全文获取类型
收费全文 | 1123篇 |
免费 | 29篇 |
国内免费 | 7篇 |
专业分类
1159篇 |
出版年
2021年 | 14篇 |
2020年 | 15篇 |
2019年 | 19篇 |
2018年 | 26篇 |
2017年 | 20篇 |
2016年 | 25篇 |
2015年 | 10篇 |
2014年 | 16篇 |
2013年 | 71篇 |
2012年 | 40篇 |
2011年 | 31篇 |
2010年 | 24篇 |
2009年 | 26篇 |
2008年 | 32篇 |
2007年 | 37篇 |
2006年 | 26篇 |
2005年 | 21篇 |
2004年 | 26篇 |
2003年 | 15篇 |
2002年 | 28篇 |
2001年 | 39篇 |
2000年 | 51篇 |
1999年 | 24篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1992年 | 18篇 |
1991年 | 15篇 |
1990年 | 35篇 |
1989年 | 24篇 |
1988年 | 11篇 |
1987年 | 27篇 |
1986年 | 32篇 |
1985年 | 21篇 |
1984年 | 22篇 |
1983年 | 17篇 |
1982年 | 8篇 |
1981年 | 11篇 |
1980年 | 8篇 |
1979年 | 12篇 |
1978年 | 10篇 |
1976年 | 9篇 |
1975年 | 16篇 |
1974年 | 15篇 |
1973年 | 21篇 |
1972年 | 14篇 |
1971年 | 18篇 |
1970年 | 15篇 |
1968年 | 9篇 |
1967年 | 13篇 |
1966年 | 7篇 |
排序方式: 共有1159条查询结果,搜索用时 0 毫秒
141.
142.
143.
144.
145.
We report two experiments that investigate the calculating strategy used by a low IQ savant to identify prime numbers. Hermelin and O'Connor (1990) had suggested previously that this subject may use a procedure first described by Eratosthenes to detect a prime number, namely, dividing a target number by all primes up to the square root of the target number and testing for a remainder. In the first experiment, we compare the reaction times of the savant to decide whether a number is prime with those of a control subject proficient in mathematical calculation. In addition, we measured the savant's speed of information processing using an inspection time task. We found that the reaction times of the savant, although generally faster, followed the same pattern of the control subject who reported using the Eratosthenes procedure. The savant's inspection time indicated that his speed of processing was far superior to that expected from someone of his IQ. In the second experiment, we measured the time it takes mathematics students to divide by different prime numbers and we also tested them on the prime identification task. We used their division times to simulate their performance on the prime number identification task under the assumption that they used the Eratosthenes procedure. We also simulated the reaction times that would result from a simple memory-based procedure for identifying primes. We found that the Eratosthenes simulation, in contrast to the memory simulation, provided a good fit to both the students' and the savant's reaction times. We conclude that the savant is using a complex computational algorithm to identify primes and suggest two explanations of how the apparent contradiction between his low general intelligence and his superior numerical ability might be resolved. 相似文献
146.
In three experiments, we investigated how associative word-word priming effects in German depend on different types of syntactic context in which the related words are embedded. The associative relation always concerned a verb as prime and a noun as target. Prime word and target word were embedded in visually presented strings of words that formed either a correct sentence, a scrambled list of words, or a sentence in which the target noun and the preceding definite article disagreed in syntactic gender. In contrast to previous studies (O’Seaghdha, 1989; Simpson, Peterson, Casteel, & Burgess, 1989), associative priming effects were not only obtained in correct sentences but also in scrambled word lists. Associative priming, however, was not obtained when the definite article and the target noun disagreed in syntactic gender. The latter finding suggests that a rather local violation of syntactic coherence reduces or eliminates word-word priming effects. The results are discussed in the context of related work on the effect of gender dis-/agreement between a syntactic context and a target noun. 相似文献
147.
Abrams TW Yovell Y Onyike CU Cohen JE Jarrard HE 《Learning & memory (Cold Spring Harbor, N.Y.)》1998,4(6):496-509
An important recent insight in a number of neurobiological systems is that during learning, individual dually regulated proteins with associative properties function as critical sites of stimulus convergence. During conditioning in Aplysia, the Ca2+ /calmodulin-sensitive adenylyl cyclase (AC) in mechanosensory neurons serves as a molecular site of interaction between Ca2+ and serotonin [5-hydroxytryptamine (5-HT)]-two signals that represent the CS and US in these cells. Conditioning requires that the CS and US be paired within a narrow time window and in the appropriate sequence. AC shows an analogous sequence preference: It is more effectively activated when a pulse of Ca2+ precedes a pulse of 5-HT than when the 5-HT precedes Ca2+. One mechanism that contributes to this sequence preference is that Ca2+/calmodulin binding to AC accelerates the rate of AC activation by receptor-Gs. We have identified two additional properties of AC activation that would cause pairing with Ca2+ preceding 5-HT to be more effective than simultaneous pairing or pairing with the reciprocal sequence: (1) Activation of Aplysia AC by a Ca2+ pulse rose with a delay compared with activation by a 5-HT pulse. (2) A late pulse of Ca2+, which arrived after 5-HT, acted, via calmodulin, to accelerate the decay of AC activation by receptor-Gs. Together, these activation properties of AC may contribute to the CS-US sequence requirement of classical conditioning. 相似文献
148.
Sheaves over right sided idempotent quantales 总被引:1,自引:0,他引:1
149.
Changing the position of a light source illuminating a human face induces an apparent shift of the perceived orientation of that face. The direction of this apparent shift is opposite to the shift of the light source. We demonstrated the illumination-induced apparent orientation shift (IAOS), quantified it in terms of the physical orientation shift needed to compensate for it, and evaluated the results in the context of possible mechanisms underlying orientation judgment. Results indicate that IAOS depends not only on the angle between the two light source positions, but also on the mean orientation of the face. Availability of cues coded in the visual texture of the face did not affect IAOS. The most effective cue was the location of the visible outline of the face. IAOS seems to be due to a shift of this outline when shadowed areas on the face merge with the black background. We conclude that an important mechanism for orientation judgment is based on a comparison of visible parts left and right of the profile line. 相似文献
150.
U. Tnne A. J. Hiltunen K. Engelbrektsson H. Bjrvell B. Vikander S. Borg 《Personality and individual differences》1998,24(6):797-804
The present study applied Karolinska Scales of Personality (KSP) to study (i) if patients with benzodiazepine dependence have a characteristic personality profile, (ii) if the personality characteristics in patients with benzodiazepine dependence differ from those of polydrug users and normal controls, (iii) if differences in treatment outcome existed between the groups, and (iv) if the possible difference in treatment outcome was associated with any particular personality characteristic shown by the patients. The personality characteristics of primary benzodiazepine dependent patients (BDZ) and a group of polydrug users (MIX) were studied initially (during the first week in project as an inpatient) and approximately one year after drug discontinuation, and a comparison was made with healthy controls on both test occasions. The results showed that the personality of both groups of patients differed significantly from the Controls in the following characteristics: Detachment, Socialization, Somatic Anxiety, Muscular Tension, Psychic Anxiety, and Psychasthenia. Significant differences existed between the polydrug and benzodiazepine users in Somatic and Psychic Anxiety as well as in Socialization. The MIX group differed significantly from the BDZ group and from the Controls in Suspicion. Results of treatment outcome indicated that the benzodiazepine dependent patients were significantly more successful in quitting their drug use compared to polydrug users. Further, the results demonstrated that patients scoring high in the investigated personality characteristics are those who fail the treatment goal of quitting their drug use, especially the patients with a high level of anxiety and detachment. 相似文献