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   4517篇
  免费   258篇
  国内免费   1篇
  2024年   10篇
  2023年   71篇
  2022年   54篇
  2021年   88篇
  2020年   130篇
  2019年   125篇
  2018年   222篇
  2017年   224篇
  2016年   220篇
  2015年   130篇
  2014年   171篇
  2013年   629篇
  2012年   352篇
  2011年   347篇
  2010年   202篇
  2009年   108篇
  2008年   299篇
  2007年   234篇
  2006年   229篇
  2005年   146篇
  2004年   103篇
  2003年   92篇
  2002年   98篇
  2001年   25篇
  2000年   71篇
  1999年   42篇
  1998年   32篇
  1997年   23篇
  1996年   25篇
  1995年   12篇
  1994年   27篇
  1993年   13篇
  1992年   16篇
  1991年   25篇
  1990年   21篇
  1989年   20篇
  1988年   13篇
  1987年   12篇
  1985年   9篇
  1984年   13篇
  1983年   11篇
  1979年   7篇
  1978年   7篇
  1977年   5篇
  1976年   4篇
  1975年   4篇
  1974年   7篇
  1973年   5篇
  1968年   4篇
  1966年   4篇
排序方式: 共有4776条查询结果,搜索用时 15 毫秒
131.
The aim of this study is to analyze how the length of time a patient spends in an Intensive Care Unit (ICU) affects close relatives, with regard to specific clinical variables of personality, family relationships and fear of death. The study group consisted of 57 relatives of seriously ill patients admitted to the ICU of "Virgen del Rocío" Rehabilitation and Trauma Hospital (Seville, Spain). The instruments applied were: a psychosocial questionnaire, clinical analysis questionnaire, family environment scale and fear of death scale. The relatives of patients admitted to ICU obtained higher scores in hypochondria, suicidal depression, agitation, anxious depression, guilt-resentment, paranoia, psychasthenia, psychological maladjustment and self-expression, and less in fear of their own death, as when compared to interviews with the same relatives 4 years later. The length of time a patient spent in the ICU influenced relatives in some clinical variables of personality, family relationships and fear of death  相似文献   
132.
The purpose of this survey is to detect common personality features in people infected with AIDS who have a case history of drug addiction and who live in a situation of social exclusion. The sample comprised 105 male participants from the Autonomous Community of Andalusia, divided into 4 groups: (a) 30 men with AIDS, having an intravenous drug addiction case history and who live in a condition of social exclusion; (b) 30 men with IVDA case history, also living in a situation of social exclusion; (c) 15 men in a social exclusion condition; and (d) 30 men in a condition of social adaptation. The evaluation instruments were an author-designed semi-structured interview and the Multiaxial Clinical Inventory (MCMI-II; Millon, 1987). Although some differences were found, the results indicate that there is no specific personality profile in the "social exclusion" population. People in a condition of social exclusion (AIDS, drug addicts, and poor people) may obtain similar scores in the variables studied, but there is no clear specific personality profile in the excluded population, although there may be certain situations in which the segregated groups present similar behaviors. Furthermore, these behaviors do not always correspond to personality features but are adaptive responses to a harsh and complex reality.  相似文献   
133.
In this paper, the distributional properties and power rates of the Lz, Eci2z, and Eci4z statistics when they are used as item fit statistics were explored. The results were compared to t-transformation of Outfit and Infit mean square. Four sample sizes were selected: 100, 250, 500, and 1000 examinees. The abilities were uniform and normal with mean 0 and standard deviation 1, and uniform and normal with mean -1 and standard deviation 1. The pseudo-guessing parameter was fixed at .25. Two ranges of difficulty parameters were selected: +/- 1 logits and +/- 2 logits. Two test lengths were selected: 15 and 30 items. The results showed important differences between the T-infit, T-outfit, Lz, Eci2z, and Eci4z statistics. The T-oufit, T-infit, and Lz statistics showed poor standardization with estimated parameters because their distributional properties were not close to the expected values. However, the Eci2z and Eci4z statistics showed satisfactory standardization on all conditions. Further, the power rates of Eci2z and Eci4z were 5% to 10% higher than the power rates of Lz, T-outfit, and T-infit to detect items that do not fit Rasch model.  相似文献   
134.
In the context of a medium-term study designed to integrate the simulation of different types and processes of learning-such as classical, operant, and some cognitive types--one must start with other more elementary ones that are facilitators of the more complex types and processes. Of special interest is habituation, owing to the filtering out of irrelevant stimuli, which means that the simulated agent does not have to respond to them. This paper presents two difference functions constructed to computationally simulate the characteristics that define habituation. The behavior of these functions is described, as are differences arising from stimulus intensity and interstimulus intervals. Results are compared with existing empirical data.  相似文献   
135.
The nucleus accumbens (NAcc) has been shown to play a role in motor and spatial learning. Protein kinase C (PKC) has been implicated in the mechanisms of initiation and maintenance of long-term potentiation that is thought to be involved in the storage of long-term memory. In the present study, the importance of de novo synthesis of PKC-gamma within the NAcc in the acquisition and retention of spatial discrimination learning was assessed using an antisense knockdown approach. Separate groups of Long-Evans rats were exposed to acute microinfusions (6microg/microl) of PKC-gamma antisense oligodeoxynucleotide (AS-ODN), control oligodeoxynucleotide (C-ODN) or vehicle into the NAcc at 24 and 3h before each training session. Behavioral findings showed that the blockade of NAcc-PKC-gamma translation caused impairments in the early phase of learning and retention of spatial information. Biochemical experiments showed that PKC-gamma expression was reduced and Ca(2+)/phospholipid-dependent protein kinase C (PKC) activity was blocked significantly in the AS-ODN-treated rats in comparison with control rats. The present findings suggest that NAcc-PKC-gamma plays a role during the early acquisition of spatial learning. Also, retention test results suggest that NAcc-PKC-gamma may be working as an intermediate factor involved in the onset of molecular mechanisms necessary for spatial memory consolidation within the NAcc.  相似文献   
136.
The fact that early lexical and grammatical acquisition are strongly correlated has been cited as evidence against the view that the language faculty is composed of dissociable and autonomous modules (Bates & Goodman, 1997). However, previous studies have not yet eliminated the possibility that lexical-grammar associations may be attributable to language-general individual differences (e.g. children who are good at learning words are good at learning grammar). Parent report assessments of toddlers who are simultaneously learning English and Spanish (n = 113) allow an examination of the specificity of lexical-grammar relationships while holding child factors constant. Within-language vocabulary-grammar associations were stronger than cross-language relationships, even after controlling for age, proportion of language exposure, general language skill and reporter bias. Similar patterns were found based on naturalistic language samples (n = 22), ruling out a methodological artifact. These results are consistent with the view that grammar learning is specifically tied to lexical progress in a given language and provide further support for strong lexical-grammatical continuity early in acquisition.  相似文献   
137.
Perceptual discrimination between speech sounds belonging to different phoneme categories is better than that between sounds falling within the same category. This property, known as "categorical perception," is weaker in children affected by dyslexia. Categorical perception develops from the predispositions of newborns for discriminating all potential phoneme categories in the world's languages. Predispositions that are not relevant for phoneme perception in the ambient language are usually deactivated during early childhood. However, the current study shows that dyslexic children maintain a higher sensitivity to phonemic distinctions irrelevant in their linguistic environment. This suggests that dyslexic children use an allophonic mode of speech perception that, although without straightforward consequences for oral communication, has obvious implications for the acquisition of alphabetic writing. Allophonic perception specifically affects the mapping between graphemes and phonemes, contrary to other manifestations of dyslexia, and may be a core deficit.  相似文献   
138.
This study examined the dimensional structure of Templer's Death Anxiety Scale and Abdel-Khalek's Death Obsession Scale. The responses of 289 Spanish students to the Spanish forms of both scales were evaluated by means of a principal components analysis with varimax rotation. Three significant factors were identified: Death Obsession, Cognitive-Affective, and Death Anxiety. The distribution of the factor loadings for the items of both scales on Factors 1 and 3 supported the discriminant validity of the constructs specific to each of the scales, while Factor 2 showed a common component in both scales characterized by cognitive and affective aspects in relation to the idea of death.  相似文献   
139.
The present experiment examined the one-target advantage (OTA) with regard to saccadic eye movements. The OTA, previously found with manual pointing responses, refers to the finding that movements are executed faster when the limb is allowed to stop on the target compared to the situation where it has to proceed and hit a second target. Using an adapted limb movement OTA task, saccades of 5 degrees and 15 degrees were made to (a) a single target (one-target), (b) one target and immediately to another target without a change in direction (two-target-extension), and (c) one target and immediately back to the start location (two-target-reversal). Unlike manual movements, the movement times for the initial saccade in the two-target-extension condition were not prolonged compared to either of the other two conditions. Moreover, this pattern of results was found for both the shorter and longer amplitude saccades. The results indicate that the OTA does not occur in the oculomotor system and therefore is not a general motor control phenomenon.  相似文献   
140.
Prey might assess that risk level estimated in the first encounter with a predator was fixed in subsequent responses, whereas prey using flexible behavior would track short-term changes in risk. The authors examined, in the field, refuge use of Iberian rock lizards (Lacerta monticola) after simulated predator attacks and tested (a) how risk was assessed when multiple sources of risk were present simultaneously, (b) how short-term changes in risk level of successive attacks affected refuge use, and (c) whether the interval between attacks was important, insofar as attacks were considered to be coming from the same or different predators. Results suggest that lizards have a flexible estimate of risk that is based on multiple sources and flexibly dependent on previous estimates.  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