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41.
42.
The impact factor is one of the most used scientometric indicators. Its proper and improper uses have been discussed extensively before. It has been criticized extensively, yet it is still here. In this paper I propose the journal report card, which is a set of measures, each with an easily comprehensible meaning that provides a fuller picture of the journals?? standing. The set of measures in the report card include the impact factor, the h-index, number of citations at different points on the ranked list of citations, extent of uncitedness and coverage of the h-core. The report card is computed for two sets of journals, the top-20 journals in JCR 2010 and the top-20 journals in JCR 2010 for the category Information and Library Science.  相似文献   
43.
The present article reviews the mass spectrometric fragmentation processes and fragmentation energetics of leucine enkephalin, a commonly used peptide, which has been studied in detail and has often been used as a standard or reference compound to test novel instrumentation, new methodologies, or to tune instruments. The main purpose of the article is to facilitate its use as a reference material; therefore, all available mass spectrometry‐related information on leucine enkephalin has been critically reviewed and summarized. The fragmentation mechanism of leucine enkephalin is typical for a small peptide; but is understood far better than that of most other compounds. Because ion ratios in the MS/MS spectra indicate the degree of excitation, leucine enkephalin is often used as a thermometer molecule in electrospray or matrix‐assisted laser desorption ionization (ESI or MALDI). Other parameters described for leucine enkephalin include collisional cross‐section and energy transfer; proton affinity and gas‐phase basicity; radiative cooling rate; and vibrational frequencies. The lowest‐energy fragmentation channel of leucine enkephalin is the MH+b4 process. All available data for this process have been re‐evaluated. It was found that, although the published Ea values were significantly different, the corresponding Gibbs free energy change showed good agreement (1.32 ± 0.07 eV) in various studies. Temperature‐ and energy‐dependent rate constants were re‐evaluated with an Arrhenius plot. The plot showed good linear correlation among all data (R2 = 0.97), spanned over a 9 orders of magnitude range in the rate constants and yielded 1.14 eV activation energy and 1011.0 sec?1 pre‐exponential factor. Accuracy (including random and systematic errors, with a 95% confidence interval) is ±0.05 eV and 10±0.5 sec?1, respectively. The activation entropy at 470 K that corresponds to this reaction is ?38.1 ± 9.6 J mol?1 K?1. We believe that these re‐evaluated values are by far the most accurate activation parameters available at present for a protonated peptide and can be considered as “consensus” values; results on other processes might be compared to this reference value. © 2010 Wiley Periodicals, Inc., Mass Spec Rev 30:298–320, 2011  相似文献   
44.
Scientometrics - In a Letter to the Editor, the authors of this paper show, to highlight the practical risks of using the h-index, how academics’ data and bibliometric information can be...  相似文献   
45.
Exposure to 50 Hz magnetic field (MF) was evaluated in 31 multi-level apartment buildings with built-in step-down transformer stations. In each building, three apartments were selected: one apartment located immediately above the transformer room (index apartment), one located on the same floor and one on a higher floor. The mean value of measured MFs was 0.98 microT in apartments above transformers, 0.13 microT on the same floor, and 0.1 microT in on higher floors. The mean measured MF value was higher than 0.2 microT in 30 (97%) index apartments, 4 (14%) on the same floor as the index apartments and 4 (13%) on higher floors. The corresponding numbers were 25 (81%), 0 and 0, respectively, when 0.4 microT was used as cut-point. It is concluded that apartments in building with built-in transformers can be reliably classified into high and low-exposure categories based on their location in relation to transformers.  相似文献   
46.
Summary The purpose of this study was to develop a method for characterizing the page and linking patterns related to dramatic events on the Web. As a specific case, we characterized Web pages linking to the set of pages on anthrax indexed by the Yahoo directory (generally acknowledged as a high quality directory). The sample of Web pages was collected shortly after anthrax became a matter of widespread concern (November 2001). The findings show that at that time the “typical' source page was either a news item or a page with a list of links. Most of the examined links were not navigational but linked to the target page in order to provide additional content. Many Web sites added hyperlinks to pages providing presumably authoritative and high quality information on anthrax rather than supplying the information themselves. The results show that Web authors link extensively to presumably “high quality' pages. The methods presented here can be utilized in order to characterize pages and linking patterns of Web pages linking to a set of predefined pages, and the findings of this specific study can serve as a basis for comparison.  相似文献   
47.
The World Wide Web is growing at an enormous speed, and has become an indispensable source for information and research. New pages are constantly added, but there are additional processes as well: pages are moved or removed and/or their content changes. We report here the results of an eight year long project started in 1998, when multiple search engines were used to identify a set of pages containing the term informetrics. Data collection was repeated once a year for the last eight years (with the exception of 2000 and 2001) using both search engines and revisiting previously identified pages. The results show that the number of pages grew from 866 in 1998 to 28,914 in 2006 — a 33-fold growth. Besides the obvious growth of the topic on the Web, we observed both decay (pages disappearing from the Web) and modification. Even though most of the pages from 1998 either disappeared or ceased to contain the term informetrics, 165 pages (19.1%) still exist in 2006 and contain the search term. We followed the “fate” of these 165 pages: characterized the publishers, the contents and the changes that occurred the whole period. In recent years e-print servers and publishers’ sites became sources of large number of pages related to informetrics. Longitudinal studies following the evolution of a topic on the Web are very important, since they provide insights about content and the underlying Web processes.  相似文献   
48.
ABSTRACT

Objective: The aim of this in vitro study is to examine the optical effects of monolithic zirconia of different translucency and thickness, combined with substrates of different colours. Materials and methods: Zirconia specimens of two colours (A2P1, WHITE) were used for the study, three try-in pastes (Variolink Esthetic); substrates were prepared from nine types of materials (six VITA SIMULATE, three metals). Measurements were carried out at the Faculty of Atomic Physics of the Technical University of Budapest with the state-of-the-art PerkinElmer® Lambda 1050 spectrophotometer. Results: The colouring of zirconia has a major effect on dE values resulting in different colour perceptibility and acceptability. Try-in pastes, however, have no significant effects overall. Conclusion: Applying coloured zirconia is highly eligible for preparing aesthetic crowns as their substrate-covering effect makes it possible to reproduce the desired colour. Uncoloured zirconia nonetheless is unaffected by the substrate material, especially above a certain layer thickness.  相似文献   
49.
Age-related hearing loss (ARHL), a sensorineural hearing loss of multifactorial origin, increases its prevalence in aging societies. Besides hearing aids and cochlear implants, there is no FDA approved efficient pharmacotherapy to either cure or prevent ARHL. We hypothesized that selegiline, an antiparkinsonian drug, could be a promising candidate for the treatment due to its complex neuroprotective, antioxidant, antiapoptotic, and dopaminergic neurotransmission enhancing effects. We monitored by repeated Auditory Brainstem Response (ABR) measurements the effect of chronic per os selegiline administration on the hearing function in BALB/c and DBA/2J mice, which strains exhibit moderate and rapid progressive high frequency hearing loss, respectively. The treatments were started at 1 month of age and lasted until almost a year and 5 months of age, respectively. In BALB/c mice, 4 mg/kg selegiline significantly mitigated the progression of ARHL at higher frequencies. Used in a wide dose range (0.15–45 mg/kg), selegiline had no effect in DBA/2J mice. Our results suggest that selegiline can partially preserve the hearing in certain forms of ARHL by alleviating its development. It might also be otoprotective in other mammals or humans.  相似文献   
50.
A significant proportion of people living with HIV (PLHIV) who successfully achieve virological suppression fail to recover CD4+ T-cell counts. Since adipose tissue has been discovered as a key immune organ, this study aimed to assess the role of adipokines in the HIV immunodiscordant response. This is a multicenter prospective study including 221 PLHIV starting the first antiretroviral therapy (ART) and classified according to baseline CD4+ T-cell counts/µL (controls > 200 cells/µL and cases ≤ 200 cells/µL). Immune failure recovery was considered when cases did not reach more than 250 CD4+ T cells/µL at 144 weeks (immunological nonresponders, INR). Circulating adipokine concentrations were longitudinally measured using enzyme-linked immunosorbent assays. At baseline, apelin receptor (APLNR) and zinc-alpha-2-glycoprotein (ZAG) concentrations were significantly lower in INRs than in immunological responders (p = 0.043 and p = 0.034), and they remained lower during all ART follow-up visits (p = 0.044 and p = 0.028 for APLNR, p = 0.038 and p = 0.010 for ZAG, at 48 and 144 weeks, respectively). ZAG levels positively correlated with retinol-binding protein 4 (RBP4) levels (p < 0.01), and low circulating RBP4 concentrations were related to a low CD4+ T-cell gain (p = 0.018 and p = 0.039 at 48 and 144 weeks, respectively). Multiple regression adjusted for clinical variables and adipokine concentrations confirmed both low APLNR and RBP4 as independent predictors for CD4+ T cells at 144 weeks (p < 0.001). In conclusion, low APLNR and RBP4 concentrations were associated with poor immune recovery in treated PLHIV and could be considered predictive biomarkers of a discordant immunological response.  相似文献   
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