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1.
Astrid Labidi Marie-Christine Salon Alessandro Gandini Hervé Cheradame 《Polymer Bulletin》1985,14(3-4):271-278
Summary 2-Furyl vinyl ketone was polymerised using anionic, cationic and free-radical initiators. Yields and molecular weights varied with the type of activation. Whereas radical polymerisation gave a product possessing a regular vinylic structure, other kinds of units were detected in the polymers prepared with anionic and cationic catalysts. 相似文献
2.
We compare two link analysis ranking methods of web pages in a site. The first, called Site Rank, is an adaptation of PageRank to the granularity of a web site and the second, called Popularity Rank, is based on the frequencies of user clicks on the outlinks in a page that are captured by navigation sessions of users through
the web site. We ran experiments on artificially created web sites of different sizes and on two real data sets, employing
the relative entropy to compare the distributions of the two ranking methods. For the real data sets we also employ a nonparametric
measure, called Spearman's footrule, which we use to compare the top-ten web pages ranked by the two methods. Our main result
is that the distributions of the Popularity Rank and Site Rank are surprisingly close to each other, implying that the topology
of a web site is very instrumental in guiding users through the site. Thus, in practice, the Site Rank provides a reasonable
first order approximation of the aggregate behaviour of users within a web site given by the Popularity Rank. 相似文献
3.
4.
Sebastián López Gustavo M. Callicó Félix Tobajas Valentín de Armas José F. López Roberto Sarmiento 《ETRI Journal》2008,30(6):862-864
This letter presents a novel approach for organizing computational resources into groups within H.264/AVC motion estimation architectures, leading to reductions of up to 75% in the equivalent gate count with respect to state‐of‐the‐art designs. 相似文献
5.
6.
A Panahloo V Mohamed-Ali C Andrés AE Denver JS Yudkin 《Canadian Metallurgical Quarterly》1998,47(6):637-643
1. The synthesis and release of nitric oxide may play a role in the pathogenesis of peripheral vasodilatation and hyperdynamic circulation observed in liver cirrhosis. In this work, we analysed the synthesis of nitric oxide by the lympho-mononuclear cells of peripheral blood from patients with chronic alcoholic and non-alcoholic liver disease and we identified the isoform of nitric oxide synthase involved in the increased nitric oxide synthesis. 2. Patients were classified following clinical and histological criteria in non-alcoholic cirrhotic, alcoholic cirrhotic and non-cirrhotic chronic liver disease. We studied clinical and analytical characteristics, haemodynamic parameters and endotoxin levels in these patients. 3. Cirrhotic patients showed an increase of cardiac output and a decrease of peripheral vascular resistance. These patients had higher levels of plasma endotoxin than those observed in the control group. N omega-Nitro-L-arginine methyl ester (L-NAME)-inhibitable nitrite production from mononuclear lymphocyte cells was higher in patients than in the control group, the highest levels being in non-alcoholic cirrhotic patients, and the lowest levels in patients with non-cirrhotic alcoholic liver disease. 4. Immunocytochemistry studies revealed a positive immunoreactivity for the inducible isoform of nitric oxide synthase in lympho-mononuclear cells that was more evident in non-alcoholic than in alcoholic cirrhotic patients. By Northern blot, inducible nitric oxide synthase mRNA expression was observed only in lymphomononuclear cells from non-alcoholic cirrhotic patients. 5. Our patients show a correlation between nitric oxide synthesis, endotoxin levels and haemodynamic parameters. 6. These findings indicate that lympho-mononuclear cell stimulation may play a role in elevated nitric oxide production in hepatic cirrhosis. Thus, this increased nitric oxide synthesis could be implicated in the pathogenesis of the haemodynamic disturbances frequently found in cirrhotic patients. This increase seems to be induced, at least in part, by activation of an inducible isoform of nitric oxide synthase. 相似文献
7.
8.
Photosystem II membranes, dialyzed against a Cl(-)-free buffer to remove bound Cl-, lost about 65% of the control activity. A light-intensity study of the Cl(-)-free membranes showed that all PS II centers were able to evolve oxygen at about 35% of the control rate when measured in Cl(-)-free medium. The Cl(-)-depleted membranes were immediately (< 15 s) reactivated to 85-90% of the original activity by the addition of fairly high concentrations of Cl- (Kd = 0.5 mM), but both Cl- and the activity were promptly lost when the membranes immediately after reactivation were diluted in a Cl(-)-free medium. However, stabilization of Cl(-)-binding could be accomplished by prolonged incubation in the presence of Cl-. The transition to stable binding, followed using 36Cl-, occurred over several minutes. The stable binding was further characterized by a Kd of 20 microM and a t1/2 for dissociation of about 1h [Lindberg et al. (1993) Photosynth. Res. 38, 401-408]. The effects on S2 signals of removal of Cl- were studied using EPR. The depletion of Cl- was accompanied by a shift in intensity toward the g = 4.1 signal at the expense of the multiline signal. When Cl- or Br- but not F- was added to the depleted PS II membranes, the original distribution of the signals was immediately (< 30 s) restored. We propose that Cl(-)-binding responsible for high oxygen-evolution activity and normal EPR properties of the S2 state may occur either as high affinity (Kd = 20 microM) and slowly exchanging (t1/2 = 1 h), or as low affinity (Kd = 0.5 mM) and rapidly exchanging (t1/2 < 15 s). Our results suggest that Br- but not F- has a mode of binding similar to that of Cl-. The high-affinity state is the normal state of binding, but once Cl- has been removed, it will first rebind as low-affinity, rapidly exchanging followed by conversion into a high-affinity, slowly exchanging mode of binding. 相似文献
9.
András Ványolos Balázs Dóra Attila Virosztek 《Journal of Superconductivity and Novel Magnetism》2007,20(7-8):643-645
We report of a theoretical study on quasi-one dimensional unconventional charge density wave (UCDW) driven by electron–phonon
interaction. Within mean field theory, we find that the wavevector dependence of the coupling leads to a momentum dependent
single particle gap on the Fermi surface. The presence of small energy single particle excitations around the gap nodes significantly
changes the optical conductivity compared to the conventional CDW result. In addition to that, the collective phase excitation
arising from fluctuation of the order parameter leads to further qualitative changes of the conductivity and results in an
effective mass that is nonmonotonic in temperature.
相似文献
10.
INTRODUCTION AND DEVELOPMENT: Multiple sclerosis (ME) is an inflammatory disease of the myelin of the central nervous system, the origin of which is still unknown. Genetic, infectious, immunological and environmental factors have all been blamed, but none of these factors on their own can explain the whole spectrum of this disease. Of the environmental factors, fat in the diet has given rise to most discussion. At the present time, it is known that polyunsaturated essential fatty acids form a part of biological membranes. A relationship has been found between the dietary fat consumed and the plasma levels and cell membrane content. CONCLUSIONS: The possible immuno-modulation function of these fatty acids justify rigorous evaluation of this hypothesis. 相似文献