全文获取类型
收费全文 | 3389篇 |
免费 | 12篇 |
专业分类
教育 | 2329篇 |
科学研究 | 563篇 |
各国文化 | 2篇 |
体育 | 131篇 |
综合类 | 8篇 |
文化理论 | 63篇 |
信息传播 | 305篇 |
出版年
2023年 | 18篇 |
2022年 | 12篇 |
2021年 | 26篇 |
2020年 | 12篇 |
2019年 | 17篇 |
2018年 | 70篇 |
2017年 | 120篇 |
2016年 | 188篇 |
2015年 | 127篇 |
2014年 | 74篇 |
2013年 | 260篇 |
2012年 | 158篇 |
2011年 | 172篇 |
2010年 | 87篇 |
2009年 | 37篇 |
2008年 | 77篇 |
2007年 | 68篇 |
2006年 | 60篇 |
2005年 | 693篇 |
2004年 | 477篇 |
2003年 | 304篇 |
2002年 | 136篇 |
2001年 | 66篇 |
2000年 | 30篇 |
1999年 | 31篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 1篇 |
1987年 | 6篇 |
1986年 | 1篇 |
1984年 | 3篇 |
1982年 | 1篇 |
1981年 | 4篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1957年 | 3篇 |
1872年 | 2篇 |
排序方式: 共有3401条查询结果,搜索用时 31 毫秒
991.
We present results from a classroom-based intervention designed to help a class of grade 10 students (14–15 years old) learn proof while studying trigonometry in a dynamic geometry software environment. We analysed some students’ solutions to conjecture-and-proof problems that let them gain experience in stating conjectures and developing proofs. Grounded on a conception of proof that includes both empirical and deductive mathematical argumentations, we show the trajectories of some students progressing from developing basic empirical proofs towards developing deductive proofs and understanding the role of conjectures and proofs in mathematics. Our analysis of students’ solutions is based on networking Boero et al.’s construct of cognitive unity of theorems, Pedemonte’s structural and referential analysis of conjectures and proofs, and Balacheff and Margolinas’ cK¢ model, while using Toulmin schemes to represent students’ productions. This combination has allowed us to identify several emerging types of cognitive unity/rupture, corresponding to different ways of solving conjecture-and-proof problems. We also show that some types of cognitive unity/rupture seem to induce students to produce deductive proofs, whereas other types seem to induce them to produce empirical proofs. 相似文献
992.
Language Reading Research Consortium Gloria?Yeomans-Maldonado 《Reading and writing》2017,30(9):2039-2067
The current study was designed to understand the development of comprehension monitoring among beginner readers from first to third grade, and to determine the extent to which first graders’ comprehension monitoring predicts reading comprehension in grade three. Participants were 113 children (57% female) from four US states who were followed from Grade 1 (M = 7 years, SD = 4 months) to Grade 3 (M = 9 years, SD = 4 months). Measures included decoding, vocabulary, working memory, comprehension monitoring, and reading comprehension. Children’s ability to monitor comprehension grew significantly from first to third grade, with a deceleration in growth over time. In addition, comprehension monitoring in Grade 1 made a significant contribution to reading comprehension in Grade 3, even after controlling for decoding, vocabulary, and working memory. Together, these findings supplement our understanding of young readers’ development of comprehension monitoring as well as its association with reading comprehension at a later time. Practical implications of the results in the context of providing support for higher-level language skills in beginning reading instruction are discussed. 相似文献
993.
Biochemical changes of natural actomyosin from fresh pale, soft, exudative (PSE) and normal pork were studied, and the effects of different storage temperatures and different incubation temperature and times on sample superprecipitation, total sulfhydryl (-SH) content, and ATP (adenosine triphosphate) sensitivity were investigated. The results demonstrated that ATPase activity and thermal stability of PSE actomyosin were lower than those of normal pork; and that PSE actomyosin had higher -SH content than that of normal pork at all incubation temperatures and times tested. 相似文献
994.
Defiant behavior in two- and three-year-olds is a natural expression of a young child’s growing autonomy, and, although frustrating
to adults, is a natural phase of a child’s socio-emotional growth. L.S. Vygotsky’s socio-historical theory of the development
included a discussion of “crisis” periods, one of which he felt occurred at age three. The crisis that Vygotsky asserted occurred
at three is characterized by a group of seven “behaviors”, all of which indicate a struggle with the child’s position in relation
to family social structures. This study examined the occurrences and characteristics of defiant behavior in two-and three-year-old
children during outdoor play at a child development center, and the existence and context of defiant behaviors the modern
childcare setting. Patterns in defiant behaviors during play in different age groups were apparent, and suggested an instrument
to facilitate the documentation and analysis of defiant behavior in modern group-care settings. 相似文献
995.
A new attack is proposed to show that a specified group of verifiers can cooperate to forge the signature for any message by secret key substitution due to the leaked secret key or by the group public key adjustment because of the renewed members. This paper presents the improvement scheme which overcomes the security weakness of Laih and Yen's scheme. 相似文献
996.
There have been relatively few single case studies concerned with the remediation of spelling deficits among developmental
impairments. Among these there have been a small number that targeted specific components of the spelling process and used
linguistic theories as theoretical underpinning for the development of remediation procedures. This single case study examines
remediation of writing skills and aims at evaluating two different lexically based intervention methods, one of which used
Optimality Theory as its basis. We applied a rule-based remediation and an intervention method using whole-word forms to a
child with selective impairments in the lexical-graphemic components. The investigation was done with words in which phoneme-grapheme-correspondences
in word final position change due to voicing neutralization. The individual exhibited a method- and item-specific effect with
respect to the rule-based method. In addition, a transfer effect to untreated items and a generalization effect to untrained
but related tasks was observed. The absence of a method-specific and a generalization effect for the whole-word form intervention
and the success of the rule-based method is determined by the specific cognitive component(s)s that constitute the source
of the deficit and the appropriateness of Optimality Theory to address this particular deficit. 相似文献
997.
The results of this study conducted at the University of Michigan (n = 289) indicate that students with more experiences with diversity, particularly enrollment in diversity courses and positive interactions with diverse peers, are more likely to score higher on academic self-confidence, social agency, and critical thinking disposition. In addition, the study provides evidence that diversity experiences may work together to foster development of certain aspects of self.The work reported herein is supported under the National Institute for Student Achievement, Curriculum and Assessment program, agreement number R305T990402-00, CFDA/Subprogram No: 84.305T, as administered by the Office of Educational Research and Improvement (OERI), U.S. Department of Education. The findings and opinions expressed in this report do not reflect the position or policies of OERI or the U.S. Department of Education. 相似文献
998.
In two experiments with rats, we examined the developmental emergence of conditioned freezing following trace and short-delay
conditioning and also included a long-delay comparison group. In the short-delay and trace groups, a 10-sec conditioned stimulus
(CS) was paired with shock; for the trace rats, a 10-sec trace interval followed CS termination. The long-delay groups received
a 20-sec CS paired with shock, to equate for the longer interstimulus interval (ISI) in the trace group. Trace conditioning
emerged later in development than did short-delay conditioning (see Moye & Rudy, 1987). Importantly, long-delay conditioning
emerged in parallel with trace conditioning, at a similar time, and with similar strength. These findings suggest a role for
the longer ISI, as opposed to the unfilled gap per se, in the late emergence of trace conditioning. The role of the hippocampus
in trace conditioning and the possibility that young rats encode the temporal relationship between CSs and unconditioned stimuli
are also considered. 相似文献
999.
Objective: To investigate the cytokine response pattern (IL-4/IFN-γ) in infants with RSV infections and bronchiolitis during the acute phase. Methods: Four-color flow cytometry was used to measure intracellular IL-4 and IFN-γ expressions in peripheral blood CD3+ and CD8+ lymphocytes from RSV-infected and bronchiolitis infants. Serum IL-4 and IFN-γ levels were also determined. Results: RSV-infected and bronchiolitis infants showed no statistical differences from not-RSV-infected or pneumonia infants and control in the frequency of IL-4 and IFN-γ expressions in CD3+CD8- lymphocytes, showed no obvious Th1/Th2 imbalance, while IFN-γ was expressed much more frequently in CD3+CD8+ lymphocytes. Systematically, RSV-infected and bronchiolitis infants showed much lower levels of serum IL-4 and IL-4/IFN-γ ratios and much higher serum IFN-γ levels than control. However, there were no statistical differences in the above three indices between RSV-infected and not-RSV infected infants or between bronchiolitis and pneumonia infants, except that bronchiolitis infants had a higher level of serum IFN-γ than pneumonia infants statistically. Conclusions: There is no type-2 cytokine response predominance in the acute phase of RSV infection and bronchiolitis. IL-4 production is suppressed and IFN-γ production upregulated, the latter being most prominent in bronchiolitis infants. 相似文献
1000.
Betsy?L.?L.?NgEmail author W.?C.?Liu John?C.?K.?Wang 《International Journal of Science and Mathematics Education》2016,14(7):1359-1376
The present study focused on an in-depth understanding of student motivation and self-regulated learning in mathematics and science through cluster analysis. It examined the different learning profiles of motivational beliefs and self-regulatory strategies in relation to perceived teacher autonomy support, basic psychological needs (i.e. autonomy, competence, and relatedness), motivational regulations, and academic achievement. Grounded in self-determination theory, this study examined the learning profiles of 782 students from eight secondary schools in Singapore. The cluster analyzes revealed four distinct learning profiles, and they were compared in association with perceived teacher autonomy support, needs satisfaction, motivational regulations, and grades. Cluster profiling enables teachers to have better understanding of their students’ self-regulated learning so that they can apply effective teaching strategies to foster their motivation. The findings offer a perspective to secondary students’ psychological needs along with some insights into their perceived task value and self-efficacy in the contexts of mathematics and science. 相似文献