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   58881篇
  免费   3077篇
  国内免费   1428篇
耳鼻咽喉   453篇
儿科学   1021篇
妇产科学   789篇
基础医学   4209篇
口腔科学   416篇
临床医学   7607篇
内科学   14025篇
皮肤病学   94篇
神经病学   3939篇
特种医学   5251篇
外国民族医学   2篇
外科学   9356篇
综合类   9016篇
现状与发展   3篇
预防医学   1277篇
眼科学   851篇
药学   3307篇
  24篇
中国医学   1122篇
肿瘤学   624篇
  2024年   83篇
  2023年   850篇
  2022年   1550篇
  2021年   2311篇
  2020年   2011篇
  2019年   1829篇
  2018年   1907篇
  2017年   1664篇
  2016年   1723篇
  2015年   1856篇
  2014年   3975篇
  2013年   3784篇
  2012年   3239篇
  2011年   3572篇
  2010年   3015篇
  2009年   3085篇
  2008年   3186篇
  2007年   3189篇
  2006年   2906篇
  2005年   2373篇
  2004年   1926篇
  2003年   1695篇
  2002年   1370篇
  2001年   1301篇
  2000年   1014篇
  1999年   900篇
  1998年   895篇
  1997年   826篇
  1996年   642篇
  1995年   635篇
  1994年   532篇
  1993年   471篇
  1992年   438篇
  1991年   345篇
  1990年   290篇
  1989年   254篇
  1988年   250篇
  1987年   214篇
  1986年   178篇
  1985年   225篇
  1984年   172篇
  1983年   92篇
  1982年   136篇
  1981年   103篇
  1980年   85篇
  1979年   83篇
  1978年   73篇
  1977年   44篇
  1976年   38篇
  1975年   18篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
BackgroundArthroscopic management of the posterior ankle impingement with the patient in supine position has the advantage of dealing with anterior ankle pathology at the same time without the need to change position of the patient. This study aims at evaluation of the safety of portal establishment and instrumentation of this technique.MethodsSixteen fresh-frozen cadaver specimens were used. The relationships of the posteromedial and posterolateral portals to the adjacent tendons and nerves and the relationship of the coaxial portal tract with the posterior ankle capsule and the flexor hallucis longus tendon were studied.ResultAngle θ1 between the intermalleolar line and the posterior ankle coaxial portal tract averaged 1° (−10° to 22°). Angle θ2 between the intermalleolar line and the metal rod where the neurovascular bundle started to move averaged 19° (10° to 30°). Angle θ3 between the intermalleolar line and the metal rod where it reached the lateral border of the Achilles tendon was larger than angle θ2 in all specimens. The angle of safety (θs) averaged 18° (−1° to 26°).ConclusionsInjury to the tendon, nerves or vessels is possible during establishment of the portals and resection of the os trigonum.  相似文献   
992.
The aim of this retrospective, single-centre study was to identify the risk factors for bleeding after dental extractions in patients aged over 60 who were being treated with antiplatelet drugs. A total of 338 patients who fulfilled the inclusion criteria were enrolled, and their personal and clinical details, and complications with bleeding after extraction, were retrieved and recorded. There were 182 men and 156 women (mean (SD) age 72 (8) years). A total of 469 teeth were extracted, with a mean (SD) of 1.4 (0.6) teeth/patient. Seventy-seven patients (23%) developed mild, and 55 (16%) severe, bleeding postoperatively. No patient developed a major cardiovascular or cerebrovascular event. We calculated the significance of the association of different variables with the occurrence of postoperative haemorrhage using a multivariate stepwise logistic regression model. The presence of three or more coexisting conditions, a complicated tooth extraction, and the use of two antiplatelet drugs were independent risk factors, while discontinuation of antiplatelet treatment four or more days before the tooth was extracted was a protective factor. This suggests that clinicians should assess the thrombotic risk associated with the interruption of antiplatelet drugs as well as the risk of bleeding for each patient before dental extraction. Strong and effective measures for haemostasis may be preferred over blind discontinuation of antiplatelet drugs. This study is registered in the Chinese Clinical Trial Registry (No. ChiCTR1800014355).  相似文献   
993.
This is a case series on the abnormal sonographic appearance and outcome of the fetal hyaloid artery (HA) detected during between 1987 and 2015 at one medical center. Fifteen cases were detected during fetal anatomy scans, usually performed at 14 to 16 weeks’ gestation. Three other cases were diagnosed following referral for a second opinion. In nine fetuses, the HA regressed normally throughout pregnancy. Of them, eight neonates had normal outcomes and one had cataract at the same eye. All nine other cases ended with adverse outcomes. Failure of the HA to regress in the third trimester appears to be an indicator of congenital blindness.  相似文献   
994.
995.
IntroductionAppropriate spiral artery remodeling is critical for successful fetal development and pregnancy outcomes. The vascular smooth muscle cell (VSMC) loss and separation, involving cell apoptosis and migration, plays an important role in this process. Decidual natural killer cells (dNK)-derived interferon gamma (IFN-γ), a key regulator of uterine arterial remodeling, can facilitate separation of VSMC layers, however, the specific mechanisms of it action are unknown. Long non-coding RNA MEG3 functions as tumor suppressor by regulating apoptosis and migration. Moreover, IFN-γ has been shown to influence cell vitality through regulating MEG3 expression. However, the functional role of dNK derived IFN-γ and MEG3 on VSMC viability, as well as the relationship between IFN-γ and MEG3 in VSMCs, has not been completely elaborated.MethodsThe up-regulation strategies and reagent treatment were employed to detect the effects of MEG3 and dNK/IFN-γ on VSMC proliferation, apoptosis and migration. At the same time, MEG3, p53 and matrix metalloproteinase 2 (MMP-2) expressions were investigated.Results: dNK/IFN-γ treatment led to up-regulation of MEG3 expression in VSMCs. Both MEG3 over-expression and dNK/IFN-γ treatment inhibited VSMC proliferation, stimulated VSMC migration and resulted in a small but significant induction of VSMC apoptosis, as well as promoted p53 and MMP-2 expression in VSMCs.DiscussionMEG3 is regulated by dNK-derived IFN-γ and regulates VSMC migration and apoptosis. Therefore, it may be an important positive regulator in VSMC loss from the maternal uterine spiral arteries during vascular transformation.  相似文献   
996.
[目的]观察葛根素联合纳洛酮治疗椎基底动脉供血不足疗效。[方法]使用随机平行对照方法,将40例住院患者按随机数字表法随机分为两组。对照组20例口服阿司匹林,0.4mg/次,3次/d。治疗组20例葛根素,0.4mg/次,1次/d,静滴;纳洛酮,0.8mg/次,1次/d,静滴。均连续治疗20d为1疗程。观测临床症状、体征、不良反应。连续治疗2疗程,判定疗效。[结果]治疗后,治疗组痊愈10例,显效5例,有效2例,无效1例,总有效率95.00%。对照组痊愈8例,显效4例,有效1例,无效7例,总有效率65.0%。治疗组疗效优于对照组(P0.05)。[结论]葛根素联合纳洛酮治疗椎基底动脉供血不足效果显著,值得推广。  相似文献   
997.
《Revista portuguesa de cardiologia》2014,33(4):241.e1-241.e5
Intercoronary communication or ‘coronary arcade’ is a rare congenital coronary anomaly. We present the case of a 65‐year‐old man with atypical chest pain for four months. The 12‐lead ECG and echocardiogram were normal. Treadmill exercise testing was interrupted at peak exercise due to consecutive salvos of ventricular premature beats, without significant ST‐T changes. Coronary angiography showed no significant coronary stenosis, but a connection between the right coronary and circumflex arteries was observed, consistent with coronary arcade. The functional importance of this variant is not clear, but it may cause myocardial ischemia by coronary steal or function as a natural bypass, in which case it may play a protective role in the myocardium if significant atherosclerosis develops.  相似文献   
998.
Takotsubo cardiomyopathy is a clinical disorder characterized by a transient dilatation and akynesis or dyskinesis of the left ventricular (LV) apex, mimicking an anterior wall acute myocardial infarction in the absence of significant coronary artery disease (CAD). It typically occurs during an episode of severe emotional or physical stress. Recent reports suggested the potential of dobutamine stress echocardiography (DSE) in inducing the aforementioned syndrome. The transient dysfunction of the LV does not fit any known coronary distribution. Furthermore, there is no obstructive CAD demonstrated at angiography to account for the observed dysfunction. Consequently, the pathophysiology of this syndrome is still undetermined. Here, we report a case of DSE‐induced Takotsubo cardiomyopathy in which high‐resolution intracoronary imaging was utilized to exclude possible vessel alterations to help provide potential mechanistic explanations for the development of this condition.  相似文献   
999.
BACKGROUND: The superior mesenteric artery (SMA) first approach was proposed recently as a new modification of the standard pancreaticoduodenectomy. Increasing evidence showed that a periadventiceal dissection of the SMA with early transection of the inflow during pancreaticoduodenec-tomy associates better early perioperative results, and setup the scene for long-term oncological benefits. The objectives of the current study are to compare the operative results and long-term oncological outcomes of SMA first approach pan-creaticoduodenectomy (SMA-PD) with standard pancreatico-duodenectomy (S-PD).DATA SOURCES: Electronic search of the PubMed/MEDLINE, EMBASE, Web of Science and Cochrane Library was performed until July 2015. We considered randomized controlled trials (RCTs) and non-randomized comparative studies (NRCSs) comparing SMA-PD with S-PD to be eligible if they included patients with periampullary cancers.RESULTS: A total of one RCT and thirteen NRCSs met the in-clusion criteria, involving 640 patients with SMA-PD and 514 patients with S-PD. The SMA-PD was associated with less in-traoperative bleeding, less blood transfusions and higher rate of associated venous resections. The pancreatic fistula and delayed gastric emptying had a significantly lower rate in the SMA-PD group. There were no differences between the two approaches regarding overall complications, major complica-tion rates and in-hospital mortality. There was no difference regarding R0 resection rate, and one-, two- or three-year over-all survival. The SMA-PD was associated with a lower local, hepatic and extrahepatic metastatic rate.CONCLUSIONS: The SMA-PD is associated with better perioperative outcomes, such as blood loss, transfusion re-quirements, pancreatic fistula, and delayed gastric emptying. Although the one-, two- or three-year overall survival rate is not superior, the SMA-PD has a lower local and metastatic re-currence rate.  相似文献   
1000.
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