全文获取类型
收费全文 | 832篇 |
免费 | 47篇 |
专业分类
879篇 |
出版年
2024年 | 3篇 |
2023年 | 11篇 |
2022年 | 12篇 |
2021年 | 22篇 |
2020年 | 19篇 |
2019年 | 27篇 |
2018年 | 37篇 |
2017年 | 32篇 |
2016年 | 38篇 |
2015年 | 36篇 |
2014年 | 31篇 |
2013年 | 89篇 |
2012年 | 62篇 |
2011年 | 60篇 |
2010年 | 34篇 |
2009年 | 38篇 |
2008年 | 51篇 |
2007年 | 48篇 |
2006年 | 54篇 |
2005年 | 34篇 |
2004年 | 31篇 |
2003年 | 20篇 |
2002年 | 12篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 9篇 |
1997年 | 3篇 |
1996年 | 13篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 3篇 |
1972年 | 1篇 |
排序方式: 共有879条查询结果,搜索用时 0 毫秒
21.
In a basic microeconomic model (joint production and consumer's utility curves) three key optima appear: the best technological mix, the maximum profit point and the consumer's utility optimum. Compromise analysis can help to clarify their connections. This paper and other recent research attempt to specify the conditions which guarantee that these three optima coincide. Thus compromise programming becomes a valuable surrogate of economic optimization. 相似文献
22.
Aranzazu Azpiroz Amaia Arregui Eduardo Fano Larraitz Garmendia Jos Ramn Snchez-Martin 《Aggressive behavior》1994,20(1):67-72
There is currently much interest in the potential impact of psychological factors on immune responses. An attempt was made to assess the effects of dominant/subordinate polarity in male mice on the cytotoxic activities of their natural-killer (NK) cells. On the basis of repeated agonistic encounters, categories of subordinate and dominat animals were selected. These animals were compared with manipulated controls (introduced to a novel test cage without an opponent on each occasion) and undisturbed controls (who remained in isolation without manipulation). In terms of NK activity, immunosuppression was observed in both dominant and subordinate categories when compared to undisturbed controls. There were, however, no differences between the fighting exposed subjects and the manipulated controls, suggesting that stress accounts for any changes. © 1994 Wiley-Liss, Inc. 相似文献
23.
Barrio Eduardo Alejandro Pailos Federico Szmuc Damian 《Journal of Philosophical Logic》2020,49(1):93-120
Journal of Philosophical Logic - In this article, we will present a number of technical results concerning Classical Logic, ST and related systems. Our main contribution consists in offering a... 相似文献
24.
In this article we identify three previously unnoticed problems with flexible moral theories, i.e., theories according to which different moral rules apply when there is full compliance and when there is partial compliance. The first problem is that flexible theories are necessarily very complex, which undermines their ability to motivate and guide action. The second problem is that flexible theories allow for a troubling kind of (moral) domination: the duties an agent has depend on other agents' willingness to comply. Finally, flexible theories introduce indeterminacy: it is sometimes impossible to determine which moral rules apply. When agents stand at the threshold—i.e., when a different rule would apply if a single additional act of noncompliance took place—it is impossible to determine which rule should apply. 相似文献
25.
Marques-Carneiro José Eduardo Polgári Patrik Koning Estelle Seyller Emilie Martin Brice Van der Burg Erik Giersch Anne 《Attention, perception & psychophysics》2020,82(6):2821-2836
Attention, Perception, & Psychophysics - Learning and imitating a complex motor action requires to visually follow complex movements, but conscious perception seems too slow for such tasks.... 相似文献
26.
We searched the Internet for expressions linking topics, such as crime, and vehicles, such as disease, as similes (crime is like a disease) and as metaphors (crime is a disease). We counted the number of times the expressions were accompanied by explanations (crime is like a disease because it spreads by direct personal influence). Similes were more likely than metaphors to be accompanied by explanations. Similes may be preferred if a writer wants to
express an out-of-the-ordinary relation between the topic and the vehicle. 相似文献
27.
The authors studied gender differences in response to hypothetical infidelity in Spanish students. Using a forced-choice methodology, the authors asked a sample of 266 participants to indicate which kind of infidelity would be more distressing: emotional or sexual. Men were significantly more distressed by sexual infidelity than were women, and women were significantly more distressed by emotional infidelity than were men. Results supported the hypothesis that particular infidelity types, which resemble adaptive problems that human beings faced in the past, contribute to the psychology of jealousy. The results are consistent with previous cross-cultural research. 相似文献
28.
29.
30.
Positive and Negative Expectations of Hopelessness as Longitudinal Predictors of Depression,Suicidal Ideation,and Suicidal Behavior in High‐Risk Adolescents 下载免费PDF全文
Adam G. Horwitz MS Johnny Berona MS Ewa K. Czyz PhD Carlos E. Yeguez BS Cheryl A. King PhD 《Suicide & life-threatening behavior》2017,47(2):168-176
The relationship between hopelessness and depression in predicting suicide‐related outcomes varies based on the anticipation of positive versus negative events. In this prospective study of adolescents at elevated risk for suicide, we used two Beck Hopelessness Scale subscales to assess the impact of positive and negative expectations in predicting depression, suicidal ideation, and suicidal behavior over a 2‐ to 4‐year period. In multivariate regressions controlling for depression, suicidal ideation, and negative‐expectation hopelessness, positive‐expectation hopelessness was the only significant predictor of depressive symptoms and suicidal behavior. Clinical interventions may benefit from bolstering positive expectations and building optimism. 相似文献