全文获取类型
收费全文 | 68371篇 |
免费 | 2580篇 |
国内免费 | 26篇 |
出版年
2020年 | 700篇 |
2019年 | 845篇 |
2018年 | 1201篇 |
2017年 | 1217篇 |
2016年 | 1296篇 |
2015年 | 923篇 |
2014年 | 1126篇 |
2013年 | 6006篇 |
2012年 | 1964篇 |
2011年 | 2001篇 |
2010年 | 1302篇 |
2009年 | 1236篇 |
2008年 | 1838篇 |
2007年 | 1770篇 |
2006年 | 1637篇 |
2005年 | 1413篇 |
2004年 | 1338篇 |
2003年 | 1314篇 |
2002年 | 1302篇 |
2001年 | 2093篇 |
2000年 | 2004篇 |
1999年 | 1538篇 |
1998年 | 711篇 |
1996年 | 776篇 |
1995年 | 761篇 |
1994年 | 752篇 |
1993年 | 716篇 |
1992年 | 1459篇 |
1991年 | 1307篇 |
1990年 | 1335篇 |
1989年 | 1186篇 |
1988年 | 1214篇 |
1987年 | 1178篇 |
1986年 | 1187篇 |
1985年 | 1124篇 |
1984年 | 1022篇 |
1983年 | 894篇 |
1982年 | 688篇 |
1979年 | 1058篇 |
1978年 | 766篇 |
1975年 | 906篇 |
1974年 | 930篇 |
1973年 | 1030篇 |
1972年 | 878篇 |
1971年 | 820篇 |
1970年 | 728篇 |
1969年 | 764篇 |
1968年 | 924篇 |
1967年 | 822篇 |
1966年 | 745篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
D DeJianne T R McGuire A Pruzan-Hotchkiss 《Journal of comparative psychology (Washington, D.C. : 1983)》1985,99(1):74-80
Food-deprived Drosophila melanogaster extend their proboscises following sucrose stimulation of the front tarsi (the proboscis extension reflex). Médioni and Vaysse (1975) reported that the inhibition of this response can be conditioned over trials if such proboscis extensions are punished by applying an aversive stimulus to the foreleg tarsi. In this study, Médioni and Vaysse's basic observations of conditioning were replicated, with a different strain of flies and a modified conditioning apparatus. 相似文献
912.
D D Thiessen T M Barth 《Journal of comparative psychology (Washington, D.C. : 1983)》1985,99(3):306-310
Three experiments were conducted with adult male Meriones unguiculatus in an attempt to demonstrate that ventral scent marking can act to transfer body heat to the object marked. Experiment 1 showed that surgical removal of the ventral gland pad reduced the amount of heat transferred by 50%, even though intact and glandless animals did not differ in the average frequency of scent marking. Experiment 2 demonstrated that the difference in heat transfer due to the presence or absence of the scent pad was not due to differential pressure applied to the substrate during marking. Experiment 3 showed that the pattern of ventral hair spread that occurs as an animal moves over an object is different between intact and glandless animals but that this difference does not account for the difference in heat transfer. It is suggested that heat transfer to the environment with ventral scent marking may increase thermoregulatory competence and also may function to volatilize sebum used in chemocommunication. 相似文献
913.
Bornstein’s hypothesis that there is a loss of color discrimination in tropical areas was not supported in earlier research
in the Cook Islands. Using a more sensitive color vision test (the Farnsworth-Munsell 100-Hue Test), a loss of color discrimination
in the red-purple and blue-green regions of the spectrum was found. The lack of sex differences in this color discrimination
loss supports a physiological rather than a genetic explanation of the observed decrement. 相似文献
914.
915.
DAVID W. HEAD BECKY HEAD JAMES L. HEAD 《Journal of counseling and development : JCD》1985,63(10):621-624
Due to the death of a severely disabled infant from Bloomington, Indiana, a series of events set in motion by the U.S. Department of Health and Human Services has resulted in cautions to health care providers. The resulting policies and procedures warn hospital personnel against withholding nutritional sustenance or medical treatment from severely disabled infants. This article presents dimensions that might serve as a background for counselors to assist families in considering options related to disabled infants. These dimensions include the meaning of life, cost to benefit ratio, medical options, legal precedent, and a theological perspective. This issue is related to counseling practice through counselor ethics, values, and the need for information that counselors can provide to parents during the decision process. 相似文献
916.
L C Drickamer 《Journal of comparative psychology (Washington, D.C. : 1983)》1985,99(4):411-419
Five experiments were performed to investigate the effects of social status in groups of female mice on reproduction and on the release or urinary chemosignals that accelerate or delay the onset of sexual maturation in young females. Treatment of young female mice with urine from bottom-ranking mice in groups of 5 adult females resulted in delays in puberty comparable to those produced by treatment with urine pooled from females housed at moderate to high densities. Treatment of young females with urine from top-ranking females from the same groups resulted in ages for puberty not different from those of control females treated with water. There was an interaction between the social rank of a female and the stages of the estrous cycle with respect to the presence in the urine of chemosignals from grouping that delay puberty and estrus that accelerate puberty. Within groups of 5 adult mice, top-ranking females were in estrus more frequently than bottom-ranking females. Individually caged adult females treated with urine from top-ranking females were in estrus more frequently than females treated with urine from bottom-ranking females. When grouped females were separated into individual cages and mated, there was differential reproductive success: More top-ranking females conceived and bore litters than bottom-ranking females. Bottom-ranking females produced more female pups, relative to top- and middle-ranking females. 相似文献
917.
An experiment with 42 human Ss used the transswitching procedure to examine tonic stimulus control of phasic and tonic conditioned vasomotor heart rate, and electrodermal reactions. The conditional stimulus (CSs) were photos of angry and friendly human faces, and the unconditional stimulus (US) was a human scream. In one tonic context (blue light), the CSs were paired with the US, in the other context (yellow light), the CSs were presented unpaired. Following acquisition, an extinction series was run with the US omitted during both tonic contexts. Phasic vasomotor and skin conductance reactions differed in the positive and negative tonic segments (stronger in positive). The skin conductance responses also differed during extinction, but the vasomotor responses did not. Tonic differences (following onset of the tonic stimuli) in unelicited skin conductance response frequency, finger pulse volume, and heart rate were also found, although these developed more slowly than the phasic differences. The finger pulse volume tonic difference was greater in extinction than the skin conductance response frequency. There was no effect of the angry-friendly facial expressions, either directly or in interaction with the transswitching effects. The results were interpreted to mean that the transswitching phenomenon is not limited to one another autonomic effector, but is more generalized across the ANS (sympathetic branch). The absence of influence of the facial expressions indicates the relative weakness of the “preparedness” hypothesis in comparison with more influential contextual factors. 相似文献
918.
919.
Syntactic determinants of sentence comprehension in aphasia 总被引:5,自引:0,他引:5
920.