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51.
Recent studies have shown that adolescents use the Internet not only to maintain social relationships with distant relatives and friends but also to create new relationships online; some of these friendships become integrated into their social circle. Research has focused mainly on the effect of the Internet on existing relationships or the nature of online-only ties, so studies comparing the quality of online and face-to-face relationships are missing. The goal of this study is to bridge this gap. In keeping with previous studies on social association, we argue that the quality of social relationships is dependent on duration and diversity of topics and activities carried together. Time is important, as it facilitates the development of a collective shared history and identity. Intimacy develops through the participation in shared activities and discussion of diverse issues of personal concern. Using a representative sample of the adolescent population in Israel, we find that closeness to a friend is a function of social similarity, content and activity multiplexity, and duration of the relationships. Friendships originated in the Internet are perceived as less close and supportive because they are relatively new and online friends are involved in less joint activities and less topics of discussion. The implications of the findings are discussed.  相似文献   
52.
The importance of the Physical Education (PE) teacher’s body, particularly for teaching PE, has been highlighted in literature. PE teachers are expected to be clear role models to students through their acts, behaviours and bodies. However, their strong embodied subjectivities, particularly those related to their teaching practices, may be problematised. This paper explores the ways in which a group of 15 pre-service PE teachers from a Spanish university constructed perspectives about the body and health in relation to their professional practices. Body journals were used to collect data, which were analysed using a Deleuze-Guattarian approach. The findings reveal the significant emphasis participants placed on their own bodies while teaching PE and the pressure they felt to conform to certain expectations of their professional roles. In response, we propose critical reflection on the content of Physical Education Teacher Education (PETE) programmes and incorporation of alternative pedagogical approaches to alleviate the heavy reliance on pre-service teachers’ bodies.  相似文献   
53.
Billi  Marco  Blanco  Gustavo  Urquiza  Anahí 《Minerva》2019,57(3):293-315

Over the last few decades climate change has been gaining importance in international scientific and political debates. However, the social sciences, especially in Latin America, have only lately become interested in the subject and their approach is still vague. Scientific understanding of global environmental change and the process of designing public policies to face them are characterized by their complexity as well as by epistemic and normative uncertainties. This makes it necessary to problematize the way in which research efforts understand ‘the social’ of climate change. How do ‘the climate’ and ‘the social’ interpenetrate as scientific objects? What does the resulting field look like? Is the combination capable of promoting reflexivity and collaboration on the issue, or does it merely become dispersed with diffuse boundaries? Our paper seeks to answer these and other related questions using Chile as a case study and examining peer-reviewed scientific research on the topic. By combining in-depth qualitative content analysis of each paper with a statistical meta-analysis, we were able to: characterize the key content and forms of such literature; identify divisions and patterns within it; and, discuss some factors and trends that may help explain these. We conclude that the literature displays two competing trends: while it is inclined to become fragmented beyond the scope of the ‘mitigation’ black box, it also tends to cluster along the lines of methodological distinctions traditionally contested within the social sciences. This, in turn, highlights the persistence of disciplinary divisions within an allegedly interdisciplinary field.

  相似文献   
54.
The purpose was to assess sleep patterns, quantity and quality in adolescent (16.2?±?1.2 yr) Middle Eastern academy soccer players (n?=?20) and the influence of an intermission upon these characteristics. On a 17-day training camp (located one time zone west of home) including three discrete matches, sleep was assessed pre- (PRE) and post-match (POST) via wrist actigraphy. Retrospective actigraphy analysis identified sleep characteristics, including if players experienced a sleep intermission (YES) or not (NO) proximal to dawn, and bedtime (hh:mm), get-up time (hh:mm), time in bed (h), sleep duration (h) and sleep efficiency (%). Within YES two bouts were identified (BOUT1 and BOUT2). No differences were seen between PRE and POST, nor between BOUT1 and BOUT2 (p?>?.05). Overall players did not meet National Sleep Foundation (NSF) guidelines (7:04?±?1:16?h vs. recommended 8–10?h for 14–17 yr). Sleep duration was significantly reduced (~ ?13% or ?1:06) in YES compared to NO (6:33?±?1:05 vs. 7:29?±?1:17, p?<?.01). Despite players in YES waking earlier due to an intermission, they did not compensate for this with a later wake time, rising significantly earlier compared to NO (09:40?±?00:38 vs. 10:13?±?00:40, p?<?.05). These players on average do not obtain sufficient sleep durations relative to NSF guidelines, with decrements increased by an intermission proximal to dawn. High inter- and intra-individual variance in the players sleep characteristics indicates the need for individualized sleep education strategies and interventions to promote appropriate sleep.  相似文献   
55.
A discriminant method for optimizing activity in nuclear medicine studies is validated by comparison with ROC (received operating characteristic)-curves. The method is tested in 21 single photon emission computerized tomography (SPECT), performed with a cardiac phantom. Three different lesions (Lb L2 and L3) were placed in the myocardium-wall by pairs fbr each SPECT. Three activities (84, 37 or 18.5 MBq) of 99mTc were used as background. Linear discriminant analysis was used to select the parameters that characterize image quality among the measured variables in the images [(Background-to-Lesion (B/Li) and Signal-to-Noise (S/N) ratios)]. Two clusters with different image quality (P=0.021 ) were obtained. The ratios B/Lj, B/L2 and B/L3 are the parameters used to construct the function with 100% of cases correctly classified into the clusters. The value of 37 MBq was the lowest tested activity for which good results for the B/Li ratios were obtained. The result coincides with the applied ROC-analysis (r=0.89).  相似文献   
56.
The current study examined bidirectional, longitudinal links between prosocial and problem behavior. Participants (= 500) were recruited from a Northwestern city in the United States and assessed for 3 consecutive years from 2009 to 2011 (Mage of youth at Time 1 = 13.32, SD = 1.05; 52% girls; 67% European American, 33% single‐parent families). Results suggested that effects of earlier prosocial behavior toward family and strangers were predictive of fewer problem behaviors 2 years later, while results for prosocial behavior toward friends were more mixed. Results also suggested depression predicted lower prosocial behavior toward family members and anxiety predicted higher prosocial behavior toward friends. Findings show a complex pattern of relations that demonstrate the need to consider targets of helping.  相似文献   
57.
Social media technologies have begun to enter the governmental workplace as tools to accomplish improved public service and engagement. Widespread recognition of the potential of social media technology for achieving public outcomes does not match our understanding about how and why specific tools are being used for specific purposes. This paper makes use of newly collected national survey data from local government managers in five different agencies to address the questions: which social media tools are being used, for which tasks or purposes; and what organizational characteristics influence the coupling of task and technology. Findings reveal patterns of social media tool application for particular purposes, although organizations do not all use social media tools in the same way. Moreover, regression analysis shows that different organizational factors – work characteristics, innovativeness, technology and management capacity and stakeholder influence – predict each of the four technology–task couplings — social media for dissemination, social media for feedback on service quality, social media for participation, and social media for internal work collaboration. This study demonstrates that social media tools are not a monolithic group and calls for greater research attention to the complex interactions among social media technology, task and organizational context.  相似文献   
58.
Objectives: This study was designed to investigate the association of gender, fibre type composition, and anaerobic performance with the basal skeletal muscle signalling cascades regulating muscle phenotype. Design: Muscle biopsies were obtained from 25 men and 10 women all young and healthy. Methods. Protein phosphorylation of Thr172AMPKα, Ser221ACCβ, Thr286CaMKII as well as total protein abundance of PGC-1α, SIRT1, and CnA were measured by Western blot and anaerobic performance by the Wingate test. Results: Percent type I myosin heavy chain (MHC I) was lower in men (37.1?±?10.4 vs. 58.5?±?12.5, P?P?P?221ACCβ and Thr286CaMKII fractional phosphorylation tended to be higher in men (P?=?.1). PGC1-α and SIRT1 total protein expression was similar in men and women, whereas CnA tended to be higher in men (P?=?.1). Basal AMPKα phosphorylation was linearly related to the percentage of MHC I in men (r?=?0.56; P?Conclusion: In summary, skeletal muscle basal AMPKα phosphorylation is higher in men compared to women, with no apparent effect on anaerobic performance.  相似文献   
59.
60.
This paper deals with systems that can switch their structure, including the differentiation order. It is shown that there are several non-equivalent cases for them, which all coincide when the derivation order is not switched but fixed at 1. For each of these cases, (asymptotic) stability results are obtained in this paper. This is accomplished by generalizing Common Lyapunov Functions (CLF) and Multiple Lyapunov Functions (MLF) methods, the latter when applied to fractional switching systems (FSS) in the resetting. Several examples are presented to illustrate that such Lyapunov functions exist for linear and nonlinear switched order systems. It is shown that the resetting fractional switching can be easily implemented by standard software. Finally, applications in adaptive integer-order problems are made by exploiting features of both fractional and integer-order systems.  相似文献   
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