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   2228192篇
  免费   182912篇
  国内免费   4125篇
耳鼻咽喉   31682篇
儿科学   70996篇
妇产科学   64521篇
基础医学   318754篇
口腔科学   66303篇
临床医学   196845篇
内科学   430378篇
皮肤病学   47057篇
神经病学   181403篇
特种医学   89606篇
外国民族医学   632篇
外科学   341482篇
综合类   58578篇
现状与发展   5篇
一般理论   765篇
预防医学   173989篇
眼科学   52249篇
药学   168138篇
  2篇
中国医学   4257篇
肿瘤学   117587篇
  2018年   20484篇
  2015年   20977篇
  2014年   29253篇
  2013年   44678篇
  2012年   60296篇
  2011年   63516篇
  2010年   37407篇
  2009年   35544篇
  2008年   60527篇
  2007年   64639篇
  2006年   65090篇
  2005年   63546篇
  2004年   62539篇
  2003年   59941篇
  2002年   58397篇
  2001年   99563篇
  2000年   102571篇
  1999年   87125篇
  1998年   24695篇
  1997年   22590篇
  1996年   22455篇
  1995年   21679篇
  1994年   20482篇
  1993年   19263篇
  1992年   72660篇
  1991年   70578篇
  1990年   69098篇
  1989年   66752篇
  1988年   62453篇
  1987年   61459篇
  1986年   58460篇
  1985年   56574篇
  1984年   42904篇
  1983年   36898篇
  1982年   22500篇
  1981年   20312篇
  1980年   18976篇
  1979年   41982篇
  1978年   29632篇
  1977年   24959篇
  1976年   23289篇
  1975年   24848篇
  1974年   30638篇
  1973年   29383篇
  1972年   27283篇
  1971年   25708篇
  1970年   23874篇
  1969年   22735篇
  1968年   20641篇
  1967年   18846篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
83.
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   
84.
85.
86.

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   
87.
To evaluate the changes in alveolar contour after guided bone regeneration (GBR) with two different combinations of biomaterials in dehiscence defects arou  相似文献   
88.
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   
89.
Advancement in microelectromechanical system has facilitated the microfabrication of polymeric substrates and the development of the novel class of controlled drug delivery devices. These vehicles have specifically tailored three dimensional physical and chemical features which together, provide the capacity to target cell, stimulate unidirectional controlled release of therapeutics and augment permeation across the barriers. Apart from drug delivery devices microfabrication technology’s offer exciting prospects to generate biomimetic gastrointestinal tract models. BioMEMS are capable of analysing biochemical liquid sample like solution of metabolites, macromolecules, proteins, nucleic acid, cells and viruses. This review summarized multidisciplinary application of biomedical microelectromechanical systems in drug delivery and its potential in analytical procedures.  相似文献   
90.
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   
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