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   24091篇
  免费   2035篇
  国内免费   641篇
耳鼻咽喉   166篇
儿科学   420篇
妇产科学   186篇
基础医学   2897篇
口腔科学   521篇
临床医学   3725篇
内科学   2581篇
皮肤病学   98篇
神经病学   3917篇
特种医学   973篇
外国民族医学   4篇
外科学   1482篇
综合类   3603篇
现状与发展   1篇
一般理论   16篇
预防医学   2323篇
眼科学   470篇
药学   2162篇
  123篇
中国医学   621篇
肿瘤学   478篇
  2024年   109篇
  2023年   979篇
  2022年   1513篇
  2021年   1901篇
  2020年   1566篇
  2019年   1223篇
  2018年   922篇
  2017年   850篇
  2016年   760篇
  2015年   757篇
  2014年   1541篇
  2013年   1742篇
  2012年   1241篇
  2011年   1419篇
  2010年   972篇
  2009年   1010篇
  2008年   1039篇
  2007年   1007篇
  2006年   903篇
  2005年   719篇
  2004年   579篇
  2003年   507篇
  2002年   436篇
  2001年   329篇
  2000年   319篇
  1999年   241篇
  1998年   242篇
  1997年   247篇
  1996年   167篇
  1995年   129篇
  1994年   123篇
  1993年   113篇
  1992年   95篇
  1991年   90篇
  1990年   82篇
  1989年   61篇
  1988年   81篇
  1987年   60篇
  1986年   55篇
  1985年   87篇
  1984年   75篇
  1983年   51篇
  1982年   56篇
  1981年   47篇
  1980年   52篇
  1979年   42篇
  1978年   36篇
  1977年   43篇
  1976年   36篇
  1974年   33篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
991.
992.
PurposeThe purpose of this study was to report procedures developed to annotate abdominal computed tomography (CT) images from subjects without pancreatic disease that will be used as the input for deep convolutional neural networks (DNN) for development of deep learning algorithms for automatic recognition of a normal pancreas.Materials and methodsDual-phase contrast-enhanced volumetric CT acquired from 2005 to 2009 from potential kidney donors were retrospectively assessed. Four trained human annotators manually and sequentially annotated 22 structures in each datasets, then expert radiologists confirmed the annotation. For efficient annotation and data management, a commercial software package that supports three-dimensional segmentation was used.ResultsA total of 1150 dual-phase CT datasets from 575 subjects were annotated. There were 229 men and 346 women (mean age: 45 ± 12 years; range: 18–79 years). The mean intra-observer intra-subject dual-phase CT volume difference of all annotated structures was 4.27 mL (7.65%). The deep network prediction for multi-organ segmentation showed high fidelity with 89.4% and 1.29 mm in terms of mean Dice similarity coefficients and mean surface distances, respectively.ConclusionsA reliable data collection/annotation process for abdominal structures was developed. This process can be used to generate large datasets appropriate for deep learning.  相似文献   
993.
994.
995.
996.
Background and objectiveBurns are a serious health problem leading to several thousand deaths annually, and despite the growth of science and technology, automated burns diagnosis still remains a major challenge. Researchers have been exploring visual images-based automated approaches for burn diagnosis. Noting that the impact of a burn on a particular body part can be related to the skin thickness factor, we propose a deep convolutional neural network based body part-specific burns severity assessment model (BPBSAM).MethodConsidering skin anatomy, BPBSAM estimates burn severity using body part-specific support vector machines trained with CNN features extracted from burnt body part images. Thus BPBSAM first identifies the body part of the burn images using a convolutional neural network in training of which the challenge of limited availability of burnt body part images is successfully addressed by using available larger-size datasets of non-burn images of different body parts considered (face, hand, back, and inner forearm). We prepared a rich labelled burn images datasets: BI & UBI and trained several deep learning models with existing models as pipeline for body part classification and feature extraction for severity estimation.ResultsThe proposed novel BPBSAM method classified the severity of burn from color images of burn injury with an overall average F1 score of 77.8% and accuracy of 84.85% for the test BI dataset and 87.2% and 91.53% for the UBI dataset, respectively. For burn images body part classification, the average accuracy of around 93% is achieved, and for burn severity assessment, the proposed BPBSAM outperformed the generic method in terms of overall average accuracy by 10.61%, 4.55%, and 3.03% with pipelines ResNet50, VGG16, and VGG19, respectively.ConclusionsThe main contributions of this work along with burn images labelled datasets creation is that the proposed customized body part-specific burn severity assessment model can significantly improve the performance in spite of having small burn images dataset. This highly innovative customized body part-specific approach could also be used to deal with the burn region segmentation problem. Moreover, fine tuning on pre-trained non-burn body part images network has proven to be robust and reliable.  相似文献   
997.
This article is concerned with the tracking of nonequilibrium motions with model predictive control (MPC). It proposes to parametrize input and state trajectories of a dynamic system with basis functions to alleviate the computational burden in MPC. As a result of the parametrization, an optimization problem with fewer variables is obtained, and the memory requirements for storing the reference trajectories are reduced. The article also discusses the generation of feasible reference trajectories that account for the system's dynamics, as well as input and state constraints. In order to cope with repeatable disturbances, which may stem from unmodeled dynamics for example, an iterative learning procedure is included. The approach relies on a Kalman filter that identifies the repeatable disturbances based on previous trials. These are then included in the system's model available to the model predictive controller, which compensates them in subsequent trials. The proposed approach is evaluated on a quadcopter, whose task is to balance a pole, while flying a predefined trajectory.  相似文献   
998.
Introduction and objectivesThe AEU Guidelines of 2017 consider laparoscopic and robot-assisted approaches as investigational procedures. The surgical learning curve is defined as the minimum number of cases that a surgeon has to perform in order to reproduce a technique considered as standard.The aim of this study is to analyze, within our department, the implementation of a laparoscopic radical cystectomy (LRC) program compared with a well consolidated and standardized open radical cystectomy (ORC) program.Material and methodsRetrospective cohort analysis of two cystectomy groups: LRC (n = 196) (20062016) vs. ORC (n = 96) (2003-2005).Comparison of the evolution over time of the following parameters: operative time, blood transfusion rates, resection margins, postoperative complications, hospital stay and recurrence.Three time periods have been defined for LRC: implementation (2006-09) (LRC-I), development (2010-14) (LRC-D) and consolidation (2015-16) (LRC-C); comparing each of them with the control group (ORC).The chi-square test was used for the comparison of the qualitative variables and the Anova test for the numerical ones.ResultsWhen compared to ORC, LRC presented longer operative times in LRC-I and LRC-D periods. We observed a trend toward shorter operative time than ORC in the consolidation period (LRC-C).LRC also presented lower intraoperative transfusion rates in all periods and lower postoperative rates in CRL-D and CRL-C. Overall complications in LRC-D and LRC-C were lower in LRC, having fewer major complications (Clavien≥3) in the 3 periods. A decrease in mortality and hospital stay after the LRC-I phase was also observed. These results were consolidated during the two last periods of the study.We have not observed significant differences between ORC and LRC when comparing surgical margins and recurrence rates, neither in the total series, nor in the comparison between the different periods. These results endorse the oncologic safety of LRC from the beginning of the implementation process.ConclusionsWhen compared to ORC, LRC improves perioperative transfusion rates, complications and hospital stay from its implementation period, maintaining oncological safety. On the contrary, longer operative times during implementation and development were observed. However, in our series, we observed a trend toward shorter operative times than ORC approach in the consolidation period. We have validated the laparoscopic approach for radical cystectomy in our service.  相似文献   
999.
Anatomical endoscopic enucleation of the prostate has been proposed as a potentially superior benign prostatic hyperplasia surgery than conventional transurethral resection of prostate. However, the learning curve of the procedure is steep, hence limiting its generalisability worldwide. In order to overcome the learning curve, a proper surgical training is extremely important. This review article discussed about various aspects of surgical training in anatomical endoscopic enucleation of the prostate. In summary, no matter what surgical technique or energy modality you use, the principle of anatomical enucleation should be followed. When one starts to perform prostate enucleation, a 50 to 80 g prostate appears to be the ‘best case’ to begin with. Mentorship is extremely important to shorten the learning curve and to prevent drastic complications from the procedure. A proficiency-based progression training programme with the use of simulation and training models should be the best way to teach and learn about prostate enucleation. Enucleation ratio efficacy is the preferred measure for assessing skill level and learning curve of prostate enucleation. Morcellation efficiency is commonly used to assess morcellation performance, but the importance of safety rather than efficiency must be emphasised.  相似文献   
1000.
袁丽洁  武卓  李敏  雷涛  祝婷 《护理学杂志》2020,35(22):85-88
目的 探讨人工智能技术在个性化抑郁症护理中的应用,实现精准护理以加速抑郁症患者的康复。方法 将60例抑郁症患者按病种和病情分层随机分配为对照组和观察组各30例.对照组采用传统护理方法;观察组采用基于深度学习情感分类模型分类后的个性化护理方案,即利用脑电图像(EEG)采集设备获取大量带标记的脑电信号数据构建EEG情感训练库,标记抑郁症类型;通过深度学习情感分类模型识别抑郁症患者EEG信号对应的情感类别;根据其识别结果,采取相应的个性化护理措施。对两组患者在住院期间进行等间隔的抑郁量化评估和护理满意率调查。结果 干预4周时,观察组汉密尔顿抑郁量表(HAMD)和自评抑郁量表(SDS)的评分显著低于对照组(均P<0.05);观察组干预8周时的康复率高于对照组,但两组比较,差异无统计学意义(P>0.05)。结论 基于深度学习情感分类模型的个性化护理方法能显著缓减患者的抑郁程度,加快抑郁症患者的康复速度。  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