全文获取类型
收费全文 | 84432篇 |
免费 | 3493篇 |
国内免费 | 29篇 |
专业分类
87954篇 |
出版年
2020年 | 954篇 |
2019年 | 1172篇 |
2018年 | 1615篇 |
2017年 | 1673篇 |
2016年 | 1711篇 |
2015年 | 1239篇 |
2014年 | 1522篇 |
2013年 | 7072篇 |
2012年 | 2737篇 |
2011年 | 2826篇 |
2010年 | 1700篇 |
2009年 | 1740篇 |
2008年 | 2479篇 |
2007年 | 2369篇 |
2006年 | 2244篇 |
2005年 | 1933篇 |
2004年 | 1944篇 |
2003年 | 1852篇 |
2002年 | 1828篇 |
2001年 | 2659篇 |
2000年 | 2473篇 |
1999年 | 1905篇 |
1998年 | 967篇 |
1997年 | 804篇 |
1996年 | 885篇 |
1995年 | 813篇 |
1994年 | 798篇 |
1992年 | 1547篇 |
1991年 | 1456篇 |
1990年 | 1438篇 |
1989年 | 1397篇 |
1988年 | 1383篇 |
1987年 | 1285篇 |
1986年 | 1299篇 |
1985年 | 1373篇 |
1984年 | 1126篇 |
1983年 | 1010篇 |
1982年 | 811篇 |
1979年 | 1210篇 |
1978年 | 887篇 |
1975年 | 980篇 |
1974年 | 1105篇 |
1973年 | 1146篇 |
1972年 | 959篇 |
1971年 | 887篇 |
1970年 | 815篇 |
1969年 | 843篇 |
1968年 | 1026篇 |
1967年 | 914篇 |
1966年 | 869篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
In a conditioned inhibition paradigm (A+, B+, AX?_, pigeons received either of two keylight stimuli reliably followed by food (A+, B+). However, when one of these keylights was accompanied by another stimulus, food did not follow (AX?). For some groups, the putative inhibitor was a tone, whereas for others it was illumination of a red houselight. The birds pecked the A and B stimuli at a high rate. When X was red houselight, the birds pecked A at a much lower rate in the presence of X. When X was a tone, discrimination between A and AX was much poorer. Moreover, in a transfer test, red houselight inhibited responding to the other keylight, B, but tone did not. These results indicate that red houselight becomes a conditioned inhibitor more quickly than tone in appetitive situations, just as red houselight becomes a conditioned excitor more quickly in those situations. These results contradict the assertion that the latter outcome occurs because red houselight is a stronger appetitive excitor than tone at the start of the experiment (the “head start” hypothesis). 相似文献
962.
963.
M J Howes J E Hokanson D A Loewenstein 《Journal of personality and social psychology》1985,49(4):1110-1113
Scores on the Beck Depression Inventory (BDI) were periodically obtained from the roommates of college students who exhibited a persistent mild depression over a 3-month period. For comparative purposes, BDI scores were also obtained from roommates of individuals who were transiently depressed and from subjects with nondepressed roommates. In comparison with control subjects, the roommates of persistently depressed persons displayed a progressive increase in BDI score over the course of the study. 相似文献
964.
965.
966.
967.
968.
The following survey is intended to demonstrate and discuss some principle problems of biomagnetism and the application in clinical fields. The development of special technical parameters especially by the SQUID method is initiating new possibilities of research and completing the neurobiologically determinated basis and conditions of neuropsychiatric disorders. The Magnetoencephalography (MEG) will be represent an important role of a new functional diagnostic method. 相似文献
969.
R Witkowski E Ullrich P Pietsch K Weber K Heller T Losanowa I Nitz 《Psychiatrie, Neurologie, und medizinische Psychologie》1985,37(5):255-261
We present four cases of Prader-Willi syndrome. Two of them have an abnormality of a chromosome 15, the other both show different chromosomal abnormalities. Translocations or deletions were found recently in the bands 15q11/12 in about 60% of the cases of Prader-Willi syndrome. The consequences for diagnosis, symptomatology and genetic counselling of the syndrome are discussed. 相似文献
970.