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61.
Manfred Mller Vladimir V. Tsukruk Jürgen Wendling Joachim H. Wendorff Holger Bengs Helmut Ringsdorf 《Macromolecular chemistry and physics.》1992,193(10):2659-2668
The synthesis and the results of the structural study of two copolysiloxanes with laterally fixed trinitrofluorenone (TNF) units is reported. The two copolysiloxanes having 2,4 ( 1a ) and 5,3 ( 1b ) dimethylsiloxane comonomer units per TNF side group differ significantly in their phase behaviour as evident from optical microscopy, differential scanning calorimetry and X-ray scattering: 1b shows a nematic mesophase whereas 1a is an amorphous material. The different phase behaviour is discussed in terms of microphase separation between the siloxane backbone and TNF side groups. 相似文献
62.
63.
Frank Kirchhoff Carsten Ohlemeyer Helmut Kettenmann 《Pflügers Archiv : European journal of physiology》1992,420(5-6):573-577
A perfusion system was constructed which allows the fast application of different solutes underneath a water immersion objective. The perfusion system is mounted into the immersion objective by milling a slot into the frontal metal plate of the lens holder. It consists of a five-channel pipette fixed to the objective and solution reservoirs gated by computer controlled magnetic valves. Up to five different solutions can be applied to the specimen under study. The solution between objective and specimen is completely exchanged after 1–2 s as determined from fluorescence measurements. This arrangement is optimized for [Ca2+] measurements with a fluorescence measurement system in tissue slices, where upright microscopes are required. It offers the advantage of saving a micromanipulator for the perfusion pipette and facilitates a fast, reproducible and precise positioning of the perfusion system. 相似文献
64.
Expression of adhesion molecules in allergic lung diseases 总被引:4,自引:0,他引:4
Popper HH Pailer S Wurzinger G Feldner H Hesse C Eber E 《Virchows Archiv : an international journal of pathology》2002,440(2):172-180
Endothelial adherence and migration of leukocytes into tissue is mediated by different sets of adhesion molecules. The expression of these sets might not only preselect the types of leukocytes that enter the inflammatory sites, but also activate these leukocytes, induce adherence to epithelial cells, and cause the release of cytokines. Atopic asthma, extrinsic allergic alveolitis, and sarcoidosis as examples of immunologic lung diseases were investigated for the expression of adhesion molecules. Bronchial biopsies in chronic obstructive lung disease (COPD) and resected lung tissue of juvenile emphysema were chosen for controls. Immunohistochemistry was done on sections from bronchial and transbronchial biopsies and on smears from bronchoalveolar lavage cells. In all three types of immune disorders, lymphocytes expressed the integrins alpha4/beta1 (VLA4) and ICAM3, whereas lymphocytes in COPD bronchitis and in emphysema controls were unreactive. Eosinophils in atopic asthma bronchitis in contrast to COPD bronchitis also expressed both VLA4 and ICAM3. The expression of VCAM1 on endothelial cells was only seen in atopic asthma and was related to disease activity. The expression of other adhesion molecules was nonspecific. Expression of VCAM1 on endothelial cells and its ligand VLA4 on lymphocytes and eosinophils seems to be a specific event in atopic asthma. Expression of VLA4 and ICAM3 on lymphocytes, however, might be a specific event in all three immune reactions. 相似文献
65.
Solid mesoionic 2‐[2‐(isopropenylcarbonyloxy)ethylthio]‐1‐methyl‐6‐oxo‐3‐phenyl‐5‐propyl‐1,6‐dihydropyrimidin‐3‐ium‐4‐olate was complexed in water using β‐cyclodextrin (β‐CD) and randomly methylated β‐CD, which resulted in polymerizable complexes with 2:1 stoichiometry. The β‐CD complex was characterized using 1H NMR, ROESY NMR and UV spectroscopy. Polymerization of the complex prepared from methylated β‐CD led to a photosensitive polymer, which precipitated during polymerization and was nearly free of CD. Polymerization was carried out with a water‐soluble redox initiator. In addition, a copolymer with methyl methacrylate was prepared from the complexes, which showed a different mass‐dependent distribution in the incorporation in comparison to a copolymer prepared without CD in organic solvents.
66.
Martina Mennicken Ren Nagelsdiek Helmut Keul Hartwig Hcker 《Macromolecular chemistry and physics.》2004,205(2):143-153
Summary: Bis(hydroxy)telechelic bisphenol A polycarbonate (PC) was prepared via melt polycondensation of bisphenol A (BPA) and diphenyl carbonate (DPC) using lanthanum(III ) acetylacetonate as a catalyst for transesterification. Subsequently, the polycarbonate was converted to a bifunctional macroinitiator for atom transfer radical polymerization (ATRP) with the reagent, α‐chlorophenylacetyl chloride. The macroinitiator was used for the polymerization of styrene (S) and methyl methacrylate (MMA) to give PS‐block‐PC‐block‐PS and PMMA‐block‐PC‐block‐PMMA triblock copolymers. These block copolymers were characterized by NMR and GPC. When styrene and methyl methacrylate were used in large excess, significant shifts toward high molecular weights were observed with quantitative consumption of the macroinitiator. Several ligands were studied in combination with CuCl as the ATRP catalyst. Kinetic studies reveal the controlled nature of the polymerization reaction for all the ligands used.
67.
The formation of IncM plasmid encoded pili is dependent on the incubation temperature of the corresponding host strains. By labelling the short, rigid M pili with the donor specific bacteriophage luminal diameter M, the presence of pili at 30 degrees C but not at 37 degrees C incubation temperature could be demonstrated for E. coli K12 substrains carrying different IncM group plasmids. In contrast, such a temperature dependence of M pilus formation is not observed in S. typhimurium substrains. 相似文献
68.
Bernhard W. Endres Joachim H. Wendorff Bernd Reck Helmut Ringsdorf 《Macromolecular chemistry and physics.》1987,188(6):1501-1509
The dielectric relaxation properties of a combined main-chain/side-chain liquid-crystalline polymer were investigated. It was found that the rotation of the side chain about the main chain (δ-process) is not as strongly restricted as in side-chain liquid-crystalline polymers. This is attributed to the facts that the side chain is attached to the flexible spacer within the chain backbone and that the concentration of the side chains is comparatively small. Two low-temperature relaxation processes were observed to occur in the glassy smectic and the crystalline state. They are attributed to intramolecular motions with in the mesogenic groups. 相似文献
69.
70.