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41.
Are books going out of print faster than they used to? Or is this merely an illusion born of nostalgia or discontent? A brief statistical analysis of the data provides the answer.  相似文献   
42.
This research was sponsored by Brigham Young University and the State Nationalities Affairs Commission of the Government of China.  相似文献   
43.
The understanding of swimming propulsion is a key factor in the improvement of performance in this sport. Propulsive forces have been quantified under steady conditions since the 1970s, but actual swimming involves unsteady conditions. Thus, the purpose of the present article was to review the effects of unsteady conditions on swimming propulsion based on studies that have compared steady and unsteady conditions while exploring their methods, their limitations and their results, as well as encouraging new studies based on the findings of this systematic review. A multiple database search was performed, and only those studies that met all eligibility criteria were included. Six studies that compared steady and unsteady conditions using physical experiments or numerical simulations were selected. The selected studies verified the effects of one or more factors that characterise a condition as unsteady on the propulsive forces. Consequently, much research is necessary to understand the effect of each individual variable that characterises a condition as unsteady on swimming propulsion, as well as the effects of these variables as a whole on swimming propulsion.  相似文献   
44.
In microcirculation, red blood cells (RBCs) flowing through bifurcations may deform considerably due to combination of different phenomena that happen at the micro-scale level, such as: attraction effect, high shear, and extensional stress, all of which may influence the rheological properties and flow behavior of blood. Thus, it is important to investigate in detail the behavior of blood flow occurring at both bifurcations and confluences. In the present paper, by using a micro-PTV system, we investigated the variations of velocity profiles of two working fluids flowing through diverging and converging bifurcations, human red blood cells suspended in dextran 40 with about 14% of hematocrit level (14 Hct) and pure water seeded with fluorescent trace particles. All the measurements were performed in the center plane of rectangular microchannels using a constant flow rate of about 3.0 × 10−12 m3/s. Moreover, the experimental data was compared with numerical results obtained for Newtonian incompressible fluid. The behavior of RBCs was asymmetric at the divergent and convergent side of the geometry, whereas the velocities of tracer particles suspended in pure water were symmetric and well described by numerical simulation. The formation of a red cell-depleted zone immediately downstream of the apex of the converging bifurcation was observed and its effect on velocity profiles of RBCs flow has been investigated. Conversely, a cell-depleted region was not formed around the apex of the diverging bifurcation and as a result the adhesion of RBCs to the wall surface was enhanced in this region.  相似文献   
45.
In Portugal, the number of students in higher education increased from 80,000 in 1975 to 381,000 in 2000 (a change from 11% to 53% in the age group 18–22), meaning a major change in the diversity of student population with consequences well known and studied in other countries. The teaching of chemistry at the University of Aveiro, for the first‐year students of science and engineering, has been subjected to continuous attention to implement quality and student‐centred approaches. The work devoted to excellence and deep learning by several authors has been carefully followed and considered. This communication reports research work on chemistry teaching, associated with those developments for first‐year students. The work included the design of strategies and the adoption of teaching and learning activities exploring ways to stimulate active learning by improving the quality of classroom interactions. In addition to regular lectures, large classes' teaching based on student‐generated questions was explored. In order to improve students' motivation and stimulate their curiosity, conference‐lectures were adopted to deal with selected topics of wide scientific, technological and social interest. Quantitative analysis and discussion of selected case studies, together with the organization of laboratory classes based on selected enquiry‐based experiments, planned and executed by students, stimulated deep learning processes. A sample of 32 students was followed in the academic year of 2000/01 and the results obtained are here discussed in comparison with those of a sample of 100 students followed in 2001/02. Particular attention was paid to the quality of classroom interactions, the use of questions by students and their views about the course design.  相似文献   
46.
47.
Thirty-six children (half 6–8 years old and half 10–12) in Northeast Brazil heard three hypothetical dilemmas featuring a choice between telling the truth and keeping a promise. Each dilemma was initiated by a different kind of lie: an exculpable pro-social lie (teasing), a lie in the personal domain (hiding) and a lie in the service of an anti-social act (cheating). They were asked to choose between truth and promise, and to attribute choices to adults and to peers. More younger than older children chose truth on all three dilemmas. Both regression and SSA analysis showed that “peer-judgments” predicted own judgments on all three dilemmas, but “adult-judgments” did so only on the dilemma, which featured an exculpable lie and involved no adults. The findings may be interpreted as supporting either (a) a constructivist account of development or (b) a learning account that features implicit processes.  相似文献   
48.
This study analysed the modulation of jump performance, vertical stiffness as well as joint and intralimb coordination throughout a 30-s vertical jump test. Twenty male athletes performed the test on a force plate while undergoing kinematic analysis. Jump height, power output, ground contact time, vertical stiffness, maximum knee and hip flexion angles, and coordination by continuous relative phase (CRP) were analysed. Analysis of variance was used to compare variables within deciles, and t-tests were used to compare CRP data between the initial and final jumps. Results showed reduction in jump height, power output, and vertical stiffness, with an increase in contact time found during the test. Maximum knee and hip flexion angles declined, but hip angle decreased earlier (10–20% of the test) than knee angle (90–100%). No changes were observed in CRP for thigh–leg coupling when comparing initial and final jumps, but the trunk–thigh coupling was more in-phase near the end of the test. We conclude that fatigue causes reduction in jump performance, as well as changes in stiffness and joint angles. Furthermore, changes in intralimb coordination appear at the last 10% of the test, suggesting a neuromotor mechanism to counterbalance the loss of muscle strength.  相似文献   
49.
This article presents a case study on the political thought and citizenship conceptions of children and adolescents. Considering children and adolescents as reflexive citizens and partners in community development processes, it is our purpose to understand the development of political thought, and particularly how children conceive the exercise of citizenship and participation. Participants were 97 children of a primary and middle secondary (basic) school, aged 5 to 14?years, organized into age groups of 12 children each. Focus group discussions were used as participatory research methodology which involves children as active collaborators, a method that appears to be a good alternative to the traditional individual interviews used in previous research. Results point to the existence of a developmental process of political thought that begins before the start of formal schooling, and a parallel evolution of the conception of social organization and the concepts of citizenship and participation.  相似文献   
50.
Transition to Higher Education (HE) is a significant life event and it is supposed to be a very agreeable experience to students. However, such impact is not linear, being mediated by students' psychosocial variables and by their own perceptions concerning the HE environment. Transition to HE encompasses many tasks to cope with changes: dealing with new kinds of responsibilities and managing emotions. A wide variety of emotions take place in the HE transition, either of a positive or negative nature, such as joy of enrolment success and fears of social rejection. This research focused on the transition to HE, approaching freshmen's personal and developmental variables. Results confirm that the impact of transition has a mostly emotional nature and that related concerns differ according to students' gender and socio-cultural background. With greater joy or greater anxiety, HE transition may be perceived as a stage of a long process towards adulthood.  相似文献   
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