998 resultados para POLYCRYSTALLINE SM2-XCEXCUO4-Y


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Adsorption of CO has been investigated on the surfaces of polycrystalline transition metals as well as alloys by employing electron energy loss spectroscopy (eels) and ultraviolet photoelectron spectroscopy (ups). CO adsorbs on polycrystalline transition metal surfaces with a multiplicity of sites, each being associated with a characteristic CO stretching frequency; the relative intensities vary with temperature as well as coverage. Whilst at low temperatures (80- 120 K), low coordination sites are stabilized, the higher coordination sites are stabilized at higher temperatures (270-300 K). Adsorption on surfaces of polycrystalline alloys gives characteristic stretching frequencies due to the constituent metal sites. Alloying, however, causes a shift in the stretching frequencies, indicating the effect of the band structure on the nature of adsorption. The up spectra provide confirmatory evidence for the existence of separate metal sites in the alloys as well as for the high-temperature and low-temperature phases of adsorbed CO.

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The increasing rate of pregnancies in teenagers and the high incident of the infections of sexual transmission (HIV/ AIDS, for example), these are health related issues (and especially the sexual and reproductive health), which have received great attention on the part of investigators and of the public opinion in general. Recently, there has been evidenced that teenagers carry out very easily risk sexual behaviors, and those who have not presented the above mentioned behaviors also show high levels of intention to carry out them. There is the hypothesis that besides cognitive variables such as attitudes, subjective norms, perceived behavioral control and intention, the personality of the young persons is an aspect that plays an important paper in their sexual and reproductive health. Significant correlations were found between the variales of the TPB and the personality traits; the results suggest that the direction of these correlations is associated with the specific type of behavior or situation that is assessed. Keywords: personality, theory of planned behavior, adolescents, reproductive sexuality.

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The collection consists of records of the administration of the school; records of a Lower East Side documentation project, including photographs; and letters from a project on the Men's and Women's Department of Der Tag. The collection is arranged in four series: Series I. Administration, Series II. Committee on Research, Series III. Der Tag Project, and Series IV. East Side Project.

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The Grand Street Boys' Association began in 1916 as a reunion of men who had grown up on or near Grand Street in the Lower East Side neighborhood of Manhattan and quickly grew into an active club, open to all men (and eventually women) regardless of religion, ethnicity, or social class. The Association promoted welfare projects, acts of fellowship and tolerance, scholarships, youth employment, war efforts, and the elimination of discrimination in sports, among other projects. The collection documents the activities of the Association, as well as the Grand Street Boys' Foundation, its financial arm established in 1945, and its Hobbycraft Program, a charitable program tasked with collecting and redistributing donated items to charitable and nonprofit organizations. Materials include administrative records, financial records, correspondence, minutes, membership records, newsletters, yearbooks, artifacts, speeches, and photographs relating to both the New York Grand Street Boys' Association and the Association's Grand Street House in England. Series I, comprising the majority of the collection, contains the records of the Grand Street Boys' Association. In it are extensive membership records, meeting minutes, annual yearbooks, financial records, administrative material, newsletters, and artifacts. Series II documents the Grand Street Boys' Foundation and contains administrative records and financial records. Some overlap of material will be found in Series I and II such as material pertaining to the relationship between the Association and Foundation. Series III consists of photographs documenting both the Association and Foundation. The photographs show members and highlight the activities of the Grand Street Boys.

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Contains published and manuscript material relating to the activities and administration of the congregation and its subsidiary organizations including reports and weekly bulletins, early financial records and lists of those honored at religious services, copies of resolutions and forms of service and prayers for various occasions in manuscript form. Contains also material relating to the cemetery photographs, the Hebra Hased Va-Amet (the congregational burial society) and to later clergy in the congregation, Henry Pereira Mendes, David de Sola Pool and Louis Coleman Gerstein including published copies of their sermons.

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Collection includes promotional material such as posters and pamphlets, surveys conducted by the BJE, and press releases. Also includes numerous publications, the majority being bulletins, newsletters, educational material, and bibliographies.

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A model is suggested for mammalian male determination based on interactions postulated to occur among an autosomal repressor gene, an X-linked male-determining gene termed Tdx, and multiple copies of certain DNA sequences on the Y chromosome that do not code for any protein. The repressor, synthesised in limited amounts, has higher affinity for the Y-linked sequences than for Tdx and its affinity for Tdx is greater than that of RNA polymerase. In XY cells the Y effectively binds all available repressor, permitting transcription of Tdx to occur. In XX cells, since competition from the Y-linked high-affinity sequences is absent, the repressor binds to Tdx and prevents transcription. As a result of this competition between Tdx and the Y-linked high-affinity sites for limiting concentrations of the autosomal repressor, the product of the Tdx gene (TDX) is synthesized in the male but not in the female. It is suggested that in determination of the male sex, the role of the Y chromosome is to serve as a sink for the Tdx repressor. The proposed interactions provide a plausible explanation for the genetic properties of several anomalies of sexual development in mouse, man, and other mammals. The model suggests that the postulated multiple, highaffinity sequences on the Y chromosome of the mouse are included among the DNA sequences referred to as the Sxr-Bkm sequences.

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Effect of sonochemical irradiation on the conversion of 2-alkoxytetrahydrofurans to γ-butyro-1actores by Jones reagent, and its extension to the highly stereoselective synthesis of quercus lactone a, is reported.