全文获取类型
收费全文 | 33242篇 |
免费 | 1311篇 |
国内免费 | 18篇 |
专业分类
34571篇 |
出版年
2020年 | 351篇 |
2019年 | 403篇 |
2018年 | 694篇 |
2017年 | 695篇 |
2016年 | 783篇 |
2015年 | 567篇 |
2014年 | 587篇 |
2013年 | 2758篇 |
2012年 | 1235篇 |
2011年 | 1343篇 |
2010年 | 673篇 |
2009年 | 679篇 |
2008年 | 964篇 |
2007年 | 901篇 |
2006年 | 848篇 |
2005年 | 2027篇 |
2004年 | 1382篇 |
2003年 | 1143篇 |
2002年 | 882篇 |
2001年 | 936篇 |
2000年 | 883篇 |
1999年 | 670篇 |
1998年 | 383篇 |
1997年 | 372篇 |
1996年 | 300篇 |
1995年 | 308篇 |
1994年 | 282篇 |
1993年 | 313篇 |
1992年 | 535篇 |
1991年 | 493篇 |
1990年 | 520篇 |
1989年 | 487篇 |
1988年 | 455篇 |
1987年 | 440篇 |
1986年 | 450篇 |
1985年 | 465篇 |
1984年 | 432篇 |
1983年 | 403篇 |
1982年 | 312篇 |
1981年 | 297篇 |
1979年 | 342篇 |
1978年 | 339篇 |
1977年 | 290篇 |
1976年 | 291篇 |
1975年 | 345篇 |
1974年 | 422篇 |
1973年 | 320篇 |
1972年 | 295篇 |
1969年 | 281篇 |
1968年 | 284篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The present experiments were designed to teach pigeons to discriminate two locations represented by color photographs. Two sets of photographs were taken at two distinctive locations on a university campus. These sets represented several standpoints at each location. For the true-discrimination group, pictures from the two locations were differentially associated with reward; for the pseudodiscrimination group, half of the views from each location were arbitrarily but consistently associated with reward. The former group acquired the discrimination much more rapidly. These birds also showed good transfer to new views from the standpoints used in training and to a new standpoint at each location not used in training. In a second experiment, another group of pigeons could terminate any training trial by pecking an “advance” key. Three of 4 subjects used this option to reduce the duration of trials in which pictures from the negative location were presented. These data suggest that pigeons can integrate views shown in pictures into a “concept” of a location. The method used here may be the experimental analogue of a common, natural process by which animals learn to identify locations. 相似文献
92.
93.
K Friemert 《Psychiatrie, Neurologie, und medizinische Psychologie》1988,40(11):671-677
Basing on the author's experiences during his study stay at the Serbsky All-Union Research Institute for General and Forensic Psychiatry in Moscow a report is given about the theoretical foundations and the carrying-out of forensic-psychiatric expert-opinions in the field of penal as well as civil law in the U.S.S.R. Some peculiarities in comparison with the practice in the G.D.R. are taken in special account. 相似文献
94.
95.
S Martin K Housley H Mccoy P Greenhouse F Stigger M A Kenney S Shoffner V Fu M Korslund F G Ercanli-Huffman 《Perceptual and motor skills》1988,67(3):879-884
The Rosenberg Self-esteem Scale was administered to 550 14- and 16-yr.-old (+/- 6 mo.) girls. Self-esteem scores were categorized by weight and weight by height. Scores on the Quetelet Index for obesity were correlated with self-esteem scores. Mean self-esteem of the low- and middle-weight by height group was significantly higher than the mean of the high-weight by height group. In analyzing weight alone, the self-esteem of the middle-weight group was significantly higher than the self-esteem of the high-weight group. The correlation of the obesity index and self-esteem indicated that as weight increased self-esteem decreased. 相似文献
96.
S W?sser W Handrick F B Spencker W Braun 《Psychiatrie, Neurologie, und medizinische Psychologie》1988,40(2):95-101
Observations on three children with neurolisteriosis (one case of meningitis, two cases of meningoencephalitis, each Serovar 4 b), show that even after the neonatal period, listeriosis must not be ignored in the process of diagnosis and therapy. It is the bacteriological examination of the cerebrospinal fluid, together with the blood culture, and not clinical symptoms and serology that guarantee a timely diagnosis and therapy (ampicillin and gentamicin). 相似文献
97.
D K Simonton 《Psychological bulletin》1988,104(2):251-267
98.
99.
100.