全文获取类型
收费全文 | 21899篇 |
免费 | 61篇 |
国内免费 | 2篇 |
专业分类
21962篇 |
出版年
2022年 | 12篇 |
2020年 | 31篇 |
2019年 | 28篇 |
2018年 | 3512篇 |
2017年 | 2833篇 |
2016年 | 2275篇 |
2015年 | 220篇 |
2014年 | 108篇 |
2013年 | 249篇 |
2012年 | 611篇 |
2011年 | 2428篇 |
2010年 | 2544篇 |
2009年 | 1512篇 |
2008年 | 1766篇 |
2007年 | 2233篇 |
2006年 | 78篇 |
2005年 | 246篇 |
2004年 | 215篇 |
2003年 | 154篇 |
2002年 | 106篇 |
2001年 | 47篇 |
2000年 | 75篇 |
1999年 | 36篇 |
1998年 | 40篇 |
1997年 | 40篇 |
1996年 | 24篇 |
1995年 | 11篇 |
1994年 | 20篇 |
1993年 | 13篇 |
1992年 | 22篇 |
1991年 | 19篇 |
1990年 | 23篇 |
1989年 | 13篇 |
1988年 | 21篇 |
1987年 | 20篇 |
1986年 | 18篇 |
1985年 | 19篇 |
1984年 | 14篇 |
1983年 | 20篇 |
1982年 | 17篇 |
1981年 | 17篇 |
1979年 | 21篇 |
1978年 | 19篇 |
1977年 | 16篇 |
1976年 | 30篇 |
1975年 | 25篇 |
1974年 | 18篇 |
1973年 | 13篇 |
1972年 | 12篇 |
1971年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
12.
13.
14.
15.
16.
17.
18.
19.
High-resolution CRT displays are subject togeometric distortion: lines that are straight in the internal coordinates of the graphics software and hardware are curved when projected onto a plane in the observer’s line of sight. As the available resolution of CRT screens increases, it becomes more difficult to measure and correct for this distortion. We present a simple, highly accurate method for determining the mapping between internal coordinates and the viewing plane. It requires that an observer, using a calibration program, adjust triples of displayed points until they are collinear. A metal straightedge placed between the observer and the screen aids in this judgment. We describe the calibration of an IBM Enhanced Graphics Display in high-resolution mode (350 × 640 pixels), and illustrate how to use the estimated mapping to choose internal coordinates to draw undistorted figures that are accurate to within 0.5 pixel. The method can be used to assess or to correct the accuracy of visual displays. The method is relevant to experiments in spatial vision, spatial perception, perception of dot patterns, and any application in which geometrically accurate stimuli are required. 相似文献
20.
The purposes of this study were to assess the career development needs of entering medical students as measured by the Medical Career Development Inventory and to examine gender differences in responses to the inventory. A total of 115 entering medical students (representing two entering classes) took the inventory two months prior to matriculation. Analysis suggested that this sample of entering students had formed a vocational identity and that they had evaluated the suitability and viability of a commitment to a physician's career. However, the participants had not formed a clear picture of their specialty interest and goals. No significant gender differences were indicated. A recommended career assistance workshop is presented as appropriate for these students' needs. 相似文献