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   24224篇
  免费   227篇
  24451篇
  2024年   10篇
  2023年   55篇
  2022年   81篇
  2021年   119篇
  2020年   149篇
  2019年   139篇
  2018年   3633篇
  2017年   2982篇
  2016年   2393篇
  2015年   310篇
  2014年   216篇
  2013年   613篇
  2012年   867篇
  2011年   2646篇
  2010年   2673篇
  2009年   1549篇
  2008年   1938篇
  2007年   2338篇
  2006年   213篇
  2005年   309篇
  2004年   260篇
  2003年   196篇
  2002年   127篇
  2001年   68篇
  2000年   104篇
  1999年   50篇
  1998年   48篇
  1997年   30篇
  1996年   21篇
  1995年   14篇
  1994年   17篇
  1993年   19篇
  1992年   13篇
  1991年   18篇
  1990年   16篇
  1989年   15篇
  1988年   11篇
  1987年   16篇
  1986年   10篇
  1985年   15篇
  1984年   8篇
  1981年   8篇
  1979年   7篇
  1973年   9篇
  1972年   8篇
  1971年   14篇
  1969年   7篇
  1968年   18篇
  1966年   11篇
  1965年   12篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
161.
Objectives: To understand the impact of physicians and patients religious/spiritual orientation on discussions of spiritual issues. Methods: We performed semi-structured interviews of 10 Missouri family physicians and 10 patients of these physicians, selecting subjects nonrandomly to represent a range of demographic factors, practice types, and chronic or terminal illness. We coded and evaluated transcribed interviews for themes. Results: Respondents expressed that similar belief systems facilitate patient–physician spiritual interactions and bring confidence to their relationships. Those holding dissimilar faiths noted limited ability to address spiritual questions directly. They cited significant barriers to spiritual interaction but considered that ecumenism, use of patient-centered care, and negotiation skills lessen these barriers. Conclusions: Our respondents view spirituality similarly to other aspects of the physician–patient relationship involving differing viewpoints. Where discordance exists, cross-cultural, patient-centered, diplomatic approaches facilitate spiritual discussions.  相似文献   
162.
163.
Four experiments were designed to investigate whether the frequency of words used to create pseudowords plays an important role in lexical decision. Computational models of the lexical decision task (e.g., the dual route cascaded model and the multiple read-out model) predict that latencies to low-frequency pseudowords should be faster than latencies to high-frequency pseudowords. Consistent with this prediction, results showed that when the pseudowords were created by replacing one internal letter of the base word (Experiments 1 and 3), high-frequency pseudowords yielded slower latencies than low-frequency pseudowords. However, this effect occurred only in the leading edge of the response time (RT) distributions. When the pseudowords were created by transposing two adjacent internal letters (Experiment 2), high-frequency pseudowords produced slower latencies in the leading edge and in the bulk of the RT distributions. These results suggest that transposed-letter pseudowords may be more similar to their base words than replacement-letter pseudowords. Finally, when participants performed a go/no-go lexical decision task with one-letter different pseudowords (Experiment 4), high-frequency pseudowords yielded substantially faster latencies than low-frequency pseudowords, which suggests that the lexical entries of high-frequency words can be verified earlier than the lexical entries of low-frequency words. The implications of these results for models of word recognition and lexical decision are discussed.  相似文献   
164.
Statistical learning is one of the key mechanisms available to human infants and adults when they face the problems of segmenting a speech stream (Saffran, Aslin, & Newport, 1996) and extracting long-distance regularities (G6mez, 2002; Pe?a, Bonatti, Nespor, & Mehler, 2002). In the present study, we explore statistical learning abilities in rats in the context of speech segmentation experiments. In a series of five experiments, we address whether rats can compute the necessary statistics to be able to segment synthesized speech streams and detect regularities associated with grammatical structures. Our results demonstrate that rats can segment the streams using the frequency of co-occurrence (not transitional probabilities, as human infants do) among items, showing that some basic statistical learning mechanism generalizes over nonprimate species. Nevertheless, rats did not differentiate among test items when the stream was organized over more complex regularities that involved nonadjacent elements and abstract grammar-like rules.  相似文献   
165.
Confirmatory factor analysis examined the factor structure of DSM IV Attention Deficit Hyperactivity Disorder symptoms and analyzed the differences in informants' ratings of ADHD symptoms by children's age and sex. A sample of 1,018 Spanish school children, 574 girls and 444 boys, ages 4 to 12 years, was rated by teachers and parents. Confirmatory factor analysis showed a similar fit for the three-factor model of Inattention, Hyperactivity, and Impulsivity (teachers: CFI = .976, RMR = .041, % of total variance = 83.2; parents: CFI = .969, RMR = .037, % of total variance = 82.7) and for the two-factor model of Inattention and Hyperactivity Impulsivity (teachers: CFI = .958, RMR = .044, % of total variance = 79.3; parents: CFI = .961, RMR = .038, % of total variance, 79.9). The two-factor model was selected as a parsi monious representation of the teachers' and parents' ratings of ADHD symptoms. Analyses of variance indicated significant differences in teachers' and parents' mean ratings across sex and school grades of children.  相似文献   
166.
This study examined the dimensional structure of Tomás-Sábado and Gómez-Benito's Death Anxiety Inventory and Templer, et al.'s Death Depression Scale-Revised. The responses of 244 Spanish nurses to the Spanish forms of both scales were evaluated by means of a principal axis factor analysis with direct Oblimin rotation. Five significant factors were identified: Internally Generated Death Anxiety, Death Depression, Externally Generated Death Anxiety, Death Threat, and Death Sadness, accounting for 51.6% of the variance. The distribution of the factor loadings for the items of both scales on the five factors supported the discriminant validity of the constructs specific to each of the scales and justified their use in evaluating death anxiety and death depression independently.  相似文献   
167.
In this paper we present the syntax and semantics of a temporal action language named Alan, which was designed to model interactive multimedia presentations where the Markov property does not always hold. In general, Alan allows the specification of systems where the future state of the world depends not only on the current state, but also on the past states of the world. To the best of our knowledge, Alan is the first action language which incorporates causality with temporal formulas. In the process of defining the effect of actions we define the closure with respect to a path rather than to a state, and show that the non-Markovian model is an extension of the traditional Markovian model. Finally, we establish relationship between theories of Alan and logic programs.  相似文献   
168.
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   
169.
The purpose of this paper is to examine the effectiveness of Reconnecting Youth, a prevention program for at-risk high school youth. Data are from a large, independently evaluated effectiveness trial in two diverse urban school districts. A total of 1,218 students participated; 50% were male; average age was 15. We tested whether positive efficacy trial effects could be replicated, and whether any negative behavioral effects occur when clustering high-risk youth. Although mixed program effects were observed at immediate post-intervention, only negative effects were found at 6-month follow-up. These effects included less optimal scores on measures of GPA, Anger, School Connectedness, Conventional Peer Bonding, and Peer High-Risk Behaviors. Overall, we found little support for the use of this social-influence—model intervention aimed at increasing school connectedness for high-risk youth. Further, this study provides evidence that clustering high-risk youth in preventive interventions has the potential for iatrogenic effects.  相似文献   
170.
Previous studies have suggested that nonnative (L2) linguistic sounds are accommodated to native language (L1) phonemic categories. However, this conclusion may be compromised by the use of explicit discrimination tests. The present study provides an implicit measure of L2 phoneme discrimination in early bilinguals (Catalan and Spanish). Participants classified the 1st syllable of disyllabic stimuli embedded in lists where the 2nd, task-irrelevant, syllable could contain a Catalan contrastive variation (/epsilon/-/e/) or no variation. Catalan dominants responded more slowly in lists where the 2nd syllable could vary from trial to trial, suggesting an indirect effect of the /epsilon/-/e/ discrimination. Spanish dominants did not suffer this interference, performing indistinguishably from Spanish monolinguals. The present findings provide implicit evidence that even proficient bilinguals categorize L2 sounds according to their L1 representations.  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