全文获取类型
收费全文 | 20770篇 |
免费 | 42篇 |
专业分类
20812篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 9篇 |
2021年 | 12篇 |
2020年 | 21篇 |
2019年 | 27篇 |
2018年 | 3496篇 |
2017年 | 2824篇 |
2016年 | 2257篇 |
2015年 | 205篇 |
2014年 | 84篇 |
2013年 | 129篇 |
2012年 | 584篇 |
2011年 | 2403篇 |
2010年 | 2521篇 |
2009年 | 1487篇 |
2008年 | 1705篇 |
2007年 | 2185篇 |
2006年 | 34篇 |
2005年 | 220篇 |
2004年 | 167篇 |
2003年 | 116篇 |
2002年 | 69篇 |
2001年 | 37篇 |
2000年 | 55篇 |
1999年 | 16篇 |
1998年 | 25篇 |
1997年 | 18篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1990年 | 14篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1976年 | 4篇 |
1974年 | 2篇 |
1969年 | 2篇 |
1967年 | 4篇 |
1966年 | 2篇 |
1965年 | 2篇 |
1959年 | 1篇 |
1956年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Kang SY Lee KY Park MJ Kim YC Markelonis GJ Oh TH Kim YC 《Neurobiology of learning and memory》2003,79(1):11-18
We previously reported that a total methanolic extract of the underground part of Angelica gigas Nakai (Umbelliferae) (here-in-after abbreviated AG) significantly inhibited acetylcholinesterase (AChE) activity. We characterized 12 coumarin derivatives including both decursin and decursinol from extracts of AG. In this study, we evaluated the anti-amnestic activity of decursin, a major coumarin constituent isolated from AG, in vivo using ICR mice with amnesia induced by scopolamine (1 mg/kg body weight, s.c.). Decursin, when administered to mice at 1 and 5 mg/kg body weight i.p., significantly ameliorated scopolamine-induced amnesia as measured in both the passive avoidance test and the Morris water maze test. Moreover, decursin significantly inhibited AChE activity by 34% in the hippocampus of treated mice. These results indicate that decursin may exert anti-amnestic activity in vivo through inhibition of AChE activity in the hippocampus. 相似文献
92.
In modern digital applications, users often interact with virtual representations of themselves or others, called avatars. We examined how these avatars and their perspectives influence stimulus–response compatibility in a Simon task. Participants responded to light/dark blue stimuli with left/right key presses in the presence of a task-irrelevant avatar. Changes in stimulus–response compatibility were used to quantify changes in the mental representation of the task and perspective taking toward this avatar. Experiments 1 and 2 showed that perspective taking for an avatar occurred in orthogonal stimulus–response mappings, causing a compatibility effect from the avatar’s point of view. In the following two experiments we introduced a larger variety of angular disparities between the participant and avatar. In Experiment 3, the Simon effect with lateralized stimulus positions remained largely unaffected by the avatar, pointing toward an absence of perspective taking. In Experiment 4, after avatar hand movements were added in order to strengthen the participants’ sense of agency over the avatar, a spatial compatibility effect from the avatar’s perspective was observed again, and hints of the selective use of perspective taking on a trial-by-trial basis were found. Overall, the results indicate that users can incorporate the perspective of an avatar into their mental representation of a situation, even when this perspective is unnecessary to complete a task, but that certain contextual requirements have to be met. 相似文献
93.
94.
Two apparently contradictory ideas are closely linked in Israeli political discourse: Israel is powerful and independent and Israel is vulnerable and dependent. This study used content analysis and focus groups, as well as existing survey data analyzed by others, to explore how this paradox has been reflected in newspapers and conversations during six different time periods from 1948 to 1996. The goal was not to explain the paradox but to examine its consequences for Israeli perceptions of U.S. policy in the Middle East—and, in the process, to explore Israeli self-images. The nature of U.S. strategic interests was originally treated as problematic and in need of political discussion, but in the past 25 years these interests have become taken for granted. Surprisingly, even after the end of the Cold War, a critical discourse moment in which a reexamination of U.S. interests in the Middle East would seem inevitable, the U.S. role remains taken for granted and largely unexamined. The strong/vulnerable paradox explains this absence of discussion: Examining U.S. interests too closely upsets the delicate balance that keeps the sense of vulnerability in check. 相似文献
95.
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
96.
97.
98.
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
99.
Fred J. Hanna Fred Bemak Rita Chi-Ying Chung 《Journal of counseling and development : JCD》1999,77(2):125-134
Wisdom is introduced as a fundamental quality of the effective multicultural counselor. Wisdom is defined, discussed, and differentiated from intelligence. The authors propose that to be an effective multicultural counselor requires more than textbook knowledge. Wisdom, as a transcultural concept, is considered in relation to culture, context, dialectical thinking, awareness, metacognition, deep interpersonal insight, and advanced empathy. Implications for counselor education and professional practice are discussed. Wisdom is an ancient subject that may provide a “new” paradigm with the potential to bring the field to a higher plateau of effectiveness in practice and training. 相似文献
100.
Luke Robinson 《Philosophical Studies》2011,156(2):289-309
What are moral principles? In particular, what are moral principles of the sort that (if they exist) ground moral obligations or—at the very least—particular moral truths? I argue that we can fruitfully conceive of such principles as real, irreducibly dispositional properties of individual persons (agents and patients) that are responsible for and thereby explain the moral properties of (e.g.) agents and actions. Such moral dispositions (or moral powers) are apt to be the metaphysical grounds of moral obligations and of particular truths about what is morally permissible, impermissible, etc. Moreover, they can do other things that moral principles are supposed to do: explain the phenomena “falling within their scope,” support counterfactuals, and ground moral necessities, “necessary connections” between obligating reasons and obligations. And they are apt to be the truthmakers for moral laws, or “lawlike” moral generalizations. 相似文献