全文获取类型
收费全文 | 2542篇 |
免费 | 17篇 |
国内免费 | 21篇 |
专业分类
教育 | 2136篇 |
科学研究 | 217篇 |
各国文化 | 1篇 |
体育 | 64篇 |
综合类 | 118篇 |
信息传播 | 44篇 |
出版年
2022年 | 17篇 |
2021年 | 31篇 |
2020年 | 51篇 |
2019年 | 38篇 |
2018年 | 21篇 |
2017年 | 18篇 |
2016年 | 23篇 |
2015年 | 50篇 |
2014年 | 136篇 |
2013年 | 146篇 |
2012年 | 238篇 |
2011年 | 235篇 |
2010年 | 153篇 |
2009年 | 129篇 |
2008年 | 129篇 |
2007年 | 136篇 |
2006年 | 172篇 |
2005年 | 154篇 |
2004年 | 152篇 |
2003年 | 147篇 |
2002年 | 111篇 |
2001年 | 106篇 |
2000年 | 68篇 |
1999年 | 25篇 |
1998年 | 27篇 |
1997年 | 16篇 |
1996年 | 17篇 |
1995年 | 9篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 4篇 |
排序方式: 共有2580条查询结果,搜索用时 15 毫秒
1.
为给航海模拟器建立实用可靠的船舶在波浪中运动的数学模型,基于二维线性势流理论,采用多系数保角变换法对每个船舶横剖面进行高精度拟合,计算各个横剖面的水动力系数和波浪激励力,利用Visual Studio自主开发出船舶在规则波中的纵向运动数值模拟程序。为验证这个数值模拟程序的可靠性,对S175集装箱船在迎浪中运动的幅值响应因子(response amplitude operator, RAO)进行数值计算。结果表明:当弗劳德数为0.275时,RAO计算结果在大部分频率范围内与试验结果吻合良好。因此,这个数值模拟程序能准确地对船舶在波浪中的运动时历进行仿真。 相似文献
2.
经济和社会的高速发展使得人力资源竞争逐渐成为国际竞争的核心,特别是高素质人才的培养已经成为制约我国经济持续发展的关键。文章根据博弈论的基本概念和研究思路,用纳什非合作博弈理论数学模型解析人才培养策略。 相似文献
3.
Barry J. Griffiths 《PRIMUS》2018,28(1):80-89
This paper describes an innovative way of randomly collecting handwritten homework in calculus classes with approximately 50 students using a standard deck of cards, which does not place an excessive burden on faculty with regard to grading. In addition to the increased awareness students develop in structuring a mathematical solution, the strategy has been successful in increasing classroom attendance, which the literature suggests leads to increased attainment. Along with personal observations and empirical data indicating that the scores from the randomly collected homework assignments strongly correlate with exam performance, perceptions of students are included, which show that students are strongly supportive of the method used. 相似文献
4.
5.
意、英、法、德、美五国科学兴隆期的出现 ,是以数学兴隆期的出现为前提和基础的。数学兴隆期开始约 80年后 ,才有科学兴隆期的起始 ;数学兴隆期峰值年出现约 80年后 ,方有科学兴隆期峰值年的显现 ;数学兴隆期结束约 80年后 ,科学兴隆期也随之消亡。 相似文献
6.
自然界中许多事物都呈现对称性,在数学学习和研究中更是如此。重视对称性的应用并且恰当地利用对称性,可以为我们提供解题思路, 帮助我们简化数学中的计算和证明。 相似文献
7.
Literacy and mathematical competencies are essential for a successful school career and precursors of these abilities develop in kindergarten. In addition to children’s early cognitive abilities, family characteristics such as the socioeconomic status and the home learning environment (HLE) are predictors of early child competencies. However, few studies outside the US and the UK have analyzed long-term effects of the early HLE on child development, simultaneously considering various explanatory factors. In this longitudinal study, data of 920 German children were obtained in kindergarten some 18 months before school entry (child mean age: 4;10). At this point, precursors of reading, spelling and mathematics were assessed. In addition, parents were asked to complete surveys on family characteristics. Child assessments were repeated with standardized measures of mathematical and literacy abilities at the end of Grade 1 and in the middle of Grade 4 (child mean age: 9;9), the final grade in German elementary schools. In Grade 4, teachers were also asked to provide their recommendation for children’s secondary school track (“Hauptschule” for lowest secondary school track, “Realschule”, or “Gymnasium” as highest secondary school track). HLE was not only a good predictor of early abilities, but also directly predicted competencies at the end of elementary school when precursors, former academic achievement and child and family characteristics were controlled for. In addition, children living in more favorable HLEs were more likely to be recommended for higher secondary school tracks by their teachers. 相似文献
8.
Appreciation of problem structure is critical to successful learning. Two experiments investigated effective ways of communicating problem structure in a computer-based learning environment and tested whether verbal instruction is necessary to specify solution steps, when deep structure is already embellished by instructional examples. Participants learned to solve algebra-like problems and then solved transfer problems that required adjustment of learned procedures. Experiment 1 demonstrated that verbal instruction helped learning by reducing learners' floundering, but its positive effect disappeared in the transfer. More importantly, students transferred better when they studied with examples that emphasized problem structure rather than solution procedure. Experiment 2 showed that verbal instruction was not necessarily more effective than nonverbal scaffolding to convey problem structure. Final understanding was determined by transparency of problem structure regardless of presence of verbal instruction. However, verbal instruction had a positive impact on learners by having them persist through the task, and optimal instructional choices were likely to differ depending on populations of learners. 相似文献
9.
魏季和 《上海大学学报(英文版)》2003,7(2):97-117
1 Introduction Withuninterruptedlyincreasinginthedemandforultracleansteel,thevacuumcirculation (RH)refiningprocesshasnowbecomeaprinciplerefiningoperationforreducingthecarbonanddegassingofmoltensteel.VariousrefiningtechnologiesusingoxygenorpowderinjectionandblowingintheRHtreatmentformakingultralow carbonandultralow sulphursteelhavebeendevelopedinrecentyears[1 10 ] .Actually ,theRHre finingprocesshasbeenextendedtobecomeamulti functionrefiningtechnology ,whichisenabledtore movecarbon ,oxygen … 相似文献
10.
John W. Adams 《Journal of Research in Special Educational Needs》2007,7(2):97-103
Identifying individuals with mathematical difficulties (MD) is becoming increasingly important in our education system. However, recognising MD is only the first stage in the provision of special educational needs (SEN). Although planning the effective remedial support is vital, there is little consensus on the interventions that are appropriate. There are two main reasons for this: first, MD has a variety of manifestations which appear to change with age; and second, there are many potential causes for the difficulties individuals experience. This paper addresses these issues by reviewing research evidence from three 'domains' of psychological research (genetic, cognitive, behavioural), all of which appear to offer insights into potential influences on mathematical ability. 相似文献