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   5561篇
  免费   640篇
  国内免费   168篇
耳鼻咽喉   55篇
儿科学   218篇
妇产科学   135篇
基础医学   124篇
口腔科学   78篇
临床医学   1220篇
内科学   1230篇
皮肤病学   113篇
神经病学   413篇
特种医学   179篇
外科学   1576篇
综合类   11篇
预防医学   314篇
眼科学   325篇
药学   161篇
肿瘤学   217篇
  2023年   106篇
  2021年   61篇
  2020年   95篇
  2019年   40篇
  2018年   126篇
  2017年   171篇
  2016年   183篇
  2015年   136篇
  2014年   221篇
  2013年   296篇
  2012年   100篇
  2011年   114篇
  2010年   228篇
  2009年   341篇
  2008年   120篇
  2007年   67篇
  2006年   110篇
  2005年   72篇
  2003年   50篇
  2002年   48篇
  2001年   107篇
  2000年   82篇
  1999年   130篇
  1998年   175篇
  1997年   201篇
  1996年   301篇
  1995年   254篇
  1994年   195篇
  1993年   118篇
  1992年   126篇
  1991年   143篇
  1990年   71篇
  1989年   135篇
  1988年   104篇
  1987年   82篇
  1986年   108篇
  1985年   97篇
  1984年   89篇
  1983年   85篇
  1982年   69篇
  1981年   71篇
  1980年   83篇
  1979年   45篇
  1978年   65篇
  1977年   46篇
  1976年   53篇
  1975年   56篇
  1972年   39篇
  1964年   49篇
  1963年   47篇
排序方式: 共有6369条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
Pulmonary arterial pressure is an important index in cardiovascular disorders, especially for pulmonary hypertension (PH). Doppler echocardiography (DE) is widely used as a noninvasive method to assess pulmonary arterial pressure. However, recent studies have found several hemodynamic factors that affect its accuracy in estimating systolic pulmonary arterial pressure (sPAP). But the effect of tricuspid regurgitation (TR) has not been investigated. Therefore, our study is aimed to determine whether the severity of TR will affect the accuracy of sPAP measured by DE in an unselected patient population. We retrospectively studied 177 patients who underwent DE and right heart catheterization (RHC) examinations. Patients were categorized into 3 groups according to the severity of TR (mild, moderate, and severe). The discrepancy in sPAP measured by DE and RHC was calculated and compared in each group. Determinants of discordant results between two methods were also evaluated. Age, gender, interval between DE and RHC, sequence of DE and RHC were similar among groups (all P>.05). Differences in sPAP, RAP, and tricuspid regurgitation pressure gradient (TR‐PG) were similar in group 1 and 2 (all P>.05), while all significantly higher in group 3 (all P<.05). The difference in sPAP between DE and RHC was affected independently by severe TR and severe PH (both P<.05). Severe TR and severe PH affect the accuracy of sPAP measured by DE. Modification of echocardiographic sPAP measurements by taking into consideration of these factors may lead to reduced systemic errors.  相似文献   
85.
Subintimal recanalization is beneficial in selected patients with peripheral chronic total occlusions (CTO). However, in complex cases, re‐entry into the true arterial lumen may prove to be unsuccessful with a conventional guidewire or a re‐entry catheter when using standard femoral artery access. Our case series describes these technical dilemmas along with strategies that can be utilized to overcome these challenges. © 2011 Wiley‐Liss, Inc.  相似文献   
86.

Community physicians have recently, albeit often reluctantly, been involved in preparations for nuclear war. This paper suggests an alternative: that they should use their skills in epidemiology and in preventive and social medicine in the prevention of nuclear war.  相似文献   
87.

1 Background and aims

Right ventricular pacing may lead to heart failure (HF). Upgrades from pacemakers to cardiac resynchronization therapy (CRT) were excluded from most randomized, controlled trials. We sought to determine the long‐term outcomes of upgrading from pacemakers to CRT with (CRT‐D) or without (CRT‐P) defibrillation in patients with no history of sustained ventricular arrhythmias.

2 Methods and results

In this observational study, clinical events were quantified in relation to the type of implant (de novo or upgrade) and device type at upgrade (CRT‐P or CRT‐D). Patients underwent CRT implantation (n = 1,545; 1,314 [85%] de novo implants and 231 [15%] upgrades) over a median of 4.6 years [interquartile range: 2.4–7.0]. In analyses of crude event rates, upgrades had a higher total mortality (adjusted hazard ratio [aHR]: 1.33; 95% confidence interval [CI] 0.10–1.61), a higher total mortality or HF hospitalization (aHR: 1.26; 95% CI 1.05–1.51), but similar mortality or hospitalization for major adverse cardiac events (MACEs, aHR: 1.15; 95% CI 0.96–1.38). No group differences emerged in any of these endpoints after propensity score matching. After inverse probability weighting in upgrades, total mortality (HR: 0.55; 95% CI 0.36–0.73), total mortality or HF hospitalization (HR: 0.56; 95% CI 0.34–0.79), and total mortality or hospitalization for MACEs (HR: 0.61; 95% CI 0.40–0.82) were lower after CRT‐D than after CRT‐P.

3 Conclusion

Upgrading from pacemakers to CRT was associated with a similar long‐term risk of mortality and morbidity to de novo CRT. After upgrade, CRT‐D was associated with a lower mortality than CRT‐P.  相似文献   
88.
89.
This article examines the risk of proliferation of nuclear weapons to several Third World countries, exemplified by recent events in Iraq, and the possibility of rapid acquisition of a nuclear weapons capability in developed countries. It considers the role of the International Atomic Energy Agency and the United Nations in preventing proliferation and calls for wider powers for the latter. The role of the civil nuclear power industry and of reprocessing of nuclear fuel to produce plutonium is stressed, with emphasis on the part played by nuclear power in Japan and the THORP reprocessing plant at Sellafield.  相似文献   
90.
Spontaneous papillary muscle rupture (PMR) is a rare cardiovascular emergency. We present a 63‐year‐old male who presents with acute dyspnea who was found to have an anterior PMR, with no evidence of coronary artery disease, infection, or trauma. A review of cases of nonischemic spontaneous PMR published in 2000–2015 identified 11 additional cases of spontaneous PMR. Posterior and anterior papillary muscles involvement was identified in 54.5% and 45.5% of cases, respectively. Rapid identification due to advances in imaging modalities and improved surgical management has led to optimal outcomes in patients with spontaneous PMR.  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