1000 resultados para Chemical Libraries


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Digital libraries (DL) have had a tremendous impact on improving the accessibility of scientific and academic publications. In developing countries, they seem to be the great hope, due to the serious existing problems with the traditional publishing and distribution mechanisms and to the potential they have on enabling access to a great panoply of publications. Moreover, accessing digital libraries over mobile devices has the potential of reaching a broader community of users and on helping to bridge the digital divide, since there are very reduced computer and Internet penetration rates in these countries, along with a higher mobile phone usage. For developed countries, accessing digital libraries on the go might also bring important added value. This paper features an analysis of the major issues related to making digital libraries accessible over mobile devices. A specific study on the possibility of using mobile digital libraries in a developing country context is also presented along with a proposal for making DSpace based digital libraries accessible over mobile phones.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Digital libraries (DL) are seen as the hope for developing countries in their struggle to access scientific and academic publications. However, building such libraries in developing countries is a real challenge. These countries usually face several difficulties, such as low computer and Internet penetration rates, poor ICT infrastructure, lack of qualified human resources, lack of financial resources, etc. Thus, it is imperative finding alternative mechanisms of building DL that best fit the specificities of these countries. This paper presents the process used for building a digital library at the University Jean Piaget of Cape Verde, created in a context of scarce access to printed materials and serious difficulties in accessing ICT resources. This paper also presents the challenges, the solutions and the adopted methodological framework.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Given the existing challenges in accessing print-based publications in developing countries, digital libraries are seen as a good alternative. Thus, it is important to understand how such libraries are used in these contexts, especially when compared with the usage of traditional libraries. This paper analyzes and compares the usage of the digital and traditional libraries of the University Jean Piaget of Cape Verde, aiming at understanding the way they are used, and the relation between the access to the existing information resources in these two libraries.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Iowa is a state rich in libraries, with 543 public libraries; more than 80 college and university libraries; and about 1,000 school libraries. Libraries enrich Iowa and support lifelong learning. The State Library of Iowa actively champions libraries and improves library services for Iowans through its management of the Enrich Iowa program. In accordance with 2006 IOWA ACTS, Chapter 1180 (16)(6), the State Library of Iowa is pleased to submit this report on the impact of state funding on Iowans and Iowa libraries through the Enrich Iowa Program.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Iowa is a state rich in libraries, with 543 public libraries; more than 80 college and university libraries; and about 1,000 school libraries. Libraries enrich Iowa and support lifelong learning. The State Library of Iowa actively champions libraries and improves library services for Iowans through its management of the Enrich Iowa program. In accordance with 2006 IOWA ACTS, Chapter 1180 (16)(6), the State Library of Iowa is pleased to submit this report on the impact of state funding on Iowans and Iowa libraries through the Enrich Iowa Program.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Iowa is a state rich in libraries, with 543 public libraries; more than 80 college and university libraries; and about 1,000 school libraries. Libraries enrich Iowa and support lifelong learning. The State Library of Iowa actively champions libraries and improves library services for Iowans through its management of the Enrich Iowa program. In accordance with 2006 IOWA ACTS, Chapter 1180 (16)(6), the State Library of Iowa is pleased to submit this report on the impact of state funding on Iowans and Iowa libraries through the Enrich Iowa Program.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This report includes the number of Iowa card holders, library checkouts and library visits in public libraries from 1995 to 2005

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This report includes the number of Iowa card holders, library checkouts and library visits in public libraries from 1995 to 2005

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This report includes the number of Iowa card holders, library checkouts and library visits in public libraries from 1995 to 2005

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This report includes the number of Iowa card holders, library checkouts and library visits in public libraries from 1995 to 2008

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Cork is the bark of the cork oak tree (Quercus suber L), a renewable and biodegradable raw bioresource concentrated mainly in the Mediterranean region. Development of its potential uses as a biosorbent will require the investigation of its chemical composition; such information can be of help to understand its interactions with organic pollutants. The present study investigates the summative chemical composition of three bark layers (back, cork, and belly) of five Spanish cork samples and one cork sample from Portugal. Suberin was the main component in all the samples (21.1 to 53.1%), followed by lignin (14.8 to 31%), holocellulose (2.3 to 33.6%), extractives (7.3 to 20.4%), and ash (0.4 to 3.3%). The Kruskal-Wallis test was used to determine whether the variations in chemical composition with respect to the production area and bark layers were significant. The results indicate that, with respect to the bark layer, significant differences were found only for suberin and holocellulose contents: they were higher in the belly and cork than in the back. Based on the results presented, cork is a material with a lot of potential because of its heterogeneity in chemical composition

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The geochemical compositions of biogenic carbonates are increasingly used for palaeoenvironmental reconstructions. The skeletal delta O-18 temperature relationship is dependent on water salinity, so many recent studies have focused on the Mg/Ca and Sr/Ca ratios because those ratios in water do not change significantly on short time scales. Thus, those elemental ratios are considered to be good palaeotemperature proxies in many biominerals, although their use remains ambiguous in bivalve shells. Here, we present the high-resolution Mg/Ca ratios of two modern species of juvenile and adult oyster shells, Crassostrea gigas and Ostrea edulis. These specimens were grown in controlled conditions for over one year in two different locations. In situ monthly Mn-marking of the shells has been used for day calibration. The daily Mg/Ca.ratios in the shell have been measured with an electron microprobe. The high frequency Mg/Ca variation of all specimens displays good synchronism with lunar cycles, suggesting that tides strongly influence the incorporation of Mg/Ca into the shells. Highly significant correlation coefficients (0.70<R<0.83, p<0.0001) between the Mg/Ca ratios and the seawater temperature are obtained only for juvenile C. gigas samples, while metabolic control of Mg/Ca incorporation and lower shell growth rates preclude the use of the Mg/Ca ratio in adult shells as a palaeothermometer. Data from three juvenile C. gigas shells from the two study sites are selected to establish a relationship: T = 3.77Mg/Ca + 1.88, where T is in degrees C and Mg/Ca in mmol/mol. (c) 2012 Elsevier B.V. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Studies from some semi-arid regions of the world have shown the beneficial effect of trees in silvopastoral systems, by promoting the formation of resource islands and increasing the sustainability of the system. No data are available in this respect for tree species of common occurrence in semi-arid Northeastern Brazil. In the present study, conducted in the summer of 1996, three tree species (Zyziphus joazeiro, Spondias tuberosa and Prosopis juliflora: ) found within Cenchrus ciliaris pastures were selected to evaluate differences on herbaceous understory and soil chemical characteristics between samples taken under the tree canopy and in open grass areas. Transects extending from the tree trunk to open grass areas were established, and soil (0-15 cm) and herbaceous understory (standing live biomass in 1 m² plots) samples were taken at 0, 25, 50, 100, 150 and 200% of the average canopy radius (average radius was 6.6 ± 0.5, 4.5 ± 0.5, and 5.3 ± 0.8 m for Z. joazeiro, P. juliflora, and S. tuberosa , respectively). Higher levels of soil C, N, P, Ca, Mg, K, and Na were found under the canopies of Z. joazeiro and P. juliflora: trees, as compared to open grass areas. Only soil Mg organic P were higher under the canopies of S. tuberosa trees, as compared to open grass areas. Herbaceous understory biomass was significantly lower under the canopy of S. tuberosa and P. juliflora trees (107 and 96 g m-2, respectively) relatively to open grass areas (145 and 194 g m-2). No herbaceous biomass differences were found between Z. joazeiro canopies and open grass areas (107 and 87 g m-2, respectively). Among the three tree species studied, Z. joazeiro was the one that presented the greatest potential for use in a silvopastoral system at the study site, since it had a larger nutrient stock in the soil without negatively affecting herbaceous understory biomass, relatively to open grass areas.