首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   981篇
  免费   328篇
  国内免费   26篇
  2024年   1篇
  2023年   20篇
  2022年   13篇
  2021年   30篇
  2020年   57篇
  2019年   51篇
  2018年   47篇
  2017年   44篇
  2016年   55篇
  2015年   39篇
  2014年   38篇
  2013年   188篇
  2012年   41篇
  2011年   61篇
  2010年   34篇
  2009年   65篇
  2008年   46篇
  2007年   41篇
  2006年   32篇
  2005年   40篇
  2004年   22篇
  2003年   29篇
  2002年   36篇
  2001年   12篇
  2000年   21篇
  1999年   18篇
  1998年   13篇
  1997年   13篇
  1996年   10篇
  1995年   12篇
  1994年   12篇
  1993年   22篇
  1992年   13篇
  1991年   13篇
  1990年   7篇
  1989年   11篇
  1988年   9篇
  1987年   10篇
  1986年   5篇
  1985年   8篇
  1984年   10篇
  1983年   9篇
  1982年   14篇
  1981年   5篇
  1980年   9篇
  1979年   13篇
  1978年   10篇
  1977年   11篇
  1976年   6篇
  1975年   9篇
排序方式: 共有1335条查询结果,搜索用时 15 毫秒
71.
The question of the morality of war is something of an embarrassment to liberal political thinkers. A philosophical tradition which aspires to found its preferred institutions in respect for individual autonomy, contract, and voluntary association, is naturally confronted by a phenomenon that is almost exclusively explained and justified in the language of States, force and territory. But the apparent difficulties involved in providing a convincing account of nature and ethics of war in terms of relations between individuals has not prevented liberal theorists from attempting this task. This paper examines a recent attempt by Igor Primoratz to sketch out the implications of a consistent liberalism for just war doctrine and, in particular, as regards the question of who may be a legitimate target of attack in wartime. Primoratz’s paper itself is a critique of Michael Waltzer’s authoritative exposition of just war theory for failing to be sufficiently and consistently liberal. The debate between these two authors is a productive site for investigating the potential and limitations of liberal theories of just war.  相似文献   
72.
Children are nearly as sensitive as adults to some cues to facial identity (e.g., differences in the shape of internal features and the external contour), but children are much less sensitive to small differences in the spacing of facial features. To identify factors that contribute to this pattern, we compared 8-year-olds' sensitivity to spacing cues with that of adults under a variety of conditions. In the first two experiments, participants made same/different judgments about faces differing only in the spacing of facial features, with the variations being kept within natural limits. To measure the effect of attention, we reduced the salience of featural information by blurring faces and occluding features (Experiment 1). To measure the role of encoding speed and memory limitations, we presented pairs of faces simultaneously and for an unlimited time (Experiment 2). To determine whether participants' sensitivity would increase when spacing distortions were so extreme as to make the faces grotesque, we manipulated the spacing of features beyond normal limits and asked participants to rate each face on a "bizarreness" scale (Experiment 3). The results from the three experiments indicate that low salience, poor encoding efficiency, and limited memory can partially account for 8-year-olds' poor performance on face processing tasks that require sensitivity to the spacing of features, a kind of configural processing that underlies adults' expertise. However, even when the task is modified to compensate for these problems, children remain less sensitive than adults to the spacing of features.  相似文献   
73.
Eight crows were taught to discriminate overlapping pairs of visual stimuli (A+ B-, B+ C-, C+ D-, and D+ E-). For 4 birds, the stimuli were colored cards with a circle of the same color on the reverse side whose diameter decreased from A to E (ordered feedback group). These circles were made available for comparison to potentially help the crows order the stimuli along a physical dimension. For the other 4 birds, the circles corresponding to the colored cards had the same diameter (constant feedback group). In later testing, a novel choice pair (BD) was presented. Reinforcement history involving stimuli B and D was controlled so that the reinforcement/nonreinforcement ratios for the latter would be greater than for the former. If, during the BD test, the crows chose between stimuli according to these reinforcement/nonreinforcement ratios, then they should prefer D; if they chose according to the diameter of the feedback stimuli, then they should prefer B. In the ordered feedback group, the crows strongly preferred B over D; in the constant feedback group, the crows' choice did not differ significantly from chance. These results, plus simulations using associative models, suggest that the orderability of the postchoice feedback stimuli is important for crows' transitive responding.  相似文献   
74.
Quantitative analyses of stimulus control and reinforcer control in conditional discriminations and delayed matching-to-sample procedures often encounter a problem; it is not clear how to analyze data when subjects have not made errors. The present article examines two common methods for overcoming this problem. Monte Carlo simulations of performance demonstrated that both methods introduced systematic deviations into the results, and that there were genuine risks of drawing misleading conclusions concerning behavioral models of signal detection and animal short-term memory.  相似文献   
75.
Choice typically is studied by exposing organisms to concurrent variable-interval schedules in which not only responses controlled by stimuli on the key are acquired but also switching responses and likely other operants as well. In the present research, discriminated key-pecking responses in pigeons were first acquired using a multiple schedule that minimized the reinforcement of switching operants. Then, choice was assessed during concurrent-probe periods in which pairs of discriminative stimuli were presented concurrently. Upon initial exposure to concurrently presented stimuli, choice approximated exclusive preference for the alternative associated with the higher reinforcement frequency. Concurrent schedules were then implemented that gave increasingly greater opportunities for switching operants to be conditioned. As these operants were acquired, the relation of relative response frequency to relative reinforcement frequency converged toward a matching relation. An account of matching with concurrent schedules is proposed in which responding exclusively to the discriminative stimulus associated with the higher reinforcement frequency declines as the concurrent stimuli become more similar and other operants-notably switching-are acquired and generalize to stimuli from both alternatives. The concerted effect of these processes fosters an approximate matching relation in commonly used concurrent procedures.  相似文献   
76.
A robust finding in the cross-cultural research is that people's memories for faces of their own race are superior to their memories for other-race faces. However, the mechanisms underlying the own-race effect have not been well defined. In this study, a holistic explanation was examined in which Caucasian and Asian participants were asked to recognize features of Caucasian and Asian faces presented in isolation and in the whole face. The main finding was that Caucasian participants recognized own-race faces more holistically than Asian faces whereas Asian participants demonstrated holistic recognition for both own-race and other-race faces. The differences in holistic recognition between Caucasian and Asian participants mirrored differences in their relative experience with own-race and other-race faces. These results suggest that the own-race effect may arise from the holistic recognition of faces from a highly familiar racial group.  相似文献   
77.
Seventeen African dwarf goats (adult females) were trained on oddity tasks using an automated learning device. One odd stimulus and three identical nonodd stimuli were presented on a screen divided into four sectors; the sector for the odd stimulus was varied pseudorandomly. Responses to the odd stimulus were deemed to be correct and were reinforced with food. In phase 1, the goats were trained on eight stimulus configurations. From trial to trial the odd discriminandum was either a + symbol or the letter S, and the nonodd discriminandum was the symbol not used as the odd one. In phase 2, the animals were similarly trained using an unfilled triangle or a filled (i.e., solid black) circle. In phase 3, three new discriminanda were used, an unfilled, small circle with radiating lines, an unfilled heart-shaped symbol, and an unfilled oval; which of the three discriminanda was odd and nonodd was varied from trial to trial. Following these training phases, a transfer test was given, which involved 24 new discriminanda sets. These were presented twice for a total of 48 transfer test trials. Results early in training showed approximately 25% correct, which might be expected by chance in a four-choice task. After 500-2,000 trials, results improved to approximately 40-44% correct. The best-performing subject reached 60-80% correct during training. On the transfer test, this subject had 47.9% correct and that significantly exceeded 25% expected by chance. This finding suggests that some exceptional individuals of African dwarf goats are capable of learning the oddity concept.  相似文献   
78.
We studied gaze perception in three infant chimpanzees (Pan troglodytes), aged 10-32 weeks, using a two-choice preferential-looking paradigm. The infants were presented with two photographs of a human face: (a) with the eyes open or closed, and (b) with a direct or an averted gaze. We found that the chimpanzees preferred looking at the direct-gaze face. However, in the context of scrambled faces, the infants showed no difference in gaze discrimination between direct and averted gazes. These findings suggest that gaze perception by chimpanzees may be influenced by the surrounding facial context. The relationship between gaze perception, face processing, and the adaptive significance of gaze perception are discussed from an evolutionary perspective.  相似文献   
79.
The study of equivalence relations exhibited by individuals with mental retardation and language limitations holds the promise of providing information of both theoretical and practical significance. We reviewed the equivalence literature with this population, defined in terms of subjects having moderate, severe, or profound mental retardation. The literature includes 55 such individuals, most of whom showed positive outcomes on equivalence tests. The results to date suggest that naming skills are not necessary for positive equivalence test outcomes. Thus far, however, relatively few subjects with minimal language have been studied. Moreover, we suggest that the scientific contributions of studies in this area would be enhanced with better documentation of language skills and other subject characteristics. With recent advances in laboratory procedures for establishing the baseline performances necessary for equivalence tests, this research area is poised for rapid growth.  相似文献   
80.
Does the perception of our actions differ from the perception of other individuals' actions when we observe them, like other individual's actions, in an offline perspective? Previous studies, using recognition as well as prediction judgments, suggest that it does even if the stimulus information is reduced to a single moving point-light. Here, we assessed whether this difference also affects the timing of actions. This was tested in two experiments, using a specific synchronization task. After some practice, self-generated action events were anticipated faster than other action events, provided that the anticipation could not be accomplished sufficiently well on the basis of easily detectable cues. The results are discussed with regard to the previous findings of off-line authorship effects in action perception.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号