全文获取类型
收费全文 | 28537篇 |
免费 | 1980篇 |
国内免费 | 549篇 |
专业分类
耳鼻咽喉 | 11篇 |
儿科学 | 792篇 |
妇产科学 | 67篇 |
基础医学 | 917篇 |
口腔科学 | 13篇 |
临床医学 | 5924篇 |
内科学 | 13748篇 |
皮肤病学 | 19篇 |
神经病学 | 390篇 |
特种医学 | 790篇 |
外科学 | 2306篇 |
综合类 | 3611篇 |
现状与发展 | 1篇 |
一般理论 | 1篇 |
预防医学 | 357篇 |
眼科学 | 4篇 |
药学 | 1544篇 |
10篇 | |
中国医学 | 507篇 |
肿瘤学 | 54篇 |
出版年
2024年 | 28篇 |
2023年 | 498篇 |
2022年 | 664篇 |
2021年 | 1142篇 |
2020年 | 1105篇 |
2019年 | 1241篇 |
2018年 | 1138篇 |
2017年 | 685篇 |
2016年 | 622篇 |
2015年 | 794篇 |
2014年 | 1869篇 |
2013年 | 1562篇 |
2012年 | 1135篇 |
2011年 | 1423篇 |
2010年 | 1195篇 |
2009年 | 1136篇 |
2008年 | 1275篇 |
2007年 | 1353篇 |
2006年 | 1215篇 |
2005年 | 1138篇 |
2004年 | 917篇 |
2003年 | 823篇 |
2002年 | 734篇 |
2001年 | 762篇 |
2000年 | 625篇 |
1999年 | 628篇 |
1998年 | 584篇 |
1997年 | 588篇 |
1996年 | 465篇 |
1995年 | 426篇 |
1994年 | 403篇 |
1993年 | 337篇 |
1992年 | 341篇 |
1991年 | 302篇 |
1990年 | 269篇 |
1989年 | 186篇 |
1988年 | 197篇 |
1987年 | 176篇 |
1986年 | 184篇 |
1985年 | 160篇 |
1984年 | 182篇 |
1983年 | 121篇 |
1982年 | 111篇 |
1981年 | 77篇 |
1980年 | 68篇 |
1979年 | 55篇 |
1978年 | 42篇 |
1977年 | 16篇 |
1976年 | 27篇 |
1973年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 734 毫秒
991.
Li Shen Pardeep S. Jhund Inder S. Anand Ankeet S. Bhatt Akshay S. Desai Aldo P. Maggioni Felipe A. Martinez Marc A. Pfeffer Adel R. Rizkala Jean L. Rouleau Karl Swedberg Muthiah Vaduganathan Orly Vardeny Dirk J. van Veldhuisen Faiez Zannad Michael R. Zile Milton Packer Scott D. Solomon John J.V. McMurray 《Journal of the American College of Cardiology》2021,77(16):1961-1973
BackgroundThe incidence of pneumonia and subsequent outcomes has not been compared in patients with heart failure and reduced ejection fraction (HFrEF) and preserved ejection fraction (HFpEF).ObjectivesThis study aimed to examine the rate and impact of pneumonia in the PARADIGM-HF (Prospective Comparison of Angiotensin Receptor-Neprilysin Inhibitor With Angiotensin Converting Enzyme Inhibitor to Determine Impact on Global Mortality and Morbidity in Heart Failure) and PARAGON-HF (Prospective Comparison of ARNI with ARB Global Outcomes in Heart Failure with Preserved Ejection Fraction) trials.MethodsThe authors analyzed the incidence of investigator-reported pneumonia and the rates of HF hospitalization, cardiovascular death, and all-cause death before and after the occurrence of pneumonia, and estimated risk after the first occurrence of pneumonia in unadjusted and adjusted analyses (the latter including N-terminal pro–B-type natriuretic peptide).ResultsIn PARADIGM-HF, 528 patients (6.3%) developed pneumonia after randomization, giving an incidence rate of 29 (95% CI: 27 to 32) per 1,000 patient-years. In PARAGON-HF, 510 patients (10.6%) developed pneumonia, giving an incidence rate of 39 (95% CI: 36 to 42) per 1,000 patient-years. The subsequent risk of all trial outcomes was elevated after the occurrence of pneumonia. In PARADIGM-HF, the adjusted hazard ratio (HR) for the risk of death from any cause was 4.34 (95% CI: 3.73 to 5.05). The corresponding adjusted HR in PARAGON-HF was 3.76 (95% CI: 3.09 to 4.58).ConclusionsThe incidence of pneumonia was high in patients with HF, especially HFpEF, at around 3 times the expected rate. A first episode of pneumonia was associated with 4-fold higher mortality. (Prospective Comparison of Angiotensin Receptor–Neprilysin Inhibitor With Angiotensin-Converting Enzyme Inhibitor to Determine Impact on Global Mortality and Morbidity in Heart Failure [PARADIGM-HF], NCT01035255; Prospective Comparison of ARNI [Angiotensin Receptor–Neprilysin Inhibitor] With ARB [Angiotensin Receptor Blocker] Global Outcomes in Heart Failure With Preserved Ejection Fraction [PARAGON-HF], NCT01920711) 相似文献
992.
Tapan G. Rami Rupa Bala Edward P. Gerstenfeld 《Journal of interventional cardiac electrophysiology》2006,15(2):119-123
Cardiac resynchronization therapy is an effective tool for the treatment of drug-refractory heart failure in patients with
left ventricular dysfunction and inter/intra ventricular conduction delay. Supraventricular tachycardias may prevent effect
delivery of this therapy. We report three cases in which effective therapy was limited by asymptomatic supraventricular tachycardia.
Diagnostic pacing maneuvers were performed via the implanted device to determine the underlying arrhythmia mechanism. These
cases highlight the importance of (1) treating supraventricular tachycardias before and after implantation of cardiac devices
and (2) using device based programmed stimulation to diagnose the mechanism of supraventricular tachycardias.
Dr. Gerstenfeld is supported by a Scientist Development Grant from the American Heart Association. 相似文献
993.
G. André Ng Ernest W. Lau Michael J. Griffith 《Journal of interventional cardiac electrophysiology》2002,7(3):209-214
Background: Electrophysiological study (EPS) followed by radiofrequency (RF) ablation has emerged as the treatment of choice for symptomatic narrow complex tachycardia (NCT), for which purpose, 5 catheters are typically used (4 for the initial EPS and an additional one for the subsequent RF ablation). We describe an alternative, streamlined approach using only 3 catheters [2 standard (diagnostic) and 1 deflectable, thermistor tip (mapping)] as the standard configuration for EPS and RF ablation in patients with NCT but no pre-excitation on ECG.
Methods and Results: Diagnosis was obtained in all 250 consecutive patients (mean age 45 years, 174 females): atrio-ventricular nodal re-entrant tachycardia (AVNRT) in 188 (75%), concealed accessory pathways (AP's) in 38 patients (15%), ectopic atrial tachycardia in 19 patients (8%), persistent junctional re-entrant tachycardia (PJRT) in 4 patients (2%) and atrial fibrillation in 1 patient. An additional diagnostic catheter was used for optimising atrial pacing in 3 patients and for ventricular pacing in concealed right postero-septal AP's in another 3. An additional mapping catheter was used in 31 patients with concealed left-sided AP's, 2 with multiple AP's and 1 with PJRT. Three patients had complications (1 pulmonary embolism, 1 pericardial effusion and 1 atrio-ventricular node block). Overall, the immediate success rate was 98% (224/229) with a recurrence rate of 4.4% (10/224), and the total success rate (with repeat RF ablation if necessary) was 99.2% (227/229) over a median follow-up period of 31.4 months. The average cost saving was US$474 per procedure. Procedure duration (2.0 ± 0.1 hours), fluoroscopy time (13 ± 1 minutes) and the number of radiofrequency applications (5.4 ± 0.3) also compared favourably with values reported in the literature for RF ablation of AVNRT.
Conclusion: Compared to the conventional 5-catheter configuration for the combined EPS and RF ablation procedure in treatment of patients with NCT, the described 3-catheter configuration reduces cost, procedure duration and fluoroscopy time without compromising on success rate and safety. On these bases, we advocate its widespread adoption. 相似文献
994.
Costa JM Tsutsui JM Nozawa E Morhy SS Andrade JL Ramires JF Mathias W 《Echocardiography (Mount Kisco, N.Y.)》2005,22(5):389-394
Patients in an intensive care unit (ICU) under mechanical ventilation (MV) are very difficult to image by transthoracic echocardiography, diminishing the beneficial information that could be obtained by this noninvasive approach. The objective of this study is to assess whether the addition of a contrast agent to fundamental imaging (FI) can improve or change the initial diagnosis in cardiac postoperative patients under mechanical ventilation by enhancing endocardial border delineation and Doppler flow signal. Thirty mechanically ventilated post-cardiac surgery patients (20 men, mean age 61 +/- 13 years) were evaluated with FI before and after intravenous injection of contrast. Left ventricular endocardial border delineation score index (EBDSI), estimated left ventricular ejection fraction (LVEF), and color and spectral Doppler were analyzed. The use of contrast resulted in a significant increase in the number of well-delineated segments, with a salvage rate of 77% of nondiagnostic studies. EBDSI was 1.62 +/- 0.61, before contrast, increasing to 2.05 +/- 0.53 after it (P < 0.001). There was a change in the LVEF estimation in 5 exams, and a new wall motion abnormality was detected in other 4 exams, after the use of contrast. Moreover, a significant change was observed in the quantification of mitral regurgitation in 5 patients, in the aortic transvalvular peak gradient in 1 patient, and measurement of tricuspid regurgitation peak flow velocity in 8 patients. It is concluded that in cardiac postoperative patients under mechanical ventilation, intravenous injection of a contrast agent using FI resulted in a high salvage rate of studies and changed the initial diagnosis in a significant number of patients. 相似文献
995.
BONNIE J. BAKER M.D. † MICHAEL A. BRODSKY M.D. HA DINH M.D. † BYRON J. ALLEN M.D. BARBARA COTTER L.P.N. † CATHY LUCKETT R.N. MARVIN L. MURPHY M.D. † 《Journal of cardiovascular electrophysiology》1987,1(6):527-535
The effects of propafenone on left ventricular function and hemodynamics are presented in this study. In one group of 13 patients who underwent electrophysiological testing and subsequent chronic oral therapy with propafenone, eight had left ventricular ejection fractions determined by nuclear study before and during therapy with the drug. Initial measurements ranged from 22% to 39% (mean 30%), while those on chronic therapy showed no statistical difference and ranged from 22% to 48% (mean 30%). In a separate dose titration study of 14 patients, left ventricular ejection fraction showed a modest but significant decrease (52%± 9% to 48%± 11%; p < 0.05). This change was more marked in patients with an initial low ejection fraction. Propafenone appears to be safe in these patients but should be administered with caution in patients with particularly low ejection fractions. 相似文献
996.
Jay N. Cohn M.D. 《Cardiovascular drugs and therapy / sponsored by the International Society of Cardiovascular Pharmacotherapy》1994,8(1):119-122
Summary Vasodilator drugs, particularly intravenously infused nitroprusside and an orally administered combination of hydralazine and isosorbide dinitrate, exert a profoundly favorable hemodynamic effect in the setting of heart failure complicating a prior myocardial infarction. Although these oral drugs also may relieve symptoms and improve exercise tolerance, the long-term benefits appear to be related to inhibition or reversal of the left ventricular dilation that results in a progressive fall in left ventricular ejection fraction. The long-term efficacy of both ACE inhibitors and hydralazine-nitrate in symptomatic heart failure makes the vasodilator combination a rational alternative to an ACE inhibitor and possibly an effective agent for cotherapy with an ACE inhibitor. Trials are needed to test the additive efficacy of this vasodilator combination and to develop other safe and effective drugs that target the progressive remodeling process in heart failure. 相似文献
997.
Sehra R Coppess MA Altemose GT Militello CA Miller JM 《Journal of cardiovascular electrophysiology》2000,11(5):582-586
We report a case of atrial tachycardia masquerading as atrial flutter in a man who had previously undergone catheter ablation for atrial flutter. The recurrent arrhythmia was electrocardiographically almost identical to the prior atrial flutter; at repeat electrophysiologic study, although bidirectional conduction block was observed in the tricuspid annulus-inferior vena caval isthmus, the atrial arrhythmia was readily initiated. Activation mapping suggested typical atrial flutter, but entrainment techniques demonstrated intra-atrial reentry not involving the ablated isthmus. This case illustrates the need to apply entrainment techniques even in cases of apparent "typical" atrial flutter to confirm that putative ablation targets are necessary for tachycardia perpetuation. 相似文献
998.
Does primary stenting preserve cardiac function in myocardial infarction? A case-control study 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《Heart (British Cardiac Society)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Sasao H Tsuchihashi K Hase M Nakata T Shimamoto K 《Heart (British Cardiac Society)》2000,84(5):515-521
OBJECTIVE—To investigate whether coronary stenting limits myocardial injury and preserves left ventricular function.
DESIGN AND SETTING—Prospective multicentre case-control study of primary percutaneous transluminal coronary angioplasty (PTCA) with and without stenting, performed in seven cardiovascular centres.
SUBJECTS AND METHODS—45 consecutive patients with acute myocardial infarction who were treated with successful primary stenting (Stent group) and did not have restenosis were paired with 45 matched control subjects with acute myocardial infarction treated by successful primary PTCA without stenting, also with no restenosis (POBA group).
RESULTS—In comparison with the POBA group, the Stent group—especially those patients with a left anterior descending coronary artery lesion—had a smaller hypokinesis area (mean (SD): 15.1 (20.0) v 34.4 (24.3) chords), reduced hypokinesis area/risk area (25.2 (31.9)% v 58.8 (40.1)%), and a larger ejection fraction (63.3 (10.2)% v 51.7 (11.7)%) evaluated by quantitative left ventriculography using the centreline method. In the Stent group, the correlation between risk area and hypokinesis area was significantly shifted downward. Multiple logistic regression analysis on infarct size limitation (hypokinesis area/risk area < 50%) identified preinfarction angina in all subjects and preinfarction angina and stenting in patients with left anterior descending coronary artery leasions as explanatory factors.
CONCLUSIONS—Primary PTCA using a coronary stent is effective in preventing myocardial injury and restoring left ventricular function in patients with anterior acute myocardial infarction.
Keywords: acute myocardial infarction; primary stenting; left ventricular function; preinfarction angina 相似文献
DESIGN AND SETTING—Prospective multicentre case-control study of primary percutaneous transluminal coronary angioplasty (PTCA) with and without stenting, performed in seven cardiovascular centres.
SUBJECTS AND METHODS—45 consecutive patients with acute myocardial infarction who were treated with successful primary stenting (Stent group) and did not have restenosis were paired with 45 matched control subjects with acute myocardial infarction treated by successful primary PTCA without stenting, also with no restenosis (POBA group).
RESULTS—In comparison with the POBA group, the Stent group—especially those patients with a left anterior descending coronary artery lesion—had a smaller hypokinesis area (mean (SD): 15.1 (20.0) v 34.4 (24.3) chords), reduced hypokinesis area/risk area (25.2 (31.9)% v 58.8 (40.1)%), and a larger ejection fraction (63.3 (10.2)% v 51.7 (11.7)%) evaluated by quantitative left ventriculography using the centreline method. In the Stent group, the correlation between risk area and hypokinesis area was significantly shifted downward. Multiple logistic regression analysis on infarct size limitation (hypokinesis area/risk area < 50%) identified preinfarction angina in all subjects and preinfarction angina and stenting in patients with left anterior descending coronary artery leasions as explanatory factors.
CONCLUSIONS—Primary PTCA using a coronary stent is effective in preventing myocardial injury and restoring left ventricular function in patients with anterior acute myocardial infarction.
Keywords: acute myocardial infarction; primary stenting; left ventricular function; preinfarction angina 相似文献
999.
1000.
Alan Bulava Petr Heinc Martin Hutyra Milan Kaminek Malvina Krivankova Marek Richter Jan Lukl 《Journal of interventional cardiac electrophysiology》2006,16(2):117-122
A sixty-year-old man with previous history of coronary artery disease was admitted due to progressive worsening of dyspnoea at exertion (NYHA III functional class) and no angina. Coronary angiography confirmed occlusion of the right coronary artery which was naturally bypassed by homocollaterals with TIMI 3 flow to the peripheral branches. The lesion was not technically suitable for percutaneous angioplasty. The left coronary artery was without stenosis. On echocardiography, both the left ventricle and the left atrium were dilated and hemodynamically significant mitral regurgitation was present. Surface ECG showed a left bundle branch block with repeated runs of monomorphic ventricular ectopic beats (PVC). Radiofrequency catheter ablation of the focus in the posteroseptal region of the left ventricle underneath the mitral valve was performed using electroanatomical mapping system. After the procedure, mitral regurgitation decreased and reverse remodeling of the left ventricle and the left atrium occurred with concomitant significant clinical improvement of the patient. The authors discuss several treatment strategies: mitral valve repair surgery combined with revascularization, implantation of a biventricular ICD system or elimination of the focus of monomorphic VT runs by radiofrequency catheter ablation as a possible causal approach in the treatment of PVC-induced cardiomyopathy. 相似文献