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101.
Emiliano Carretti Irene Natali Caterina Matarrese Paola Bracco Richard G. Weiss Piero Baglioni Antonella Salvini Luigi Dei 《Journal of Cultural Heritage》2010,11(4):1555-380
The procedures for making and applying a new family of high viscosity aqueous polymeric dispersions based on poly(vinyl alcohol)-borax (PVA-borax) matrices are presented. A specific system of this type has been used to remove an oxidized varnish coating from the surface of “Coronation of the Virgin with Saints”, a 15th century egg tempera painting on wood by Neri di Bicci (Florence, 1418–1492). FTIR spectra showed that the oxidized varnish was constituted of highly aged shellac resin. Good cleaning performance was attained when the liquid portion of the dispersion consisted of a mixture of water and acetone. Rheological investigations indicate that the acetone content does not affect the mechanical properties of the polymeric dispersion. Those mechanical properties permit easy removal of the cleaning agent simply by peeling it from the surface by means of a forceps or spatula once it has carried out its cleaning function. Optical microscopic and FTIR investigations show that the cleaning agent is able to remove the oxidized varnish coating from the surface of the Neri di Bicci painting without leaving detectable residues. 相似文献
102.
The hypothesis that there is a greater frequency of children of alcoholics in special classes for Emotional/Behavioral Disordered (ED) and Learning Disabled (LD) children was explored. A random sample of students in ED, LD, and regular classes was selected and administered the Children of Alcoholics Screening Test. Parents completed the Friel Co-Dependency Assessment Inventory. An analysis of variance in CAST and FCAI scores did not reveal any significant differences among groups. Significant differences were noted in the relationship of marital status and chemical dependency in immediate family. Reported incidence of chemical dependency in the immediate family was identified as a concern warranting further exploration. Issues that may have affected the study such as sample size, respondent participation, and various roles exhibited in the family were considered. The possible impact alcoholism has on children and appropriate program intervention in the schools were discussed. 相似文献
103.
The goal of this article is to contribute to understanding the interplay between students' disciplinary engagement and their identity construction. The term appropriation, borrowed from scholars in linguistics and education, was chosen to capture this broader sense of productive learning that sits at the nexus of disciplinary engagement and identity. Appropriation implies deep conceptual understanding, but it also involves a reflexive process of transforming scientific discourse in a way that is authentic and personal. The core aim of this article is to turn the term appropriation into a theoretical construct by means of an analytic process of defining, operationalizing, and testing the definition against student interview and classroom data. Five discourse markers for operationalizing appropriation were discovered through this process. Appropriation, in our study, implies students’ discourse is (A) an expression of a personal “signature“ idea, (B) grounded in the discipline, (C) thick, in that it involves a metacognitive and epistemological dimension, (D) non-incidental, in the sense of being consistently used throughout classroom activities, and (E) a carrier of social relationships, in that it positions the student within classroom. The study is grounded in an extended intervention on thermodynamics in an Italian secondary school class (grade 12). 相似文献
104.
The purpose of this study was to explore the relationships between mechanical power, thrust power, propelling efficiency and sprint performance in elite swimmers. Mechanical power was measured in 12 elite sprint male swimmers: (1) in the laboratory, by using a whole-body swimming ergometer (W'TOT) and (2) in the pool, by measuring full tethered swimming force (FT) and maximal swimming velocity (Vmax): W'T = FT · Vmax. Propelling efficiency (ηP) was estimated based on the “paddle wheel model” at Vmax. Vmax was 2.17 ± 0.06 m · s?1, ηP was 0.39 ± 0.02, W'T was 374 ± 62 W and W'TOT was 941 ± 92 W. Vmax was better related to W'T (useful power output: R = 0.943, P < 0.001) than to W'TOT (total power output: R = 0.744, P < 0.01) and this confirms the use of the full tethered test as a valid test to assess power propulsion in sprinters and to estimate swimming performance. The ratio W'T/W'TOT (0.40 ± 0.04) represents the fraction of total mechanical power that can be utilised in water (e.g., ηP) and was indeed the same as that estimated based on the “paddle wheel model”; this supports the use of this model to estimate ηP in swimming. 相似文献
105.
Tom Broos Isabel Hilliger Mar Pérez-Sanagustín Nyi-Nyi Htun Martijn Millecamp Paola Pesántez-Cabrera Lizandro Solano-Quinde Lorena Siguenza-Guzman Miguel Zuñiga-Prieto Katrien Verbert Tinne De Laet 《British journal of educational technology : journal of the Council for Educational Technology》2020,51(4):938-954
Many Latin-American institutions recognise the potential of learning analytics (LA). However, the number of actual LA implementations at scale remains limited, notwithstanding considerable effort made to formulate guidelines and frameworks to support the LA policy development. Guidance on how to coordinate the interaction between the LA policymaking and implementation is mostly missing, leaving a difficult challenge up to practitioners. In this study we propose a coordination model to support future LA initiatives at scale. We explore the problem by comparing two cases in Belgium and Ecuador. Following up we use the LA implementation timeline as a driver for planning the interaction between the policymaking and implementation. We continue by testing an application of the model with LA experts predominantly from Latin-American institutions, asking them to map low-level items of the SHEILA policy framework to four implementation phases. The results of this mapping support that LA policy building can be spread over time, that it can coincide with LA implementation at scale, and that both efforts can be coordinated. It is hoped that this study will provide additional guidance for future Latin-American and other LA initiatives. 相似文献
106.
This study explored how a study abroad experience affected preservice teachers' (PSTs') dispositions towards and plans for teaching English Language Learners (ELLs). This qualitative study involved 16 elementary education initial licensure PSTs who participated in a 2-month study abroad trip to Germany. Data in the form of surveys, interviews, and reflections were collected. The PSTs' experiences left them feeling like outsiders, fostering greater empathy for ELLs. As the PSTs faced the challenges of studying abroad, they developed ways of coping, which influenced their dispositions toward ELLs and the accommodations they wanted to make when teaching ELLs in their future classrooms. A model of the PSTs' learning progression within the study abroad experience is offered as a lens to consider their transformations. Findings suggest it would be beneficial for educators traveling abroad with PSTs to find ways to make explicit the connections between personal encounters and future teaching experiences. 相似文献
107.
108.
Giuseppe Lippi Paola Avanzini Roberta Musa Franca Sandei Rosalia Aloe Gianfranco Cervellin 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2013,23(1):64-69
Background:
In vitro hemolysis can be induced by several biological and technical sources, and may be worsened by forced aspiration of blood in vacuum tubes. This study was aimed to compare the probability of hemolysis by drawing blood with a commercial evacuated blood collection tube, and S-Monovette used either in the “vacuum” or “aspiration” mode.Materials and methods:
The study population consisted in 20 healthy volunteers. A sample was drawn into 4.0 mL BD Vacutainer serum tube from a vein of one upper arm. Two other samples were drawn with a second venipuncture from a vein of the opposite arm, into 4.0 mL S-Monovette serum tubes, by both vacuum an aspiration modes. After separation, serum potassium, lactate dehydrogenase (LD) and hemolysis index (HI) were tested on Beckman Coulter DxC.Results:
In no case the HI exceed the limit of significant hemolysis. As compared with BD Vacutainer, no significant differences were observed for potassium and LD using S-Monovette with vacuum method. Significant increased values of both parameters were however found in serum collected into BD Vacutainer and S-Monovette by vacuum mode, compared to serum drawn by S-Monovette in aspiration mode. The mean potassium bias was 2.2% versus BD Vacutainer and 2.4% versus S-Monovette in vacuum mode, that of LD was 2.7% versus BD Vacutainer and 2.1% versus S-Monovette in vacuum mode. None of these variations exceeded the allowable total error.Conclusions:
Although no significant macro-hemolysis was observed with any collection system, the less chance of producing micro-hemolysis by S-Monovette in aspiration mode suggest that this device may be used when a difficult venipuncture combined with the vacuum may increase the probability of spurious hemolysis. 相似文献109.
110.