全文获取类型
收费全文 | 2880篇 |
免费 | 368篇 |
国内免费 | 703篇 |
出版年
2024年 | 11篇 |
2023年 | 48篇 |
2022年 | 86篇 |
2021年 | 99篇 |
2020年 | 122篇 |
2019年 | 101篇 |
2018年 | 143篇 |
2017年 | 138篇 |
2016年 | 134篇 |
2015年 | 106篇 |
2014年 | 105篇 |
2013年 | 235篇 |
2012年 | 187篇 |
2011年 | 255篇 |
2010年 | 221篇 |
2009年 | 206篇 |
2008年 | 239篇 |
2007年 | 310篇 |
2006年 | 316篇 |
2005年 | 225篇 |
2004年 | 145篇 |
2003年 | 93篇 |
2002年 | 80篇 |
2001年 | 41篇 |
2000年 | 45篇 |
1999年 | 39篇 |
1998年 | 25篇 |
1997年 | 24篇 |
1996年 | 17篇 |
1995年 | 21篇 |
1994年 | 17篇 |
1993年 | 15篇 |
1992年 | 14篇 |
1991年 | 3篇 |
1990年 | 18篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 1篇 |
1985年 | 11篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1974年 | 1篇 |
排序方式: 共有3951条查询结果,搜索用时 46 毫秒
861.
Both the physical elevation that appears to correspond to eye level and the visually perceived pitch of a visual field are linear functions of the physical pitch of a normally illuminated, complexly structured visual field. One of the possible bases for the large effect of physical pitch on the elevation of visually perceived eye level (VPEL) is that the visual field generates a mental representation which specifies spatial coordinates and these determine the VPEL elevation ('implicit-surface model'; ISM). The influence on the elevation of VPEL is nearly as large when the visual field contains either one or two long pitched-from-vertical or rolled-from-vertical lines in otherwise total darkness as when it consists of a well-illuminated and complexly structured pitched room (L Matin and W Li, 1994 Vision Research 34 311-330), and, in order to examine the ISM, we employed a rolled-from-vertical, two-line configuration within a frontoparallel plane viewed in otherwise total darkness. Measurements of visually perceived pitch were made by a manual matching procedure and VPEL measurements were made by the psychophysical setting of the elevation of a small visual target to appear at eye level while each of three subjects viewed the two-line configuration at each of three horizontal eccentricities with the configuration at each of seven roll orientations. In direct contradiction to the ISM, the perceived pitch of the two-line configuration did not deviate significantly from the erect orientation ('vertical') for any roll at any eccentricity, but the elevation of VPEL changed systematically with the roll of the configuration both at left and at right eccentricities, and did not change at all with the two-line configuration centered on the median plane. Consistent with our previous work and with our previous interpretation regarding the basis for VPEL (L Matin and W Li, 1994 Vision Research 34 2577-2598), the variation of VPEL for the two-line visual field equals the average of the VPEL variations produced by viewing each of the single lines separately. 相似文献
862.
The aim in the experiments was to examine whether the detection of structure-from-motion (SFM) in noise was facilitated when target and noise were segregated by colour and/or luminance polarity. The SFM target was a rotating 'V-shape' structure simulated with limited-lifetime Gaussian micropatterns and embedded in random-motion noise. Threshold levels of V-shape slant were measured for stimuli in which target and noise were segregated or unsegregated by colour/luminance, and under two conditions, with and without static form cues to the SFM target. The presence or absence of static form cues to the SFM target was manipulated by varying the relative numbers of micropatterns in target and noise. In the absence of static form cues, segregation of target and noise by colour and/or luminance polarity did not facilitate target detection, even when subjects knew which micropatterns belonged to the target. On the other hand, when static form cues were present, segregation improved performance. These results imply that SFM processing is 'form-cue invariant' except when the target form is immediately identifiable in the static view of the stimulus. The significance of the results for understanding the role of colour vision in breaking camouflage and in 'grouping' is discussed. 相似文献
863.
Successful navigation in the world requires differentiating an obstacle in one's path from an aperture through which one could pass. An approaching obstacle is specified by texture expansion within the obstacle's contour and the deletion of background texture outside the object. In contrast, an approaching aperture contains texture expansion within the aperture's frame and accretion of background texture within the aperture's contour. This study investigated 3- to 5-month-old infants' discrimination of obstacles from apertures, examining eyeblink responses to the movement of both kinds of objects against backgrounds varying in salience. Obstacles produced stronger looming reactions than apertures, and the salience of the background influenced responses to apertures but not obstacles. These findings imply that infants differentiate obstacles from apertures based on their relative patterns of accretion versus deletion of background texture, and suggest that infants recognize the functional consequences of contact with these objects. 相似文献
864.
现在采用返回抑制范式所进行的空间非信息线索作用的研究,大多以非线索化位置反应时为参照,发现线索化位置的反应先易化后抑制。后者即返回抑制。本研究采用在返回抑制范式上增设中性线索化条件的方法,发现当靶子可以出现的位置为四个时,相对于中性线索化条件,非线索化位置反应快。这种非线索化位置的易化作用是独立存在的,它能使生物体尽快地对出现在多个非线索化位置的靶子作出反应。 相似文献
865.
时间顺序信息加工的实验研究 总被引:8,自引:2,他引:6
该研究运用Glucksberg和McCloskey(1981)的问答模型,通过两个实验检查了项目的时序信息是通过项目学习时的时序编码获得的,还是在项目提取时建构的;时序加工是自动的,还是控制的两个问题。结果表明:项目的时序信息是通过项目学习时的时序编码获得的,而不是在项目提取时建构的;时序信息的编码是控制的。 相似文献
866.
胎教音乐对胎儿影响的实验研究 总被引:8,自引:0,他引:8
该项研究从三个方面探讨了胎教音乐对胎儿的作用。结果发现:胎教音乐可以使胎动时间延长,并证明在胎儿后期即存在条件反射;胎儿出生后能够再认胎教音乐,说明在胎儿后期已经存在听觉记忆;胎儿的性别及神经活动类型是影响其对音乐反应的重要因素。该研究的意义在于:证明了胎儿期心理现象的存在。把对“胎儿期有无心理现象”的历史争论引入了心理学的实验过程。 相似文献
867.
868.
869.
870.