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41.
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It is conceivable that the high-T c superconducting perovskites are conventional electronphonon superconductors. In this case one expects significant strong-coupling effects because of the unusually high ratiok B T c / of the order 0.1 and greater. We use a set of reasonable models for the Eliashberg function 2 F() (which takes into account available information on the phonon spectra and which fit the measuredT c 's) and calculate strong-coupling effects in the specific heatc s (T)/T c , the ratio 0/k B T c , the critical fieldsH c (T) andH c2 (T) including Pauli limiting, and other measurable quantities. Strongcoupling corrections turn out to be in the range of 0 to about 100%, depending on the quantity of interest. We discuss the perspectives of using strong-coupling effects as indicators for conventional electron-phonon superconductivity in the new materials.  相似文献   
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44.
A rapid flow-injection sandwich enzyme immunoassay suitable for the direct determination of proteins in biological samples is described. The proposed system utilizes highly active adenosine deaminase—antibody conjugates in conjunction with a flow-through immunoreactor and an ammonium ion-selective potentiometric detector. After appropriate sample/reagent injection steps, the enzyme activity bound to the reactor is measured by diverting a coninuously flowing stream of substrate (adenosine) through the packed immunocolumn and detecting liberated ammonium ions downstream with a tubular ammonium ion-selective electrode. The bound enzyme activity is directly proportional to the concentration of analyte in the original sample. By using non-equilibrium flow-rates of sample and reagent slugs, a single protein assay takes less than 12 min, including regeneration of the reactor. The proposed method is shown to be selective, reproducible and capable of determining accurately the model protein (human IgC) at sub-μg ml?1 concentrations.  相似文献   
45.
K K Lee  A E Ellis 《Electrophoresis》1989,10(10):729-731
A rapid and sensitive silver-lipopolysaccharide staining method has been developed by using PhastSystem. The total time of the procedure (including time of Phastgel electrophoresis) is within 2 h. It is at least 10 times faster than the previous reported methods and the sensitivity is also increased.  相似文献   
46.
Applied Biochemistry and Biotechnology - By inserting metallocatalysts (such as platinum, osmium, or ruthenium) at the reducing site of photosystem I (PSI), electrons that emerge from PSI can be...  相似文献   
47.
Expense and inconvenience have restricted the use of the filtered xenon are lamp (solar simulator) as a UV source for conducting large-scale animal studies. Because sunscreen immunoprotective levels are significantly affected by the UV power spectrum of the source it is imperative that a solar simulating source be used for accurate measurements of sunscreen protection levels that are relevant to human UV exposures from sunlight. However, relatively inexpensive sunlamps, e. g. the UVA-340, that emit a UV power spectrum similar to that of a solar simulator are available. Unlike FS-type UVB sunlamps, which have a significant amount of effective immunosuppressive nonsolar UV energy at wavelengths below 295 nm, the immunosuppression effectiveness spectrum of UVA-340 sunlamps was nearly identical to that of a solar simulator. The purpose of this study was to evaluate this sunlamp for conducting photoimmunological and sunscreen immune protection studies. Groups of C3H mice were exposed to a range of UVA-340 sunlamp doses (0.25 KJ/m2 to 20.0 KJ/m2) to establish a dose-response curve and determine the minimum immune suppression dose (MISD) for induction of local-type suppression of contact hypersensitivity (CH). The MISD, defined as the lowest UV dose given to produce ~50% suppression of the CH response in mice, was determined to be 1.0 kJ/m2 for UVA-340 sunlamps. Immune protection tests on four marketed sunscreen lotions (sun protection factors [SPF] 4, 8, 15 and 30) were then conducted with UVA-340 sunlamps using MISD as the endpoint. The immune protection factors for these sunscreens were equivalent to the level of protection predicated by their labeled SPF. These results are similar to those we have previously obtained using a solar simulator. We conclude from these data that the immunosuppressive effects of UVA-340 sunlamps are similar to those of a solar simulator; however, further studies are needed to determine if UVA-340, or similar, sunlamps are a viable alternative to the solar simulator for conducting large-scale animal experiments that require a relevant UV solar spectrum.  相似文献   
48.
Novel palladium hollow spheres were synthesized using silica spheres as a template, and they were successfully applied as recyclable heterogeneous catalysts for Suzuki cross coupling reactions.  相似文献   
49.
Poly-S-vinyl-O-tert-butylthiocarbonate is an excellent precursor to poly(vinyl mercaptan) because the tert-butyloxycarbonyl blocking group can be removed by either acid hydrolysis or thermolysis under conditions which minimize the oxidation of the liberated mercaptan to disulfide. Dilatometric studies of the homopolymerization of S-vinyl-O-tert-butylthiocarbonate demonstrated that the polymerization rate was directly proportional to the concentration of free-radical initiator; no thermal initiation was observed. The molecular weight of the homopolymers and copolymers ranged from 30,000 to 50,000 (GPC). Copolymerization of S-vinyl-O-tert-butylthiocarbonate (M2) with styrene, (r1 = 3.0, r2 = 0.2), methyl methacrylate (r1 = 1.40, r2 = 0.17) and vinyl acetate (r1 = 0.04, r2 = 11.0) indicated that a sulfur atom adjacent to the vinyl group increases the resonance stability (Q2 = 0.5) and the electron density (e2 = ?1.4) of the double bond and the corresponding radical. Water-soluble copolymers could be prépared by incorporating either N-vinylpyrrolidone (r1 = 0.12, r2 = 3.94) or N-isopropylacrylamide (r1 = 1.17, r2 = 0.3) with M2. The water solubility of the copolymers decreased markedly when the tert-butyloxycarbonyl group was removed. Copolymers of M2 with N-vinyl-O-tert-butylcarbamate (r1 = 0.13, r2 = 5.10) were utilized to prepare crosslinked poly(vinyl amine–vinyl mercaptan); the crosslinking resulted from urea linkages formed during thermolysis of the copolymer.  相似文献   
50.
Lee HY  Kim BG 《Organic letters》2000,2(13):1951-1953
A tandem free radical cyclization-rearrangement sequence was designed and executed to produce tricyclo[4.3.2.0(1,5)]undecane 7 from cyclopentene 6A in a single operation. The total synthesis of suberosenone was accomplished from 7.  相似文献   
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