全文获取类型
收费全文 | 21450篇 |
免费 | 114篇 |
国内免费 | 207篇 |
出版年
2024年 | 3篇 |
2023年 | 22篇 |
2022年 | 32篇 |
2021年 | 46篇 |
2020年 | 41篇 |
2019年 | 42篇 |
2018年 | 3519篇 |
2017年 | 2853篇 |
2016年 | 2291篇 |
2015年 | 219篇 |
2014年 | 122篇 |
2013年 | 161篇 |
2012年 | 629篇 |
2011年 | 2457篇 |
2010年 | 2577篇 |
2009年 | 1518篇 |
2008年 | 1767篇 |
2007年 | 2247篇 |
2006年 | 119篇 |
2005年 | 297篇 |
2004年 | 224篇 |
2003年 | 161篇 |
2002年 | 92篇 |
2001年 | 53篇 |
2000年 | 77篇 |
1999年 | 31篇 |
1998年 | 31篇 |
1997年 | 25篇 |
1996年 | 13篇 |
1995年 | 6篇 |
1994年 | 9篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1990年 | 10篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 7篇 |
1985年 | 3篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1979年 | 5篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1969年 | 4篇 |
1966年 | 2篇 |
1955年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
Adolescent Substance Use: Preliminary Examinations of School and Neighborhood Context 总被引:1,自引:0,他引:1
Kevin W. Allison Isiaah Crawford Peter E. Leone Edison Trickett Alina Perez-Febles Linda M. Burton Ree Le Blanc 《American journal of community psychology》1999,27(2):111-141
In considering the influences of microsystems on adolescent substance use, familial and peer contexts have received the most extensive attention in the research literature. School and neighborhood settings, however, are other developmental contexts that may exert specific influences on adolescent substance use. In many instances, school settings are organized to provide educational services to students who share similar educational abilities and behavioral repertoires. The resulting segregation of students into these settings may result in different school norms for substance use. Similarly, neighborhood resources, including models for substance use and drug sales involvement, may play an important role in adolescent substance use. We briefly review literature examining contextual influences on adolescent substance use, and present results from two preliminary studies examining the contribution of school and neighborhood context to adolescent substance use. In the first investigation, we examine the impact of familial, peer, and school contexts on adolescent substance use. Respondents were 283 students (ages 13 to 18) from regular and special education classrooms in six schools. Although peer and parental contexts were important predictors of substance use, school norms for drug use accounted for variance in adolescent use beyond that explained by peer and parental norms. Data from a second study of 114 adolescents (mean age = 15) examines neighborhood contributions to adolescent substance use. In this sample, neighborhood indices did not contribute to our understanding of adolescent substance use. Implications for prevention are presented. 相似文献
103.
Zusammenfassung. Das hier vorgestellte Modell lernt graduell, Planungsaufgaben aus der Klasse der Maschinenbelegungsprobleme (job-shop-scheduling problems) zu lösen. Mit Hilfe des Chunking-Mechanismus von Soar wird episodisches Wissen über die Belegungsreihenfolge von Aufträgen auf Maschinen memoriert. Bei der Entwicklung des Modells wurden zahlreiche qualitative (z. B. Transfereffekte) und quantitative Befunde (z. B. Bearbeitungszeiten) aus einer früheren empirischen Untersuchung berücksichtigt. In einer Validierungsstudie wurden dieselben Aufgaben von 14 Probanden und dem Modell bearbeitet. Die Passung von Simulationsdaten und empirischen Ergebnissen fiel insgesamt gut aus. Allerdings löst das Modell die Aufgaben schneller und zeigt auch einen etwas besseren Lernverlauf als die Probanden. Das Modell liefert eine Erklärung für das Rauschen, das typischerweise bei Bearbeitungszeiten zu beobachten ist: es handelt sich um erworbenes Wissen, das mehr oder weniger gut und auch unterschiedlich häufig auf neue Situationen übertragen wird. Der Lernverlauf der Probanden entspricht nur für aggregierte Daten einer Potenzfunktion (power law). Der vorgestellte Mechanismus zeigt, wie ein symbolisches Modell der Informationsverarbeitung graduelle Verhaltensänderungen generiert und wie der offensichtliche Erwerb allgemeiner Prozeduren ohne explizites Lernen von deklarativen Regeln erfolgen kann. Es wird nahegelegt, daß es sich hier um die Modellierung einer Form impliziten Lernens handelt. Summary. The model presented here gradually learns how to perform a job-shop scheduling task. It uses Soar's chunking mechanism to acquire episodic memories about the order to schedule jobs. The model was based on many qualitative (e.g., transfer effects) and quantitative (e.g., solution time) regularities found in previously collected data. The model was tested with new data where scheduling tasks were given to the model and to 14 subjects. The model generally fit these data with the restrictions that the model performs the task (in simulated time) faster than the subjects, and its performance improves somewhat more quickly than the subjects' performance. The model provides an explanation of the noise typically found in problem solving times - it is the result of learning actual pieces of knowledge that transfer more or less to new situations but rarely by an average amount. Only when the data are averaged (i.e., over subjects) does the smooth power law appear. This mechanism demonstrates how symbolic models can exhibit a gradual change in behavior and how the apparent acquisition of general procedures can be performed without resorting to explicit declarative rule generation. We suggest that this may represent a type of implicit learning. 相似文献
104.
105.
106.
Luc Steels 《Kognitionswissenschaft》1999,8(4):143-150
Linguistics must again concentrate on the evolutionary nature of language, so that language models are more realistic with respect to human natural languages and have a greater explanatory force. Multi-agent systems are proposed as a possible route to develop such evolutionary models and an example is given of a concrete experiment in the origins and evolution of word-meaning based on a multi-agent approach. 相似文献
107.
自控摄入小剂量酒精影响熟练驾驶行为的实验研究 总被引:1,自引:1,他引:0
一个小样本受试者内设计实验,受试者在实验允许的酒精剂量范围内自由选择摄入量。实验安排饮酒前,酒后30分钟、110分钟和170分钟四个测试阶段,分别检验受试者在模拟驾驶和实际驾驶两项任务中的认知行为。酒后30分钟实际驾驶的技能与其他三个测试期相比存在有意义的差别显著性;模拟测试任务中酒后对红、黄两种信号灯的认知反应时之间呈现显著性差别,酒后110分钟对黄色信号灯的反应明显延迟。研究提示:受试对酒精感受性的估计是不可靠的,小剂量酒精也能对驾驶行为构成伤害。 相似文献
108.
109.
Color filling-in is a phenomenon in which the color of an object appears to be filled-in by the color of the surrounding field. We have studied the question of whether monkeys perceive color filling-in with near-foveal stimuli under steady fixation. Two monkeys were trained to fixate steadily and to attend to a disk, surrounded by an annulus of the complementary color, in parafoveal vision. Using displays in which the color of the disk was gradually changed to that of the annulus, we trained the animals to signal when they perceived a uniform color field. During the experiment, we introduced a small percentage of trials in which the disk color remained constant, and looked for 'filling-in' responses in these trials. Three human subjects were also tested for comparison. All subjects produced 'filling-in' responses with frequencies that were significantly higher for static disks with blurred borders than for moving disks or disks with sharp borders. This indicates that the monkeys' responses reflected perceptual filling-in, rather than random behavior. The time course of filling-in was similar in monkeys and humans. For the blurred static disks, responses occurred first after 3-4 s of fixation, reaching a probability of 0.2-0.8 by the end of 6 s, depending on the subject. 相似文献
110.
Esther Hess 《American journal of psychoanalysis》2018,78(2):137-158
This article considers the meaning and significance of authority, and its relevance to the transference process, within the framework of psychotherapy in the orthodox Jewish (Haredi) community in Israel. In this community, deeply-rooted habits of obedience to the commandments of the Torah and the authority of the Rabbi are integral to maintaining an orthodox way of life. Clinical vignettes with Haredi patients are presented to illustrate the complexities that arise when both patient and therapist belong to the orthodox community, and highlight the authority-related issues that are central to the therapy. This combination of factors requires a sensitive and finely-tuned approach which will enable the therapist to maintain the treatment framework while still accommodating the orthodox way of life. 相似文献