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   1480236篇
  免费   122978篇
  国内免费   8870篇
耳鼻咽喉   18903篇
儿科学   47336篇
妇产科学   41592篇
基础医学   208051篇
口腔科学   38864篇
临床医学   135065篇
内科学   293456篇
皮肤病学   33921篇
神经病学   120302篇
特种医学   56782篇
外国民族医学   503篇
外科学   218125篇
综合类   48251篇
现状与发展   17篇
一般理论   502篇
预防医学   115629篇
眼科学   32980篇
药学   106731篇
  83篇
中国医学   8354篇
肿瘤学   86637篇
  2021年   14233篇
  2019年   13826篇
  2018年   18893篇
  2017年   14963篇
  2016年   16318篇
  2015年   19440篇
  2014年   26823篇
  2013年   37662篇
  2012年   51636篇
  2011年   54905篇
  2010年   33095篇
  2009年   31197篇
  2008年   48863篇
  2007年   51334篇
  2006年   51616篇
  2005年   49723篇
  2004年   46438篇
  2003年   44086篇
  2002年   42213篇
  2001年   74529篇
  2000年   75910篇
  1999年   62643篇
  1998年   17735篇
  1997年   16143篇
  1996年   16144篇
  1995年   15292篇
  1994年   13765篇
  1993年   12856篇
  1992年   46052篇
  1991年   43647篇
  1990年   41652篇
  1989年   39704篇
  1988年   36291篇
  1987年   35455篇
  1986年   32940篇
  1985年   31349篇
  1984年   23859篇
  1983年   20050篇
  1982年   12226篇
  1981年   10799篇
  1979年   20712篇
  1978年   14580篇
  1977年   12085篇
  1976年   11367篇
  1975年   11619篇
  1974年   13990篇
  1973年   13535篇
  1972年   12637篇
  1971年   11473篇
  1970年   10913篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
刘峰 《新中医》2021,53(18):41-44
目的:观察益心舒胶囊联合常规疗法治疗非瓣膜性心房颤动的疗效。方法:纳入96 例气阴亏虚兼瘀血内阻型非瓣膜性心房颤动患者,采用随机数字表法分为对照组和观察组各48 例。2 组患者均予常规降压、降糖、调脂以及调整心态、饮食等治疗措施,并服用华法林钠片治疗,观察组加予益心舒胶囊治疗。2 组疗程均为3 个月。观察2 组治疗前及治疗3 个月后凝血功能指标、心房颤动发作情况、血浆N 末端B 型利钠肽原(NT-proBNP) 以及血液流变学水平的变化。结果:治疗后,2 组凝血酶原时间(PT)、活化部分凝血活酶时间(APTT)、凝血酶时间(TT)、国际标准化比值(INR) 均较治疗前增加(P<0.01),观察组PT、APTT、TT、INR 均长于或高于对照组(P<0.01)。2 组心房颤动发作时间与发作频率均较治疗前缩短或降低(P<0.01),观察组心房颤动发作时间与发作频率均短于或低于对照组(P<0.01)。2 组血浆NT-proBNP 水平均较治疗前降低(P<0.01),观察组血浆NT-proBNP 水平均低于对照组(P<0.01)。2 组红细胞比容(HCT)、纤维蛋白原(Fb)、全血黏度、血浆比黏度均较治疗前降低(P<0.01),观察组4 项指标值均低于对照组(P<0.01)。结论:在常规治疗基础上加服益心舒胶囊治疗气阴亏虚兼瘀血内阻型非瓣膜性心房颤动,在改善患者的凝血功能、心功能以及缓解临床症状方面疗效明显,且可有效改善血液流变学水平。  相似文献   
83.
BACKGROUND AND PURPOSE:Accurate and reliable detection of white matter hyperintensities and their volume quantification can provide valuable clinical information to assess neurologic disease progression. In this work, a stacked generalization ensemble of orthogonal 3D convolutional neural networks, StackGen-Net, is explored for improving automated detection of white matter hyperintensities in 3D T2-FLAIR images.MATERIALS AND METHODS:Individual convolutional neural networks in StackGen-Net were trained on 2.5D patches from orthogonal reformatting of 3D-FLAIR (n = 21) to yield white matter hyperintensity posteriors. A meta convolutional neural network was trained to learn the functional mapping from orthogonal white matter hyperintensity posteriors to the final white matter hyperintensity prediction. The impact of training data and architecture choices on white matter hyperintensity segmentation performance was systematically evaluated on a test cohort (n = 9). The segmentation performance of StackGen-Net was compared with state-of-the-art convolutional neural network techniques on an independent test cohort from the Alzheimer’s Disease Neuroimaging Initiative-3 (n = 20).RESULTS:StackGen-Net outperformed individual convolutional neural networks in the ensemble and their combination using averaging or majority voting. In a comparison with state-of-the-art white matter hyperintensity segmentation techniques, StackGen-Net achieved a significantly higher Dice score (0.76 [SD, 0.08], F1-lesion (0.74 [SD, 0.13]), and area under precision-recall curve (0.84 [SD, 0.09]), and the lowest absolute volume difference (13.3% [SD, 9.1%]). StackGen-Net performance in Dice scores (median = 0.74) did not significantly differ (P = .22) from interobserver (median = 0.73) variability between 2 experienced neuroradiologists. We found no significant difference (P = .15) in white matter hyperintensity lesion volumes from StackGen-Net predictions and ground truth annotations.CONCLUSIONS:A stacked generalization of convolutional neural networks, utilizing multiplanar lesion information using 2.5D spatial context, greatly improved the segmentation performance of StackGen-Net compared with traditional ensemble techniques and some state-of-the-art deep learning models for 3D-FLAIR.

White matter hyperintensities (WMHs) correspond to pathologic features of axonal degeneration, demyelination, and gliosis observed within cerebral white matter.1 Clinically, the extent of WMHs in the brain has been associated with cognitive impairment, Alzheimer’s disease and vascular dementia, and increased risk of stroke.2,3 The detection and quantification of WMH volumes to monitor lesion burden evolution and its correlation with clinical outcomes have been of interest in clinical research.4,5 Although the extent of WMHs can be visually scored,6 the categoric nature of such scoring systems makes quantitative evaluation of disease progression difficult. Manually segmenting WMHs is tedious, prone to inter- and intraobserver variability, and is, in most cases, impractical. Thus, there is an increased interest in developing fast, accurate, and reliable computer-aided automated techniques for WMH segmentation.Convolutional neural network (CNN)-based approaches have been successful in several semantic segmentation tasks in medical imaging.7 Recent works have proposed using deep learning–based methods for segmenting WMHs using 2D-FLAIR images.8-11 More recently, a WMH segmentation challenge12 was also organized (http://wmh.isi.uu.nl/) to facilitate comparison of automated segmentation of WMHs of presumed vascular origin in 2D multislice T2-FLAIR images. Architectures that used an ensemble of separately trained CNNs showed promising results in this challenge, with 3 of the top 5 winners using ensemble-based techniques.12Conventional 2D-FLAIR images are typically acquired with thick slices (3–4 mm) and possible slice gaps. Partial volume effects from a thick slice are likely to affect the detection of smaller lesions, both in-plane and out-of-plane. 3D-FLAIR images, with isotropic resolution, have been shown to achieve higher resolution and contrast-to-noise ratio13 and have shown promising results in MS lesion detection using 3D CNNs.14 Additionally, the isotropic resolution enables viewing and evaluation of the images in multiple planes. This multiplanar reformatting of 3D-FLAIR without the use of interpolating kernels is only possible due to the isotropic nature of the acquisition. Network architectures that use information from the 3 orthogonal views have been explored in recent works for CNN-based segmentation of 3D MR imaging data.15 The use of data from multiple planes allows more spatial context during training without the computational burden associated with full 3D training.16 The use of 3 orthogonal views simultaneously mirrors how humans approach this segmentation task.Ensembles of CNNs have been shown to average away the variances in the solution and the choice of model- and configuration-specific behaviors of CNNs.17 Traditionally, the solutions from these separately trained CNNs are combined by averaging or using a majority consensus. In this work, we propose the use of a stacked generalization framework (StackGen-Net) for combining multiplanar lesion information from 3D CNN ensembles to improve the detection of WMH lesions in 3D-FLAIR. A stacked generalization18 framework learns to combine solutions from individual CNNs in the ensemble. We systematically evaluated the performance of this framework and compared it with traditional ensemble techniques, such as averaging or majority voting, and state-of-the-art deep learning techniques.  相似文献   
84.
目的探讨足趾移植长手指全形再造手术的临床疗效。方法自2015年6月至2019年6月,对16例因外伤致手指缺损患者采用足趾移植长手指全形再造术,术后评估供区及受区的感觉功能、运动功能及外观形态,分析指甲畸形及增生性瘢痕的发生情况,并记录术后发生感染、血肿、皮片坏死及供区愈合不良等情况;通过调查问卷的方式分析患者的满意度。结果所有患者术后获随访1~12个月,其中2例受区发生感染,1例受区皮片边缘发生坏死,经换药后予以缓解;其余患者的供、受区均未出现长时间的痛疼感觉,受区感觉功能恢复达87.50%,受区运动功能恢复均较满意,手指外形基本满意。供区感觉受影响者2例,运动功能受限者1例,外形一般者2例。所有患者无指甲畸形及增生性瘢痕发生;满意者1例,基本满意者14例,不满意者1例。结论采用足趾移植长手指全形再造手术,基本可以满足患者及医师对于缺损手指进行完美修复的目标。  相似文献   
85.
86.
87.
88.
89.

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   
90.
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   
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