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   2025088篇
  免费   157525篇
  国内免费   5607篇
耳鼻咽喉   27881篇
儿科学   63485篇
妇产科学   56734篇
基础医学   297120篇
口腔科学   57240篇
临床医学   189940篇
内科学   386320篇
皮肤病学   40650篇
神经病学   167996篇
特种医学   76781篇
外国民族医学   531篇
外科学   294222篇
综合类   49270篇
现状与发展   3篇
一般理论   694篇
预防医学   168820篇
眼科学   46286篇
药学   150650篇
  7篇
中国医学   4392篇
肿瘤学   109198篇
  2018年   21898篇
  2017年   16675篇
  2016年   18269篇
  2015年   21129篇
  2014年   29536篇
  2013年   45470篇
  2012年   62086篇
  2011年   65669篇
  2010年   38296篇
  2009年   35466篇
  2008年   60717篇
  2007年   64741篇
  2006年   64716篇
  2005年   63124篇
  2004年   60794篇
  2003年   58088篇
  2002年   56242篇
  2001年   87483篇
  2000年   89648篇
  1999年   75628篇
  1998年   22151篇
  1997年   20205篇
  1996年   19851篇
  1995年   18834篇
  1994年   17841篇
  1993年   16683篇
  1992年   61815篇
  1991年   60533篇
  1990年   59069篇
  1989年   56321篇
  1988年   52585篇
  1987年   51538篇
  1986年   49075篇
  1985年   47155篇
  1984年   35993篇
  1983年   30771篇
  1982年   18934篇
  1981年   17058篇
  1979年   34449篇
  1978年   24697篇
  1977年   20516篇
  1976年   19630篇
  1975年   20577篇
  1974年   25399篇
  1973年   24625篇
  1972年   23122篇
  1971年   21517篇
  1970年   20138篇
  1969年   19015篇
  1968年   17562篇
排序方式: 共有10000条查询结果,搜索用时 139 毫秒
101.
ABSTRACT

Purpose

To investigate the expression of IL-11 and its receptor IL-11Rα and to quantify density of CD163+ M2 macrophages in proliferative diabetic retinopathy (PDR).  相似文献   
102.
Annals of Nuclear Medicine - The Response Evaluation Criteria In Solid Tumors (RECIST) is the most used radiological method for evaluating response after peptide receptor radionuclide therapy...  相似文献   
103.

Purpose

Chest wall pain is an uncommon but bothersome late complication following lung stereotactic body radiation therapy. Despite numerous studies investigating predictors of chest wall pain, no clear consensus has been established for a chest wall constraint. The aim of our study was to investigate factors related to chest wall pain in a homogeneous group of patients treated at our institution.

Patients and methods

All 122 patients were treated with the same stereotactic body radiation therapy regimen of 48 Gy in three fractions, seen for at least 6 months of follow-up, and planned with heterogeneity correction. Chest wall pain was scored according to the Common Terminology Criteria for Adverse Events classification v3.0. Patient (age, sex, diabetes, osteoporosis), tumour (planning target volume, volume of the overlapping region between planning target volume and chest wall) and chest wall dosimetric parameters (volumes receiving at least 30, 40, and 50 Gy, the minimal doses received by the highest irradiated 1, 2, and 5 cm3, and maximum dose) were collected. The correlation between chest wall pain (grade 2 or higher) and the different parameters was evaluated using univariate and multivariate logistic regression.

Results

Median follow-up was 18 months (range: 6–56 months). Twelve patients out of 122 developed chest wall pain of any grade (seven with grade 1, three with grade 2 and two with grade 3 pain). In univariate analysis, only the volume receiving 30 Gy or more (P = 0.034) and the volume of the overlapping region between the planning target volume and chest wall (P = 0.038) significantly predicted chest wall pain, but these variables were later proved non-significant in multivariate regression.

Conclusion

Our analysis could not find any correlation between the studied parameters and chest wall pain. Considering our present study and the wide range of differing results from the literature, a reasonable conclusion is that a constraint for chest wall pain is yet to be defined.  相似文献   
104.
105.
106.
107.
Porocarcinoma is an unusual, locally aggressive and potentially fatal neoplasm. Several cutaneous malignancies have been described in association with porocarcinoma, including squamous cell carcinoma, basal cell carcinoma and tricholemmal carcinoma. Previous reports have indicated that the occurrence of malignant tumours in combination with porocarcinoma is extremely rare, in particular with regard to Bowen disease (BD). We report an uncommon case of porocarcinoma occurring synchronously in a single BD lesion in a 63‐year‐old woman with multiple BD lesions. The clinical and histological findings confirmed this diagnosis.  相似文献   
108.
Reactive lymphoid infiltrates of the skin composed predominantly of gamma‐delta (γδ) T cells are not well described in the literature. Herein we report a case of an otherwise healthy 4‐year‐old male who presented with a waxing and waning papular rash characterized by small, discrete crusted papules spread across his trunk, face and extremities. Clinical evaluation revealed no evidence of systemic disease. Microscopic examination revealed a dermal, perivascular infiltrate of highly atypical lymphocytes with a γδ T cell phenotype, worrisome for primary cutaneous γδ T cell lymphoma. The clinical course, however, was that of a reactive condition and prompted consideration of a diagnosis of pityriasis lichenoides et varioliformis acuta (PLEVA) and lymphomatoid papulosis (LyP). In many ways, this case defies current classification schemes and seems to expand the spectrum of reactive γδ T cell infiltrates of the skin.  相似文献   
109.
110.
DNA methylation at CpG dinucleotides is an important epigenetic regulator common to virtually all mammalian cell types, but recent evidence indicates that during early postnatal development neuronal genomes also accumulate uniquely high levels of two alternative forms of methylation, non-CpG methylation and hydroxymethylation. Here we discuss the distinct landscape of DNA methylation in neurons, how it is established, and how it might affect the binding and function of protein readers of DNA methylation. We review studies of one critical reader of DNA methylation in the brain, the Rett syndrome protein methyl CpG-binding protein 2 (MeCP2), and discuss how differential binding affinity of MeCP2 for non-CpG and hydroxymethylation may affect the function of this methyl-binding protein in the nervous system.  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