全文获取类型
收费全文 | 4530篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
4533篇 |
出版年
2018年 | 112篇 |
2017年 | 93篇 |
2016年 | 180篇 |
2015年 | 95篇 |
2014年 | 32篇 |
2013年 | 53篇 |
2012年 | 256篇 |
2011年 | 252篇 |
2010年 | 17篇 |
2009年 | 25篇 |
2008年 | 37篇 |
2007年 | 34篇 |
2006年 | 43篇 |
2005年 | 1322篇 |
2004年 | 660篇 |
2003年 | 445篇 |
2002年 | 137篇 |
2001年 | 26篇 |
2000年 | 10篇 |
1999年 | 23篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1994年 | 11篇 |
1992年 | 25篇 |
1991年 | 42篇 |
1990年 | 58篇 |
1989年 | 44篇 |
1988年 | 26篇 |
1987年 | 42篇 |
1986年 | 37篇 |
1985年 | 29篇 |
1984年 | 25篇 |
1983年 | 19篇 |
1982年 | 3篇 |
1979年 | 32篇 |
1978年 | 10篇 |
1977年 | 7篇 |
1976年 | 10篇 |
1975年 | 28篇 |
1974年 | 32篇 |
1973年 | 30篇 |
1972年 | 26篇 |
1971年 | 25篇 |
1970年 | 17篇 |
1969年 | 19篇 |
1968年 | 16篇 |
1967年 | 18篇 |
1966年 | 16篇 |
1965年 | 7篇 |
1932年 | 3篇 |
排序方式: 共有4533条查询结果,搜索用时 0 毫秒
871.
We aimed to expand upon the demographic characteristics and gender differences among those who have met someone on the Internet who they later met offline and had sex with as well as any relationship with cybersex, sexually transmitted infections, and online sexual problems. We analyzed data collected through an online questionnaire in 2002 in Sweden including a total population of 1836 respondents of which 1458 used the Internet for sexual purposes. Of those, 35% men and 40% women reported to have met offline sex partners online. The majority reported an occurrence of one to two times, whereas 10% reported six or more times. The analysis suggested women aged 34-49 and 50-65 years, homo- and bisexual men, and singles more likely to have this experience. They were also more likely to have engaged in cybersex. No relationships were found with sexually transmitted infections or online sexual problems. The results suggest that using the Internet to find sex partners may be less hazardous for the general Internet users than pointed out by prior research about this behavior often focusing on specific sub groups of Internet users. 相似文献
872.
Robert H. Stupnisky Robert D. Renaud Raymond P. Perry Joelle C. Ruthig Tara L. Haynes Rodney A. Clifton 《Social Psychology of Education》2007,10(3):303-330
Due to its widespread popularity, self-esteem is continually being promoted to students despite limited empirical support
for its effectiveness in improving their academic achievement. As a result, constructs that are potentially more salient to
academic performance, such as perceived control, have gone relatively unnoticed. Although past research has examined the link
between students’ academic achievement and either their self-esteem or perceived control, few studies have compared both constructs simultaneously to elucidate which one is more important to academic success. This longitudinal study directly
contrasted the effects of self-esteem and perceived control on the academic performance of 802 first-year college students.
After accounting for incoming ability (high school grades), age, and gender, a structural equation model showed perceived
control positively predicted students’ GPA. In contrast, the predictive effect of self-esteem on GPA was non-existent. Findings
indicate that compared to self-esteem, perceived control is a more powerful predictor of first-year college students’ GPA.
Implications for utilizing educational interventions to boost perceived control among college students are discussed. 相似文献
873.
It is often assumed that indeterminacy in mereological relations—in particular, indeterminacy in which collections of objects
have fusions—leads immediately to indeterminacy in what objects there are in the world. This assumption is generally taken
as a reason for rejecting mereological vagueness. The purpose of this paper is to examine the link between mereological vagueness
and existential vagueness. I hope to show that the connection between the two forms of vagueness is not nearly so clear-cut
as has been supposed. 相似文献
874.
Maria Caama?o 《Erkenntnis》2009,70(3):331-364
The incommensurability thesis, as introduced by T.S. Kuhn and P.K. Feyerabend, states that incommensurable theories are conceptually
incompatible theories which share a common domain of application. Such claim has often been regarded as incoherent, since
it has been understood that the determination of a common domain of application at least requires a certain degree of conceptual
compatibility between the theories. The purpose of this work is to contribute to the defense of the notion of local or gradual
incommensurability, as proposed by late Kuhn. The application of this notion would allow to render the incommensurability
thesis coherent. To support this view, a typical example of incommensurability will be formally analyzed by applying the structuralist
metatheory developed, among others by W. Balzer, C.U. Moulines and J.D. Sneed. The structural reconstruction of the relation
between the phlogiston theory and the oxygen theory offered here will reveal that they are locally incommensurable, and will
even make possible to determine the ontological reduction relation that they also exemplify.
相似文献
Maria Caama?oEmail: |
875.
María Dimitropoulou Jon Andoni Du?abeitia Panagiotis Blitsas Manuel Carreiras 《Behavior research methods》2009,41(2):584-589
The appropriate selection of both pictorial and linguistic experimental stimuli requires a previous languagespecific standardization
process of the materials across different variables. Considering that such normative data have not yet been collected for
Modern Greek, in this study normative data for the color version of the Snodgrass and Vanderwart picture set (Rossion & Pourtois,
2004) were collected from 330 native Greek adults. Participants named the pictures (providing name agreement ratings) and
rated them for visual complexity and age of acquisition. The obtained measures represent a useful tool for further research
on Greek language processing and constitute the first picture normative study for this language. The picture norms from this
study and previous ones may be downloaded from brm.psychonomic-journals.org/content/supplemental. 相似文献
876.
877.
Bard KA 《Animal cognition》2007,10(2):233-242
Primate species differ in their imitative performance, perhaps reflecting differences in imitative capacity. The developmentally
earliest form of imitation in humans, neonatal imitation, occurs in early interactions with social partners, and may be a
more accurate index of innate capacity than imitation of actions on objects, which requires more cognitive ability. This study
assessed imitative capacity in five neonatal chimpanzees, within a narrow age range (7–15 days of age), by testing responses
to facial and vocal actions with two different test paradigms (structured and communicative). Imitation of mouth opening was
found in both paradigms. In the communicative paradigm, significant agreement was found between infant actions and demonstrations.
Additionally, chimpanzees matched the sequence of three actions of the TC model, but only on the second demonstration. Newborn
chimpanzees matched more modeled actions in the communicative test than in the structured paradigm. These performances of
chimpanzees, at birth, are in agreement with the literature, supporting a conclusion that imitative capacity is not unique
to the human species. Developmental histories must be more fully considered in the cross-species study of imitation, as there
is a greater degree of innate imitative capacity than previously known. Socialization practices interact with innate and developing
competencies to determine the outcome of imitation tests later in life. 相似文献
878.
W Boucsein F Schaefer E N Sokolov C Schr?der J J Furedy 《Integrative Physiological and Behavioral Science》2001,36(2):137-153
A framework for accounting for emotional phenomena proposed by Sokolov and Boucsein (2000) employs conceptual dimensions that parallel those of hue, brightness, and saturation in color vision. The approach that employs the concepts of emotional quality. intensity, and saturation has been supported by psychophysical emotional scaling data gathered from a few trained observers. We report cortical evoked potential data obtained during the change between different emotions expressed in schematic faces. Twenty-five subjects (13 male, 12 female) were presented with a positive, a negative, and a neutral computer-generated face with random interstimulus intervals in a within-subjects design, together with four meaningful and four meaningless control stimuli made up from the same elements. Frontal, central, parietal, and temporal ERPs were recorded from each hemisphere. Statistically significant outcomes in the P300 and N200 range support the potential fruitfulness of the proposed color-vision-model-based approach to human emotional space. 相似文献
879.
Sverker Sikstr?m 《Psychonomic bulletin & review》2001,8(3):408-438
The mirror effect refers to a rather general empirical finding showing that, for two classes of stimuli, the class with the higher hit rates also has a lower false alarm rate. In this article, a parsimonious theory is proposed to account for the mirror effect regarding, specifically, high- and low-frequency items and the associated receiver-operating curves. The theory is implemented in a recurrent network in which one layer represents items and the other represents contexts. It is shown that the frequency mirror effect is found in this simple network if the decision is based on counting the number of active nodes in such a way that performance is optimal or near optimal. The optimal performance requires that the number of active nodes is low, only nodes active in the encoded representation are counted, the activation threshold is set between the old and the new distributions, and normalization is based on the variance of the input. Owing to the interference caused by encoding the to-be-recognized item in several preexperimental contexts, the variance of the input to the context layer is greater for highthan for low-frequency items, which yields lower hit rates and higher false alarm rates for high- than for low-frequency items. Although initially the theory was proposed to account for the mirror effect with respect to word frequency, subsequent simulations have shown that the theory also accounts for strength-based mirror effects within a list and between lists. In this case, consistent with experimental data, the variance theory suggests that focusing attention to the more difficult class within a list affects the hit rate, but not the false alarm rate and not the standard deviations of the underlying density, leading to no mirror effect. 相似文献
880.
Much research within decision-making has used the standard gambling paradigm, where decision outcomes depend only on chance. Many real life decisions, however, imply personal control over decision outcomes. This paper addressed the question of how internal controllability influences decision-making. Internal controllability is assumed (i) to enhance unrealistic optimism and (ii) to result in a better cost:benefit ratio. Both tendencies support each other and predict an enhanced attractiveness for internal and controllable choice options. Participants read a scenario and made a decision afterwards. Results supported the prediction: decision-makers take the option they can personally control. This finding widens the narrow perspective inherent in much previous research based on the gambling paradigm. 相似文献