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   1510篇
  免费   81篇
  国内免费   15篇
耳鼻咽喉   1篇
儿科学   15篇
妇产科学   23篇
基础医学   488篇
口腔科学   7篇
临床医学   79篇
内科学   76篇
皮肤病学   1篇
神经病学   578篇
特种医学   9篇
外科学   57篇
综合类   87篇
预防医学   54篇
眼科学   23篇
药学   63篇
中国医学   21篇
肿瘤学   24篇
  2024年   2篇
  2023年   14篇
  2022年   24篇
  2021年   30篇
  2020年   26篇
  2019年   26篇
  2018年   27篇
  2017年   57篇
  2016年   49篇
  2015年   56篇
  2014年   90篇
  2013年   180篇
  2012年   56篇
  2011年   112篇
  2010年   78篇
  2009年   108篇
  2008年   86篇
  2007年   85篇
  2006年   104篇
  2005年   55篇
  2004年   66篇
  2003年   45篇
  2002年   38篇
  2001年   23篇
  2000年   14篇
  1999年   21篇
  1998年   12篇
  1997年   11篇
  1996年   15篇
  1995年   21篇
  1994年   9篇
  1993年   9篇
  1992年   5篇
  1991年   7篇
  1990年   2篇
  1989年   2篇
  1988年   2篇
  1987年   4篇
  1986年   2篇
  1985年   6篇
  1982年   3篇
  1981年   3篇
  1980年   2篇
  1977年   4篇
  1976年   3篇
  1973年   1篇
  1970年   1篇
  1969年   2篇
  1967年   2篇
  1966年   1篇
排序方式: 共有1606条查询结果,搜索用时 62 毫秒
31.
Abstract

The most salient and discussed features of agrammatism are the omission and substitution of grammatical morphemes, whether bound or free, in speech production. Cross-linguistic studies have shown that language-specific features determine the pattern of omissions and substitutions found; morphological markers are almost never omitted if the resulting form is a non-word; substitutions are mis-selections from existing paradigms. In the present paper we investigate the ways in which agrammatism is manifested in Algerian Arabic, a Semitic language where simple (Ø-prefixed and Ø-suffixed) words are described as consisting of three morphemes: the discontinuous consonantal root, the discontinuous vocalic base and a CV template or skeleton (McCarthy 1975). Our findings are comparable to those previously reported, in that the three agrammatic subjects who participated in this study do omit and substitute free-standing and bound grammatical markers, and never produce non-words. More specifically, their performance is characterized by omissions of linear bound morphemes in prefixed and suffixed words, as well as substitutions of morphologically complex forms by simpler and more frequent ones. An interpretation of the subjects' performance in the light of current linguistic and psycholinguistic theories on the lexicon is proposed.  相似文献   
32.
Ria De Bleser 《Aphasiology》2013,27(12):1427-1437
  相似文献   
33.
Background: Online priming studies have found that verbs (e.g., arrest) provide immediate access to typical agents (e.g., policeman) and patients (e.g., criminal) by generating expectancies from a verb to its related thematic roles and vice versa. These findings have contributed significantly to theories of thematic roles. However, these investigations and theoretical implications have been limited to young adults. Investigating verb–thematic role processing in older adults is important for understanding the semantic system in normal ageing, which aids in assessment, characterisation, and treatment of disorders that affect semantic processing in older adults.

Aims: The current study investigates verb–thematic role priming in young adults and extends the investigation to older adults. It was predicted that both groups would show priming effects but that the older adult group would have slower reaction times overall.

Methods & Procedures: Using a lexical decision task with a short stimulus onset asynchrony (250 ms), the current study investigated bidirectional agent–verb and patient–verb priming of younger and older adults.

Outcomes & Results: Consistent with our predictions, the younger participants exhibited bidirectional priming for agent–verb pairs and patient–verb pairs in the participant and item analyses. The older adults also showed priming for patient–verb pairs, but unexpectedly they did not exhibit priming for agent–verb pairs. Reaction times for the older participants were slower than the reaction times for the younger participants in all conditions.

Conclusions: Neither participant nor methodological factors readily explain the unexpected results. Theoretical explanations for the findings are explored.  相似文献   
34.
35.
In two experiments we assessed whether seeing objects automatically activates information regarding how to manipulate them. In Experiment 1 participants categorized photographs of objects that could be manipulated either with a power or a precision grip into artefacts or natural kinds. Target-objects were preceded by primes consisting of photographs of hands in grasping postures (precision or power grip). Experiment 2 involved a preliminary motor training phase in which each visual prime was associated with the actual motor action. In both experiments, natural kinds graspable with a power grip produced the fastest responses. In Experiment 2 we also found a congruency effect between the prime and the kind of grip required by the object (precision, power). Results suggest that visual stimuli automatically activate motor information. Specific motor programs are, however, activated only if motor training is performed before the categorization task. Implications of the results for the understanding of the organization of conceptual and motor information in the brain are discussed.  相似文献   
36.
负性情绪刺激的反应启动效应事件相关电位的实验研究   总被引:3,自引:0,他引:3  
目的:许多研究观察到,有机体对负性情绪刺激的反应比对中性或正性刺激快,本研究应用事件相关电位中的单侧化准备电位将反应时划分为刺激加工阶段和反应准备阶段,从而得以直接观察负性刺激的反应启动效应。方法:本研究选取国际情感图片系统的正、中、负性图片作为剌激材料,以正常大学生为被试,令其按键表示对图片情绪属性的判断,同时记录脑电。结果:正、负性情绪刺激引起的刺激锁定单侧化准备电位的潜伏期比中性条件下的潜伏期缩短,观察反应锁定单侧化准备电位的潜伏期可见,负性刺激引起的潜伏期显著短于中性和正性条件。结论:对情绪性刺激的心理加工评价过程较短,观察反应锁定单侧化准备电位的潜伏期可见,负性剌激引起的潜伏期显著短于中性和正性条件,表明负性刺激具有反应启动效应.  相似文献   
37.

Background

The Refined Semantic Network (RSN) for the UMLS was previously introduced to complement the UMLS Semantic Network (SN). The RSN partitions the UMLS Metathesaurus (META) into disjoint groups of concepts. Each such group is semantically uniform. However, the RSN was initially an order of magnitude larger than the SN, which is undesirable since to be useful, a semantic network should be compact. Most semantic types in the RSN represent combinations of semantic types in the UMLS SN. Such a “combination semantic type” is called Intersection Semantic Type (IST). Many ISTs are assigned to very few concepts. Moreover, when reviewing those concepts, many semantic type assignment inconsistencies were found. After correcting those inconsistencies many ISTs, among them some that contradicted UMLS rules, disappeared, which made the RSN smaller.

Objective

The authors performed a longitudinal study with the goal of reducing the size of the RSN to become compact. This goal was achieved by correcting inconsistencies and errors in the IST assignments in the UMLS, which additionally helped identify and correct ambiguities, inconsistencies, and errors in source terminologies widely used in the realm of public health.

Methods

In this paper, we discuss the process and steps employed in this longitudinal study and the intermediate results for different stages. The sculpting process includes removing redundant semantic type assignments, expanding semantic type assignments, and removing illegitimate ISTs by auditing ISTs of small extents. However, the emphasis of this paper is not on the auditing methodologies employed during the process, since they were introduced in earlier publications, but on the strategy of employing them in order to transform the RSN into a compact network. For this paper we also performed a comprehensive audit of 168 “small ISTs” in the 2013AA version of the UMLS to finalize the longitudinal study.

Results

Over the years it was found that the editors of the UMLS introduced some new inconsistencies that resulted in the reintroduction of unwarranted ISTs that had already been eliminated as a result of their previous corrections. Because of that, the transformation of the RSN into a compact network covering all necessary categories for the UMLS was slowed down. The corrections suggested by an audit of the 2013AA version of the UMLS achieve a compact RSN of equal magnitude as the UMLS SN. The number of ISTs has been reduced to 336. We also demonstrate how auditing the semantic type assignments of UMLS concepts can expose other modeling errors in the UMLS source terminologies, e.g., SNOMED CT, LOINC, and RxNORM that are important for health informatics. Such errors would otherwise stay hidden.

Conclusions

It is hoped that the UMLS curators will implement all required corrections and use the RSN along with the SN when maintaining and extending the UMLS. When used correctly, the RSN will support the prevention of the accidental introduction of inconsistent semantic type assignments into the UMLS. Furthermore, this way the RSN will support the exposure of other hidden errors and inconsistencies in health informatics terminologies, which are sources of the UMLS. Notably, the development of the RSN materializes the deeper, more refined Semantic Network for the UMLS that its designers envisioned originally but had not implemented.  相似文献   
38.
《Immunobiology》2020,225(4):151972
Neutrophils are an essential cellular component of the innate immune system, responsible for multiple effector mechanisms and aspects of inflammation. Neutrophil priming results in a rapid elevation in antimicrobial activities and can be measured by reactive oxygen species production, bacterial endocytosis, and de-novo synthesis of components such as interleukins. Mannose binding lectin (MBL), a C-type lectin pathogen recognition receptor is associated with immune functions including complement activation, opsonization and modulating immune responses. Whether MBL opsonization of pathogen can induce neutrophil priming has not been studied so far. Hence, studies were performed using MBL and neutrophils of Capra hircus (domestic goat) to evaluate the effects of MBL + MASPs interactions on neutrophil functions. It was found that MBL + MASPs opsonization of zymosan stimulates neutrophil functions including increased oxidative burst, enhanced endocytosis and modulates the expression level of NCF4, XBP1, CCL2, and CR1 genes. The results suggest that MBL-MASP complex can regulate neutrophil functioning.  相似文献   
39.
Exaggerated effects of word length upon reading-aloud performance define pure alexia, but have also been observed in semantic dementia. Some researchers have proposed a reading-specific account, whereby performance in these two disorders reflects the same cause: impaired orthographic processing. In contrast, according to the primary systems view of acquired reading disorders, pure alexia results from a basic visual processing deficit, whereas degraded semantic knowledge undermines reading performance in semantic dementia. To explore the source of reading deficits in these two disorders, we compared the reading performance of 10 pure alexic and 10 semantic dementia patients, matched in terms of overall severity of reading deficit. The results revealed comparable frequency effects on reading accuracy, but weaker effects of regularity in pure alexia than in semantic dementia. Analysis of error types revealed a higher rate of letter-based errors and a lower rate of regularization responses in pure alexia than in semantic dementia. Error responses were most often words in pure alexia but most often nonwords in semantic dementia. Although all patients made some letter substitution errors, these were characterized by visual similarity in pure alexia and phonological similarity in semantic dementia. Overall, the data indicate that the reading deficits in pure alexia and semantic dementia arise from impairments of visual processing and knowledge of word meaning, respectively. The locus and mechanisms of these impairments are placed within the context of current connectionist models of reading.  相似文献   
40.
以BioCreative V CDR语料库为例,选定现有的领域标注体系作为参照,通过数据质量控制工作流,采用半自动化标注方法实现药物疾病语义关系语料库的标准化构建,总结该语料库的质量及其应用。  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