全文获取类型
收费全文 | 16048篇 |
免费 | 426篇 |
国内免费 | 192篇 |
出版年
2015年 | 37篇 |
2013年 | 35篇 |
2012年 | 1571篇 |
2011年 | 1707篇 |
2010年 | 432篇 |
2009年 | 187篇 |
2008年 | 1353篇 |
2007年 | 1381篇 |
2006年 | 1225篇 |
2005年 | 1040篇 |
2004年 | 916篇 |
2003年 | 832篇 |
2002年 | 765篇 |
2001年 | 578篇 |
2000年 | 673篇 |
1999年 | 276篇 |
1998年 | 90篇 |
1997年 | 68篇 |
1996年 | 77篇 |
1995年 | 47篇 |
1994年 | 95篇 |
1993年 | 115篇 |
1992年 | 113篇 |
1991年 | 114篇 |
1990年 | 106篇 |
1989年 | 102篇 |
1988年 | 125篇 |
1987年 | 132篇 |
1986年 | 108篇 |
1985年 | 127篇 |
1984年 | 118篇 |
1983年 | 151篇 |
1982年 | 97篇 |
1981年 | 101篇 |
1980年 | 86篇 |
1979年 | 96篇 |
1978年 | 83篇 |
1966年 | 49篇 |
1965年 | 135篇 |
1964年 | 104篇 |
1963年 | 128篇 |
1962年 | 55篇 |
1958年 | 148篇 |
1957年 | 122篇 |
1956年 | 99篇 |
1955年 | 61篇 |
1954年 | 57篇 |
1953年 | 65篇 |
1952年 | 59篇 |
1951年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
841.
This study explored infants' ability to infer communicative intent as expressed in non-linguistic gestures. Sixty children aged 14, 18 and 24 months participated. In the context of a hiding game, an adult indicated for the child the location of a hidden toy by giving a communicative cue: either pointing or ostensive gazing toward the container containing the toy. To succeed in this task children had to do more than just follow the point or gaze to the target container. They also had to infer that the adult's behaviour was relevant to the situation at hand - she wanted to inform them that the toy was inside the container toward which she gestured. Children at all three ages successfully used both types of cues. We conclude that infants as young as 14 months of age can, in some situations, interpret an adult behaviour as a relevant communicative act done for them. 相似文献
842.
Teaching research ethics: Can web-based instruction satisfy appropriate pedagogical objectives? 总被引:1,自引:1,他引:0
Schrag B 《Science and engineering ethics》2005,11(3):347-366
Ethical tasks faced by researchers in science and engineering as they engage in research include recognition of moral problems in their practice, finding solutions to those moral problems, judging moral actions and engaging in preventive ethics. Given these issues, appropriate pedagogical objectives for research ethics education include (1) teaching researchers to recognize moral issues in their research, (2) teaching researchers to solve practical moral problems in their research from the perspective of the moral agent, (3) teaching researchers how to make moral judgments about actions, and (4) learning to engage in preventive ethics. If web-based research ethics education is intended to be adequate and sufficient for research ethics education, then it must meet those objectives. However there are reasons to be skeptical that it can. 相似文献
843.
844.
After a person has become stuck on a problem, they sometimes achieve a clear and sudden solution through insight--the so-called Aha! experience. Because of its distinctive experience, the origins and characteristics of insight have received considerable attention historically in psychological research. However, despite considerable progress in characterizing insight, the underlying mechanisms remain mysterious. We argue that research on insight could be greatly advanced by supplementing traditional insight research, which depends on a few complex problems, with paradigms common in other domains of cognitive science. We describe a large set of mini-insight problems to which multiple methods can be applied, together with subjective reports to identify insight problem-solving. Behavioral priming and neuroimaging methods are providing evidence about what, where, and how neural activity occurs during insight. Such evidence constrains theories of component processes, and will help to demystify insight. 相似文献
845.
Eye movements in natural behavior 总被引:1,自引:0,他引:1
The classic experiments of Yarbus over 50 years ago revealed that saccadic eye movements reflect cognitive processes. But it is only recently that three separate advances have greatly expanded our understanding of the intricate role of eye movements in cognitive function. The first is the demonstration of the pervasive role of the task in guiding where and when to fixate. The second has been the recognition of the role of internal reward in guiding eye and body movements, revealed especially in neurophysiological studies. The third important advance has been the theoretical developments in the fields of reinforcement learning and graphic simulation. All of these advances are proving crucial for understanding how behavioral programs control the selection of visual information. 相似文献
846.
We directly compared chimpanzee infants and human infants for categorical representations of three global-like categories (mammals, furniture and vehicles), using the familiarization-novelty preference technique. Neither species received any training during the experiments. We used the time that participants spent looking at the stimulus object while touching it as a measure. During the familiarization phase, participants were presented with four familiarization objects from one of three categories (e.g. mammals). Then, they were tested with a pair of novel objects, one was a familiar-category object and another was a novel-category object (e.g. vehicle) in the test phase. The chimpanzee infants did not show significant habituation, whereas human infants did. However, most important, both species showed significant novelty-preference in the test phase. This indicates that not only human infants, but also chimpanzee infants formed categorical representations of a global-like level. Implications for the shared origins and species-specificity of categorization abilities, and the cognitive operations underlying categorization, are discussed. 相似文献
847.
Past studies of galliform anti-predator behavior show that they discriminate between aerial and ground predators, producing distinctive, functionally referential vocalizations to each class. Within the category of aerial predators, however, studies using overhead models, video images and observations of natural encounters with birds of prey report little evidence that galliforms discriminate between different raptor species. This pattern suggests that the aerial alarm response may be triggered by general features of objects moving in the air. To test whether these birds are also sensitive to more detailed differences between raptor species, adult chickens with young were presented with variously sized trained raptors (small, intermediate, large) under controlled conditions. In response to the small hawk, there was a decline in anti-predator aggression and in aerial alarm calling as the young grew older and less vulnerable to attack by a hawk of this size. During the same developmental period, responses to the largest hawk, which posed the smallest threat to the young at all stages, did not change; there were intermediate changes at this time in response to the middle-sized hawk. Thus the anti-predator behavior of the adult birds varied in an adaptive fashion, changing as a function of both chick age and risk. We discuss these results in light of current issues concerning the cognitive mechanisms underlying alarm calling behavior in animals. 相似文献
848.
Most studies of animal tool use require subjects to use one object to gain access to a food reward. In many real world situations, however, animals perform more than one action in sequence to achieve their goals. Of theoretical interest is whether animals have the cognitive capacity to recognize the relationship between consecutive action sequences in which there may be one overall goal and several subgoals. Here we ask if cotton-top tamarins, a species that in captivity uses tools to solve means-end problems, can go one step further and use a sequence of tools (means) to obtain food (end). We first trained subjects to use a pulling tool to obtain a food reward. After this initial training, subjects were presented with problems in which one tool had to be used in combination with a second in order to obtain food. Subjects showed great difficulty when two tools were required to obtain the food reward. Although subjects attended to the connection between the tool and food reward, they ignored the physical connection between the two tools. After training on a two-tool problem, we presented subjects with a series of transfer tests to explore if they would generalize to new types of connections between the tools. Subjects readily transferred to new connections. Our results therefore provide the first evidence to date that tamarins can learn to solve problems involving two tools, but that they do so only with sufficient training. 相似文献
849.
In this paper the moral responsibility of a Healthcare Organization (HCO) is conceived as an inextricable aspect of the identity of the HCO. We attempt to show that by exploring this relation a more profound insight in moral responsibility can be gained. Referring to Charles Taylor we explore the meaning of the concept of identity. It consists of three interdependent dimensions: a moral, a dialogical, and a narrative one. In section two we develop some additional arguments to apply his concept of personal identity to organizations. The final section works out the relationship of three dimensions of identity to some actual issues in contemporary HCOs: the tension between care and justice, the importance of dialogues about the diversity of goods, and the relevance of becoming familiar with the life-story of the HCO. Identity of an HCO is established and developed in commitments to and identification with certain goods that are central for a HCO. However, many of these goods are interwoven with everyday practices and policies. Therefore, moral responsibility asks for articulation of goods that often stay implicit and should not be reduced to a merely procedural approach. However difficult this articulation may be, if it is not tried at all HCOs run the risk of drifting away from their very identity as healthcare institutions: to offer care to patients and to do this in accordance with demands of social justice. 相似文献
850.
The transmission of tool use is a rare event in monkeys. Such an event arose in a group of semi-free-ranging Tonkean macaques (Macaca tonkeana) in which leaning a pole against the parks fence (branch leaning) appeared and spread to several males. This prompted us to test individual and social learning of this behavior in seven young males. In the first experiment, three males learned individually to obtain a food reward using a wooden pole as a climbing tool. They began using the pole to retrieve the reward only when they could alternatively experience acting on the object and reaching the target. In a second experiment, we first tested whether four other subjects could learn branch leaning after having observed a group-mate performing the task. Despite repeated opportunities to observe the demonstrator, they did not learn to use the pole as a tool. Hence we exposed the latter subjects to individual learning trials and they succeeded in the task. Tool use was not transmitted in the experimental situation, which contrasts with observations in the park. We can conclude that the subjects were not able to recognize the target as such. It is possible that they recognized it and learned the task individually when we alternated the opportunity to act upon the object and to reach the reward. This suggests that these macaques could then have associated the action they exercised upon the pole and the use of the pole as a means to reach the reward. 相似文献