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   247070篇
  免费   12402篇
  国内免费   6924篇
耳鼻咽喉   3476篇
儿科学   8588篇
妇产科学   3283篇
基础医学   17101篇
口腔科学   5073篇
临床医学   28773篇
内科学   43030篇
皮肤病学   3126篇
神经病学   12000篇
特种医学   12887篇
外国民族医学   22篇
外科学   43862篇
综合类   21876篇
现状与发展   25篇
一般理论   1篇
预防医学   15765篇
眼科学   4880篇
药学   24624篇
  100篇
中国医学   4714篇
肿瘤学   13190篇
  2023年   2600篇
  2022年   8716篇
  2021年   10973篇
  2020年   5719篇
  2019年   12390篇
  2018年   7397篇
  2017年   5857篇
  2016年   7217篇
  2015年   10210篇
  2014年   18735篇
  2013年   16306篇
  2012年   19667篇
  2011年   16555篇
  2010年   15230篇
  2009年   14760篇
  2008年   13326篇
  2007年   13366篇
  2006年   11219篇
  2005年   7455篇
  2004年   3874篇
  2003年   3415篇
  2002年   2786篇
  2001年   2280篇
  2000年   2058篇
  1999年   1347篇
  1998年   1789篇
  1997年   1585篇
  1996年   1265篇
  1995年   1315篇
  1994年   1236篇
  1993年   955篇
  1992年   1169篇
  1991年   1027篇
  1990年   1082篇
  1989年   1061篇
  1988年   971篇
  1987年   870篇
  1986年   704篇
  1985年   2051篇
  1984年   2193篇
  1983年   1587篇
  1982年   1734篇
  1981年   1695篇
  1980年   1518篇
  1979年   1303篇
  1978年   1066篇
  1977年   926篇
  1976年   984篇
  1975年   718篇
  1974年   711篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
《Clinical neurophysiology》2021,132(10):2357-2364
ObjectivesTo investigate the subcortical somatosensory evoked potentials (SEPs) to electrical stimulation of either muscle or cutaneous afferents.MethodsSEPs were recorded in 6 patients suffering from Parkinson’s disease (PD) who underwent electrode implantation in the pedunculopontine (PPTg) nucleus area. We compared SEPs recorded from the scalp and from the intracranial electrode contacts to electrical stimuli applied to: 1) median nerve at the wrist, 2) abductor pollicis brevis motor point, and 3) distal phalanx of the thumb. Also the high-frequency oscillations (HFOs) were analysed.ResultsAfter median nerve and pure cutaneous (distant phalanx of the thumb) stimulation, a P1-N1 complex was recorded by the intracranial lead, while the scalp electrodes recorded the short-latency far-field responses (P14 and N18). On the contrary, motor point stimulation did not evoke any low-frequency component in the PPTg traces, nor the N18 potential on the scalp. HFOs were recorded to stimulation of all modalities by the PPTg electrode contacts.ConclusionsStimulus processing within the cuneate nucleus depends on modality, since only the cutaneous input activates the complex intranuclear network possibly generating the scalp N18 potential.SignificanceOur results shed light on the subcortical processing of the somatosensory input of different modalities.  相似文献   
2.
ObjectiveNew-onset postoperative atrial fibrillation (POAF) after cardiac surgery is common, with rates up to 60%. POAF has been associated with early and late stroke, but its association with other cardiovascular outcomes is less known. The objective was to perform a meta-analysis of the studies reporting the association of POAF with perioperative and long-term outcomes in patients with cardiac surgery.MethodsWe performed a systematic review and a meta-analysis of studies that presented outcomes for cardiac surgery on the basis of the presence or absence of POAF. MEDLINE, EMBASE, and the Cochrane Library were assessed; 57 studies (246,340 patients) were selected. Perioperative mortality was the primary outcome. Inverse variance method and random model were performed. Leave-one-out analysis, subgroup analyses, and metaregression were conducted.ResultsPOAF was associated with perioperative mortality (odds ratio [OR], 1.92; 95% confidence interval [CI], 1.58-2.33), perioperative stroke (OR, 2.17; 95% CI, 1.90-2.49), perioperative myocardial infarction (OR, 1.28; 95% CI, 1.06-1.54), perioperative acute renal failure (OR, 2.74; 95% CI, 2.42-3.11), hospital (standardized mean difference, 0.80; 95% CI, 0.53-1.07) and intensive care unit stay (standardized mean difference, 0.55; 95% CI, 0.24-0.86), long-term mortality (incidence rate ratio [IRR], 1.54; 95% CI, 1.40-1.69), long-term stroke (IRR, 1.33; 95% CI, 1.21-1.46), and longstanding persistent atrial fibrillation (IRR, 4.73; 95% CI, 3.36-6.66).ConclusionsThe results suggest that POAF after cardiac surgery is associated with an increased occurrence of most short- and long-term cardiovascular adverse events. However, the causality of this association remains to be established.  相似文献   
3.
4.

Background

The objective of the study was to evaluate the outcomes of clinically localized prostate cancer treated with prostatectomy versus radiation therapy within the context of a prospective prostate cancer screening study.

Patients and Methods

Within the PLCO (Prostate, Lung, Colorectal, and Ovary) trial, patients who were diagnosed with clinically localized prostate cancer and subsequently received treatment with prostatectomy or radiation therapy (with or without hormonal treatment) were included. Univariate and multivariate Cox regression analyses were then performed to determine factors affecting overall and prostate cancer-specific survival. Factors with P < .05 in univariate analysis were included in the multivariate analysis.

Results

A total of 3953 patients were included in the current analysis. These included 2044 patients treated with prostatectomy and 1909 patients treated with radiation therapy with or without hormonal treatment. In an adjusted multivariate analysis for factors affecting overall survival, prostatectomy was associated with better overall survival compared with radiation therapy (hazard ratio, 0.548; 95% confidence interval [CI], 0.440- 681; P < .001). Likewise, in an adjusted multivariate analysis for factors affecting prostate cancer-specific survival, prostatectomy was associated with better prostate cancer-specific survival compared with radiation therapy (hazard ratio, 0.485; 95% CI, 0.286- 0.822; P = .007). Similar findings were found with propensity score matching and repeating the same analyses on the post-matching cohort.

Conclusion

Prostatectomy seems to predict better overall and prostate cancer-specific survival compared with radiation therapy among patients with clinically localized prostate cancer diagnosed within the PLCO trial.  相似文献   
5.
目的对治疗前原发性骶尾部脊索瘤(PSC)CT图像分型,并分析其CT征象,为诊断和个性化治疗提供依据。方法回顾性分析101例PSC患者治疗前的CT图像,包括肿瘤的部位、范围、大小、密度、肿瘤与邻近结构的关系。按照肿瘤的部位由上及下分为Ⅰ~Ⅳ型,并根据肿瘤侵犯的范围从小到大分为a^d亚型。采用Kruskal-Wallis H检验比较PSC各亚型的占比,并对各亚型之间进行两两比较。采用R×C列联表精确概率检验比较分型和亚型肿瘤钙化的发生率。采用单因素方差分析及LSD-t检验对各分型和亚型肿瘤的大小和密度进行分析、比较。结果101例PSC中,Ⅰ~Ⅳ型的发生率分别为17.8%、30.7%、36.6%、14.9%,a^d亚型的占比分别为9.9%、25.7%、58.4%、5.9%。各亚型的占比差异具有统计学意义(P=0.012)。c亚型明显高于a亚型(P=0.039),d亚型明显低于a亚型(P=0.036),其余各型之间无明显差异。各分型肿瘤内钙化的差异无统计学意义(P=0.233);各亚型肿瘤内钙化的差异有统计学意义(P=0.003),a^d亚型肿瘤钙化的比率逐渐增加。Ⅰ型肿瘤的左右径及上下径明显大于Ⅱ~Ⅳ型(P<0.05)。a亚型与b亚型肿瘤之间前后径的差异无统计学意义(P=0.102),b^d亚型之间前后径的差异均有统计学意义(P<0.05);不同亚型肿瘤之间的左右径、上下径之间的差异均有统计学意义(P<0.05),a亚型径线最小,d亚型径线最大。结论101例PSC中,Ⅱ、Ⅲ型最多见,肿瘤较少累及第一骶骨;各亚型中,a型较少见,c亚型最多见,d亚型最少见。肿瘤的密度与分型无关,肿瘤内钙化与亚型有关。Ⅰ型肿瘤侵犯的范围较Ⅱ~Ⅳ型广泛,a^d亚型肿瘤的径线逐渐增大,CT分型有利于判断肿瘤的范围。PSC诊断延迟现象比较明显,但很少发生远处侵犯和转移。CT图像可对治疗前PSC分型,为诊断和个性化治疗提供依据。  相似文献   
6.

Background

Purulent bacterial pericarditis is a rare and potentially fatal disease. The course may be fulminant, and the presentation may pose a diagnostic challenge.

Case report

An otherwise healthy 75-year-old male was brought to the emergency department in a state of general deterioration, confusion, and shock. Bedside ultrasound showed a significant pericardial effusion. His condition quickly deteriorated and the resuscitation included emergent bedside pericardiocentesis. The drainage was purulent and later cultures grew out Streptococcus pneumoniae.

Why should an emergency physician be aware of this?

Purulent pericarditis is extremely rare but should be considered in the patient with a fulminant infectious process (particularly pneumonia) and signs of pericardial effusion. Treatment should include appropriate antibiotics and early drainage.  相似文献   
7.
We report two British cases of liver abscess, due to Klebsiella pneumoniae and associated with synchronous infection elsewhere, which required liver resection for definitive treatment. They illustrate the geographic spread of aggressive K pneumoniae liver infection and demonstrate the importance of early aggressive treatment.  相似文献   
8.
9.
10.
Central illustration: cumulative major adverse cardiac events (MACE) and bioresorbable vascular scaffold (BVS) thrombosis rates after 1, 2, 3, 4 and 5 years.
  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