全文获取类型
收费全文 | 657990篇 |
免费 | 8553篇 |
国内免费 | 1947篇 |
专业分类
电工技术 | 12224篇 |
综合类 | 615篇 |
化学工业 | 97325篇 |
金属工艺 | 25018篇 |
机械仪表 | 18867篇 |
建筑科学 | 15576篇 |
矿业工程 | 2835篇 |
能源动力 | 17786篇 |
轻工业 | 55831篇 |
水利工程 | 6353篇 |
石油天然气 | 11159篇 |
武器工业 | 43篇 |
无线电 | 77738篇 |
一般工业技术 | 126673篇 |
冶金工业 | 133388篇 |
原子能技术 | 12813篇 |
自动化技术 | 54246篇 |
出版年
2021年 | 5698篇 |
2020年 | 4137篇 |
2019年 | 5413篇 |
2018年 | 9135篇 |
2017年 | 8911篇 |
2016年 | 9307篇 |
2015年 | 6517篇 |
2014年 | 10924篇 |
2013年 | 29709篇 |
2012年 | 17397篇 |
2011年 | 24043篇 |
2010年 | 19049篇 |
2009年 | 21438篇 |
2008年 | 22041篇 |
2007年 | 21753篇 |
2006年 | 19129篇 |
2005年 | 17650篇 |
2004年 | 17060篇 |
2003年 | 16722篇 |
2002年 | 15911篇 |
2001年 | 16147篇 |
2000年 | 15097篇 |
1999年 | 16183篇 |
1998年 | 42361篇 |
1997年 | 29399篇 |
1996年 | 22631篇 |
1995年 | 16902篇 |
1994年 | 14672篇 |
1993年 | 14394篇 |
1992年 | 10227篇 |
1991年 | 9712篇 |
1990年 | 9496篇 |
1989年 | 9158篇 |
1988年 | 8470篇 |
1987年 | 7372篇 |
1986年 | 7279篇 |
1985年 | 8215篇 |
1984年 | 7577篇 |
1983年 | 6704篇 |
1982年 | 6275篇 |
1981年 | 6479篇 |
1980年 | 6048篇 |
1979年 | 5856篇 |
1978年 | 5631篇 |
1977年 | 6836篇 |
1976年 | 9015篇 |
1975年 | 4884篇 |
1974年 | 4603篇 |
1973年 | 4655篇 |
1972年 | 3843篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Lecture capture with real‐time rearrangement of visual elements: impact on student performance 下载免费PDF全文
The primary goal of this study is to create and test a lecture‐capture system that can rearrange visual elements while recording is still taking place, in such a way that student performance can be positively influenced. The system we have devised is capable of integrating and rearranging multimedia sources, including learning content, the instructor and students' images, into lecture videos that are embedded in a website for students to review after school. The present study employed a two‐group experimental design, with 153 participants (145 females and 8 males) making up an experimental group in which lecture courses were recorded using the new lecture‐capture system, and 149 participants (140 females and 9 males) forming a control group whose lectures were recorded by traditional means. All participants were in the freshman college and studying Introduction to Computer and Information Science in one of six classes, and were randomly assigned to one of the two groups. The participants' midterm examination and final examination scores were collected as indicators of their academic performance, with their mathematics entrance scores used as a pre‐test. The findings obtained from analysis of covariance (ANCOVA) suggest that appropriate rearrangement of visual elements in lecture videos can significantly impact students' learning performance. 相似文献
62.
63.
Greg A. Breed Paul M. Severns Andrew M. Edwards 《Journal of the Royal Society Interface》2015,12(103)
Lévy flights have gained prominence for analysis of animal movement. In a Lévy flight, step-lengths are drawn from a heavy-tailed distribution such as a power law (PL), and a large number of empirical demonstrations have been published. Others, however, have suggested that animal movement is ill fit by PL distributions or contend a state-switching process better explains apparent Lévy flight movement patterns. We used a mix of direct behavioural observations and GPS tracking to understand step-length patterns in females of two related butterflies. We initially found movement in one species (Euphydryas editha taylori) was best fit by a bounded PL, evidence of a Lévy flight, while the other (Euphydryas phaeton) was best fit by an exponential distribution. Subsequent analyses introduced additional candidate models and used behavioural observations to sort steps based on intraspecific interactions (interactions were rare in E. phaeton but common in E. e. taylori). These analyses showed a mixed-exponential is favoured over the bounded PL for E. e. taylori and that when step-lengths were sorted into states based on the influence of harassing conspecific males, both states were best fit by simple exponential distributions. The direct behavioural observations allowed us to infer the underlying behavioural mechanism is a state-switching process driven by intraspecific interactions rather than a Lévy flight. 相似文献
64.
65.
66.
67.
68.
69.
70.