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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of organic chemistry 26 (1961), S. 1050-1052 
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 18 (1974), S. 379-397 
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The macrocyclic polyethers 4′-methylbenzo-15-crown-5 (15C5) and 4′-methylbenzo-18-crown-6 (18C6) as well as the corresponding crown polymers and crown-styrene copolymers were used as carriers for the transport of sodium and potassium picrate or the corresponding chlorides across a stirred, chloroform membrane. The observation of pronounced bathochromic shifts in the optical spectra of picrate salts on increasing the interionic ion pair distance could be utilized in determining the nature and structure of the migrating species. These species were found to be ion pair crown complexes of at least two kinds, viz., crown-complexed tight ion pairs and crown-separated ion pairs. The feasibility to thus identify the detailed structure of the migrating ionic entity is important as solvents of low polarity such as chloroform or hexane have been used as liquid membranes to represent the interior of biomembranes. The structure of the ion pair is expected to be an important consideration in correlating properties such as membrane potentials or cation selectivities with ionic distribution equilibria. Ion pair extraction equilibrium constants were determined in the H2O−CHCl3 system for the various crown species. The values for 18C6 with sodium and potassium picrate are nearly the same as those for the corresponding polymers. The same was found with 15C5 and sodium picrate; but the potassium forms, in addition to a 1∶1 complex, a 1∶2 complex with 15C5, making the corresponding polymer a more effective extracting agent. The ionic distribution data were interpreted in terms of the salt partition coefficients and the complex formation constants of the ion pair crown complexes in chloroform. The salt migration across the liquid membrane was found to be controlled by the diffusion of the ion pair complex in the chloroform, the extraction equilibrium across the interphase being rapidly established. The thickness of the diffusion layer adjacent to the water-chloroform interphase was estimated to be 50 μ. The ratios of the salt fluxes under otherwise identical conditions were found to be governed by the extraction equilibrium constants, the selectivity ratio for the potassium-to-sodium picrate with 18C6 being 118. This ratio, which was also determined for other crown species, was found to be anion dependent.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 171 (1999), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Light-dependent H2 evolution did not occur in nitrogen-deprived cultures of Rhodovulum sulfidophilum in the presence of ethanol. When ethanol was added to cells which had been grown with ammonia, derepression of the nitrogen fixation genes (nifHD) was inhibited at an ethanol concentration of 1 mM. On the other hand, when cells had nitrogenase-catalyzed proton-reducing activity prior to ethanol addition, reduction of the nifHD transcript level did not occur after the addition. In cells grown with ammonia, concomitant addition of an auxiliary oxidant such as dimethylsulfoxide or sodium bicarbonate resulted in derepression of nitrogenase activity in the presence of ethanol. These results suggest that the electron-accepting process is necessary for derepression of nif genes in cultures which use ethanol as the electron donor.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 1993-1995 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Calculations of the radiation from a four-period polarizing undulator by use of the general radiation equation and numerical integration including the effects of electron-beam emittance, energy spread, and finite observation distance are presented. Accurate electron-beam profiles have been experimentally determined and modeled by the Monte Carlo method. Good agreement is found in spectral intensity between the measured and calculated spectra. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 1592-1594 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We developed a polarization modulation spectroscopy in the extreme ultraviolet (XUV) region for magnetic circular dichroism (MCD) measurements. We used a polarizing undulator with crossed and retarded magnetic fields. It enables us to obtain radiation adjusting the polarization states arbitrarily and rapidly. The undulator is essential in our polarization modulation spectroscopy for MCD study in the XUV region. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 6 (1999), S. 367-369 
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 6 (1999), S. 486-488 
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 4 (1995), S. 67-73 
    ISSN: 1573-4846
    Keywords: photostability of laser-dye ; inorganic-organic matrix ; optical solid material ; fluorescence decay ; mobility of dye
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The laser dye, 4-dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4H-pyran (DCM) was incorporated in various inorganic-organic host matrices by the sol-gel technique. The photostability of the DCM-doped materials under CW argon laser irradiation was investigated. The absorption of DCM monomer ar 480 nm decreased with increasing irradiation time and was accompanied by an increase in the absorption at 352 nm by inactive photoproducts. Photostability was estimated by measuring the decay rates of DCM fluorescences in different host matrices. The rates exhibited two components; a rapid decay within the first several tens of seconds followed by a slower luminescence decay. The rapid decay depended upon the DCM content in the matrix while the slow decay component was related to the mobility of the DCM in the different matrices. The silica host matrix containing phenyl and a small amount of epoxy groups exhibited the best photostability of the materials examined.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    International journal of clinical oncology 4 (1999), S. 338-342 
    ISSN: 1437-7772
    Keywords: Key words Telomerase ; Bile duct carcinoma ; Malignancy grade
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background. Studies of human tumors and human tumor cell lines indicate that telomerase activity may play a critical role in the tumor cell growth by sustaining cellular immortality. Telomerase activity has been detected in different percentages in various carcinomas, but the incidence of positive telomerase activity in bile duct carcinomas and surrounding normal bile duct tissues in its relation with malignancy grades of tumors, depth of invasion, lymphatic and vascular invasion, and lymph node metastases has not been studied. Methods. Telomerase activity was assayed in surgically resected specimens of seven human bile duct carcinomas and seven adjacent nonneoplastic tissues using the PCR-based Oncor TRAP (a telomeric repeat amplification protocol)-eze telomerase detection kit. The correlation between the results of telomerase activity and clinicopathological data was examined. Results. The telomerase activity was detected in six of seven (86%) bile duct carcinoma cases with only one negative case in our series, whereas no telomerase activity was detected in nonneoplastic adjacent bile duct tissues. Although the number of cases in our study was small, telomerase activity was regarded as independent of tumor grade, depth of invasion, lymphatic and intravascular invasion, or lymph node metastasis. Conclusions. These results indicate that increased telomerase activity is a common phenomenon in the majority of bile duct carcinomas, and that it is negative in nonneoplastic bile duct tissues.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric surgery international 13 (1998), S. 442-444 
    ISSN: 1437-9813
    Keywords: Key words Lymphangioma ; Scrotum ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 7-year-old boy who presented with a painful left hemiscrotal mass was diagnosed with acquired lymphangioma of the scrotum. Chronic friction from a cast for Perthes' disease might have been the cause of sudden enlargement of a congenital lymphangioma of the scrotum. Magnetic resonance imaging (MRI) was useful for preoperative diagnosis and determining the extent of the scrotal lesions. Total excision of the mass leaving the overlying skin was successfully performed. The clinical significance of MRI for preoperative diagnosis and planning surgical resection of this lesion is discussed.
    Type of Medium: Electronic Resource
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