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排序方式: 共有412条查询结果,搜索用时 15 毫秒
61.
Mihály Tapolyai Mária Faludi Virág Réti Zsolt Lengvárszky Tibor Szarvas Tibor Fülöp Gabriella Bekő Klára Berta 《Hemodialysis international. International Symposium on Home Hemodialysis》2013,17(3):406-412
Correct estimation of the dialysis patients' hydration status remains an important clinical challenge. Bioimpedance measurements have been validated by various physiological tests, and the use of brain‐type natriuretic peptide (BNP) has been validated by inferior vena cava diameter measurements. This is an observational cohort study that evaluated the correspondence between bioimpedance‐measured overhydration percentage (OH%) and BNP. We measured predialysis OH% by bioimpedance apparatus (Body Composition Monitor) and BNP by microparticle enzyme‐linked immunoassay in 41 prevalent stable hemodialysis patients, 19 (46%) women, aged 58.9 ± 14.5 years. The cohort's average BNP was 2694 ± 3278 pg/mL and 10 (24.4%) of these 41 patients had BNP < 500 pg/mL (average 260.7 ± 108.5). The OH% was 8.5 ± 7.0% among those with a BNP < 500 pg/mL, while the rest of the population had an OH% of 21.4 ± 8.0%, corresponding to excess volumes of 1.6 ± 1.3 and 4.4 ± 3.8 L, respectively. The OH% vs. BNP relationship was best described by the exponential regression of y = 216.4e0.097x, predicting a BNP of 216.4 pg/mL at 0% overhydration status (r 0.61). Receiver‐operating curves revealed an area under the curve of 0.885 for BNP when the OH% was set ≥15% of overhydration and an area under the curve of 0.918 for OH% when the BNP was set ≥500 pg/mL for being abnormal. We conclude that in our cohort there was a high degree of correspondence between these two tests with an exponential relationship between the measurements. 相似文献
62.
Robert Brüll Guru Geertz Hans Kothe Tibor Macko Michael Rudschuck Mirko Wenzel Kurt Engelsing Jürgen Wüst Martin Bastian 《大分子材料与工程》2008,293(5):400-408
The supramolecular structure in pipe walls of isotactic PP‐R is a function of compound composition and processing parameters, which both influence the mechanical properties of the pipes. µFTIR shows a gradient of the crystallinity across the pipe wall, with a lower‐crystalline outer layer, and a higher‐crystalline core layer. The rate of extrusion has an influence on the thickness of the outer layer. The nucleating effect on the morphological profile throughout the pipe wall can be visualised. µFTIR shows a homogeneous distribution of the primary antioxidant in the pipe wall. Both the spectral crystallinity and the antioxidant concentration distribution are calculated.
63.
Fábián TK Hermann P Beck A Fejérdy P Fábián G 《International journal of molecular sciences》2012,13(4):4295-4320
There are numerous defense proteins present in the saliva. Although some of these molecules are present in rather low concentrations, their effects are additive and/or synergistic, resulting in an efficient molecular defense network of the oral cavity. Moreover, local concentrations of these proteins near the mucosal surfaces (mucosal transudate), periodontal sulcus (gingival crevicular fluid) and oral wounds and ulcers (transudate) may be much greater, and in many cases reinforced by immune and/or inflammatory reactions of the oral mucosa. Some defense proteins, like salivary immunoglobulins and salivary chaperokine HSP70/HSPAs (70 kDa heat shock proteins), are involved in both innate and acquired immunity. Cationic peptides and other defense proteins like lysozyme, bactericidal/permeability increasing protein (BPI), BPI-like proteins, PLUNC (palate lung and nasal epithelial clone) proteins, salivary amylase, cystatins, prolin-rich proteins, mucins, peroxidases, statherin and others are primarily responsible for innate immunity. In this paper, this complex system and function of the salivary defense proteins will be reviewed. 相似文献
64.
In the present study, a novel windscreen wiper-on-cylinder machine has been used to investigate the influence of sliding speed
and normal force on the coefficient of friction. Using this machine it is possible to measure the friction force not only
on specimen level, as in former studies to be available in the literature, but also on structural level by considering the
whole windscreen wiper. As measurement results are strongly influenced by both the real, non-circular cross-section, and the
eccentricity of the rotating glass cylinder an analytical model has been developed to explain the measurement results. The
good agreement to be found between theory and experiment confirms the validity of the model. Majority of the results belongs
to partial contact where the wiper blade is not in contact with the glass countersurface along its total length. After the
discussion of experimental results, as a last step, authors made an attempt to compare quantitatively the predictive capability
of two different contact models widely used in mixed friction model of sliding rubber components. The results show that the
difference in film thickness due to solid–solid contact can be larger than three orders of magnitude in case of a typical
windscreen wiper. 相似文献
65.
66.
Camille Descour Tamara Meijer-Vissers Tibor Macko Matthew Parkinson Dario Cavallo Martin van Drongelen Gerhard Hubner Han Goossens Robbert Duchateau 《Polymer》2012,53(15):3096-3106
The zirconium acetamidinate catalyst {Cp*Zr(Me)2[N(Et)C(Me)N(tBu)]} (Cp* = ?5-C5Me5) was used to synthesize both random and block copolymers based on 4-methyl-1-pentene (4M1P) and 1-pentene. The polymers have been characterized by NMR spectroscopy, SEC, DSC, high temperature HPLC and CRYSTAF. Unexpectedly, the yields and molecular weights decreased with increasing amounts of 1-pentene. The reason for this behavior is that 1-pentene occasionally undergoes 2,1-misinsertions trapping the catalyst in a dormant state. These 2,1-misinsertions do not seem to occur with the bulky 4M1P (branched α-olefin). Adding a small amount of ethylene reactivates the catalyst. Unlike most semi-crystalline polymers, the density of the crystalline phase of isotactic P4M1P can be lower than of the amorphous phase, when crystallized under very high pressures. To characterize this peculiar behavior of 4M1P-based polymers, various samples have been subjected to Pressure-Volume-Temperature (PVT) measurements. While the P4M1P homopolymers and block copolymers show the expected decrease in specific volume upon crystallization, the 4M1P-rich random copolymers proved not to vary in specific volume under the same conditions. 相似文献
67.
Balázs Tukora Tibor Szalay 《International Journal of Machine Tools and Manufacture》2011,51(12):871-879
The determination of the cutting force coefficients is a critical point in the case of using the mechanistic cutting force model for predicting the forces during milling processes. The main reason is that the computations require a series of experiments with special geometrical conditions, and the validity of the results is limited. In this paper a cutting force predicting method, based on the mechanistic cutting force model will be introduced, together with an algorithm for determining the cutting force coefficients in the course of a single experiment without restrictions in regard to the cutting geometry. Besides the fact that the proposed method lifts the geometrical restrictions of the previously published solutions, it makes it possible to calculate the coefficients just when they are needed for force prediction right at the machining process, to avoid the problem of the limited validity of the coefficients. In this case the real-time measuring of the cutting forces is needed, while the forthcoming forces can be predicted with an appropriate look-forward algorithm, which is also presented. 相似文献
68.
The generic ring model considers algorithms that operate on elements of an algebraic ring by performing only the ring operations and without exploiting properties of a given representation of ring elements. It is used to analyze the hardness of computational problems defined over rings. For instance, it is known that breaking RSA is equivalent to factoring in the generic ring model (Aggarwal and Maurer, Eurocrypt 2009). Do hardness results in the generic ring model support the conjecture that solving the considered problem is also hard in the standard model, where elements of ? n are represented by integers modulo n? We prove in the generic ring model that computing the Jacobi symbol of an integer modulo n is equivalent to factoring. Since there are simple and efficient non-generic algorithms which compute the Jacobi symbol, this provides an example of a natural computational problem which is hard in the generic ring model, but easy to solve if elements of ? n are given in their standard representation as integers. Thus, a proof in the generic ring model is unfortunately not a very strong indicator for the hardness of a computational problem in the standard model. Despite this negative result, generic hardness results still provide a lower complexity bound for a large class of algorithms, namely all algorithms solving a computational problem independent of a given representation of ring elements. From this point of view, results in the generic ring model are still interesting. Motivated by this fact, we also show that solving the quadratic residuosity problem generically is equivalent to factoring. 相似文献
69.
College student drinkers (N ?=?314) participated in a health survey in which they (a) completed an alcohol-related memory association task (expectancy accessibility measure), (b) rated their positive expectancies about alcohol use (expectancy strength measure), and (c) reported their level of alcohol involvement. Hierarchical regression analyses showed that both expectancy accessibility and expectancy strength predicted frequency of alcohol use and alcohol-related problems. Moreover, moderational analyses showed that the association between expectancy strength and frequency of alcohol use was greater for those who generated more alcohol responses on the expectancy association task. These findings, suggest that the outcome association measure and Likert scale ratings of expectancies may assess distinct properties of expectancy representations, which may have independent and interactive effects on different aspects of drinking behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
70.
Somlai J Gorjánácz Z Várhegyi A Kovács T 《The Science of the total environment》2006,367(2-3):653-665
High radon concentration (average 410 kBq m-3) has been measured in a tunnel of a uranium mine, located 15-55 m below the village of Kovágószolos, Hungary. The mine was closed in 1997; the artificial ventilation of the tunnel was then terminated and recultivation works begun. In this paper, a study has been made as to whether the tunnel has an influence on the radon concentration of surface dwellings over the mining tunnel. At different distances from the surface projection of the mining tunnel, radon concentration, the gamma dose, radon exhalation and radon concentration of soil gas were measured. The average radon concentration in the dwellings was 483 Bq m-3. Significantly higher radon concentrations (average 667 Bq m-3) were measured in houses within +/-150 m from the surface projection of the mining tunnel +50 m, compared with the houses further than the 300-m belt (average 291 Bq m-3). The average radon concentration of the soil gas was 88.8 kBq m-3, the average radon exhalation was 71.4 Bq m-2 s-1 and higher values were measured over the passage as well. Frequent fissures crossing the passage and running up to the surface and the high radon concentration generated in the passage (average 410 kBq m-3) may influence the radon concentration of the houses over the mining tunnel. 相似文献