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   2198篇
  免费   277篇
  国内免费   61篇
耳鼻咽喉   5篇
儿科学   27篇
妇产科学   20篇
基础医学   353篇
口腔科学   34篇
临床医学   391篇
内科学   313篇
皮肤病学   23篇
神经病学   122篇
特种医学   539篇
外国民族医学   1篇
外科学   94篇
综合类   140篇
现状与发展   1篇
预防医学   109篇
眼科学   20篇
药学   211篇
中国医学   81篇
肿瘤学   52篇
  2024年   13篇
  2023年   30篇
  2022年   75篇
  2021年   97篇
  2020年   115篇
  2019年   110篇
  2018年   113篇
  2017年   109篇
  2016年   106篇
  2015年   106篇
  2014年   159篇
  2013年   169篇
  2012年   155篇
  2011年   127篇
  2010年   86篇
  2009年   95篇
  2008年   70篇
  2007年   87篇
  2006年   80篇
  2005年   69篇
  2004年   63篇
  2003年   73篇
  2002年   43篇
  2001年   58篇
  2000年   31篇
  1999年   30篇
  1998年   33篇
  1997年   38篇
  1996年   33篇
  1995年   19篇
  1994年   23篇
  1993年   14篇
  1992年   12篇
  1991年   18篇
  1990年   8篇
  1989年   7篇
  1988年   6篇
  1987年   8篇
  1986年   4篇
  1985年   6篇
  1984年   9篇
  1983年   6篇
  1982年   7篇
  1981年   6篇
  1980年   1篇
  1979年   2篇
  1977年   1篇
  1976年   3篇
  1974年   2篇
  1970年   1篇
排序方式: 共有2536条查询结果,搜索用时 31 毫秒
101.
BackgroundChronic obstructive pulmonary disease (COPD) has variable subtypes involving mixture of large airway inflammation, small airway disease, and emphysema. This study evaluated the relationship between visually assessed computed tomography (CT) subtypes and clinical/imaging characteristics.MethodsIn total, 452 participants were enrolled in this study between 2012 and 2017. Seven subtypes were defined by visual evaluation of CT images using Fleischner Society classification: normal, paraseptal emphysema (PSE), bronchial disease, and centrilobular emphysema (trace, mild, moderate and confluent/advanced destructive). The differences in several variables, including clinical, laboratory, spirometric, and quantitative CT features among CT-based visual subtypes, were compared using the chi-square tests and one-way analysis of variance.ResultsSubjects who had PSE had better forced expiratory volume in 1 second (FEV1) (P=0.03) percentage and higher lung density (P<0.05) than those with moderate to confluent/advanced destructive centrilobular emphysema. As the visual grade of centrilobular emphysema worsened, pulmonary function declined and modified Medical Research Council, COPD assessment test (CAT) score, and quantitative assessment (emphysema index and air trapping) increased. The bronchial subtype was associated with higher body mass index (BMI), better lung function and higher lung density. Participants with trace emphysema showed a rapid increase in functional small airway diseaseConclusionsClassifying subtypes using visual CT imaging features can reflect heterogeneity and pathological processes of COPD.  相似文献   
102.
《Pancreatology》2021,21(8):1498-1505
ObjectivesThe aim of this study was to quantitatively evaluate the stiffness of pancreatic parenchyma and solid focal pancreatic lesions (FPLs) by virtual touch tissue imaging and quantification (VTIQ) technique and to investigate the potential usefulness of VTIQ method in the prediction of post-operative pancreatic fistula (POPF) after pancreatectomy.MethodsIn this prospective study, patients who scheduled to undergo pancreatectomy were initially enrolled and received VTIQ assessment within one week before surgery. VTIQ elastography (Siemens ACUSON Sequoia, 5C-1 transducer) was used to measure the shear wave velocity (SWV) value of FPLs and the body part pancreatic parenchyma. The palpation stiffness of pancreas was qualitatively evaluated during operation by surgeons. POPF was finally diagnosed and graded through a three-weeks post-operative follow-up according to international study group of pancreatic fistula (ISGPF). SWV values were compared between POPF positive and negative group. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic efficacy of SWV value in predicting POPF.ResultsFrom December 2020 to June 2021, 44 patients were finally enrolled in this study, among which, 26 patients were identified to develop POPF after pancreatectomy. The SWV value of pancreatic parenchyma in POPF positive group was significantly lower than that in POPF negative group (P = 0.001). However, there was no significant difference in palpation stiffness between the two groups (P = 0.124). Besides, neither the SWV value of FPL nor the SWV ratio between FPL to surrounding pancreatic parenchyma differ significantly between POPF positive and negative group (P > 0.05). Taking SWV value of pancreatic parenchyma >1.10 m/s as a cut-off value for predicting POPF, area under the receiver operating characteristic curve (AUROC) was 0.864 with 72.2% sensitivity, 92.3% specificity, 86.7% positive predictive value (PPV) and 82.8% negative predictive value (NPV), respectively.ConclusionsVTIQ technique might be a potential non-invasive imaging method to predict POPF before pancreatectomy in future clinical practice.  相似文献   
103.
目的 采用声触诊组织成像定量(VTIQ)技术测量正常成人睾丸剪切波速度(SWV),分析影响睾丸弹性硬度的主要因素,探讨其评价男性睾丸生精功能的价值。方法 招募200名正常成年男性志愿者行睾丸常规超声检查,测量双侧睾丸体积。以VTIQ技术测量双侧睾丸上极、中份、下极的SWV,比较双侧睾丸、不同年龄组睾丸SWV差异,并与年龄、睾丸体积和精子活动率和精子密度进行相关性分析。结果 200名正常成年男性左右侧睾丸SWV均为(1.23±0.18)m/s,左右侧差异无统计学意义(t=-0.376,P=0.710)。21~30岁组、31~40岁组、41~50岁与51~60岁组间双侧睾丸SWV值总体差异均有统计学意义(P均<0.001)。睾丸SWV与年龄呈正相关(r=0.454,P<0.001),与睾丸体积、精子活动率和精子密度分别呈负相关(r=-0.649、-0.668、-0.675,P均<0.001)。结论 VTIQ技术可定量测量睾丸组织硬度,有望用于初步评估睾丸生精功能。  相似文献   
104.
目的 探讨声触诊组织量化成像(VTIQ)评价注射A型肉毒毒素治疗脑卒中后前臂旋前肌痉挛肌肉硬度改变的价值。方法 收集31例脑卒中后前臂旋前肌痉挛患者,在其松弛状态下,于超声引导注射A型肉毒毒素,并于治疗前和治疗后1个月对双侧旋前圆肌、旋前方肌行VTIQ检查,测量剪切波速度(SWV),对比治疗前后以及患侧与健侧SWV差异。于治疗前后对患侧上肢肌力进行改良Ashworth量表(MAS)评分并比较其差异,评价其与SWV的相关性。结果 治疗前患侧旋前圆肌SWV值高于健侧(P=0.005);治疗后1个月,患侧旋前圆肌、旋前方肌SWV值与健侧比较差异均无统计学意义(P均>0.05)。治疗后患侧旋前圆肌、旋前方肌SWV值均小于治疗前(P均<0.05),治疗前后患侧上肢MAS评分差异有统计学意义(Z=-2.252,P=0.024)。治疗前后患侧上肢肌张力MAS评分与治疗前后患侧旋前圆肌的SWV值呈正相关(rs=0.629、0.653,P均<0.001)。结论 VTIQ可用于动态观察脑卒中后前臂旋前肌痉挛患者旋前圆肌、旋前方肌的肌肉硬度,由此定量评估注射A型肉毒毒素治疗脑卒中后前臂旋前肌痉挛的疗效。  相似文献   
105.
ObjectivesThis study designed and evaluated an end-to-end deep learning solution for cardiac segmentation and quantification.BackgroundSegmentation of cardiac structures from coronary computed tomography angiography (CCTA) images is laborious. We designed an end-to-end deep-learning solution.MethodsScans were obtained from multicenter registries of 166 patients who underwent clinically indicated CCTA. Left ventricular volume (LVV) and right ventricular volume (RVV), left atrial volume (LAV) and right atrial volume (RAV), and left ventricular myocardial mass (LVM) were manually annotated as ground truth. A U-Net−inspired, deep-learning model was trained, validated, and tested in a 70:20:10 split.ResultsMean age was 61.1 ± 8.4 years, and 49% were women. A combined overall median Dice score of 0.9246 (interquartile range: 0.8870 to 0.9475) was achieved. The median Dice scores for LVV, RVV, LAV, RAV, and LVM were 0.938 (interquartile range: 0.887 to 0.958), 0.927 (interquartile range: 0.916 to 0.946), 0.934 (interquartile range: 0.899 to 0.950), 0.915 (interquartile range: 0.890 to 0.920), and 0.920 (interquartile range: 0.811 to 0.944), respectively. Model prediction correlated and agreed well with manual annotation for LVV (r = 0.98), RVV (r = 0.97), LAV (r = 0.78), RAV (r = 0.97), and LVM (r = 0.94) (p < 0.05 for all). Mean difference and limits of agreement for LVV, RVV, LAV, RAV, and LVM were 1.20 ml (95% CI: −7.12 to 9.51), −0.78 ml (95% CI: −10.08 to 8.52), −3.75 ml (95% CI: −21.53 to 14.03), 0.97 ml (95% CI: −6.14 to 8.09), and 6.41 g (95% CI: −8.71 to 21.52), respectively.ConclusionsA deep-learning model rapidly segmented and quantified cardiac structures. This was done with high accuracy on a pixel level, with good agreement with manual annotation, facilitating its expansion into areas of research and clinical import.  相似文献   
106.
107.
108.
109.
110.
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