ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The fine structure of the preterminal nerve fibers of the rabbit myometrial smooth muscle was studied using potassium permanganate fixation or glutaraldehyde fixation with postosmification. The preterminal fibers were mostly formed by 2–10 axons enveloped by Schwann cells. Two kinds of axons and axon terminals were found. (1) Adrenergic axons, which contained many small, granular vesicles (diameter 300–600 Å) and large granular vesicles (diameter 700–1200 Å) which represented ca. 2% of the total count of the vesicles. (2) Nonadrenergic axons, which contained small agranular vesicles (diameter 300–600 Å) and large granular vesicles (diameter 700–1200 Å). Both types of axons formed preterminal varicosities along their course. The real terminal varicosities, representing the anatomical end of the axons, were usually larger than the preterminal ones and showed close contact to the plasma membranes of the smooth muscle cells. Both adrenergic and nonadrenergic terminals were found close to the smooth muscle cells, but a gap of at least 2000 Å was always present between the two cell membranes. The axons and preterminal varicosities of both types of nerves were in intimate contact with each other within the preterminal nerve fiber. Axo-axonal interactions between the two types of axons are possible in the rabbit myometrium. The relative proportion of the nonadrenergic axons from the total was about one fourth.
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  • 35
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 136 (1973), S. 569-578 
    ISSN: 1432-0878
    Schlagwort(e): Myoepithelium ; Bryozoaire (Alcyonidium polyoum) ; Vacuole ; Striated muscle, muscular insertion ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé L'épithélium pharyngien d'Alcyonidium polyoum possède des cellules pourvues d'une très grande vacuole. L'incompressibilité du liquide vacuolaire permet un élargissement brusque de l'organe lors de la contraction du manchon musculaire strié qui enserre cette vacuole. Les fibres musculaires sont insérées sur le plasmalemme apical par des filaments unitifs. Le point d'attache est relié à la lame amorphe du cell-coat qui entoure les microvillosités par des fibrilles, réalisant probablement une liaison mécamique plus efficace. Le reticulum sarcoplasmique porte des ribosomes. Le cytoplasme apical renferme des vésicules de diverses catégories.
    Notizen: Summary Pharyngeal cells of Alcyonidium polyoum (Bryozoa) are provided with very large vacuoles. Each vacuole is enveloped by a thin layer of striated muscle, whose contraction enlarges the organ. Filaments join the muscular elements to the apical plasmalemma. This point of muscular insertion is connected by fibrils with the amorphic lamina of cell-coat which surrounds the microvilli. Ribosomes are often found on dyads. Various vesicles are located in the apical cytoplasm.
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  • 36
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A method proposed recently for the generation of modified Hartree-Fock virtual orbitals has been tested by performing a simple configuration-interaction calculation for the ground state of the He atom. A very compact truncated basis set was constructed by using an a priori criterion based on the probability density within the region of the occupied orbital. The best results were obtained by making the virtual orbital energies more positive.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
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  • 37
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 459-473 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In this paper we obtain formulae useful in methods for the direct minimization of the energy functional in the LCAO-MO-MC-SCF approach. The formulae are appropriate for dealing with variations in both the linear and nonlinear parameters. We include formulae for the usual closed- and open-shell problems as special cases.
    Materialart: Digitale Medien
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  • 38
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 1-13 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The treatment of electrostatic interactions between molecular groups is based on quantum mechanical electron density distributions. A general method is suggested using tesseral harmonic multipole expansions and representing each set of point multipoles by a cluster of discrete charges small with respect to atomic dimensions. The procedure is carried out for the amino group with an electron density derived from the wave function of ammonia. We evaluate the optical rotation of two aminopyrrolidones as a test case. Expansions are compared for several approximate wave functions for ammonia.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 39
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 51-62 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The energy terms arising in the water calculation by the FSGO method are analyzed as a function of the bond angle in order to gain insight into the reasons for the particular equilibrium configuration. The analysis is made in terms of symmetrically orthogonalized orbitals so as to exclude three- and four-orbital electron repulsion terms.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 40
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 87-108 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The instabilities of the solutions to the Hartree-Fock equations for the nonalternants in the pentalene, heptalene, etc., series and in the azulene, etc., series are examined. The systems are found to have symmetry-adapted solutions which are unstable for values of the core integral β close to the standard (spectroscopic) value; for example, the pentalene solution is unstable with β equal to 75% of its standard value. The “broken” symmetry solutions although exhibiting only a very slightly lower energy (0.01 eV) may exhibit dramatically different values for other properties, e.g., 30% changes in bond orders. The off-diagonal charge-density wave (CDW) appearing in the “broken” symmetry solutions at the onset of instability is amplified as the cooperative phenomena dominate, until in the “fully correlated” limit, the linked-ethylenic (bond alternating) structure is obtained.
    Zusätzliches Material: 10 Ill.
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  • 41
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 133-134 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 42
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973) 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 43
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 759-777 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The electron spin dipole-dipole interaction in CH2 has been calculated as a function of bond angle with configuration-interaction wave functions built from contracted gaussianlobe basis functions. The values D = 0.781 cm-1 and E = 0.050 cm-1 were obtained for the spin dipole-dipole contribution to these parameters for the best CI wave function at the equilibrium geometry. The angular dependence of D shows that the assumption of perfect orbital following is not valid. Based on previous estimates of the spin-orbit contribution to D, the total D is estimated to be 0.9 ± 0.1 cm-1 which is higher than the current experimental value 0.76 ± 0.02 cm-1.
    Zusätzliches Material: 4 Ill.
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  • 44
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973) 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 45
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Expressions are derived for the n-dependent, hydrogen-like relativistic corrections to the magnetic dipole and electric quadrupole radial hyperfine integrals of an arbitrary atomic state.Good agreement has been obtained earlier between these corrections and the relativistic Hartree-Fock results for s1/2 states. The agreement remains good for the p1/2 states. For the p3/2 states in heavier atoms the hydrogenic corrections still reproduce the Hartree-Fock trend. For the higher l values the agreement is poor. Numerical tables are given for 1 ≤ Z ≤ 100 for the s1/2, p1/2, and p3/2 magnetic dipole cases and the p3/2 quadrupole case.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 46
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 27-34 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: SCF-LCAO-MO-CI calculations made on 2- and 4-amino-, and 2,4-diaminopteridines indicate that the most favorable site where the protonation can take place is N-1.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 47
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 15-25 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: It is shown that gauge terms can be introduced into the Gaussian functions used as the basis functions for an ab initio calculation of the energy of a molecule in the presence of a uniform magnetic field so that all the integrals become independent of the origin of the vector potential. The perturbation treatment of the diamagnetic susceptibility is considered in the molecular orbital approximation. The results show that the susceptibility can be calculated using only the unperturbed orbitals and their first-order corrections. All the integrals that arise can be expressed in terms of known functions.
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  • 48
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 285-300 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Formulae are presented for the evaluation of some definite integrals in which the Laguerre orthogonal functions are contained. In some cases mechanical quadratures are to be preferred, and a scheme is presented for generating such a quadrature as it is needed.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 49
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 345-355 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Upper and lower bounds for the second-order energy in both coupled and uncoupled Hartree-Fock perturbation theories are derived. Using these bounds inequalities are derived for the error in the geometric approximation.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 50
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 521-536 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Alternant molecular orbitals for the lithium metal are constructed in different ways. The corresponding first-order density matrix is calculated for different shapes of the Fermi surface. Numerical methods to calculate the first-order density matrix are described.
    Zusätzliches Material: 1 Ill.
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  • 51
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 547-560 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The all-valence electron band structures of the periodic DNA models polyC, polyT, and polyA have been calculated with the aid of the CNDO/2 and MINDO/2 crystal orbital (CO) method.According to the obtained results the valence and conduction bands are always of π type. The widths of the bands are usually larger in the CNDO case, than those obtained for the same systems in the PPP CO approximation. On the other hand the MINDO results show similar widths as the PPP ones. The forbidden bandwidths are by 3-4 eV larger in the CNDO/2 case, than in the PPP one, while the MINDO/2 CO method has resulted in similar gaps like the PPP calculation.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 52
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 187-193 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A theorem is proved which demonstrates the relationship between a product of group functions describing the correlated motion of a particular group of electrons in an N-electron system and a wave function obtained from the exact wave function which describes the correlation of the same group of electrons. By considering such products of group functions as elements in a variational wave function, an expansion for correlated wave functions is suggested, which emphasizes the correlated motion of groups of electrons in the whole system.
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  • 53
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 223-232 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Approximate and ab initio molecular wave functions are obtained using Gaussian expansions of different length for the Slater orbitals. The expectation values of several one-electron operators are obtained and the accuracy of different wave functions discussed.
    Zusätzliches Material: 6 Tab.
    Materialart: Digitale Medien
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  • 54
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 333-344 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Consideration is given to the problem of interactions between molecular systems (magnetic couplings being neglected) by highlighting the fact that the main difficulty of a perturbation theory that takes into account the exchange effects, resides in the differentiated symmetry of the unperturbed state and of the state of interaction (at an overlap other than zero). This difficulty has been overcome by choosing for the Schrödinger equation of the interacting systems a particular representation on the set of unperturbed functions and by reversing the symmetry properties onto the operators. This will lead to a new equation no longer presenting any difficulties for the symmetry interconnection. This equation is used for a double perturbational expansion both in Coulomb and in exchange terms, thus obtaining general perturbation equations. Explicit solutions are provided (up to the second total order) which are briefly discussed.
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  • 55
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 383-404 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: After a discussion of different concepts of anisotropy with reference to the icosahedron, the unusual problems surrounding the construction of icosahedral irreducible tensors are discussed. Tables of these tensors are then presented and applied to orbital problems, molecular polarization phenomena and to the construction of projection operators.
    Zusätzliches Material: 1 Ill.
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  • 56
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A proof of the convergence of the double infinite series form of the radial factor in the bipolar expansion of r12-1 is given. It consists of demonstrating the validity of the required term-by-term integrations.
    Materialart: Digitale Medien
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  • 57
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 853-867 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A class of reference full density matrices and their reduced density matrices is presented. These density matrices are designed to be of value as references from which to describe and measure the effects of electron correlation in atoms, molecules, and solids. A given reference full density matrix is constructed to contain the least possible information consistent with having the (recognized) symmetry properties of - and reducing to the 1-matrix of - a given “true” full density matrix (which in a typical application is constructed from a correlated variational wave function). Therefore, the reduced density matrices derived from are representable and depend only upon the 1-matrix of and the (recognized) symmetry properties of for their construction. Furthermore, the property of containing the least possible information consistent with the given constraints makes these reference density matrices ideally suitable as references from which to describe the electron correlation contained in the “true” full density matrix .
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  • 58
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 869-876 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The method of functional iteration applied to orbital optimization is proposed. The main problem, i.e., the most economical parametrization of the rotations of the molecular orbitals, is resolved. First and second derivatives of rotations with respect to the parameters are given. The fact that the orbital space can be decomposed in subspaces such that energy is invariant against transformations of these subspaces into themselves is explicitly taken into consideration.
    Zusätzliches Material: 2 Ill.
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  • 59
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 893-903 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An ab initio valence bond (VB) method for calculating energies and wave functions for simple electronic systems is described and the results of its application to methylene are given together with extensive comparisons with previous theoretical results.
    Zusätzliches Material: 2 Ill.
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  • 60
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 951-958 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Various optimization criteria are compared for the hydrogen atom to find orbitals which improve lower bounds computed from the Weinstein, Temple, and Stevenson-Crawford formulas. Minimization of squared energy deviation, “variance,” is recommended because the resulting lower bound orbitals give excellent lower bounds, converge to the exact wave function, are relatively easy to optimize, and are insensitive to the estimated energy eigenvalue. New linear combinations of Gaussian orbitals which minimize the variance are presented for the 1s, 2s, 2p, 3s, 3p, and 3d orbitals. These orbitals are compared with previous linear combinations with regard to their expectation values and local properties.
    Zusätzliches Material: 3 Tab.
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  • 61
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 991-998 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The third-order interaction between two nonpolar molecules due to the instantaneous induced dipole effect of an infinitely long linear molecule is assessed following arguments similar to earlier research on three-body effects. It is found that an attractive force favors small polar angles in approach to the linear molecule; such behavior could be of interest to processes such as those involved in replication of DNA.
    Zusätzliches Material: 1 Ill.
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  • 62
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 131-132 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 63
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 139-153 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A theoretical study of the spin-optimized self-consistent field methods is given in a second quantization formalism using the occupation-branching number representation and a biorthogonal basis treatment given by Moshinsky and Seligman. A diagrammatic presentation can then be introduced. Further investigation will be thus facilitated.
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  • 64
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 195-213 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The Green functions and Kubo linear-response theory are used to calculate the absorption coefficient of a collection of diatomic molecules embedded in a one-dimensional lattice. The effect of the environment is restricted to the coupling between the molecular internal vibration and lattice vibrations. For the molecular oscillators, both harmonic and anharmonic models are considered. The absorption line shape is expressed in closed form whether the molecular frequency falls outside or within the allowed phonon frequency range. In both cases a frequency shift is found. In the anharmonic case there is a broadening of the absorption lines. Expressions for the shift and line width are given.
    Zusätzliches Material: 1 Ill.
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  • 65
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 623-634 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A modified Gaussian function g(u, v, w, a, R) = const s(a, R) is considered where l = u + v + w, s (a, R) is a 1s-type Gaussian function centered at R, a is the coefficient in the exponent of the 1 s Gaussian function and X, Y, Z are components of R. General formulae are derived for overlap integrals, kinetic energy integrals, nuclear attraction integrals, and electron repulsion integrals, valid for any l. The formulae are much simpler than those derived by Huzinaga for Cartesian Gaussian functions.
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  • 66
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 667-674 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A simple, “nearly free electron” model for the dihydrides of Be, Mg, Ca, Sr and Ba is investigated. To zeroth order the valence electrons are assumed to form a free gas. Effects of band structure are included in second-order pseudopotential perturbation theory. The stability of three probable crystal structures is investigated, and lattice parameters are calculated for two different choices of the pseudopotential.
    Zusätzliches Material: 2 Ill.
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  • 67
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 647-665 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A computational approach for general Heisenberg spin Hamiltonians for a finite number of interacting doublet species is described. Maximum use of permutation and point group symmetry is incorporated in factorizing the secular equation. Associated problems in the computation of symmetric group characters, related frequencies, and selection of linearly independent kets from a large linearly dependent set are also solved.
    Zusätzliches Material: 1 Tab.
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  • 68
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 725-737 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An ab initio self-consistent computation has been performed on the permanganate ion (MnO4-) in a large basis set of contracted gaussian functions. The ground state description as well as those of the first two excited states are discussed and compared with those obtained experimentally from photoelectron spectroscopy, ESCA, optical spectroscopy and magnetic circular dichroism.
    Zusätzliches Material: 11 Tab.
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  • 69
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. i 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 70
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 63-73 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The exchange polarization energy and higher-order exchange corrections arising in the second order of the Murrell-Shaw and Musher-Amos (MS-MA) theory are evaluated analytically for the hydrogen molecule ion. At large internuclear distances the second-order exchange energy predicted by MS-MA theory behaves like \documentclass{article}\pagestyle{empty}\begin{document}$- \frac{1}{{18}}Re^{ - R}$\end{document}. It represents only 80% of the difference between the exact result of Holstein and the asymptotic value of the first-order exchange energy. The same result holds for the case of Hirschfelder-van der Avoird (HAV) and Hirschfelder-Silbey (HS) theories.
    Zusätzliches Material: 3 Tab.
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  • 71
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 127-130 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 72
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 569-581 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Applying an extended form of the Mulliken approximation and a monopole approximation for the Coulomb integrals the Hartree-Fock nonorthogonal energy expression is decoupled. Thus, the total energy splits into a sum of one-electron increments. The increments are minimized directly with respect to the linear coefficients and orbital exponents. Further, the ZDO approximation is used in the decoupled energy expression to avoid difficulties arising in connection with the evaluation of multicenter integrals. “Rigid core” calculations were carried out for the valence electrons of first-row diatomics. In case of nonpolar molecules good results are obtained for equilibrium distances and force constants. The method fails for molecules with atoms having very different nuclear charges.
    Zusätzliches Material: 1 Ill.
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  • 73
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 609-622 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Various molecular properties have been calculated for pyridine and pyrazine from Gaussian lobe ab initio SCF molecular wave functions. Values are compared with available experimental data. In general, agreement is satisfactory with the exception of the rather sensitive asymmetry parameter of the quadrupole coupling tensor. The distributions of total electronic charge, and of selected molecular orbitals have been displayed as plots of the charge density contours in two dimensions.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 74
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 641-646 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: For an estimation of the pair correlation the interelectronic distance r12 in geminal ψk(12) is introduced. The calculations are carried out by the local energy method [1, 2]. The influence of other electrons are taken into consideration with the help of the one- and two-electron integrals depending upon r1 and r2 as parameters. If the strong orthogonality condition is satisfied all two-electron integrals and most of the one-electron integrals vanish. All atomic orbitals are expressed in terms of Gaussian functions. A trial calculation is made for the beryllium atom.POUR tenir compte de la corrélation, on introduit la distance interélectronique r12 dans la géminale ψk(12). Le calcul est réalisé par une méthode des énergies locales [1, 2]. L'influence des autres électrons est décrite par des intégrales à un et deux electrons, dépendantes de r1 et r2 comme paramètres. Dans les conditions de l'orthogonalité forte, toutes les intégrales à un électron et la plupart des intégrales à deux électrons disparaissent. Pour simplifier l'algorithme du problème, toutes les orbitales sont exprimées par les fonctions de Gauss. Le calcul est réalisé sur le modèle de l'atome Be.Für Berechnung der Korrelation wird der Interelektronenabstand r12 in Geminal ψk(12) eingeführt. Die Berechnung wird mit der Lokalenenergiemethode durchgeführt [1, 2]. Die Einwirkung der anderen Elektronen wird durch 1- und 2-Elektronenintegrale berücksichtigt, die von Parametern r1 und r2 abhängen. Bei Erfüllung der starken Orthogonalitätsbedingung verschwinden alle 2-Elektronen- und die Mehrzahl der 1-Elektronenintegrale. Alle Orbitale werden durch Gaussfunktionen ausgedrückt. Eine Berechnung für das Atom Be wird durchgeführt.
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  • 75
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 675-686 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: As until now proposed in the literature, in the local energy calculations we can distinguish “few-points” procedures, in which the number M of configurational points is strictly related to the number N of trial functions used, and statistical “many-points” procedures, in which the number M of points can be arbitrarily increased. In this paper we demonstrate that the energy errors resulting from a “many-points” calculation M points/N functions (M 〉 N) can be connected in a simple way with the errors of the (MN) partial calculations N points/N functions.This suggests a possible approach for the problem of the choice of the configurational points to be introduced in the calculation, and leads to a simple interpretation of the numerical meaning of the error associated with the ordinary Ritz energy. Numerical examples on the hydrogen atom are reported.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 76
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 717-723 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: It is shown how to obtain pseudonatural orbitals directly from the equations of motion. A sample calculation on the ground state of the Be atom is given.
    Materialart: Digitale Medien
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  • 77
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 155-171 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Exchange perturbation theory of the Rayleigh-Schrödinger type is applied, in first and second orders, to the problem of bonding in rare-gas halides. The basic model is that of a four-electron, three-center system with one effective electron replacing the unpaired electrons of a halogen atom, and two spin-paired electrons representing the closed shells of the rare-gas atom. On the basis of exchange perturbation theory, the model verifies a direct parallelism between bonding in rare-gas compounds and the phenomenon of super-exchange in ionic solids with paramagnetic cations. It is found that the observed stability and specific geometric configuration of the xenon and krypton fluorides are readily reproduced by the model. In addition, the model explains why other dihalides cannot exist. The two principal components of the interaction energy are found to be indirect exchange between halogen atoms via the rare-gas atoms (attractive in the stable configurations) and, in compounds with coordination higher than two, simultaneous interactions between three halogen atoms (always repulsive). The observed approximate constancy of the binding energy per bond in xenon fluorides with increasing coordination is accounted for.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 78
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Slater orbital r12-1 integrals are calculated with a numerical Fourier-transform method based on a formulation first given by Bonham, Peacher and Cox. Spherical wave expansions are introduced that decouple the Feynman integrations for the charge distribution Fourier transforms. The Feynman integrals are evaluated semianalytically, and their properties are analyzed in detail. The final computational step involves a numerical integration over charge distribution quantities. Results for (coplanar) multicenter exchange integrals over 1s orbitals are given. As long as the charge distributions are overlapping considerably, the method gives good results, even when these distributions are highly asymmetric. The method as presently implemented fails when highly disconnected charge distributions are involved.
    Zusätzliches Material: 4 Tab.
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  • 79
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 253-284 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Tensorial sets adapted to sequences of finite subgroups are applied to the crystal field problem, and a general method for generating sequence-adapted molecular tensors using finite group algebra is formulated. All subgroup sequences of the abstract finite group G(24), isomorphic to the octahedral, O, tetrahedral, Td, and symmetric, S(4), groups are tabulated with explicit isomorphisms provided. The sequences fall into eight equivalence classes. A catalog of irreducible representations of G(24) adapted to a member of each of the eight sequence classes is given together with the transformations which generate representations adapted to all other sequences. With this data it is possible to systematically generate tensorial sets adapted to any sequence of a realization of G(24). Unitary transformations which adapt conventional forms of first- and second-rank irreducible tensorial sets of the rotation group to the eight sequences of the octahedral group are provided. Forms suitable for use with magnetic fields are included. The problem of a d1 ion in a trigonal crystal field is treated with sequence-adapted molecular tensors, and the utility of different sequences for descent in symmetry is discussed.
    Zusätzliches Material: 13 Tab.
    Materialart: Digitale Medien
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  • 80
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 1051-1061 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The coarse structure magnetic theory presented here is a reformulation of conventional magnetic theory which emphasizes the spin-free (i.e., the coulombic) nature of the electron-electron interaction. We show that the magnetic properties of a system for which fine and hyperfine structure can be neglected depend only on the energy spectrum of a spin-free Hamiltonian. As an example, we treat the Heisenberg linear chain.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 81
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 1077-1090 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The infinite interaction range model (IIRM) for ferromagnetic systems is presented in its spin-free formulation. In this formulation the states are labelled by partitions which provide a natural variable for thermodynamic computation. We have extended the calculations of Kittel and Shore by computing to a practical thermodynamic limit (N ∼ 100,000). The heat capacity, magnetic susceptibility and the magnetization of the first two functions exhibit a critical temperature while the magnetization is zero at zero field for all temperatures. Spontaneous magnetization is obtained by linear extrapolation from high field or equivalently by a polarized partition function. Relationships are explored among IIRM, the Heisenberg model and the mean field model. Application to IIRM of the Yang-Lee condition for a phase transition yields a critical temperature identical to that obtained by the direct calculation.
    Zusätzliches Material: 5 Ill.
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  • 82
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 1175-1182 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Theoretical electronic wave functions, potential curves, and expectation values of some one-electron properties are given for the c3IIu state of the hydrogen molecule. The calculations are carried out by the matrix Hartree-Fock method and use a 2-center basis of Slater-type orbitals. A total energy of -0.7292 a.u. is obtained in the best calculation. Our potential curve is reasonably consistent with that calculated by Browne, but we have examined the region of small internuclear distances (those at and below Re for the ground state) more extensively than any previous calculation. At R ≦ 1.6 a.u. our calculated potential curve is in excellent agreement with experiment.
    Zusätzliches Material: 1 Ill.
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  • 83
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 1203-1220 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The expressions for matrix elements of spin-independent operators F and G with the use of Young operators are obtained in the case of arbitrary nonorthogonalized orbital configuration, including both singly and doubly filled orbitals and corresponding to the definite value of total spin. The formulas obtained do not require a preliminary construction of linear combinations of determinants and turn into known Löwdin formulas in the particular case of fully antisymmetric spatial states.
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  • 84
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 1227-1228 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 85
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 637-637 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 86
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 699-705 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A discussion of Hartree damping in closed-shell Hartree-Fock theory is given indicating when the method might force convergence of intrinsically divergent cases. An alternative, but closely related principle, “level shifting” is described, and the advantages of the latter procedure discussed.
    Zusätzliches Material: 1 Tab.
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  • 87
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 687-698 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The half-projected Hartree-Fock function (HPHF) for singlet states is defined as a linear combination of two Slater determinants, which contains only spin eigenfunctions with even quantum number. Using a self-consistent procedure based on the generalized Brillouin's theorem, the RHF, HPHF and PHF functions are deduced for the ground states of the Li-, Be, B+, and C2+ systems, in a limited basis set. It is found that the HPHF function yields better energy values than the RHF function, very close to that of the PHF one. The HPHF scheme seems thus to be useful as a substitute for the PHF model, specially in the case of large electronic systems in which the latter method becomes unmanageable.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 88
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A procedure for the use of the plethysm operation for classification of the permitted electronic terms of impurity complexes in a crystal is presented. The cases of polyatomic symmetrical complexes are discussed as examples.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
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  • 89
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973) 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 90
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 561-568 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A quadratically convergent process using a continued fraction method for finding the square root of the overlap matrix used in Löwdin orthogonalization is presented. The continued fraction method is compared to several other methods for finding the square root of a matrix. The method is found to be more efficient than the other methods when high accuracy is desired.
    Zusätzliches Material: 1 Tab.
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  • 91
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 635-636 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 92
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973) 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 93
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 707-715 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A core model approach to the calculation of deuteron quadrupole coupling constants is investigated using NH3 as an example. First the deuteron quadrupole coupling constant is calculated from a CNDO wave function. This result is subsequently improved by recomputing the N - D bond orbital by means of a variational calculation using the CNDO function to construct a core potential for the bond Hamiltonian. In order to simplify integrations a single-center basis is chosen to represent the variational wave function. A projection operator formalism is used as a computational scheme to maintain orthogonality of the bond orbital to core orbitals. Excellent agreement with experiment is obtained. The procedure is applicable to more complicated molecules.
    Zusätzliches Material: 4 Tab.
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  • 94
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 779-783 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The time-dependent variational principle due to Frenkel is derived from Hamilton's principle using a suitable general expression for the variational wave function. The connections with a recent comment of P. O. Löwdin and P. K. Mukherjee on the same subject are discussed.
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  • 95
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 807-817 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: By performing calculations on H2 O similar to the calculations of Dunning and McKoy on C2H4 and HCHO [1a], it is shown that the singlet excited states of the water molecule cannot be adequately represented by an ab initio calculation (no semiempirical elements) using a valence-like basis set (either minimum basis or double zeta) of Slater-type orbitals. The triplets which are the lowest states of their symmetry appear to be described more accurately than the other states, and the lowest four triplet excitation energies are calculated to be 8.1, 8.4, 9.5, and 10.3 eV. The implications for the applicability of simple molecular orbital theory of the type commonly applied are discussed.
    Zusätzliches Material: 4 Tab.
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  • 96
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Several schemes are discussed for partitioning the second-order reduced density matrix Γ into two parts, Γ0 and Γ′.The Γ0s are based on the independent particle model and the Γ′s are corrections due to electron correlation. The difficulties of choosing a Γ0 that will serve as a suitable reference point for studying electron correlation are discussed.In order to compare alternative partitioning schemes, an atomic wave function for the 1S ground state of the Be atom in the configuration-interaction approximation was selected. A fifty-two configuration wave function was computed and contour graphs were made of the total pair density Γ(1 2) and of the “correlation pair density” Γ′(1 2) for several choices of the reference Γ0.
    Zusätzliches Material: 14 Ill.
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  • 97
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 927-944 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An interpretation of degenerate symmetry spaces associated with a given atomic or molecular configuration is presented, and the theory necessary for atomic applications is discussed in detail. Löwdin's symmetric projection operator for spin and orbital angular momentum is applied on a well-defined sequence of Slater determinants. In this way a degenerate LS space is divided into orthogonal invariant subspaces which can be classified according to internal couplings of angular momentum. A procedure is found which permits expression of each of these LS eigenfunctions as the smallest possible number of successively orthogonalized projected Slater determinants. In particular, minimum size Hartree-Fock interacting spaces (important in rapidly convergent correlation energy calculations) are obtained in their most compact form. An optimum partition of degenerate spaces of three and four excited (atomic or molecular) configurations is obtained in general. Interpretations, simplifications, and systematizations in atomic configuration interaction calculations are discussed in light of present results.
    Zusätzliches Material: 5 Tab.
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  • 98
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 971-984 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The 1P and 3P states arising from the configuration (1s)2(2s)(2p) of the Be isoelectronic sequence are investigated. In the single configuration approximation, the energies of the two states are expressed as E0 + K2s2p and E0 - K2s2p, respectively. K2s2p is the exchange integral between the 2s and 2p electrons and E0 is the energy of a model in which K2s2p is deleted. First we calculate the 2s- and 2p-orbitals in this model. Second, by taking account of K2s2p in this model, effects of this term on the 2p-orbitals in the 1,3P states are investigated. In this manner, an explanation is given for the following facts which are obtained from a minimal Slater-type orbital set; (1) for Be and B+, the 2p-orbital of the 1P state is broader than that of the 3P state; (2) for C2+, the extension of the 2p-orbital in the two states is almost the same; (3) for O4+ and Ne6+, in contrast to Be and B+, the 2p-orbital of the 1P state is tighter than that of the 3P state.
    Zusätzliches Material: 6 Ill.
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  • 99
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 999-1019 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The electron spin dipole-dipole contribution to the zero field splitting has been evaluated for the 3A2 (n → π*) and 3A1 (π → π*) states of formaldehyde using a CI wave function constructed from contracted Gaussian-lobe functions. The values D = 0.539 cm-1 and E = 0.031 cm-1 were obtained for the 3A2(n → π*) state and D = -0.588 cm-1 and E = 0.058 cm-1 were obtained for the 3A1 (π → π*) state using the CI wave function constructed from SCF orbitals of the respective parent configurations. An analysis of the effect of CI on the parameters is given for the 3A2 (n n → π*) state of formaldehyde and the 3B1 ground state of methylene. Numerical results are given which show that internally consistent self-consistent field orbitals (ICSCF) are superior to canonical SCF orbitals as a starting point for a CI calculation. Our CI wave function for the 1A1 ground state gave an energy of -114.13658 hartrees which is significantly lower than any previously reported energy calculation. This wave function gives a dipole moment of 2.22 Debye (C+O-) in good agreement with the experimental value of 2.33 ± 0.02 Debye.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 1039-1043 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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