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   1553篇
  免费   103篇
  国内免费   7篇
耳鼻咽喉   20篇
儿科学   48篇
妇产科学   16篇
基础医学   177篇
口腔科学   46篇
临床医学   149篇
内科学   317篇
皮肤病学   45篇
神经病学   123篇
特种医学   77篇
外科学   297篇
综合类   21篇
一般理论   1篇
预防医学   60篇
眼科学   39篇
药学   129篇
中国医学   4篇
肿瘤学   94篇
  2024年   2篇
  2023年   13篇
  2022年   36篇
  2021年   110篇
  2020年   67篇
  2019年   76篇
  2018年   82篇
  2017年   44篇
  2016年   54篇
  2015年   60篇
  2014年   84篇
  2013年   95篇
  2012年   142篇
  2011年   127篇
  2010年   70篇
  2009年   61篇
  2008年   79篇
  2007年   70篇
  2006年   73篇
  2005年   51篇
  2004年   44篇
  2003年   32篇
  2002年   21篇
  2001年   17篇
  2000年   16篇
  1999年   8篇
  1998年   10篇
  1997年   12篇
  1996年   13篇
  1995年   9篇
  1992年   2篇
  1991年   6篇
  1990年   3篇
  1989年   2篇
  1988年   4篇
  1987年   5篇
  1986年   7篇
  1985年   7篇
  1984年   6篇
  1983年   3篇
  1982年   5篇
  1981年   2篇
  1980年   4篇
  1979年   2篇
  1978年   3篇
  1977年   5篇
  1976年   5篇
  1975年   2篇
  1973年   4篇
  1970年   4篇
排序方式: 共有1663条查询结果,搜索用时 578 毫秒
221.
222.
223.
224.
Inguinal hernia is the commonest surgical operation. This is a large study from a district general hospital. The study spanned over 2 years with 2 further years of follow up. It is a retrospective analysis of eight hundred and seventy seven (877)inguinal hernia operations performed in a district general hospital. The following factors were looked at: type of repair, grade of surgeon performing the procedure and outcome of various repairs. The results showed that the most common technique was the Lichenstein’s repair(58%). Recurrence rates were between 0.4%–30% depending on types of hernia repair.  相似文献   
225.
We describe the initial—and successful—use of the TandemHeart System''s catheters to provide extracorporeal membrane oxygenation (ECMO), in 2 patients. In 1 patient, who was experiencing severe primary respiratory failure, the catheters provided a standard venovenous ECMO circuit. In the other patient, who had severe, acute pulmonary hypertension and right-heart failure, the catheters enabled a novel right atrial-to-left atrial circuit for ECMO. We discuss the potential of the TandemHeart System''s catheters to provide novel and possibly superior vascular routes for the delivery of ECMO in different types of cardiopulmonary failure.Key words: Extracorporeal circulation, extracorporeal membrane oxygenation/instrumentation/methods, heart failure/therapy, heart-assist devices, hemodynamics, methods, pneumonia/complications, respiratory insufficiency/therapy, technology assessment, biomedical, treatment outcomeExtracorporeal membrane oxygenation (ECMO) first came into wide clinical use as a tool to enable open-heart surgery through cardiopulmonary bypass (CPB) in the 1960s.1,2 By the 1970s, there was hope that ECMO technology could provide effective temporary oxygenation in patients who had a major, yet reversible, lung injury but in whom mechanical ventilation was not completely effective.3 A generation later, ECMO technology is a well-established, widely used method of support in neonatal and pediatric patients who experience severe respiratory failure.4 In contrast, progress in the application of ECMO to improve outcomes of respiratory failure in adults has been much slower. A large National Institutes of Health-sponsored trial of ECMO use in severe respiratory failure of various causes5 failed to show a benefit and thereby dampened enthusiasm for this application for more than a decade. New technology and implementation methods, however, have reinvigorated interest in the use of ECMO when severe respiratory failure occurs in adults.6,7 Indeed, data from the recently completed, large, prospective CESAR trial suggest that ECMO may already be of great usefulness in patients who are experiencing severe respiratory failure.8–10There have also been encouraging reports of the successful use of ECMO to support patients who are experiencing acute right-heart failure,11 acute refractory left-heart failure,12 postcardiotomy heart failure,13 prolonged cardiac arrest,14 and postoperative cardiogenic shock.15 In these circumstances, ECMO has served temporarily (sometimes along with mechanical hemodynamic support) until heart recovery, or as a bridge to heart transplantation, heart–lung transplantation, or the placement of a left ventricular (LV) assist device.The TandemHeart® PTVA® System (CardiacAssist, Inc.; Pittsburgh, Pa) is a new, percutaneously placed, ventricular assist device that has proved to be effective in the short-term management of acute heart failure.16 The system features innovative vascular-access catheters that enable a minimally invasive approach to mechanical LV assistance. We report here the 1st experience of using these catheters to perform ECMO, in 2 patients. One patient had severe primary respiratory failure, and the other had respiratory failure and right-heart failure caused by severe pulmonary hypertension. The TandemHeart catheters were placed in different intravascular locations in each patient. Our experience suggests that the TandemHeart catheter system can offer innovative and superior options for ECMO delivery to different populations of patients who experience cardiopulmonary failure.  相似文献   
226.
Background The missed diagnosis of acute myocardial infarction has been studied in the Emergency Department, but few studies have investigated how often coronary ischemia is correctly identified in the outpatient setting. Methods This was a single center retrospective observational study of patients with Health Alliance Plan medical insurance hospitalized at a US tertiary center with acute myocardial infarction in 2004. Outpatient encounters in the 30 days preceding acute myocardial infarction were reviewed by two independent cardiologists for presenting symptoms and diagnostic decision-making in order to classify patient presentations as acute coronary ischemia, stable angina or neither. Results There were 331 patients with acute myocardial infarction, including 190 (57%) with a primary diagnosis of AMI and evaluated by a physician in the preceding 30 days. This group included 68 patients with 95 documented outpatient encounters by a primary care physician, cardiologist, or other internal medicine specialist which formed the final study population. Mean interval between these encounters and AMI was 17 ± 11 days. Of these patients, 7 (10%) had symptoms of acute coronary ischemia, 5 (7%) had stable angina symptoms, and 56 (83%) had no symptoms of coronary ischemia at their outpatient encounters. Of the 7 patients with acute coronary ischemic symptoms, 5 were correctly identified and 2 were misidentified. Conclusion A majority of patients with subsequent AMI visit an outpatient provider in the month preceding AMI. However, few present with symptoms of coronary ischemia in the outpatient setting (10%) and these symptoms are not always identified as such.  相似文献   
227.
Objectives Our aim was to investigate the effect of etoricoxib on the anticonvulsant activity of phenytoin and diazepam against seizure models in mice. In addition the acute adverse effect of etoricoxib was assessed with a chimney test. Methods The maximal seizure pattern was induced in mice by giving an alternating current of 50 mA for 0.2 s, while chemical seizures were induced by intraperitoneal injection of pentylenetetrazole at its CD97 dose (97% convulsive dose for the clonic phase). Test drug was administered 45 min before the electrical or chemical induction of seizures in combination with conventional antiepileptics. The ability of the test drug to reduce or abolish the extensor phase of maximal electroshock and clonic‐type seizures in the chemical induction method was selected as anti‐seizure criteria. Key findings Concurrent treatment with etoricoxib at an oral dose of 10 mg/kg reduced the anticonvulsant potency of phenytoin. The protective effects of diazepam against pentylenetetrazole‐induced convulsions was significantly increased and the mortality rate was reduced by concurrent treatment with etoricoxib (10 mg/kg p.o.) when compared with diazepam groups. No neurotoxic effect was observed with etoricoxib (10 mg/kg p.o.) and it had no impact on motor coordination in the chimney test in mice. Etoricoxib applied at its highest dose (10 mg/kg) significantly enhanced the free plasma levels of diazepam whereas the free plasma levels of phenytoin were significantly reduced. Conclusions The obtained results suggest that the preferential cyclooxygenase‐2 inhibitor etoricoxib significantly reduced the anticonvulsant action of phenytoin and significantly increased the beneficial action of diazepam against maximal electroshock and pentylenetetrazole‐induced convulsions in a mouse model.  相似文献   
228.
Cigarette smoking is associated with the development of several diseases and antioxidants play a major role in the prevention of smoking-related diseases. Apoptosis is suggested as a possible contributing factor in the pathogenesis of smoking-induced toxicity. Therefore the present study was designed to investigate the influence of chronic cigarette smoke exposure on apoptosis and the modulatory effect of bacoside A (triterpenoid saponin isolated from the plant Bacopa monniera) on smoking-induced apoptosis in rat brain. Adult male albino rats of Wistar strain were exposed to cigarette smoke and simultaneously administered with bacoside A (10 mg/kg b.w./day, orally) for a period of 12 weeks. Expression of brain hsp70 was analyzed by Western blotting. Apoptosis was identified by DNA fragmentation, terminal deoxynucleotidyl transferase-mediated deoxy uridine triphosphate nick end labeling (TUNEL) staining and transmission electron microscopy. The results showed that exposure to cigarette smoke induced hsp70 expression and apoptosis as characterized by DNA laddering, increased TUNEL-positive cells and ultrastructural apoptotic features in the brain. Administration of bacoside A prevented expression of hsp70 and neuronal apoptosis during cigarette smoking. We speculate that apoptosis may be responsible for the smoking-induced brain damage and bacoside A can protect the brain from the toxic effects of cigarette smoking.  相似文献   
229.
The accuracy of in vitro inhibition parameters in scaling to in vivo drug-drug interactions (DDI) was examined for over 40 drugs using seven human P450-selective marker activities in pooled human liver microsomes. These data were combined with other parameters (systemic C(max), estimated hepatic inlet C(max), fraction unbound, and fraction of the probe drug cleared by the inhibited enzyme) to predict increases in exposure to probe drugs, and the predictions were compared with in vivo DDI gathered from clinical studies reported in the scientific literature. For drugs that had been tested as precipitants of drug interactions for more than one P450 in vivo, the order of inhibitory potencies in vitro generally aligned with the magnitude of the in vivo interactions. With the exception of many drugs known to be mechanism-based inactivators, the use of in vitro IC(50), the fraction of the affected drug metabolized by the target enzyme [f(m(CYP))] and an estimate of free hepatic inlet C(max), was generally successful in identifying those drugs that cause at least a 2-fold increase in the exposure to P450 marker substrate drugs. For CYP3A, incorporation of inhibition of both hepatic and intestinal metabolism was needed for the prediction of DDI. Many CYP3A inhibitors showed a different inhibitory potency for three different CYP3A marker activities; however, these differences generally did not alter the conclusions regarding whether a drug would cause a CYP3A DDI in vivo. Overall, these findings support the conclusion that P450 in vitro inhibition data are valuable in designing clinical DDI study strategies and can be used to predict the magnitudes of DDI.  相似文献   
230.
Transient ischemic dilatation (TID) of the left ventricle observed during single photon myocardial perfusion emission computed tomography (SPECT) is an important non-perfusion finding that may not only suggest underlying significant (usually multi-vessel) coronary artery disease (CAD) but also an independent prognostic factor of adverse outcomes regardless of abnormal or normal perfusion finding. We present a patient with no significant epicardial coronary disease who had significant TID and considerable decrease in the left ventricular ejection fraction with left ventricular dilatation after a rest-stress Tc-99 tetrofosmin SPECT study in the setting of severe aortic stenosis. With the advent of gated SPECT imaging the additive value of determining rest and post stress EF, as demonstrated in this case, aided in the recognition of TID and transient decrease in the left ventricular ejection fraction. These are not necessarily related to obstructive epicardial coronary disease, but are a result of severe aortic valve disease causing subendocardial ischemia in the setting of multilple other non-ischemic etiologies of TID such as left ventricular hypertrophy and diabetes mellitus.  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