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   3899篇
  免费   262篇
  国内免费   48篇
耳鼻咽喉   4篇
儿科学   156篇
妇产科学   12篇
基础医学   160篇
口腔科学   1篇
临床医学   743篇
内科学   837篇
皮肤病学   15篇
神经病学   48篇
特种医学   422篇
外科学   440篇
综合类   624篇
预防医学   209篇
眼科学   8篇
药学   146篇
  6篇
中国医学   205篇
肿瘤学   173篇
  2024年   8篇
  2023年   54篇
  2022年   141篇
  2021年   190篇
  2020年   164篇
  2019年   95篇
  2018年   134篇
  2017年   112篇
  2016年   105篇
  2015年   136篇
  2014年   263篇
  2013年   265篇
  2012年   208篇
  2011年   251篇
  2010年   193篇
  2009年   191篇
  2008年   164篇
  2007年   170篇
  2006年   147篇
  2005年   164篇
  2004年   140篇
  2003年   135篇
  2002年   98篇
  2001年   76篇
  2000年   79篇
  1999年   58篇
  1998年   59篇
  1997年   42篇
  1996年   38篇
  1995年   50篇
  1994年   48篇
  1993年   30篇
  1992年   23篇
  1991年   18篇
  1990年   18篇
  1989年   19篇
  1988年   12篇
  1987年   9篇
  1986年   19篇
  1985年   11篇
  1984年   14篇
  1983年   7篇
  1982年   9篇
  1981年   9篇
  1980年   12篇
  1979年   5篇
  1978年   5篇
  1975年   2篇
  1973年   2篇
  1972年   2篇
排序方式: 共有4209条查询结果,搜索用时 15 毫秒
91.
92.
目的 分析胎儿胸外心脏的超声表现,讨论其超声诊断价值。 方法 根据胸外心脏的分型,回顾性分析10例早期胎儿胸外心脏的超声表现,总结其声像图特征。 结果 10例胎儿胸外心脏中除1例为单纯性胸外心脏,其余9例均合并其他畸形。经尸检证实7例中,3例胸型,心脏部分或全部位于胸腔外;3例胸腹型,心脏部分位于胸腔,部分与腹腔脏器突出腹壁;1例腹型,心脏与部分腹腔脏器突出腹壁。 结论 超声对早孕期胎儿胸外心脏具有极高诊断率及重要临床意义。  相似文献   
93.
目的:通过体表测量计算胸腔容积评价肺发育、胸廓缩小程度及漏斗胸畸形程度。方法将90只健康4周龄SD大鼠分成实验组和对照组,实验组70只,对照组20只。实验组从胸骨旁切断下位3对肋软骨制作漏斗胸大鼠模型。分别于术前,术后2、4、8、12周测量胸部多条径线,并进行组间比较。胸腔容积大小用数学公式计算,利用阿基米德原理测量及C T三维重建所得,采用SPSS17.0进行 t检验及直线回归分析。结果实验采用多条径线测量结果,经过数学计算,阿基米德原理测量,以及CT三维重建所得结果实验组与对照组比较,差异有统计学意义(P<0.05)。结论通过体表测量计算胸腔容积的方法是可行的,该方法可替代CT检查对于评估漏斗胸形成过程中的胸腔容积的改变。  相似文献   
94.
Bedside ultrasound is often used as a part of the evaluation of patients who are critically ill. The McConnell sign is an important echocardiographic finding in some critically ill patients with pulmonary embolism and an acute right ventricular infarct. We present 3 critically ill patients with confirmed acute chest syndrome who showed the McConnell sign on echocardiography. In patients with sickle cell disease presenting with chest pain and shortness of breath, the presence of the McConnell sign does not narrow the differential diagnosis between pulmonary embolism, an acute right ventricular infarct, and acute chest syndrome.  相似文献   
95.

Background

Acute chest syndrome (ACS) is the leading cause of death for patients with sickle cell disease (SCD). Early recognition of ACS improves prognosis.

Objective

Investigate the use of bedside lung ultrasound (BLU) in identification of early pulmonary findings associated with ACS in SCD patients.

Methods

Prospective, observational study of a convenience sample of SCD patients presenting to the Emergency Department (ED) for a pain crisis. BLU interpretations were made by an emergency physician blinded to the diagnosis of ACS, and were validated by a second reviewer. The electronic medical record was reviewed at discharge and at 30?days.

Results

Twenty SCD patients were enrolled. Median age was 31?years, median hemoglobin was 7.7?g/dL. Six patients developed ACS. Five patients in the ACS group had lung consolidations on BLU (83%) compared to 3 patients in the non-ACS group (21%), p?=?0.0181, (OR?=?12.05, 95% CI 1.24 to 116.73). The ACS group was also more likely to have a pleural effusion and B-lines on BLU than the non-ACS group, p?=?0.0175; 0.1657, respectively. In the ACS group, peripheral and frank consolidations on BLU was 83% and 50% sensitive, 79% and 100% specific for ACS, respectively; whereas an infiltrate on initial chest X-ray (CXR) was only 17% sensitive. BLU identified lung abnormalities sooner than CXR (median 3.6 vs. 31.8?h).

Conclusions

Pulmonary abnormalities on BLU of an adult SCD patient presenting to the ED for a painful crisis appear before CXR, and highly suggest ACS. BLU is a promising predictive tool for ACS.  相似文献   
96.
Setting: Tanzania is a high-burden country for tuberculosis (TB), and prisoners are a high-risk group that should be screened actively, as recommended by the World Health Organization. Screening algorithms, starting with chest X-rays (CXRs), can detect asymptomatic cases, but depend on experienced readers, who are scarce in the penitentiary setting. Recent studies with patients seeking health care for TB-related symptoms showed good diagnostic performance of the computer software CAD4TB.Objective: To assess the potential of computer-assisted screening using CAD4TB in a predominantly asymptomatic prison population.Design: Cross-sectional study.Results: CAD4TB and seven health care professionals reading CXRs in local tuberculosis wards evaluated a set of 511 CXRs from the Ukonga prison in Dar es Salaam. Performance was compared using a radiological reference. Two readers performed significantly better than CAD4TB, three were comparable, and two performed significantly worse (area under the curve 0.75 in receiver operating characteristics analysis). On a superset of 1321 CXRs, CAD4TB successfully interpreted >99%, with a predictably short time to detection, while 160 (12.2%) reports were delayed by over 24 h with conventional CXR reading.Conclusion: CAD4TB reliably evaluates CXRs from a mostly asymptomatic prison population, with a diagnostic performance inferior to that of expert readers but comparable to local readers.  相似文献   
97.
AimThis clinical practice guideline for the evaluation and diagnosis of chest pain provides recommendations and algorithms for clinicians to assess and diagnose chest pain in adult patients.MethodsA comprehensive literature search was conducted from November 11, 2017, to May 1, 2020, encompassing randomized and nonrandomized trials, observational studies, registries, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases. Additional relevant studies, published through April 2021, were also considered.StructureChest pain is a frequent cause for emergency department visits in the United States. The “2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain” provides recommendations based on contemporary evidence on the assessment and evaluation of chest pain. This guideline presents an evidence-based approach to risk stratification and the diagnostic workup for the evaluation of chest pain. Cost-value considerations in diagnostic testing have been incorporated, and shared decision-making with patients is recommended.  相似文献   
98.
Spontaneous pneumothorax is an uncommon problem in childhood. However, it is frequent enough that most paediatricians will encounter this at some point in their careers. Traditional management for children and young people with a moderate to large pneumothorax has involved either needle thoracocentesis, chest drain insertion or both. However, recent clinical trials have suggested that a conservative approach may be possible and in some circumstances preferable to immediate intervention. This short article offers a suggested framework for management of spontaneous pneumothorax in children and young people.  相似文献   
99.
100.
Thus far, there has been a paucity of studies that have assessed the value of the different gastroesophageal reflux disease (GERD) symptom characteristics in identifying patients with long-segment Barrett's esophagus versus those with short-segment Barrett's esophagus. To determine if any of the symptom characteristics of GERD correlates with long-segment Barrett's esophagus versus short-segment Barrett's esophagus. Patients seen in our Barrett's clinic were prospectively approached and recruited into the study. All patients underwent an endoscopy, validated GERD symptoms questionnaire and a personal interview. Of the 88 Barrett's esophagus patients enrolled into the study, 47 had short-segment Barrett's esophagus and 41 long-segment Barrett's esophagus. Patients with short-segment Barrett's esophagus reported significantly more daily heartburn symptoms (84.1%) than patients with long-segment Barrett's esophagus (63.2%, P = 0.02). There was a significant difference in reports of severe to very severe dysphagia in patients with long-segment Barrett's esophagus versus those with short-segment Barrett's esophagus (76.9%vs. 38.1%, P = 0.02). Longer duration in years of chest pain was the only symptom characteristic of gastroesophageal reflux disease associated with longer lengths of Barrett's mucosa. Reports of severe or very severe dysphagia were more common in long-segment Barrett's esophagus patients. Only longer duration of chest pain was correlated with longer lengths of Barrett's esophagus.  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