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   60835篇
  免费   5841篇
  国内免费   2035篇
耳鼻咽喉   464篇
儿科学   1349篇
妇产科学   563篇
基础医学   4454篇
口腔科学   488篇
临床医学   6807篇
内科学   14341篇
皮肤病学   339篇
神经病学   564篇
特种医学   2763篇
外国民族医学   44篇
外科学   6571篇
综合类   11558篇
现状与发展   10篇
预防医学   2192篇
眼科学   184篇
药学   4752篇
  47篇
中国医学   2109篇
肿瘤学   9112篇
  2024年   61篇
  2023年   990篇
  2022年   1430篇
  2021年   2635篇
  2020年   2701篇
  2019年   2329篇
  2018年   2259篇
  2017年   2478篇
  2016年   2654篇
  2015年   2879篇
  2014年   4452篇
  2013年   4479篇
  2012年   3889篇
  2011年   4011篇
  2010年   3313篇
  2009年   3024篇
  2008年   2935篇
  2007年   2922篇
  2006年   2712篇
  2005年   2451篇
  2004年   1968篇
  2003年   1753篇
  2002年   1450篇
  2001年   1253篇
  2000年   1103篇
  1999年   929篇
  1998年   757篇
  1997年   649篇
  1996年   553篇
  1995年   539篇
  1994年   474篇
  1993年   362篇
  1992年   340篇
  1991年   259篇
  1990年   251篇
  1989年   198篇
  1988年   186篇
  1987年   164篇
  1986年   140篇
  1985年   171篇
  1984年   145篇
  1983年   79篇
  1982年   76篇
  1981年   73篇
  1980年   67篇
  1979年   46篇
  1978年   32篇
  1977年   26篇
  1976年   22篇
  1975年   14篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
《Indian heart journal》2022,74(1):34-39
BackgroundShort term outcomes of patients with pulmonary hypertension are not available from low and middle-income countries including India.MethodsWe conducted a prospective study of 2003 patients with pulmonary hypertension, from 50 centres (PROKERALA) in Kerala, who were followed up for one year. Pulmonary hypertension (PH) was mainly diagnosed on the basis of Doppler echocardiography. The primary outcome was a composite end-point of all-cause death and hospital admission for heart failure. All cause hospitalisation events constituted the secondary outcome.ResultsMean age of study population was 56 ± 16 years. Group 1 and Group 2 PH categories constituted 21.2% and 59% of the study population, respectively. Nearly two-thirds (65%) of the study participants had functional class II symptoms. 31% of Group 1 PH patients were on specific vasodilator drugs.In total, 83 patients (4.1%) died during the one-year follow-up period. Further, 1235 re-hospitalisation events (61.7%) were reported. In the multivariate model, baseline NYHA class III/IV (OR 1.87, 95% C.I. 1.35–2.56), use of calcium channel blockers (OR 0.18, 95% C.I. 0.04–0.77), vasodilator therapy (OR 0.5, 95% C.I. 0.28–0.87) and antiplatelet agents (OR 1.80, 95% C.I. 1.29–2.51) were associated with primary composite outcome at one-year (p < 0.05).ConclusionIn the PROKERALA registry, annual mortality rate was 4%. More than half of the patients reported re-hospitalisation events on follow up. Uptake of guideline directed therapies were suboptimal in the study population. Quality improvement programmes to improve guideline directed therapy may improve clinical outcomes of PH patients in India.  相似文献   
72.
73.
ObjectiveThis study aimed to analyze and evaluate the results of mid-term follow-up after fetal pulmonary valvuloplasty (FPV) in fetuses with pulmonary atresia with intact ventricular septum (PA/IVS).MethodsFrom August 31, 2018, to May 31, 2019, seven fetuses with PA/IVS and hypoplastic right heart were included in this study. All underwent echocardiography by the same specialist and were operated on by the same team. Intervention and echocardiography data were collected, and changes in the associated indices noted during follow-up were analyzed.ResultsAll seven fetuses successfully underwent FPV. The median gestational age at FPV was 27.54 weeks. The average FPV procedural time was 6 ?min. Persistent bradycardia requiring treatment occurred in 4/7 procedures. Finally, five pregnancies were successfully delivered, and the other two were aborted. Compared to data before fetal cardiac interventions (FCI), tricuspid valve annulus diameter/mitral valve annulus diameter (TV/MV) and right ventricle diameter/left ventricle diameter (RV/LV) of all fetuses had progressively improved. The maximum tricuspid regurgitation velocity decreased from 4.60 ?m/s to 3.64 ?m/s. The average follow-up time was 30.40 ?± ?2.05 months. During the follow-up period, the diameter of the tricuspid valve ring in five children continued to improve, and the development rate of the tricuspid valve was relatively obvious from 6 months to 1 year after birth. However, the development of the right ventricle after birth was relatively slow. It was discovered that there were individual variations in the development of the right ventricle during follow-up.ConclusionThe findings support the potential for the development of the right ventricle and tricuspid valve in fetuses with PA/IVS who underwent FCI. Development of the right ventricle and tricuspid valve does not occur synchronously during pregnancy. The right ventricle develops rapidly in utero, but the development of tricuspid valve is more apparent after birth than in utero.  相似文献   
74.
75.
目的:基于原发肿瘤及淋巴结CT特征建立评分模型预测食管鳞癌患者喉返神经旁淋巴结(RLN-LN)转移风险。方法:回顾性收集2014年1月至2019年12月于北京大学肿瘤医院行食管癌根治术并清扫RLN-LN的92例食管鳞癌患者。根据术后淋巴结病理结果分为RLN-LN转移组(n=37)和非转移组(n=55)。评估术前CT图像,记录食管癌患者年龄、性别、分化程度、肿瘤位置、肿瘤大小(肿瘤长度、肿瘤厚度、厚度/长度)、RLN-LN大小(淋巴结短径、长径、短径/多平面重建(MPR)最长径]。采用多元logistic回归筛选独立预测因子并建立评分模型,采用ROC曲线评估评分模型及独立预测因子诊断RLN-LN转移的效能,采用Z检验比较曲线下面积(AUC)的差异。应用Hosmer-Lemeshow检验和校准曲线评估模型拟合度。结果:肿瘤位置、肿瘤长度、RLN-LN短径、短径/MPR最长径是RLN-LN转移的独立预测因子,其诊断RLN-LN转移的AUC分别为0.586、0.705、0.831、0.777。基于以上4个CT特征建立评分模型,评分模型诊断RLN-LN转移的AUC为0.903(95%CI 0.846~0.959),优于各单一CT特征(Z=5.812,P<0.001;Z=2.161,P=0.030;Z=2.929,P=0.003;Z=4.052,P<0.001)。拟合优度Hosmer-Lemeshow检验结果显示P=0.555,校准曲线提示评分模型预测RLN-LN转移风险与实际转移风险之间具有良好的一致性。结论:基于CT图像的评分模型有助于食管鳞癌RLN-LN转移状态危险分层。  相似文献   
76.
BackgroundPulmonary sarcomatoid carcinoma (PSC) is a rare type of non-small cell lung cancer (NSCLC). Metastases are often detected at the first diagnosis. Despite high rates of distant metastasis, there is insufficient data describing the characteristics of PSC metastasis.MethodsWe performed a Surveillance, Epidemiology, and End Results (SEER) database-based analysis of clinicopathological features and prognosis of distant metastasis in PSC patients. Data queried for this analysis included PSC patients in the database between 2010 and 2016.ResultsA total of 934 patients met the criteria for inclusion in the analysis and included, at the time of diagnosis, 512 (54.8%) patients with metastasis, including bone (n=152; 16.3%), brain (n=108; 11.6%), liver (n=70; 7.5%), lung (n=142; 15.2%) metastases. Binary logistic regression showed that patients with giant cell carcinoma [odds ratio (OR) 4.023, 95% confidence interval (CI): 2.113–7.661, P<0.001] and spindle cell carcinoma (OR 3.151, 95% CI: 1.699–5.843, P<0.001) were associated with metastasis. Log-rank test and Kaplan-Meier plots indicated poor prognosis in metastatic patients [the 1-, 3-, and 5-year overall survival (OS) rates were 14.1%, 5.5%, and 4.8%, respectively]. Multivariable analysis showed younger and chemotherapy as improved prognostic factors of PSC patients with single metastasis site.ConclusionsThe SEER database-based analysis revealed the clinical features of distant metastasis of PSC and showed that different histological types posed distinct metastasis potential. Besides, age and chemotherapy were the independent prognostic factors of PSC patients with single metastasis site.  相似文献   
77.
ObjectiveEach pulmonary segment is an anatomical and functional unit. However, it is fundamentally difficult to precisely distinguish every pulmonary segment using the conventional pulmonary intersegmental planes from computed tomography images. Building arteriopulmonary segments is likely to be an effective way to identify pulmonary segments.MethodsThe thoracic computed tomography images of 40 patients were collected. The anatomic structures of interest were extracted in the transverse, sagittal, and coronal planes using the semi-automated segmentation tools provided by Amira software. The intrapulmonary vessels were subsequently segmented and reconstructed. The distributions of the pulmonary arteries, veins, and bronchi were observed. In patients with pulmonary masses, the mass was also reconstructed.ResultsThe three-dimensional reconstructed images showed the branches of the pulmonary artery ramified up to their eighth order covering the entire lung as well as evident intersegmental gaps without pulmonary arteries. The segmental artery was closely accompanied by the segmental bronchi in 486 pulmonary segments (90% of total number of segments). The size and spatial location of the pulmonary mass within a pulmonary segment were also clearly visible.ConclusionsDemarcation of arteriopulmonary segments can be used to precisely distinguish every pulmonary segment and provide its detailed anatomical structure before pulmonary segmentectomy.  相似文献   
78.
目的:研究乳腺癌细胞中转录调节因子c-Myb的表达对肺转移的影响及其分子机制。方法:构建c-Myb高表达的4T1乳腺癌细胞株,种植小鼠构建乳腺癌动物模型,检测实验动物肺转移情况,通过荷瘤抑制试验检测肺转移抑制效果。提取组织进行荧光PCR检测相关炎症因子的表达。利用Medisapiens数据库的生物信息学资源,对c-Myb和Ccl2的表达与乳腺癌患者的预后进行分析。结果:高表达c-Myb的荷瘤小鼠肺部转移灶明显减少,其中炎症相关因子表达受限。由数据库分析得出,c-Myb高表达患者生存期得以延长。结论:乳腺癌中c-Myb的表达能够通过炎症因子Ccl2抑制肺转移从而延长患者生存期。  相似文献   
79.
PurposeTo investigate and compare venous sac and feeding artery embolization (VFE) with feeding artery embolization (FAE) alone for treatment of pulmonary arteriovenous malformations (PAVMs), based on difference in outcomes in decrease of the size of the draining vein.Materials and MethodsTwenty-six patients (7 male and 19 female; median age [interquartile range], 58 years [46–65 years]) with 42 simple PAVMs treated with coil embolization between August 2005 and December 2018 were retrospectively evaluated. Twenty PAVMs were treated with FAE early in the study period and compared with 22 PAVMs treated with VFE later in the study period. Follow-up computed tomography images obtained 8–20 months after embolotherapy were used for outcome analysis. Data related to patient demographics; follow-up period; baseline diameters of the feeding artery, venous sac, and draining vein; draining vein diameter after treatment; and decrease in the size of the draining vein, including the number reaching a threshold of 70% decrease, were compared between the 2 groups.ResultsThe draining vein decreased in size by a median of 46.4% in the FAE group and 66.3% in the VFE group, and the difference between the 2 groups was statistically significant (P = .009). There were no significant differences in the other parameters.ConclusionsVFE leads to a greater decrease in the size of the draining vein than FAE, suggesting that VFE results in more complete occlusion than FAE for treatment of PAVMs.  相似文献   
80.
神经内分泌肿瘤病程中易发生肝转移。目前,神经内分泌肿瘤肝转移(NENLM)的治疗方法日益多样化,这使得过去单纯从形态学变化的角度评价其治疗效果具有一定的局限性。新兴的影像学生物标志物能够从功能层面描述肿瘤治疗相关的变化,为NENLM的疗效评价提供新的方法和思路。本文主要总结影像学评价NENLM早期疗效的现状及研究进展,旨在为有效评价NENLM的早期疗效提供参考,并为进一步探索与NENLM早期疗效相关的生物标志物提供思路。  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