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  • crystal structure  (95)
  • Life and Medical Sciences  (51)
  • Wiley-Blackwell  (146)
  • 1
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 1047-1052 
    ISSN: 0044-2313
    Schlagwort(e): Zirconium fluoride ; hafnium fluoride ; ternary fluorides ; KPdMIVF7 (MIV = Zr, Hf) ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: The Crystal Structure of KPdMIVF7 (MIV = Zr, Hf)Blue single crystals of KPdZrF7 are obtained by heating the binary fluorides in sealed Pt-tubes under dry argon (solid state reaction, T ≍ 720°C, t ≍ 14 d). The compound crystallizes orthorhombically in the space group Pnna-D2h6 (Nr. 52); lattice parameters are a = 1 132.3(5) pm, b = 797.5(2) pm, c = 639.8(1) pm; Z = 4 (Four cycle diffractometer data, AED2). According to [F4PdF2/1ZrF5] distortet [PdF6]-octaedra are connected with pentagonal-bipyramidal [ZrF7]-polyhedra via two bridging F-, resulting in [PdZrF11]-groups. These [PdZrF11]-groups built up a threedimensional-network with K+ in its spacings. KPdHfF7 crystallizes isotypically (a = 1 136.1(3) pm, b = 796.4(2) pm und c = 638.8(1) pm; four cycle diffractometer data, AED2).
    Notizen: Durch Tempern der binären Fluoride im verschweißten Pt-Rohr unter Schutzgas (Ar, Festkörperreaktion, T ≍ 720°C, t ≍ 14d) erhält man blaue Einkristalle von KPdZrF7 [eigener Strukturtyp, orthorhombisch, Pnna-D2h6 (Nr. 52); a = 1 132,3(5) pm, b = 797,5(2) pm, c = 639,8(1) pm; Z = 4; Vierkreisdiffraktometerdaten AED2]. Pd2+ ist verzerrt oktaedrisch von 6 F- umgeben, wohingegen Zr4+ pentagonalbipyramidal von 7 F- koordiniert wird. Beide Koordinationspolyeder sind gemäß [F4PdF2/1ZrF5] kantenverknüpft und bilden mit weiteren solcher [PdZrF11]-Einheiten durch Eckenverknüpfung ein dreidimensionales Raumnetz, in dessen Lücken K+ eingelagert ist. Nach Vierkreisdiffraktometerdaten (AED2) kristallisiert KPdHfF7 isotyp (a = 1 136,1(3) pm, b = 796,4(2) pm und c = 638,8(1) pm).
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 993-1000 
    ISSN: 0044-2313
    Schlagwort(e): Zirconium(IV) fluoride ; hafnium(IV) fluoride ; Cs2Cu3MIVF12 (MIV = Zr, Hf) ; crystal structure ; magnetic properties ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Cs2Cu3MIVF12 (MIV = Zr, Hf) - Crystal Structure and Magnetic BehaviourColourless single crystals of Cs2Cu3ZrF12 are obtained by heating the binary fluorides in sealed Pt-tubes under dry argon (solid state reaction, T ≍ 700°C, t ≍ 7-10 d). The compound crystallizes trigonal-rhomboedrical in the space group R3m-D3d5 (Nr. 166); lattice parameters are a = 716.61(6) pm, c = 2 046.4(2) pm, Z = 3 (Four cycle diffractometer data, AED 2). The structure is dominated by layers of corner-sharing, Jahn-Teller-distorted [CuF6]-Octahedra, which are connected via regular [ZrF6]-Octahedra to stackings parallel [00.1]. Cs+-ions are located in the spacings of the octahedra-network. From powder data Cs2Cu3HfF12 with a = 716.32(4) pm, c = 2 048.6(2) pm is isotypic. Both compounds show antiferromagnetic behaviour already at temperatures about 200 K.
    Notizen: Durch Umsetzung der binären Fluoride im verschweißten Pt-Rohr unter Schutzgas (Ar, Festkörperreaktion, T ≍ 700°C, t ≍ 20d) erhält man farblose Einkristalle von Cs2Cu3ZrF12. [Trigonal-rhomboedrisch, R3m-D3d5 (Nr. 166), a = 716,61(6) pm, c = 2 046,4(2) pm, Z = 3 (Vierkreisdiffraktometerdaten, AED 2)]. Strukturbestimmend sind Schichten eckenverknüpfter, Jahn-Teller-verzerrter [CuF6]-Oktaeder, welche - über reguläre [ZrF6]-Oktaeder verknüpft - Stapel entlang [00.1] bilden. In den Hohlräumen der Struktur sind Cs+-Ionen eingelagert. Nach Pulverdaten kristallisiert Cs2Cu3HfF12 mit a = 716,32(4) pm, c = 2 048,6(2) pm isotyp. Beide Stoffe zeigen bereits bei Temperaturen um 200 K antiferromagnetisches Verhalten.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 4 (1974), S. 97-105 
    ISSN: 0045-205X
    Schlagwort(e): Life and Medical Sciences
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Zusätzliches Material: 16 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 1385-1394 
    ISSN: 0044-2313
    Schlagwort(e): Palladium ; quaternary fluorides ; LiPdGaF6 ; RbPdAlF6 ; K1.06Pd0.95Fe1.05F6 ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: The Crystal Structure of LiPdGaF6, RbPdAlF6 and K1.06Pd0.95Fe1.05F6Single crystals of LiPdGaF6 (blue; trigonal, P31c-D3d2 (No. 163), a = 505.72(2), c = 923.7(2) pm; LiCaAlF6-Type [1]), RbPdAlF6 (violet; orthorhombic, Pnma-D2h16 (No. 62), a = 729.0(1), b = 711.1(1), c = 1006.5(2) pm; CsAgFeF6-Type [2]) and K1.06Pd0.95Fe1.05F6 (greenish-blue; tetragonal, P42/mbc-D4h13 (No. 135), a = 1 279.07(7), c = 800.2(1) pm; K1,08MnFeF6-Type [3]; four cycle diffractometer data, Siemens AED2) are obtained by heating the binary fluorides in sealed Pd-tubes under dry argon [solid state reaction, T ≈ 650, t ≈ 19 d (39 d, 24 d)].
    Notizen: Durch Umsetzung von äquimolaren Gemengen der binären Fluoride im verschweißten Pd-Rohr unter Schutzgas [Ar, Festkörperreaktion, T = 650°C, t = 19 d (39 d, 24 d)] erhält man Einkristalle von LiPdGaF6 (blau, trigonal, P31c-D3d2 (No. 163), a = 505,72(2), c = 923,7(2) pm, LiCaAlF6-Typ [1]), RbPdAlF6 (violett, orthorhombisch, Pnma-D2h16 (No. 62), a = 729,0(1), b = 711,1(1), c = 1006,5(2) pm, CsAgFeF6-Typ [2]) sowie K1,06Pd0,95Fe1,05F6 (blau-grün, tetragonal, P42/mbc-D4h13 (No. 135), a = 1279,07(7), c = 800,2(1) pm; K1,08MnFeF6-Typ [3]; jeweils Vierkreisdiffraktometerdaten).
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 29 (1991), S. 259-270 
    ISSN: 1040-452X
    Schlagwort(e): Sperm motility ; Fish ; Motility ; Sperm ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: Carp semen obtained from isolated fish after hormonal stimulation was highly variable in terms of volume of semen, osmotic pressure of the seminal plasma, and sperm capacity to move. Moreover, this last parameter was unstable when the spermatozoa were kept within the seminal plasma, and the present work was designed to investigate and possibly correct this phenomenon. Sperm potential movement was the major parameter studied and was measured by the percentage of motile cells in a final 3,000-fold dilution in a medium of low osmotic pressure in which sperm movement is known to occur (Morisawa and Suzuki, Science 210:1145-1147, 1980). This was completed with occasional measurements of flagellar beat frequencies and demembranation-reactivation of axonemal movement. The results showed that sperm potential movement was preserved upon dilution of the semen into cold 200 mM KCl medium and that semen of initially “poor” quality or spermatozoa that had lost their capacity to move during storage in the semen recovered gradually their potential movement during incubation at 2°C in the same medium. The K+ dependence for both the conservation and the regeneration of sperm capacity to move showed a minimal requirement of 50 mM KCl in media of high osmotic pressure. Na+ ions had similar properties but not divalent cations. The K+ activation was not pH dependent between pH 9.03 and 6.04. Whatever the functional state of live spermatozoa, demembranation-reactivation occurred in ATP-Mg2+. It is concluded that, with dilution of the semen in appropriate conditions, carp spermatozoa retain or acquire potential movement and therefore are a lower vertebrate spermatozoa model available year-round. In addition, obtaining potentially nonmotile sperm and reversion in vitro might be useful to study the control of in vitro maturation.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 35 (1993), S. 261-271 
    ISSN: 1040-452X
    Schlagwort(e): Immunocytochemistry ; Ultrastructure ; Perichromatin granules ; Interchromatin granules ; Mouse spermatids ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: We have studied the ultrastructural distribution of heterogeneous nuclear ribonucleoproteins (hnRNPs), small nuclear ribonucleoproteins (snRNPs), and ribosomal proteins during mouse spermatogenesis and spermiogenesis by means of specific antibodies and immunocytochemistry.All the above components were detectable from primary spermatocytes until the spermatid elongation phase, when the RNA synthetic activity is known to cease. Ribosomal protein (P1/P2 and L7) labeling disappeared as early as during the acrosome phase, and nucleoli were no longer labeled even during the cap phase. The nucleoplasmic structures labeled with the different anti-nucleoplasmic RNP immunoprobes corresponded, until the acrosome phase, to those previously observed as targets of the same antibodies in the nucleoplasm of somatic cell nuclei. Clusters of interchromatin granules of spermatocyte and early spermatid nuclei exhibit some labeling for hnRNP when compared with nuclei of Sertoli cells or previously analyzed liver or tissue culture cells, where these structural constituents usually remain weakly labeled or unlabeled.In spermatids in step 10, another type of nuclear granule, resembling perichromatin granules, but occurring in aggregates, can be observed. These structural constituents were labeled with antibodies recognizing nucleoplasmic snRNP antigens and therefore suggesting a non-nucleolar origin of these granules.Finally, we have observed nucleoplasmic areas of fibrogranular material, occurring only in primary spermatocytes. These components were labeled with anti-ribosomal protein antibodies but did not contain either hnRNPs or snRNPs. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 23 (1992), S. 334-352 
    ISSN: 1059-910X
    Schlagwort(e): Identified neurons ; Quantification ; Rotating/tilting ; Synaptic contacts ; Electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: With the classical Golgi techniques, numerous types of neurons can be distinguished in the cerebral cortex, each with a specific dendritic geometry and pattern of axonal ramifications. In the present review we describe two techniques which allow quantification of synapses on identified neurons: (1) Golgi-rapid impregnation-gold toning-electron microscopy, and (2) Golgi-Kopsch impregnation-gold toning-electron microscopy in combination with staining of the tissue with ethanolic phosphotungstic acid (E-PTA). Both techniques were applied on neurons in the visual cortex of young and adult rabbits. By means of rotating and tilting specimens in the electron microscope, the nondistinctive ultrastructure of obliquely sectioned synapses can be circumvented, leading to precise estimates of asymmetrical vs. symmetrical synapses without complete reconstruction of the neuron. © 1992 Wiley-Liss, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 25 (1990), S. 42-44 
    ISSN: 1040-452X
    Schlagwort(e): Ovary transfer ; Mice ; Transgenic offspring ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: Female transgenic mice may be unable to reproduce successfully if the product encoded by the transgene results in pathological changes or affects the fertility of the mouse. To approach this problem, we have produced chimaeras by transferring the ovaries of transgenic mice into normal mice of the same strain. Such chimaeras will be an ideal tool for investigating the interactions between transgenic ovaries and normal mice or vice versa. Here we show that, using this method, we were able to get large numbers of transgenic offspring even from founder transgenic female mice that were themselves infertile as a result of the overexpression of growth hormone genes. Although none of the ovary recipients were given immunosuppressant treatment, 60% of the recipients had biologically active ovaries over a mean period of about 100 days.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 40 (1995), S. 345-354 
    ISSN: 1040-452X
    Schlagwort(e): Signal transduction ; α-subunit ; β-subunit ; Peptide antisera ; Flagellum ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: Heterotrimeric G proteins play important roles as signal transducing components in various mammalian sperm functions. We were interested in the distribution of G proteins in human sperm tails. Prior to membrane preparation, spermatozoa were separated from contaminating cells which are frequently present in human ejaculates. Enriched human sperm tail membranes were generated by using hypoosmotic swelling and homogenization procedures. Antisera against synthetic peptides were used to identify G proteins in immunoblots. AS 8, an antiserum directed against an amino acid sequence that is found in most G protein α-subunits, and A 86, which detects all known pertussis toxin-sensitive α-subunits, reacted specifically with a 40-kDa protein. Antisera against individual G protein α-subunits failed to detect any specific antigens in enriched tail membranes AS 36, recognizing the ã2-subunit of G proteins, identified a 35-kDa protein in sperm tail membranes. Antisera against the 36-kDa β1-subunit did not detect any relevant proteins in the membrane fraction. Neither G protein α-subunits nor G protein β-subunits were found in the cytosol. ADP ribosylation of spermatozoal membrane or cytosolic proteins revealed no pertussis toxin-sensitive α-subunits. However, membrane preparations of nonpurified human spermatozoa contained α2 subunits, as shown immunologically and by ADP ribosylation; they most probably derived from somatic cells which are frequently present in human ejaculates. Our results stress the fact that spermatozoa need to be purified before sperm membrane preparation to avoid misinterpretations caused by contaminating cells. Furthermore, we suggest that G proteins in membranes of human sperm tails belong to a novel subtype of G protein α-subunits; the putative β-subunit was identified as a β2-subunit. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 214 (1992), S. 269-285 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Fibula reduction is a key feature of avian limb evolution. In a combined comparative and experimental approach the present study analyses the trends of fibula reduction in extant birds and their developmental basis. The study of 55 species of birds reveals four different types of tibiotarsus-to-fibula relationships. Extremely small fibulae are associated with two types of limb modification: (1) elongations of the limb primarily affect the tibiotarsus, increasing its length more than that of the fibula; (2) miniaturizations of the limb reduce both tibiotarsus and fibula length, but are reglarly associated with structural reductions of the distal parts of the fibula. True structrual reductions are distinguished from relative size reductions. The specific features of fibula reduction are analyzed through experimental mesenchyme excisions in chick limb buds. The methodical variation of experimental parameters resolves a long-standing controversy about the effects of mesenchyme reductions on the patterns of skeletal formation. Mesenchyme excisions are shown to have unequal effects on the two zeugopod bones, affecting the fibula to a greater degree than the tibiotarsus. Several of the features seen in birds with advanced fibula reductions are paralleled by the effects of mesenchyme reductions. The consequences of this differential susceptibility of the skeletal blastemata are discussed both in terms of pattern formation in limb development and in terms of its bearing on the patterns of evolutionary limb reduction. It is concluded that thresholds of cell number and blastema size in development constrain the patterns of phenotypic variation in avian limbs. © 1992 Wiley-Liss, Inc.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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