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  • Column liquid chromatography  (54)
  • Ultrastructure  (52)
  • Springer  (106)
  • American Association of Petroleum Geologists (AAPG)
  • Nature Publishing Group
  • 1995-1999  (60)
  • 1980-1984  (46)
Collection
Keywords
Publisher
  • Springer  (106)
  • American Association of Petroleum Geologists (AAPG)
  • Nature Publishing Group
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructure of the sperms ofPlumbago zeylanica (1981)
    Springer
    Protoplasma 107 (1981), S. 85-107 
    Details
    ISSN: 1615-6102
    Keywords: Male cytoplasmic inheritance ; Plumbago ; Pollen grain ; Pollen tube ; Sperm ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Male gametes ofPlumbago zeylanica were examined in pollen grains and tubes using light and electron microscopy of chemically and physically fixed tissues, and Nomarski interference microscopy of isolated, living sperm cells. Male gametes are elongate, spindleshaped cells containing a nucleus, mitochondria, ER, ribosomes, vesicles, dictyosomes, probable microfilaments, and a variable number of plastids. In mature pollen grains ofP. zeylanica, the two sperm cells are directly linked; they share a transverse cell wall with plasmodesmata and are enclosed together by the inner vegetative cell plasma membrane. One of these two sperms is also associated with the vegetative nucleus as a consistent feature of pollen grain organization. The basis of this association appears to be a long, narrow projection of the sperm cell (averaging 〈 1 μm wide and about 30 μm long) which wraps around the periphery of the vegetative nucleus and occupies embayments of that nucleus. This association is maintained throughout pollen tube growth but becomes less extensive near the completion of tube growth and is severed following tube discharge. The consistent occurrence of the sperm-vegetative nucleus association in pollen grains, tubes and isolated pollen cytoplasm suggests that the two structures may be directly connected, but attempts to visualize this type of connection were unsuccessful. Possibly, the entwining nature and extent of complementary interfaces between vegetative nucleus and sperm may have a role in stabilizing their association. Functionally, the two sperms and vegetative nucleus appear to travel as a linked unit within the pollen tube, possibly increasing the effectiveness of gamete delivery and helping to ensure nearly simultaneous transmission of sperms into the receptive megagametophyte.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01275610
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  • 2
    Electronic Resource
    Electronic Resource
    Development of a universal Raman detector for microchromatography (1997)
    Springer
    Chromatographia 44 (1997), S. 257-262 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microchromatography ; Raman spectroscopy ; Deuterated solvents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A detector for microchromatography in which Raman spectroscopy is used to identify the eluted species has been developed. The detector is designed to be applicable to a wide range of compounds without requiring the presence of a chromophore. Its use is illustrated in the analysis of nitro compounds on a 250 μm i.d. column. Raman spectra of each of the compounds could be identified as they passed the detector. The advatages of the use of fully deuterated solvents are demonstrated by the analysis of nitrobenzenes in methanol/water mobile phases. The detection limit for nitrobenzene using the Raman line at 1342 cm−1 was 75ng.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466391
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrastructure of the cyanobacterium,Mastigocladus laminosus (1982)
    Springer
    Archives of microbiology 133 (1982), S. 11-19 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Ultrastructure ; Mastigocladus laminosus ; Fischerella ; True branching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The morphology and ultrastructure of the thermophilic cyanobacteriumMastigocladus laminosus were examined by scanning and transmission electron microscopy. Mature cultures consisted of relatively old, wide filaments that branched frequently to form younger, thinner filaments. The cells of the younger filaments had a consistently cylindrical morphology, while those of older filaments were rounded and pleomorphic. The internal ultrastructure of the cells depended somewhat on their age. As young cells became larger and wider, their thylakoids underwent slight rearrangement and spread out toward the center of the cytoplasm. Polyphosphate bodies, carboxysomes (polyhedral bodies), and lipid-body-like structures increased in number as the cells aged, but ribosomes and cyanophycin granules were depleted. Cell division involved septum formation followed by ingrowth of the outer membrane and sheath. Cells in older filaments were separated from each other by a complete layer of sheath material. Septum formation in older cells was also seen to occur parallel to the long axis of the filament, thereby confirming that true branching took place.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00943762
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  • 4
    Electronic Resource
    Electronic Resource
    The effects of nitrogen limitation on the ultrastructure of the cyanobacterium Agmenellum quadruplicatum (1981)
    Springer
    Archives of microbiology 130 (1981), S. 204-212 
    Details
    ISSN: 1432-072X
    Keywords: Agmenellum quadruplicatum ; Nitrogen starvation ; Ultrastructure ; PATO poststain ; Cyanobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of nitrogen limitation on the ultrastructure of the unicellular cyanobacterium, Agmenellum quadruplicatum, were studied by thin sectioning transmission electron microscopy. Nitrogen became limiting for growth 14–15 h after transfer to nitrogen-limiting medium, but cultures retained full viability for at least 45 h. The c-phycocyanin: chlorophyll a ratio and cellular nitrogen content of the culture dropped rapidly after 14–15 h, as a progressive deterioration of major cell structures took place. Phycobilisomes were degraded first, followed by ribosomes and, then, thylakoid membranes. These structures were virtually depleted from the cells within 26 h. Intracellular polysaccharide accumulated in place of the normal cell structures throughout this period. Nitrogen limitation did not affect polyphosphate bodies, carboxysomes, lipid granules, the cell envelope, or the extra-cellular glycocalyx. All of the ultrastructural changes resulting from nitrogen limitation were reversed upon addition of nitrate to a starved culture. Most cell structures were restored within 3 h, and restoration was complete within 9 h.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00459520
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructure of the prothoracic gland of variously aged female pupae of Xyleborus ferrugineus and associated ecdysteroid titers (1980)
    Springer
    Cell & tissue research 213 (1980), S. 1-8 
    Details
    ISSN: 1432-0878
    Keywords: Ecdysteroids ; Moulting hormones ; Xyleborus ferrugineus pupae ; Ultrastructure ; Prothoracic gland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The prothoracic glands of female pupae of Xyleborus ferrugineus at three ages (0-h, 48-h and 72-h-old) were examined for ultrastructural changes that correlate with high titers of ecdysteroids in the entire pupa. In all three ages, the prothoracic gland cells appear compact with a prominent nucleus. Lysosome-like structures with concentrically oriented internal membrane are observed in both 0-h and 72-h-old gland cells. Mitochondria are abundant in the glands of both ages, and rough endoplasmic reticulum is relatively sparse. Numerous microtubules are present in the prothoracic gland cells of 48-h-old female pupae that contain relatively high titers of ecdysteroids. Rough endoplasmic reticulum also is especially abundant at this age of the pupa. Ecdysone titers, estimated by the radioimmunoassay method (RIA), were 161.04±22.61 pg/mg, 704.25±69.02 pg/mg and 298.72±26.80pg/mg body weight in 0-h, 48-h and 72-h-old female pupae, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236915
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  • 6
    Electronic Resource
    Electronic Resource
    Stomatal pore and cuticle formation inFunaria (1983)
    Springer
    Protoplasma 116 (1983), S. 1-13 
    Details
    ISSN: 1615-6102
    Keywords: Cuticle ; Peristomatal transpiration ; Stomata ; Ultrastructure ; Funaria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cuticle and pore development in the guard cells ofFunaria were investigated with the electron microscope. Pore cuticle formation is simultaneous with the creation of the pore itself. The morphology of the pore cuticle is unlike that of any cuticle described in the literature. It has many lamellae which are penetrated by electron dense fibrils. Three different cuticular morphologies exist from the pore to the subsidiary cell walls. The cuticles on the pore and outer walls contain fibrils that sometimes reach to the surface. The subsidiary cell cuticle lacks fibrils altogether. It is hypothesized that (1) cuticularization of the middle lamella contributes to ventral wall separation and (2) differences in extent of cuticular fibrils are related to greater water loss from stomata than from subsidiary cells (peristomatal transpiration).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01294225
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  • 7
    Electronic Resource
    Electronic Resource
    Topography, ultrastructure and phagocytic capacity of avian lymph nodes (1983)
    Springer
    Cell & tissue research 228 (1983), S. 389-403 
    Details
    ISSN: 1432-0878
    Keywords: Lymph node, avian ; Ultrastructure ; Macrophages ; Phagocytic capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structure of the avian lymph node (ALN) is characterized by a thin capsule, thin lymphoreticular cords, and an absence of trabeculae. It is not possible to subdivide the ALN into cortex, paracortex and medulla, or to subdivide the system of sinuses into marginal, trabecular and medullary divisions. The lymphoreticular cords contain avian germinal centers (AGC) with B-lymphocytes and the area of T-lymphocytes. Postcapillary venules are responsible for the recirculation of lymphocytes. Sinus reticular cells do not exist in the ALN, but free macrophages are present. The phagocytic capacity of the macrophages was determined by injection of vital dyes (India ink, Berlin blue) and inoculation with Candida cells. Macrophages filled with markers migrate from the lymph sinuses into the lymphoreticular cords and further into the AGC. The mobility of the macrophages is remarkably lower after phagocytosis of Candida cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00204887
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  • 8
    Electronic Resource
    Electronic Resource
    Retention behavior of morphine and its metabolites on a porous graphitic carbon column (1998)
    Springer
    Chromatographia 47 (1998), S. 667-672 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Porous graphitic carbon ; Optimization ; Morphine and metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic behaviour of a series of morphine-based opiates has been investigated using a porous graphitic carbon packing material at acid and alkaline pH. The effects of mobile phase pH, mobile phase organic percentage, column temperature and ionpairing agents were studied. All six opiates were separated within a close retention window despite large differences in measured lipophilicities of the individual opiates. The retention order was not related to the log P values of the opiates and strong retention of the fully ionised compounds was observed, particularly those with acidic functional groups. The effect of pH on the retention of the compounds indicated that the degree of ionisation of the individual compounds was important in the separation mechanism, suggesting that hydrophobic interactions were present in addition to the polar retentive effects observed above. The strong retention of the ionised glucuronide and sulphate conjugates of morphine is a particularly useful feature of the porous graphitic carbon packing material which has general applicability to the analysis of polar or ionised drug metabolites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467451
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  • 9
    Electronic Resource
    Electronic Resource
    Simultaneous determination of triprolidine, pseudoephedrine, paracetamol and dextromethorphan by HPLC (1996)
    Springer
    Chromatographia 43 (1996), S. 496-500 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Pharmaceutical formulations ; Triprolidine ; Pseudoephedrine ; Paracetamol ; Dextromethorphan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple, rapid and specific HPLC method has been developed for the determination of triprolidine, pseudoephedrine, paracetamol and dextromethorphan, in combination, in different pharmaceutical dosage forms, using a reversed-phase C18 column, gradient elution, and UV detection at 254 and 280 nm. No preliminary extraction procedure is required for liquid formulations and a very simple extraction procedure is required for tablets and creams. The recovery of the drugs ranged from 96.0 to 98.7%. The assay results obtained for eight commercially available formulations were in agreement with the amounts declared. The linearity and precision of the method have been assessed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02293000
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  • 10
    Electronic Resource
    Electronic Resource
    HPLC analysis of boldine in pharmaceuticals (1997)
    Springer
    Chromatographia 44 (1997), S. 619-622 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Boldine in pharmaceuticals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is proposed for extraction, separation, identification and quantitative measurement of boldine (I) in pharmaceuticals. The extraction of (I) from the matrix (syrups, tablets, extracts) was realized with aqueous ammonium chloride (0.02 M, pH=3.0 with perchloric acid) and the clean-up of the extract was performed by solid-phase extraction by means of cartridges containing a strong cation-exchange sorbent, from which (I) was eluted with aqueous ammonium chloride (1 M, pH=10.0 with ammonia). The final eluate was examined by HPLC. Chromatography was performed on a C-8 column with a gradient elution from 15:85 to 30:70 of acetonitrile-water containing 0.1 M sodium perchlorate (pH=3.0), in 20 min. A diode array detector was used at 302 nm for detection. The method gives recovery values greater than 98% and the reproducibility is within 6.0%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466665
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