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排序方式: 共有459条查询结果,搜索用时 15 毫秒
451.
Maíra Kerpel dos Santos PhD Alexander Acosta PhD Ryan Capote BS Bakhtawar Tabassam BS James Ley PhD Martin Quirke PhD José Almirall PhD 《Journal of forensic sciences》2023,68(4):1162-1177
The 4- Aminophenol (4-AP) colorimetric test is a fast, easy-to-use, and cost-effective presumptive assay of cannabis plant material producing different chromophores with THC-rich cannabis (blue color) and with CBD-rich cannabis (pink color). The main drawback of the 4-AP test is a brief observation window where the color rapidly changes to black, limiting the utility of the test. We now report for the first time, the identification of the product chromophores between 4-AP and CBD/THC as well as propose an explanation and a solution for the color degradation of the chromophores. The identification of the chromophores is provided by spectroscopic (UV–Vis), chromatography, and mass spectrometry (TLC and LC-QToF-MS). Oxidation of excess 4-AP (Reagent A) in the presence of NaOH (Reagent B) produces the black color observed for the previously reported 4-AP tests and reported in the literature. The adjustment of reactants concentrations and volumes of 4-AP:THC/CBD to a 1:1 ratio significantly reduces the black oxidation by-product and increases the observation window up to 2 h instead of the previously reported 5–10 min. For the first time, mass spectrometry and chromatography confirmed that the reaction of THC and CBD with 4-AP produced chromophores with m/z (M + H) = 420, consistent with proposed indophenol structures. The TLC method developed confirmed the separation between CBD and THC chromophores. The specificity of the test is also reported, showing false positive results for the presence of THC (blue color) for samples of thyme and oregano. LDA and SIMCA models showed that the optimized 4-AP procedure performs better than the previously reported 4-AP color test. 相似文献
452.
José Octavio Velázquez Gomar 《International Environmental Agreements: Politics, Law and Economics》2016,16(4):525-541
The system of multilateral environmental agreements (MEAs) comprises hundreds of conventions and protocols designed to protect the environment. Institutional interaction within the MEA system raises issues of environmental policy integration (EPI), i.e. balancing different environmental objectives and considerations. Mainstream proposals for enhancing EPI in environmental governance build upon the assumption that environmental institutions are fragmented. However, recent research reveals that the MEA system has been defragmenting over the years such that EPI is less a problem of institutional fragmentation than of effective management of institutional interplay. This paper examines the factors affecting EPI among MEAs by looking at experiences in the cluster of biodiversity-related multilateral agreements. The analysis is based on a series of interviews with MEA secretariat officials and international experts conducted between September 2011 and January 2012. The paper identifies institutional, political and cognitive barriers constraining interplay management efforts. While some have proposed regulatory changes in the cluster, national-level co-ordination appears to be the best way to advance EPI. 相似文献
453.
José María Rosales 《Journal of Political Ideologies》2016,21(3):225-241
This article explores the practices of democracy in Spain through the lens of its 20th-century constitutional moments, namely, those around the 1931 and the 1978 constitutions, with the aim of elucidating its changing ideological significance. Whereas in 1931, supporting democracy had a strongly partisan meaning, as every endorsement of the democratic ideal entailed a conflicting understanding of the Republic’s democratic character, in 1978 it gave rise to an integrative form of pluralism. Even if the former has left a deep imprint on Spanish politics, anticipating a kind of seemingly irreconcilable opposition between left and right, the latter has proved instrumental in the consolidation of the new democratic regime. After the institutional distortion of democracy during the four-decade dictatorship’s ‘organic democracy’, since 1977 the ideal of democracy was thoroughly recast into a pluralist ideology. Unlike views describing it as a consensual regime, the article argues that the politics of consensus tested since the 1977 constitutional debates paved the way for the accommodation of democratic pluralism; furthermore, the culture of pacts it contributed to set up has continued to inspire a new form of adversarial, parliamentary politics well beyond the transition years. 相似文献
454.
José A. Bauermeister Marc A. Zimmerman Tracey E. Barnett Cleopatra Howard Caldwell 《Journal of youth and adolescence》2007,36(7):877-890
Researchers have found mixed support for documenting whether work is protective or harmful during adolescence. This study
examined the association between work and problem behaviors among African American youth (N = 592; 53% female; M = 14.8 years, SD = .60) followed from mid-adolescence to young adulthood over eight Waves (90% response rate over the first four Waves and
a 68% response rate across all eight Waves). We explored three competing operationalizations of work: work history (never
worked, worked), work intensity (no work, 20 h or less, and 21 h or over), and work trajectories (never worked, episodic work,
stopped working, late starter, and consistent worker). Non-working youth reported higher marijuana use during young adulthood
than their working counterparts. Nonworkers reported lower self-acceptance during young adulthood than those working greater
number of hours per week. Differences in work trajectories for cigarette use, depression, and anxiety during adolescence imply
that when and for how long youth work are also important factors to explore. Our findings lend tentative support to the work
benefits perspective and suggest that the association between work and problem behaviors may depend on the work measure used.
We discuss the implications of employing different work measures in adolescent research.
相似文献
Cleopatra Howard CaldwellEmail: |
455.
Builes JJ Martínez B Gómez A Caraballo L Espinal C Aguirre D Montoya A Moreno M Amorim A Gusmão L Bravo ML 《Forensic science international》2007,167(1):62-69
Haplotype data were obtained from a sample of 173 unrelated male individuals from Cartagena (Colombia), for 16 Y-chromosome STRs (DYS19, DYS385, DYS389 I, DYS389 II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439, DYS460, DYS461, DYS635, GATA H4 and GATA A10). No shared haplotypes were observed, demonstrating the usefulness and informative power of these Y-STRs in male lineage identification in Cartagena. Genetic distances were calculated using previously published haplotype data and the lowest values were found for the comparisons with samples of Iberian origin. 相似文献
456.
José Antonio Muñoz Reyes Rómulo Guerra Pablo Polo Eduardo Cavieres Miguel Pita Enrique Turiégano 《Journal of school violence》2019,18(1):39-48
In this study, we applied an evolutionary perspective to analyze the relationship between aggressiveness, academic performance, and sociality in a population of 528 adolescents of both sexes. In men, we expect physical aggression (PA) and sociality to be negative predictors of academic performance. However, in women, PA would be a negative predictor of academic performance, and sociality a positive one. Our results report a negative association between academic performance and PA in both sexes. As we expected, social effect derived from the use of PA seems to be different for each sex, where men could display a rebellious attitude to increase chances of finding a mate. In contrast, results for women are not conclusive, because no relationship between academic performance and any aggressive mechanism, were predicted by sociality. We conclude that an evolutionary framework, which includes sex-specific hypotheses, is appropriate to obtain a holistic perspective of this phenomenon. 相似文献
457.
Manuel Guisado-González Jennifer González-Blanco José Luís Coca-Pérez Manuel Guisado-Tato 《The Journal of Technology Transfer》2018,43(6):1647-1666
Private companies want to eliminate outgoing spillovers while policymakers seek to maximize them. With subsidized R&D cooperation agreements both agents partially achieve their objectives. For this reason, in Europe, policymakers grant subsidies for R&D activities with the condition of establishing R&D cooperation agreements. This study explores the relationship of complementarity between R&D subsidy, R&D cooperation and absorptive capacity in the context of its contribution to labor productivity of enterprises. The data used comes from the Technological Innovation Panel (PITEC), managed by the Spanish National Statistics Institute. We selected manufacturing companies in the period 2008–2013. We evaluate the existence of complementarity through the systems approach and the interaction approach. The econometric technique that we used to estimate the coefficients of our empirical model was maximum-likelihood random effects. As a consequence of the low absorptive capacity of Spanish manufacturing firms we find that R&D subsidies and R&D cooperation agreements are not complementary variables, i.e., receiving public subsidies as a result of establishing R&D cooperation agreements has a lower impact on productivity than the sum of the individual impacts of R&D cooperation and R&D subsidies. In consequence, this result calls into question the convenience of using subsidized R&D cooperation agreements as a tool for promoting innovation in EU countries as there are notable differences between the companies in these countries in terms of absorption capacity. 相似文献
458.
Angeles Sánchez-Andrés José Antonio Barea Noemí Rivaldería Concepción Alonso-Rodríguez Esperanza Gutiérrez-Redomero 《Science & justice》2018,58(5):323-334
The variation in the epidermal ridge's width between the sexes, during various growth stages, and among different populations has been previously assessed. However, the changes that occur with aging are barely known.The goal of this study was to analyse the degree of variation in epidermal ridge width due to aging. So that, fingerprint ridge density was estimated to establish their relationship with body and hand size changes that typically occur in adulthood.In this study, a sample of 213 adults of both sexes from a Spanish native population of different age ranges—18–30?years old (“junior” group) and 50–66?years old (“senior” group)—was used. Ridge density was assessed in three counting areas of the distal phalanx of each finger (radial, ulnar, and proximal). Height, weight, and a set of anthropometric measurements for both hands were also taken.Our results show that ridge density is higher in females than males throughout adulthood and decreases with aging in the radial and ulnar areas (as the hands widen) but not in the proximal region. Thus, a relationship between hand dimensions and ridge density was found.The data indicate that aging changes may conceal the recognized sex differences in ridge density, and so a better understanding of the topological variations in the epidermal ridge width throughout the life cycle and the factors involved would facilitate the interpretation of the differences between the sexes and different age groups. 相似文献
459.
Asia Europe Journal - This article analyses trade flows EU-ASEAN, focusing on export performance and technological intensity, covering the years 2004–2016. The aim of this paper is to analyse... 相似文献