Results 41 to 50 of about 77,258 (158)

Fluoride Anion Recognition by a Multifunctional Urea Derivative: An Experimental and Theoretical Study

open access: yesSensors, 2016
In this work we demonstrate the ability of a multifaceted N,N′-disubstituted urea to selectively recognize fluoride anion (F−) among other halides. This additional function is now added to its already reported organocatalytic and organogelator properties.
Jana Schiller   +5 more
doaj   +1 more source

Teoría semántica de la dependencia asimétrica: naturalización y reducción [PDF]

open access: yes, 1999
Se dice que estamos en la era del fisicalismo. Parece ser que hay un acuerdo en que sean las que fueren las entidades que se acepten, éstas, de alguna manera, se relacionan con las entidades que las ciencias naturales dicen que hay.
Skidelsky, Liza
core  

Reduced Offspring Viability Is Associated With Long‐Term Stability of a Narrow Avian Hybrid Zone

open access: yesEcology and Evolution, Volume 15, Issue 9, September 2025.
We investigated hybrid viability in a tropical, avian hybrid zone governed by strong selection on male secondary sexual traits between the white‐collared manakin (Manacus candei) and golden‐collared manakin (M. vitellinus). We assessed putative hybrid fitness by investigating adult survival and hatching success along with a prospective selective ...
Kira M. Long   +5 more
wiley   +1 more source

Understanding Chiral Proton Catalysis Using Cinchonium Derivatives in aza‐Michael Additions

open access: yesAdvanced Synthesis &Catalysis, Volume 367, Issue 11, June 3, 2025.
Abstract This work presents a detailed mechanistic study of a quininium‐catalyzed aza‐Michael reaction, providing essential information for advancing chiral proton catalysis (CPC). The use of cinchona derivatives as chiral proton catalysts demonstrates their potential beyond their conventional roles as base‐promoted and phase‐transfer catalysts ...
Fernando Auria‐Luna   +4 more
wiley   +1 more source

PKI* y firmas digitales: aplicaciones reales

open access: yesInventum Ingeniería, Tecnología e Investigación, 2007
El uso de las claves públicas es la base para que se dé el comercio electrónico. Este documento busca sustentar que la administración de la infraestructura de llaves públicas o PKI es la solución para conseguir seguridad de la información en los negocios
Armando Carvajal
doaj   +1 more source

Phyllosilicate crystallinity in soils and weathering products from granitic rocks of Galicia [PDF]

open access: yes, 1990
[Resumen] Se ha determinado la cristalinidad de micas y filosilicatos 1: 1 dioctaédricos de los limos y arcillas de 20 perfiles edáficos desarrollados sobre rocas graníticas. Se observa una estrecha relación entre el valor del índice de cristalinidad de
García, C., Romero, R., Taboada, T. M.
core   +1 more source

Multicomponent Cyanation of 2‐Amino‐3‐cyano‐4H‐chromenes in Aqueous Media

open access: yesAsian Journal of Organic Chemistry, Volume 13, Issue 12, December 2024.
Chromenes, especially 2‐amino‐3‐cyano‐4H‐chromene derivatives, are present in biologically active compounds with potential properties, although the number of synthetic methods to date is limited. Here, we report a new protocol using a mild source of cyanide (acetone cyanohydrin), green solvents, and catalytic conditions via a multicomponent approach ...
Sandra Ardevines   +5 more
wiley   +1 more source

Hidroformilación asimétrica de olefinas con catalizadores de rodio y difosfitos metalamacrocíclicos [PDF]

open access: yes, 2007
Consultable des del TDXA portada: Escola de Doctorat. Tesi doctoral. Programa de doctorat-QuímicaTítol obtingut de la portada digitalitzadaEsta tesis se enmarca en el campo de la catálisis homogénea, concretamente en la síntesis de ligandos difosfito y ...
Crespi Serrano, Laura
core   +3 more sources

La sombra alargada del patrón: Gamonalismo y hábitos hacendatarios en Chimborazo tras la reforma agraria

open access: yesThe Journal of Latin American and Caribbean Anthropology, Volume 29, Issue 4, Page 352-363, December 2024.
Abstract This paper explores selective aspects of the historical processes of organization of the kichwa peasantry in the Andes of Ecuador. Based on the analysis of two representative cases of confrontation between peasants and landowners over access to land in the province of Chimborazo, it discusses the relevance of the concept of “gamonalismo” as ...
Víctor Bretón
wiley   +1 more source

Granitoides asociados a zonas de desgarre: modelos analógicos y aplicación al macizo de Lizio (zona de cizalla surarmoricana)

open access: yesEstudios Geologicos, 1997
El emplazamiento de granitoides en zonas de desgarre de la corteza superior se ha modelizado inyectando un fluido newtoniano en un paquete de arena en el cual se intercala una capa dúctil de silicona que actúa como un nivel de despegue potencial en el ...
T. Román Berdiel, D. Gapais, J. P. Brun
doaj   +1 more source

Home - About - Disclaimer - Privacy