首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3014篇
  免费   211篇
  国内免费   362篇
  2024年   6篇
  2023年   57篇
  2022年   50篇
  2021年   93篇
  2020年   156篇
  2019年   152篇
  2018年   159篇
  2017年   164篇
  2016年   164篇
  2015年   124篇
  2014年   150篇
  2013年   447篇
  2012年   132篇
  2011年   159篇
  2010年   99篇
  2009年   157篇
  2008年   125篇
  2007年   132篇
  2006年   127篇
  2005年   128篇
  2004年   123篇
  2003年   103篇
  2002年   76篇
  2001年   82篇
  2000年   59篇
  1999年   38篇
  1998年   37篇
  1997年   31篇
  1996年   26篇
  1995年   36篇
  1994年   22篇
  1993年   8篇
  1992年   9篇
  1991年   12篇
  1990年   9篇
  1989年   13篇
  1988年   10篇
  1987年   11篇
  1986年   6篇
  1985年   9篇
  1984年   16篇
  1983年   8篇
  1982年   13篇
  1981年   8篇
  1980年   7篇
  1979年   12篇
  1977年   4篇
  1976年   3篇
  1975年   7篇
  1974年   4篇
排序方式: 共有3587条查询结果,搜索用时 15 毫秒
111.
This paper reports data and scholarly opinion that support the perception of systemic flaws in the management of scientific professions and the research enterprise; explores the responsibility that professional status places on the scientific professions, and elaborates the concept of the responsible conduct of research (RCR). Data are presented on research misconduct, availability of research guidelines, and perceived research quality. An earlier version of this paper was presented at an International Conference on “Conflict of Interest and its Significance in Science and Medicine” held in Warsaw, Poland, 5–6 April, 2002. The opinions expressed herein are those of the author and do not necessarily represent the views of the Office of Research Integrity, the U.S. Department of Health and Human Services, or any other federal agency.  相似文献   
112.
113.
This paper sets the archetypal relationship between the tyrannical, devouring father and his sons in the context of a disjunction in the parental couple (syzygy) whereby the role of the maternal feminine is eclipsed and excluded. This is shown to originate in an omnipotent defence against infantile dependence on the mother. Successful liberation from the father's tyranny requires the restoration of mutuality between the internal couple. Although the main focus is on the internal world (and a detailed clinical illustration is given, showing the working out of this process in the analytical relationship), reference is also made to political tyranny, attitudes to the control of Nature by technological means and patriarchal forms of masculinity. The Chronos myth is amplified through the use of two modern variants in the films The Terminator and Star Wars.  相似文献   
114.
To elucidate processes underlying therapeutic change in a large-scale randomized clinical trial, we examined whether alterations in self-reported parenting practices were associated with the effects of behavioral, medication, or combination treatments on teacher-reported outcomes (disruptive behavior, social skills, internalizing symptoms) in children with attention-deficit hyperactivity disorder (ADHD). Participants were 579 children with Combined-type ADHD, aged 7–9.9 years, in the Multimodal Treatment Study of Children with ADHD (MTA). We uncovered 2 second-order factors of parenting practices, entitled Positive Involvement and Negative/Ineffective Discipline. Although Positive Involvement was not associated with amelioration of the school-based outcome measures, reductions in Negative/Ineffective Discipline mediated improvement in children's social skills at school. For families showing the greatest reductions in Negative/Ineffective Discipline, effects of combined medication plus behavioral treatment were pronounced in relation to regular community care. Furthermore, only in combination treatment (and not in behavioral treatment alone) was decreased Negative/Ineffective Discipline associated with reduction in children's disruptive behavior at school. Here, children in families receiving combination treatment who showed the greatest reductions in Negative/Ineffective Discipline had teacher-reported disruptive behavior that was essentially normalized. Overall, the success of combination treatment for important school-related outcomes appears related to reductions in negative and ineffective parenting practices at home; we discuss problems in interpreting the temporal sequencing of such process-outcome linkages and the means by which multimodal treatment may be mediated by psychosocial processes related to parenting.  相似文献   
115.
Many studies have identified the prefrontal cortex as the brain area that is critical for spatial memory, both in humans and in other primates. Other studies, however, have failed to establish this relation. Therefore, the aim of this paper was to review the literature regarding the role of the human prefrontal lobe in spatial memory. This was done by examining the evidence obtained from neuropsychological patients and from studies using brain-imaging techniques (PET and fMRI). Evidence supporting the notion that the prefrontal cortex is extensively involved in spatial working memory was found. The majority of these studies, however, suggests that frontal-lobe involvement is not related to the type of material that is being processed (e.g., spatial vs. nonspatial), but to process-specific functions, such as encoding and retrieval. Theoretically, these functions could be linked to the central executive within Baddeley's working-memory model, or to recent theories that emphasize the various processes that play a role in working memory. Also, methodological issues were discussed. Further research is needed to enhance our understanding of the precise interaction of domain-specific and general processes.  相似文献   
116.
The objective of this paper is to show how potentially incomplete preferences of a decision maker (DM) on acts can be modelled formally in a subjective ambiguity perspective. We identify acts as functions from a state space Ω to bounded support (finitely additive) probabilities over a set X of prizes. Then, we characterize preferences over equibounded acts a which have a numerical representation by the family of functionals , where u is a cardinal utility on X (representing the risk attitude of the DM) and Π is a unique pointwise closed convex set of probabilities on all events in Ω (representing the ambiguity perceived by the DM). To this end, in addition to the usual independence and continuity assumptions, we add completeness and dominance for preferences restricted to constant acts; moreover, we consider two other properties (subjective monotonicity and coherence) related with the preferences of a DM who is not able, owing to his partial knowledge, to evaluate any event in Ω.  相似文献   
117.
Although functional neuroimaging studies of human decision-making processes are increasingly common, most of the research in this area has relied on passive tasks that generate little individual variability. Relatively little attention has been paid to the ability of brain activity to predict overt behavior. Using functional magnetic resonance imaging (fMRI), we investigated the neural mechanisms underlying behavior during a dynamic decision task that required subjects to select smaller, short-term monetary payoffs in order to receive larger, long-term gains. The number of trials over which the longterm gains accrued was manipulated experimentally (2 versus 12). Event-related neural activity in right lateral prefrontal cortex, a region associated with high-level cognitive processing, selectively predicted choice behavior in both conditions, whereas insular cortex responded to fluctuations in amount of reward but did not predict choice behavior. These results demonstrate the utility of a functional neuroimaging approach in behavioral psychology, showing that (a) highly circumscribed brain regions are capable of predicting complex choice behavior, and (b) fMRI has the ability to dissociate the contributions of different neural mechanisms to particular behavioral tasks.  相似文献   
118.
The fixed point combinator (Y) is an important non-proper combinator, which is defhable from a combinatorially complete base. This combinator guarantees that recursive equations have a solution. Structurally free logics (LC) turn combinators into formulas and replace structural rules by combinatory ones. This paper introduces the fixed point and the dual fixed point combinator into structurally free logics. The admissibility of (multiple) cut in the resulting calculus is not provable by a simple adaptation of the similar proof for LC with proper combinators. The novelty of our proof—beyond proving the cut for a newly extended calculus–is that we add a fourth induction to the by-and-large Gentzen-style proof. Presented by Robert Goldblatt  相似文献   
119.
Not only do the writings of Nietzsche – early and late – fail to support the pedagogy of self-reformulation, this doctrine embodies what for him is worst in man and would destroy that which is higher. The pedagogy of self-reformulation is also incoherent. In contrast, Nietzsche offers a fruitful and comprehensive theory of education that, while non-democratic and contemptuous of egalitarian aspirations, emerges consistently from his metaphysics and philosophical anthropology. Whatever, then, we might think of his premises, Nietzsche’s philosophy of education represents an attractive model for those who would develop a meaningful, distinctive, and persuasive educational theory. It defines a domain of the possible and then straightforwardly states what is and is not to be done within it – and why.  相似文献   
120.
The supplementary motor area (SMA) is thought to play in important role in the preparation and organisation of voluntary movement. It has long been known that cortical activity begins to increase up to 2s prior to voluntary self-initiated movement. This increasing premovement activity measured in EEG is known as the Bereitschaftspotential or readiness potential. Modern functional brain imaging methods, using event-related and time-resolved functional MRI techniques, are beginning to reveal the role of the SMA, and in particular the more anterior pre-SMA, in premovement activity associated with the readiness for action. In this paper we review recent studies using event-related time-resolved fMRI methods to examine the time-course of activation changes within the SMA throughout the preparation, readiness and execution of action. These studies suggest that the pre-SMA plays a common role in encoding or representing actions prior to our own voluntary self-initiated movements, during motor imagery, and from the observation of others' actions. We suggest that the pre-SMA generates and encodes motor representations which are then maintained in readiness for action.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号