Search results for "periodic"

Analysis of Production, Impact, and Scientific Collaboration on Difficult Airway Through the Web of Science and Scopus (1981-2013).

2017

Bibliometrics, the statistical analysis of written publications, is an increasingly popular approach to the assessment of scientific activity. Bibliometrics allows researchers to assess the impact of a field, or research area, and has been used to make decisions regarding research funding. Through bibliometric analysis, we hypothesized that a bibliometric analysis of difficult airway research would demonstrate a growth in authors and articles over time.Using the Web of Science (WoS) and Scopus databases, we conducted a search of published manuscripts on the difficult airway from January 1981 to December 2013. After removal of duplicates, we identified 2412 articles. We then analyzed the art…

Predatory journals enter biomedical databases through public funding

2020

Predatory publishing is an international, cross disciplinary threat to the integrity of the scientific system • A worrying number of articles published in predatory journals are indexed in biomedical databases such as PubMed, the free access biomedical database maintained by the National Library of Medicine • Public funding, under open access policies, seems to be the mechanism by which articles are displayed in PubMed. • Providing guidance to publicly funded authors on how to publish their work in legitimate open-access venues will likely stop the wasteful use of public money to cover the fees of predatory journals.

1978

La blogosfera política española en las Elecciones Generales 2011. Una comparación entre blogs de candidatos, periodistas y ciudadanos

2015

En: Doxa Comunicación : revista interdisciplinar de estudios de comunicación y ciencias sociales. ISSN 1696-019X n. XXI, 2015, pp 78-112 El presente estudio propone un análisis de la blogosfera política española durante la campaña electoral previa a las Elecciones Generales del 20 de noviembre de 2011, con el fin de identificar los principales temas de discusión que centraron el debate en tres tipos de bitácoras: seis blogs de candidatos políticos de las principales formaciones políticas españolas, cuatro a cargo de periodistas destacados de la esfera pública central y cuatro de ciudadanos anónimos. Se plantea un análisis de contenido fundamentado en 57 categorías temáticas para establecer …

A versatile metathesis reaction for the formation of labile bonds between group 13 and group 15 atoms.

2003

Dimerization control in the self-assembly behavior of copillar[5]arenes bearing ω-hydroxyalkoxy groups.

2012

Two novel copillar[5]arenes bearing ω-hydroxyalkoxy groups are synthesized and their self-assembly properties are studied by (1)H NMR spectroscopy, specific viscosity, and X-ray measurements. The copillar[5]arene 2b bearing a 6-hydroxyhexyloxy group exhibits a reversible self-assembly behavior, leading to the formation of the self-inclusion monomer and hugging dimers. The reversible self-assembly behavior can be controlled by tuning solvent, temperature, guest, and H-bond interaction. However, the copillar[5]arene 2a bearing a short 4-hydroxybutyloxy group does not show such a self-assembly behavior to the formation of the self-inclusion monomer and hugging dimers.

A logarithmic fourth-order parabolic equation and related logarithmic Sobolev inequalities

2006

A logarithmic fourth-order parabolic equation in one space dimension with periodic boundary conditions is studied. This equation arises in the context of fluctuations of a stationary nonequilibrium interface and in the modeling of quantum semiconductor devices. The existence of global-in-time non-negative weak solutions and some regularity results are shown. Furthermore, we prove that the solution converges exponentially fast to its mean value in the ``entropy norm'' and in the Fisher information, using a new optimal logarithmic Sobolev inequality for higher derivatives. In particular, the rate is independent of the solution and the constant depends only on the initial value of the entropy.

The preparation of four- and six-membered chalcogenametallacyclic derivatives of group 4 metallocenes

1989

Abstract Four-membered metallacycles [(RC 5 H 4 ) 2 M(μ-E)] 2 (M = Zr, Hf; 1 , E = Se; 2 , E = S) were obtained by UV irradiation of dialkyl- or diaryl-metallocenes and equimolecular amounts of elemental chalcogen, but this method works only for bulky R groups. A more general route to compounds 1 and 2 involves the reaction of metallocene dichloride with chalcogenide anions. Six-membered metallacyclohexasulfanes (t-BuC 5 H 4 ) 2 MS 5 ( 3 , M = Zr, Hf) are obtained rather than compounds 2 when an excess of sulfur is used in the photolytic experiments, whereas compounds 1 were still formed when an excess of selenium was used. The observed difference is explained in terms of the solubility of …

Preparation and structural studies on dibutyltin(IV) complexes with pyridine mono- and dicarboxylic acids

2004

Abstract A number of organotin(IV) complexes with pyridine mono- and dicarboxylic acids (containing ligating –COOH group(s) and aromatic {N} atoms) were prepared in the solid state. The bonding sites of the ligands were determined by means of FT-IR spectroscopic measurements. It was found that in most cases the –COO− groups form bridges between two central {Sn} atoms, thereby leading to polymeric (oligomeric) complexes. On this basis, the experimental 119Sn Mossbauer spectroscopic data were treated with partial quadrupole splitting approximations. The calculations predicted the existence of complexes with octahedral (oh) and trigonal-bipyramidal (tbp) structures, but the formation of comple…

Adsorbed CO on group 10 metal fragments: A DFT study

2009

DFT calculations on the helicopter and cartwheel rotations of one CO molecule adsorbed at the bridge site on metal-surface fragments, characterized by two (M(8)) or three (M(14)) metal-atom layers (M = Ni, Pd, Pt) were performed by the B3LYP[LANL2DZ+6-31 g(d,p)] method, to rationalize the adsorption energetics and the steric hindrance characteristics of surface CO molecules. Potential Energy Surfaces were obtained, either fixing the C-O bond-length or allowing it to change. The behavior of the three metals, as obtained from the study of the configurational space characterizing the CO adsorption on the fragments was explained on the basis of the interaction energies involved in the different…