965 resultados para Ensino profissional
Resumo:
This dissertation describes the construction of a alternative didactic incorporating a historical approach with the use of the Roman abacus for teaching multiplication to students of 2nd year of elementary school, through activities ranging from the representation of numbers to multiplying with the Roman abacus, for learning the multiplication algorithm. Qualitative research was used as a methodological approach since the research object fits the goals of this research mode. Concerning the procedures, the research can be seen as a teaching experiment developed within the school environment. The instruments used for data collection were: observation, logbook, questionnaires, interviews and document analysis. The processing and analysis of data collected through the activities were classified and quantified in tables for easy viewing, interpretation, understanding, analysis of data and then transposed to charts. The analysis confirmed the research objectives and contributed to indicate the pedagogical use of the Roman abacus for teaching multiplication algorithm through several activities. Thus, it can be considered that this educational product will have important contributions for the teaching of this mathematical content, in Basic Education, particularly regarding to the multiplication process
Resumo:
Biological rhythms are part of the life from the simplest to the most complex living beings. In humans, one of the most important biological rhythms is the sleep-wake cycle (SWC), which represents an indispensable behavior for health, since sleep deprivation can lead to deficits in attention and memory, mood and daytime sleepiness which may affect school performance. Nevertheless, the SWC is a content rarely discussed in schools. Thus, the aim of this research was to address contents of the sleep-wake cycle, related to the content of Health to encourage healthy sleep habits. This study was conducted in a public school with 33 students of the 3rd year of high school and is divided into four stages: 1st) Study and analysis of the content of the textbook adopted by the school to subsidize the activities covered in the teaching unit (TU) and approximation with the biology teacher from the class to evaluated the feasibility of schedules for the development of TU; 2nd) Survey of students' prior knowledge, through a questionnaire, to guide the development of the TU; 3rd) Development and implementation of a TU based on meaningful learning and characterization of the students sleep habits, 4th) Evaluation of the TU as a viable proposal to teach biological rhythms concepts. Previous knowledge of students about the SWC are scarce and this content is not covered in the books adopted by the school. Alternative conceptions were observed, particularly with regard to individual differences in sleep, which may contribute to the occurrence of inadequate sleep habits, as reported by the adolescents in this study. The activities developed during UD were well received by the students who showed participative, motivated and evaluated positively the procedures used by the researcher. After the TU, students' knowledge about the concept of biological rhythms has been increased and they started to identify that the SWC changes throughout life and occur due biological and socio-cultural factors. Thus, the UD elaborated in this study represents a viable proposal to teach the concepts of biological rhythms contextualized to the content of Health, in high school
Resumo:
The evidence of the water theme in news reports is configured as an important topic of interest to contextualize, problematize and/or generate meaning in the midst of discussion of a content from different levels of education and/or disciplines of basic education. The possibilities to use this theme in classroom is also highlighted in Brazilian official documents that guide the practice of teachers of all Brazilian curricular components of this educational level. So, the theme water can be used as subsidy to teach chemistry, since contextualises the teaching of this discipline aiding in the discussion of different chemical concepts. In this perspective, the meaningful learning theory, developed by David Ausubel, has constructivist nature and says that an individual learns significantly when he can relate new information with a specific knowledge structure that integrates the prior knowledge of its structure. In this sense, the use of water as a theme for the approach prior knowledge of chemical concepts has already been characterized as an important topic that can give meaning to the content of education in chemistry. In this dissertation, a teaching unit potentially significant (TUPS) is presented based on meaningful learning theory of David Ausubel approaching the theme water. approaching the theme water. The unit was used in a class of thirty-five students of the 2nd year of high school, a public school in the city of Extremoz-RN, metropolitan region of Natal / RN. Through it was possible to discuss an issue of interest to students of the school to address the chemical contents, such as solutions, physicochemical aspects and stages of water treatment. At first, an initial questionnaire was used to identify the students' previous ideas on the topic under study to the concept of chemical solutions. It was subsequently developed and implemented a series of activities based on students' ideas. To subsidize the sequence, it was prepared four booklets that worked the content of chemical solutions, contextualizing the theme water. The results of this work showed that the alternative conceptions that students have about concepts related to the chemical solutions are similar to the ideas of other students presented in the literature and that the development of the TUPS, allied to the contextualization strategy with the theme water, not only motivated the students for the teaching of chemical content, as yet provided the learning of chemical concepts not in isolation, but making a connection between their ideas and experiences with scientific knowledge. To this, beyond of dialogued lectures, were also used strategies as experimental activities, problem solving, group discussions and construction of concept maps. The final evaluation of the unit was conducted by a questionnaire based on the Likert scale, answered individually by students, who approved the unit as conducive to teaching and learning of chemistry process
Resumo:
The scope of this Dissertation is propose the teaching of the evaporation based on the approach Science, Technology and Society (STS) because we believe that this type of approach is able to provide students with a more critical and conscious learning about science. Moreover, with this search, it´s possible to show for students the importance of role to play for them as citizens in decision making aimed to benefit all who are part of the community to which they belong. From this perspective, broached the theme evaporation in a region characterized by constant lack of water for consumption, the municipality of Santa Cruz/RN because, despite the creation of dams to regulate the flow of rivers and increase the availability of water during periods of scarcity, we know that these reservoirs have a large free liquid surface allowing high water loss by evaporation. Thus, evaporation affects the performance of reservoirs for water supply and irrigation, being a phenomenon of particular interest to study. To this end, a questionnaire in order to identify students' preconceptions on the subject was applied. Was then prepared and conducted a workshop geared toward students majoring in Physics Campus Santa Cruz, Federal Institute of Education, Science and Technology of Rio Grande do Norte (IFRN). The completion of the workshop served as a space for discussion of the topic within the context of the municipality of Santa Cruz/RN. As a product, we suggest to physics teachers a guide with recommendations to be taken into account when they teach this subject
Resumo:
During the last decades the area of science education has discussed issues related to the inclusion of the History and Philosophy of Science (HFS) in the practice of science teaching. Among the arguments put forward in favour of this approach, it is pointed out the possible enhancement of scientific content learning and the understanding of the nature of Science (NoS). In spite of such considerations, we still have a very small number of research papers reporting results of practical interventions that utilize the historical approach, moreover, there is a lack of teaching materials in this perspective. Our work has sought to contribute to this area with regard to two aspects: on the one hand, with the production of didactic material, by drawing up texts on the history of inertia for graduate students. On the other hand, we investigate whether the arguments mentioned above in relation to the didactic use of HFS sustain themselves, in a particular context. We developed and applied a didactic sequence, using the texts that we built, to teach the concept of inertia and discuss selected contents of NoS. The didactic sequence was applied in two graduate classes, one from a course of Geophysics (BSc.) and another from the Physics (teaching formation), both from the Federal University of Rio Grande do Norte (UFRN). An initial survey exposed that students, even having approached the concept of inertia in basic education, presented conceptions of common sense regarding the relationship between force and motion. The questionnaire also allowed us to identify the existence of elements of concepts considered inadequate as regards to NoS. At the end of our research, our data indicated a greater number of positive hits on the issues concerning the concept of inertia. Regarding the aspects of NoS, we were able to identify, in a few cases, a move towards a more appropriate understanding, however, certain distortions persisted, highlighting the limitations of the approach used
Resumo:
The thesis deals with the concepts of technical tra ining of middle level adopted by the Federal Institute of Education, Science and Technology of R io Grande do Norte (IFRN). Discusses these concepts from the four political-pedagogical projects built in the period 1970 to 2010, spanning three institutionalities: Federal Technica l School of Rio Grande do Norte (1970- 1998), Federal Center of Technological Education of Rio Grande do Norte (1999-2008) and IFRN (from 2008) as well as three important politic al contexts of the country: Civil-Military Dictatorship, New Republic and Period of neoliberal ideas in Brazil. The goal is to analyze the configuration of the conceptions of training adopte d in the political-pedagogical projects IFRN, with emphasis on the specificities and (dis) contin uities, placing them in the context of political, economic and educational change in development in t he country. Addresses the relationship work, education and human development in capitalist society, in order to grasp the concept of employee training engendered by that company as wel l as the possibility of a counter- hegemonic formation. We analyze the formation of mi d-level concepts outlined in the educational reforms implemented in the country. We investigate the concepts of training outlined in the political-pedagogical projects IFRN . Makes use of the historical-dialectical materialism, the literature review, the documentary research and interviews were conducted with subjects who participated in the working group coordinator of the drafting of the political- institutional educational projects. The results sho w that the training of workers in capitalist society has a unilateral character; that the traini ng required by the working class is the omnilateral training; that the formative ideas that permeated the educational reforms in the country between 1970 and 2010 were all envisaged by unilateral training; that, in certain contexts, conceptions of technical training medium level outlined in the political-pedagogical projects IFRN reflect the formative perspectives th at guide educational reforms in the country (unilateral training) and, at other times, the inst itution adopts concepts (training omnilateral) that are not consistent with such prospects; and th at between the political-pedagogical projects built from 1970 to 2010 there are more continuities than breaks in relation to the concepts of training adopted. We conclude that the challenge is to institutionalize the IFRN their educational actions omnilateral designing training undertaken in the political-pedagogical project 2009.
Resumo:
El estudio investiga los saberes literários del profesores del Enseño Fundamental de las series iniciales sobre la literatura. Cuando se piensa en la influencia del profesor como aquel que tiene papel decisivo en la enseñanza de la lectura y reconocimiento de la función y formación del mediador profesional, buscamos compreender que conocimiento tiene sobre la literatura. Optamos por los profesores que trabajan en los años iniciales del Enseño Fundamental basadas en el entendimiento de la educación básica, es de suma importância en la formación del lector literário. El estudio se caracteriza por ser un enfoque cualitativo. Adoptamos como procedimientos metodológicos, la entrevista semiestructurada, elaborada com preguntas abiertas que se centran en eventos de lectura de las practicas em família, en la escuela, en la educación superiory en el ejercicio de enseãnza grabadas en audio, además de elevar um diário de campo. La investigación lleva a cabo en cuatro escuelas de la ciudad de Natal – Rn, con dicinueve profesores que trabajan con alumnos de 1º a 5º año del Enseñanza Fundamental. El corpus de la entrevista constituye el análisis de los profesores y es analizado tomando como referencia los princípios de análisis de contenido, especificado por Laurence Bardin (1997). Se tomó como referencial sobre la lectura, la literatura y práctica pedagógica los estudios teóricos de Amarilha (1991, 1992, 1994, 1997, 2003, 2006, 2007, 2009, 2010, 2013); Cosson (2011); Lajolo (2006); Larrossa (1996, 2003); Morin (2010); Yunes (2003, 2010). Sobre la teoría literaria, Candido (2002, 2012); Zilberman (1993); Culler (1999). Acerca de la estética recepción, Eco (1994); Iser (1996); Jauss (2002). Sobre los saberes docentes, Nóvoa (1992, 1997, 2002); Perrenoud (1999, 2002), Tardif (1991, 2000, 2002, 2005). Sobre los saberes literários, Paulino (2004, 2007), dentre outros. El análisis señala que los profesores dominan vários conocimientos sobre la literatura que son transportados a la formación a través del diálogo con otras lecturas, con otros espacios interactivos, en convivência con otros lectores. Cabe destacar el saber que la literatura es humanizar el fator, por lo tanto, la necesidad de escolarizá que a través de las prácticas literárias que involucran estudiantes, professores y comunidad escola. El studio también revela que en la escuela recital literário es necesario para la enseñanza de valores, para enseñar a leer, para inculcar el amor por la lectura. En este contexto, destacamos la importancia de la mediación del profesor como formador de lectores que domina los conocimientos necesarios para satisfacer las necesidades de los estudiantes, desarrollando los letctores conocimientos para fomentar el gusto por el texto literário
Resumo:
This study aims to assess the usability of Interactive Materials developed for the courses offered by UFRN SEDIS the modality of distance education (DE), using the techniques of focus group cooperative evaluation and assessment of satisfaction. The Interactive Materials are intended to serve as an avenue where the course content reaches the student in an educational, stimulating and self-instructive enough for the student to engage and find no difficulty in using it so. After the survey data in this context were selected four Interactive Materials ("Introduction to Applied Calculus", "Science, Technology and Society", "studies the Semi-Arid" and "Cultural Geography") that adopt the framework established by UFRN for SEDIS be evaluated for their usability. Initially, a preliminary test was conducted from cooperative assessment with a student interacting with the four learning objects in order to reveal and map the major failures of usability, supporting deeper questions later. The recordings of this preliminary test were analyzed by a focus group composed of two graphic designers and two multimedia designers, and developers responsible for these objects, which helped to analyze the gap between "what was designed" and "as was used "structuring and supplementing the roadmap for cooperative evaluation and assessment of subsequent satisfaction. The cooperative evaluation was applied individually to ten students of undergraduate UFRN that tested each of the four materials. At the end, every student completed a questionnaire assessing satisfaction form adapted Wanted (Questionnaire for User Interaction Satisfaction). The analysis of the data collected in this study revealed positive, negative and notes to be considered to guide the future development of Interactive Materials, in the context of UFRN SEDIS, feedback to the process of design and evaluation with user participation
Resumo:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Resumo:
Before the scenario full of criticism about a medical model that gives privilege to the diseases and not to the diseased, there are many arguments that defend the need of redeem the humanized relationship between doctor and patient. It became indispensable to mold during the medical graduation a professional capable of perform a special care, less instrumental and more humanized; however, even though the advances of the pedagogical program of the medical graduation, we still face numerous challenges in the process of molding. This study has as general goal to understand if the students medicine experience with the Integrative Community Therapy (TCI) at the Primary Attention – APS/Family Healthy Strategy-ESF, presents potential to configure itself while strategy of teaching-learning to the integral and humanized care. It was held a qualitative research with the students of the medical graduation from the tenth to the twelfth semester that had experience with the TCI, as part of the Boarding of Family and Community Medicine – MFC. We used interviews with script and we resorted to analyze the narratives to Gadamerian Hermeneutics. It was possible to find that before join the boarding of MFC, the students were unaware the TCI and their preconceptions lined up with depreciated character. The experience with the TCI enabled the reframing of the prejudices and the build of new concepts. Internship in ESF and participate of TCI revealed potential to learning of the humanized care by the practical exercise with experiences that privilege the built of ties; the autonomy of the patient; the fulfillment of the longitudinality at the care of the patient; the acknowledgment of the power of resilience of the patients, at the strength of the collective, at the pain sharing, at the strength of a good communication, at the gains of qualified listening exercise. The absence of models of what to do was replaced by experiences of pains and joys at the learning of becoming a doctor. The pains spoke of the structural difficulties (inputs), at the get along with the socials vulnerabilities of the users and the difficult of perform a good communication with the patients. The joys were experienced at the finding of the humanized care exercise. Questions as structural difficulties, low number of people with TCI degree, a shortly experience of with TCI, show up as limitations to its utilization as pedagogical tool. In turn, the reflective potential is capable of cause resignifications about the know-how before the pain of the other being very much present at the narratives, signaling the potential of the learning of TCI. Therefore, this study advocate that the participation of the students at the TCI, beyond the power of offering the students a teaching-learning strategy to the humanized care, represents the possibility of enlarge the horizons of those future doctors at a glance much more conscious of the difficulties and potential of a professional at the ESF, contributing to the graduation of more sensitized professionals and prepared to perform an integral and humanized approach of the person and his/her community, contributing to an APS/ESF more resolute and rewarding to everyone.
Resumo:
Currently, the diagnostic ultrasound is inserted in various areas of medical action and carried out by many medical professionals, from which militate directly in the image area, such as radiologists and sonographers, but also by gynecologists, pediatricians, neurologists, general practitioners, endocrinologists, angiologists, orthopedists, rheumatologists, urologists, general and vascular surgeons. It is well known that the medical professional, for the exercise of its mission, requires a broad set of skills, competencies and attitudes developed and exercised during their training period. Living with medical students over nearly 20 years in hospital environment, I noticed gaps in the learning process by the students about what is diagnostic ultrasound and its applications, demonstrating failures as understanding the basic acoustic ultrasound, difficulties in identifying of anatomical structures in ultrasound images and inability in requests examinations and interpretations of images and reports. Based on these findings, it was developed in this Professional Masters a multimedia digital book that exposes what the ultrasound as a diagnostic modality imaging, dealing with its historiography and its physical/acoustic concepts, relating the process of formation of the ultrasound image, discussing about the features of sonographic equipments and their embedded technologies and highlighting its diagnostic applications , the latter presented through videos which will be described aspects of captured ultrasound images. This book will be available for access in digital format, serving as a teaching tool in medical education since the beginning of the course, so that can be used in conjunction with the discipline of Gross Anatomy, offered in the basic cycle of the Medicine Undergraduate Course of the Federal University of Rio Grande do Norte (UFRN).
Resumo:
INTRODUCTION: In Brazil, the health training policies have been going through deep changes, which are the fruits of the sanitary reform and of the breakage with the biomedical model, still hegemonic. Nevertheless, the paradigm of comprehensiveness is being introduced in health and, in order to consolidate this concept, the training has been gaining new methodological approaches. One can mention the teaching-service interaction (education-health system/citizenship health), whose proposal enables the expansion of the perception of the health-disease process, as well as the warranty of compromises of training in relation to SUS. OBJECTIVE: Understand, from health professionals, the relevance of teaching-service-community interaction, vocational training of students of the Faculty of Health Sciences / UFRN. METHODOLOGICAL PROCEDURES: This study is grounded on qualitative approach. The technique used to obtain research data was the focus group. Two focus groups (FG) were accomplished in two family basic health units of the municipality of Santa Cruz – RN, where there is participation of professionals of the Family Health Strategy. The discussions were performed from a previously elaborated script. The analysis of results was held from the categorical thematic content technique. RESULTS: The study had the participation of 18 health professionals, and 13 (72%) were females. For these professionals, the teaching-service interaction enables the student to understand the model of comprehensive health care, since the contact with the community enhances its perception about the health-disease process, but also enables recognizing the importance of teamwork to comprehensive health care. FINAL CONSIDERATIONS: The results highlight the importance of a policy of reorientation within the context of training so that students have an early contact with the service and therefore develop technical skills within the context in which they are inserted.
Resumo:
Inaccurate diagnosis of vulvovaginitis generates inadequate treatments that cause damages women's health. Objective: evaluate the effectiveness of methods when diagnosing vulvovaginitis. Method: a cross-sectional study was performed with 200 women who complained about vaginal discharge. Vaginal smear was collected for microbiological tests, considering the gram stain method as gold standard. The efficacy of the available methods for diagnosis of vaginal discharge was assessed (sensitivity, specificity, positive predictive value and negative predictive value). Data were inserted to Graphpad Prism 6, for statistical analysis. Results: the following results were obtained: wet mount for vaginal candidiasis: sensitivity = 31%; specificity = 97%; positive predictive value (PPV) = 54%; negative predictive value (NPV) =93%; accuracy = 91%. Wet mount for bacterial vaginosis: sensitivity = 80%; specificity =95%; positive predictive value (PPV) = 80%; negative predictive value (NPV) = 95%; accuracy = 92%. Syndromic approach for bacterial vaginosis: sensitivity = 95%; specificity=43%; positive predictive value (PPV) =30%; negative predictive value (NPV) = 97%; accuracy = 54%. Syndromic approach for vaginal candidiasis: sensitivity = 75%; specificity =91%; positive predictive value (PPV) = 26%; negative predictive value (NPV) = 98%; accuracy = 90%. Pap smear for vaginal candidiasis: sensitivity = 68%, specificity = 98%; positive predictive value (PPV) = 86%; negative predictive value (NPV) =96%; accuracy = 96%. Pap smear for bacterial vaginosis: sensitivity = 75%; specificity = 100%; positive predictive value (PPV) = 100%; negative predictive value (NPV) =94%; accuracy = 95%. There was only one case of vaginal trichomoniasis reported – diagnosed by oncological cytology and wet mount – confirmed by Gram. The syndromic approach diagnosed it as bacterial vaginosis. From the data generated and with support on world literature, the Maternidade Escola Januário Cicco’s vulvovaginitis protocol was constructed. Conclusion: Pap smear and wet mount showed respectively low and very low sensitivity for vaginal candidiasis. Syndromic approach presented very low specificity and accuracy for bacterial vaginosis, which implies a large number of patients who are diagnosed or treated incorrectly.
Resumo:
OBJECTIVE: to identify a profile of the main causes of inappropriate referrals from primary care to specialized services, as strategy for the curriculum development of core competencies related to maternal health. METHODS: a cross-sectional study was performed using document analysis of all referrals of pregnant women from primary care to the high-risk pregnancy service, state of Rio Grande do Norte, Brazil. All pregnant women referred from June to December 2014 (n = 771) were included. According to their causes the referrals were categorized as adequate, inadequate or inconclusive. RESULTS: a total of 188 referrals were classified as inadequate (24.4%) and 93 inconclusive (12.1%) totalizing 36.5% of inappropriate referrals. The main causes identified in these inappropriate referrals were: low-risk pregnancy (12.8%), unconfirmed hypertension (12.1%), risk of abortion (8.9%), teenage pregnancy (7.1%) , toxoplasmosis (5.3%), Rh incompatibility (4.6%) and urinary tract infection (4.3%). These data contributed to the formulation of the following products: 1) a continuing education program for health professionals working in primary care, undergraduate students and residents; and 2) development of a virtual platform to support professionals who need to refer patients to high-risk pregnancy service. CONCLUSION: the results of this study are relevant in the current context of education of health professionals, with potential for positively impact not only in the development of skills related to maternal health in undergraduate and graduate education, as well as contributing for improvement of the health care of the population.
Resumo:
Nos dias atuais, oferecer uma educação para o exercício da cidadania é função primordial das políticas públicas educacionais, conforme estabelece a constituição brasileira e a legislação de ensino. Essa função vem sendo defendida por muitos professores no Ensino Médio, atribuindo-se a disciplina de Química o papel de proporcionar um ensino crítico, participativo, reflexivo e humano. Segundo os documentos oficiais brasileiros para o Ensino de Química, o estudo do conceito de energia deve favorecer o desenvolvimento de competências para que o aluno compreenda a produção e o seu uso em diferentes fenômenos e possam interpretá-los de acordo com modelos explicativos, além de saber avaliar e julgar os benefícios e riscos da produção e do uso de diferentes formas de energia nos sistemas naturais construídos pelo homem, articulando com outras áreas de conhecimento na procura de promover a interdisciplinaridade. As unidades de ensino potencialmente significativas (UEPS), tomam como base um conjunto de teorias de aprendizagem que tem o intuito de promover um ensino com base na aprendizagem significativa e podem ajudar os estudantes nas diferentes relações que um conceito pode ter. Neste sentido, o estudo do conceito da energia a partir do trabalho com UEPS, pode ser uma importante proposta que favorece um ensino de Química na perspectiva construtivista. Assim, o objetivo deste trabalho é construir e avaliar uma proposta didática para o conteúdo de termoquímica na perspectiva das unidades de ensino potencialmente significativas de Moreira com alunos do Ensino Médio de uma escola pública do Município de Campina Grande-PB. Inicialmente a UEPS foi avaliada por 22 professores em formação inicial de duas instituições públicas de ensino superior. Em seguida, ela foi aplicada para 15 alunos do 2° ano da Escola Estadual de Ensino Médio Prof. Raul Córdula, localizada na cidade de Campina Grande-PB. A coleta dos dados para os professores em formação inicial teve como base um instrumento de validação de elaboração de unidades didáticas baseada na Engenharia Didática proposta por Artigue (1996 apud Guimarães e Giordan, 2011). Já para os alunos do ensino médio, os dados foram coletados no decorrer da UEPS e a avaliação final sobre a proposta didática ocorreu através de um questionário tomando como base a escala de Likert e o uso de mapas conceituais. Para a descrição dos dados, foram utilizados os pressupostos da análise de conteúdo de Bardin. Como produto educacional foi elaborado a Unidade de Ensino Potencialmente Significativa e um DVD contendo orientações de como trabalhar com a proposta. Os resultados deste trabalho apontam uma avaliação positiva quanto à proposta de ensino elaborada para a Educação Básica, onde se observa através do instrumento de validação aplicado, que a maioria das respostas atribuídas pelos professores, ficou entre os itens suficiente e mais que suficiente. Em relação aos momentos de aprendizagem dos alunos do Ensino Médio durante a aplicação da UEPS, foi possível observar que a proposta gerou motivação no processo de ensino e aprendizagem dos conceitos da termoquímica, como também se percebe que os mapas conceituais apresentados pelos alunos apresentaram mais proposições conceituais em uma segunda tentativa de elaboração, logo a proposta de ensino foi aprovada por mais de 90 % dos estudantes do nível médio. Portanto fica evidente que a proposta didática contribuiu no processo de ensino aprendizagem, despertando interesse e motivação nos estudantes pelo conteúdo de Termoquímica.