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   29405篇
  免费   1416篇
  国内免费   195篇
耳鼻咽喉   320篇
儿科学   544篇
妇产科学   706篇
基础医学   3395篇
口腔科学   1522篇
临床医学   2238篇
内科学   7924篇
皮肤病学   444篇
神经病学   2730篇
特种医学   1187篇
外科学   4233篇
综合类   113篇
一般理论   7篇
预防医学   1551篇
眼科学   433篇
药学   1615篇
中国医学   119篇
肿瘤学   1935篇
  2023年   162篇
  2022年   404篇
  2021年   803篇
  2020年   456篇
  2019年   632篇
  2018年   819篇
  2017年   574篇
  2016年   698篇
  2015年   804篇
  2014年   1106篇
  2013年   1491篇
  2012年   2280篇
  2011年   2447篇
  2010年   1408篇
  2009年   1255篇
  2008年   2128篇
  2007年   2188篇
  2006年   2013篇
  2005年   2021篇
  2004年   1796篇
  2003年   1554篇
  2002年   1448篇
  2001年   187篇
  2000年   128篇
  1999年   176篇
  1998年   241篇
  1997年   192篇
  1996年   185篇
  1995年   147篇
  1994年   133篇
  1993年   91篇
  1992年   92篇
  1991年   86篇
  1990年   71篇
  1989年   70篇
  1988年   70篇
  1987年   54篇
  1986年   50篇
  1985年   42篇
  1984年   84篇
  1983年   54篇
  1982年   72篇
  1981年   45篇
  1980年   27篇
  1979年   24篇
  1978年   26篇
  1977年   30篇
  1976年   21篇
  1974年   16篇
  1973年   22篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Individuals with schizophrenia experience problems in the perception of emotion throughout the course of the disorder. Few studies have addressed the progression of the deficit over time. The present investigation explores face emotion recognition (FER) performance throughout the course of schizophrenia. The aim of the study was to test the hypotheses that: 1) FER impairment was present in ultra high-risk (putatively prodromal) individuals, and that 2) impairment was stable across the course of the illness. Forty-three individuals with a putative prodromal syndrome, 50 patients with first episode of schizophrenia, 44 patients with multi-episode schizophrenia and 86 unaffected healthy control subjects were assessed to examine emotion recognition ability. ANCOVA analysis adjusted for possible confounder factors and subsequent planned contrasts with healthy controls was undertaken. The results revealed deficits in recognition of sadness and disgust in prodromal individuals, and of all negative emotions in both first-episode and multi-episode patients. Furthermore, there were no significant differences between clinical groups. Within the framework of the neurodevelopmental model of schizophrenia, our results suggest the presence of emotional recognition impairment before the onset of full-blown psychosis. Moreover, the deficit remains stable over the course of illness, fitting the pattern of a vulnerability indicator in contrast to an indicator of chronicity or severity.  相似文献   
942.
943.
The purpose of this study was to retrospectively compare the treatment times of Class II division 1 malocclusion subjects treated with four first premolar extractions or a non-extraction protocol and fixed edgewise appliances. Eighty-four patients were selected and divided into two groups. Group 1, treated with four first premolar extractions, consisted of 48 patients (27 males and 21 females) with a mean age of 13.03 years and group 2, treated without extractions, consisted of 36 patients (18 males and 18 females) with a mean age of 13.13 years. Group 2 was subdivided into two subgroups, 2A consisting of 16 patients treated in one phase and 2B consisting of 20 patients treated in two phases. The initial and final Treatment Priority Index (TPI), initial ages, initial mandibular crowding, and treatment times of groups 1 and 2 were compared with t-tests. These variables were also compared between group 1 and the subgroups with analysis of variance followed by Tukey's tests. The treatment times for groups 1 and 2 and subgroups 2A and 2B were 2.36, 2.47, 2.25, and 2.64 years, respectively, which were not significantly different. Treatment times with non-extraction and four premolar extraction protocols are similar.  相似文献   
944.
This study evaluated factors that may influence the presence or absence of interproximal papillae. Clinical evaluation consisted of visual determination, and quantitative analyses were made using millimeter grids on radiographs. Patients (n = 45) were divided into three groups according to age. Data were analyzed using the chi-square test followed by the Student t test (α = .05). The distance from the contact point to the bone crest had significant influence on papilla presence in both anterior and posterior sites (P < .05), whereas the width between roots of adjacent teeth did not. The papilla was missing more frequently in anterior sites. The presence of papillae was not age-dependent.  相似文献   
945.
Appropriate fluid balance is an important factor in the survival of free flaps, and recently there has been a shift towards more conservative fluid regimens. Several surgical specialties have made extensive use of the relatively non-invasive method of measuring cardiac output (CO) to optimise fluid balance during and after surgery, which has resulted in a shorter hospital stay, but little has been published in head and neck surgery. To ascertain its use in the head and neck we sent a postal questionnaire to the anaesthetic departments of 40 major head and neck units identified from the 2010 database of the British Association of Oral and Maxillofacial Surgeons (BAOMS). Questions were asked about the number of free flaps done in the unit each year, the monitoring of central venous and arterial blood pressure (and inotrope protocols), optimal target variables, and whether CO was monitored (with type of device). Thirty-two units responded (80%). While 26 units (81%) routinely monitored central venous pressure (CVP), CO was monitored in only 3 units (9%). There was a wide range of responses in relation to optimal variables and use of inotropes. As with other specialties, it is likely that CO monitoring will become widely used in head and neck reconstructive surgery. Not only does it enhance fluid optimisation, but it may also reduce hospital stay and morbidity. Appropriate clinical studies are urgently needed to evaluate its use in our specialty.  相似文献   
946.
This study investigated the prevalence of dental caries and periodontal condition in a population with sickle cell disease (SCD), analyzing some associations with disease severity. The Decayed, Missing and Filled Teeth index (DMFT) and Community Periodontal Index (CPI) were recorded for 99 individuals with SCD and 91 matched controls. Socio-demographic status, oral health behaviors, and history of clinical severity of SCD were assessed. Statistical comparisons were performed between the group with SCD and the control group, as well as multivariate logistic regression analyses with DMFT index and CPI as the dependent variables. The mean number of decayed teeth was significantly higher in individuals with HbSS. Older age, female gender, and daily smoking were identified as risk factors for higher DMFT, while older age and absence of daily use of dental floss were risk factors for the development of periodontal disease. In conclusion, risk factors known to cause caries and periodontal disease had more influence on oral health than the direct impact of SCD.  相似文献   
947.
948.
949.
950.
Purpose: To evaluate three-dimensionally the bone change following ridge preservation procedures (RPP) using computed tomography (CT). Materials and Methods: Subjects in need of implant therapy were enrolled in the study. The teeth were extracted, and sockets underwent RPP with a bioactive glass (Inion BioRestore, Inion Oy). The patients were scanned with CT within 1 week and 3 months after surgery. Horizontal and vertical radiographic measurements were performed on superimposed CT scans to evaluate bone changes in the alveolar sites during the 3-month period. Results: Thirteen subjects participated, and 32 teeth were extracted and treated with grafting. Alveolar sites treated with RPP demonstrated a preservation of about 77% of the original width dimensions, with a mean loss of 1.8 ± 1.1 mm in width. Moreover, it was observed that the vertical loss of buccal bone was 2.7 ± 1.1 mm, while the loss of lingual bone was 1.9 ± 1.2 mm. Conclusions: The CT evaluation was helpful to assess that the bone loss in width was less than the vertical bone loss of both walls 3 months after RPP.  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