全文获取类型
收费全文 | 2622篇 |
免费 | 154篇 |
专业分类
2776篇 |
出版年
2024年 | 7篇 |
2023年 | 46篇 |
2022年 | 38篇 |
2021年 | 57篇 |
2020年 | 90篇 |
2019年 | 79篇 |
2018年 | 151篇 |
2017年 | 150篇 |
2016年 | 136篇 |
2015年 | 86篇 |
2014年 | 101篇 |
2013年 | 331篇 |
2012年 | 216篇 |
2011年 | 243篇 |
2010年 | 139篇 |
2009年 | 46篇 |
2008年 | 203篇 |
2007年 | 141篇 |
2006年 | 151篇 |
2005年 | 65篇 |
2004年 | 63篇 |
2003年 | 44篇 |
2002年 | 38篇 |
2001年 | 16篇 |
2000年 | 27篇 |
1999年 | 17篇 |
1998年 | 9篇 |
1997年 | 10篇 |
1996年 | 6篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1985年 | 4篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1971年 | 2篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1966年 | 3篇 |
1965年 | 1篇 |
排序方式: 共有2776条查询结果,搜索用时 15 毫秒
81.
Xavier de Donato Rodríguez Alfonso Arroyo Santos 《Journal for General Philosophy of Science》2012,43(1):11-27
In this paper we present a new framework of idealization in biology. We characterize idealizations as a network of counterfactual and hypothetical conditionals that can exhibit different ??degrees of contingency??. We use this idea to say that, in departing more or less from the actual world, idealizations can serve numerous epistemic, methodological or heuristic purposes within scientific research. We defend that, in part, this structure explains why idealizations, despite being deformations of reality, are so successful in scientific practice. For illustrative purposes, we provide an example from population genetics, the Wright-Fisher Model. 相似文献
82.
Rodrigues CS de Oliveira VZ Camargo G Osório CM de Castilhos RM Saraiva-Pereira ML Schuler-Faccini L Jardim LB 《Journal of genetic counseling》2012,21(1):101-112
Diagnostic tests are available to detect several mutations related to adult-onset, autosomal dominant, neurodegenerative diseases.
We aimed to describe our experience in a presymptomatic testing program run by the Brazilian Public Health System from 1999
to 2009. A total of 184 individuals were eligible for presymptomatic testing due to a risk for spinocerebellar ataxia (SCA)
- SCA3 (80%), Huntington’s disease (11.9%), familial amyloidotic neuropathy (4.3%), SCA1, SCA2, SCA6, or SCA7. Most were women
(70%), married (54%), and had children prior to presymptomatic testing (67%). Their mean age at entrance was 34 (SD = 11 years).
Educational level was above the average Brazilian standard. After receipt of genetic counseling, 100 individuals (54%) decided
to undergo testing; of these, 51 were carriers. Since no individual returned for post-test psychological evaluation, we conducted
a subsequent survey, unrelated to test disclosures. We contacted 57 individuals of whom 31 agreed to participate (24 had been
tested, 7 had not). Several ascertainment concerns relating to these numerous losses prevented us from generalizing our results
from this second survey. We concluded that: decision-making regarding presymptomatic testing seems to be genuinely autonomous,
since after genetic counseling half the individuals who asked for presymptomatic testing decided in favor and half decided
against it; general characteristics of Brazilians who sought presymptomatic testing were similar to many European samples
studied previously; and individuals at risk for SCA3 may be at greater risk of depression. Although no clear-cut reason emerged
for rejection of follow-up psychological sessions after presymptomatic testing, this finding suggests adjustments to our presymptomatic
testing program are necessary. 相似文献
83.
Jorquera M Baños RM Cebolla A Rasal P Etchemendy E 《European eating disorders review : the journal of the Eating Disorders Association》2012,20(3):255-256
The purpose of the present study was to analyse the psychometric properties of the 'Questionnaire of Sociocultural Influences on the Aesthetic Body Shape Model' (CIMEC-26) in a Spanish adolescent population. This questionnaire measures the influence of agents and situations that transmit the current aesthetic model, and assesses environmental influences favouring thinness. The CIMEC-26 was administered to a sample of 4031 female primary and secondary school students ranging in age from 10 to 17 years (M?=?14, SD?=?1.34). Results suggested that the CIMEC-26 has acceptable internal consistency (α?=?.93). The oldest group (15-17 years) had the highest scores on all factors and the highest total scores, suggesting greater influence of the aesthetic body shape model and higher vulnerability to social pressure to achieve it. Factor analysis suggested three moderately interrelated components of the scale. Confirmatory factor analysis showed that both the three-factor solution and the original five-factor structure had good fit indices, although the latter showed the best fit. The CIMEC-26 proved to be an effective instrument for research on the social influence on the aesthetic body model in female adolescents. 相似文献
84.
Meilán JJ Martínez-Sánchez F Carro J Sánchez JA Pérez E 《The Spanish journal of psychology》2012,15(2):487-494
This study broaches in a novel way the analysis of cognitive impairment characteristic of the early stages of Alzheimer's Disease (AD). Specifically, we attempt to determine the acoustic speech parameters that are sensitive to the onset of the disease, and their association with the language deficit characteristic of AD. Speech analysis was carried out on 21 elderly patients with AD using Praat software, which analyzes the acoustic components of speech. The data obtained were subjected to stepwise regression, using the overall scores obtained in the test as the criterion variable, and the scores on the frequency, amplitude and periodicity variables as predictors of performance. We found that the percentage of voiceless segments explains a significant portion of the variance in the overall scores obtained in the neuropsychological test. This component seems to be related mainly to the patient's ability in phonological fluency. This finding could permit the creation of a diagnostic test for AD through analysis of the acoustic speech parameters at very low cost in terms of both time and resources. 相似文献
85.
The aim of this study was to analyse the screening utility of the Social Anxiety Screening Scale (SASS/EDAS) in a sample of 227 adolescents with social anxiety disorder and 156 Without it (14-17 years). Results showed that the EDAS subscales (Avoidance, Distress and Interference) scores were reliable in terms of internal consistency (alpha > .80). All the subscales discriminated between adolescents with and without the disorder. They also showed a positive and significant correlation with other empirically validated measures of social anxiety. The three subscales indicated relevant sensitivity (69.16-84.14%), specificity (63.46-66.03%) and areas under the curve (.74-.81%). Binary logistic regression analyses indicated the adequate predictive utility of EDAS subscales, with the Distress subscale as the best diagnostic predictor. The data provide empirical evidence of the usefulness of EDAS as a screener for adolescent social anxiety disorder in terms of reliability, convergent and discriminant validity, diagnostic accuracy and clinical usefulness. 相似文献
86.
87.
Leandro L. Di Stasi Alberto Megías Antonio Cándido Antonio Maldonado Andrés Catena 《Transportation Research Part F: Traffic Psychology and Behaviour》2012,15(4):438-444
In the last five decades, cognitive scientists and the psychologists of reasoning have dedicated a lot of effort designing usable traffic signs. This study investigated the interference effect produced by the position of the sign elements in traffic signage on response accuracy and reaction time. Sixteen drivers performed a flanker interference reaction time task. Incongruent graphical/space solutions, actually used for the airport stack-type sign, lead to increased reaction time and a reduction in the proportion of correct answers. These results suggest that incongruent visual information should be avoided, as this might impair drivers’ performance. These findings provide important information for the specification of future signage design guidelines and for improving road safety. 相似文献
88.
Monocular approaches to simultaneous localization and mapping (SLAM) have recently addressed with success the challenging problem of the fast computation of dense reconstructions from a single, moving camera. Thus, if these approaches initially relied on the detection of a reduced set of interest points to estimate the camera position and the map, they are currently able to reconstruct dense maps from a handheld camera while the camera coordinates are simultaneously computed. However, these maps of 3-dimensional points usually remain meaningless, that is, with no memorable items and without providing a way of encoding spatial relationships between objects and paths. In humans and mobile robotics, landmarks play a key role in the internalization of a spatial representation of an environment. They are memorable cues that can serve to define a region of the space or the location of other objects. In a topological representation of the space, landmarks can be identified and located according to its structural, perceptive or semantic significance and distinctiveness. But on the other hand, landmarks may be difficult to be located in a metric representation of the space. Restricted to the domain of visual landmarks, this work describes an approach where the map resulting from a point-based, monocular SLAM is annotated with the semantic information provided by a set of distinguished landmarks. Both features are obtained from the image. Hence, they can be linked by associating to each landmark all those point-based features that are superimposed to the landmark in a given image (key-frame). Visual landmarks will be obtained by means of an object-based, bottom-up attention mechanism, which will extract from the image a set of proto-objects. These proto-objects could not be always associated with natural objects, but they will typically constitute significant parts of these scene objects and can be appropriately annotated with semantic information. Moreover, they will be affine covariant regions, that is, they will be invariant to affine transformation, being detected under different viewing conditions (view-point angle, rotation, scale, etc.). Monocular SLAM will be solved using the accurate parallel tracking and mapping (PTAM) framework by Klein and Murray in Proceedings of IEEE/ACM international symposium on mixed and augmented reality, 2007. 相似文献
89.
Pilar Carrera Dolores Muñoz Amparo Caballero Itziar Fernández Dolores Albarracín 《Journal of experimental social psychology》2012,48(5):1196-1200
Three studies examined how the use of the present versus the past tense in recalling a past experience influences behavioral intentions. Experiment 1 revealed a stronger influence of past behaviors on drinking intentions when participants self-reported an episode of excessive drinking using the present tense. Correspondingly, there was a stronger influence of attitudes towards excessive drinking when participants self-reported the episode in the past tense. Experiments 2 and 3 liked this effect to changes in construal level (Liberman, Trope, & Stephan, 2007; Trope & Liberman, 2003), with the present tense being similar to a concrete construal level and the past tense being similar to an abstract construal level. 相似文献
90.
We propose a new class of multiple contraction operations — the system of spheres-based multiple contractions — which are a generalization of Grove’s system of spheres-based (singleton) contractions to the case of contractions by (possibly
non-singleton) sets of sentences. Furthermore, we show that this new class of functions is a subclass of the class of the
partial meet multiple contractions. 相似文献