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   1322篇
  免费   85篇
  国内免费   5篇
耳鼻咽喉   3篇
儿科学   75篇
妇产科学   34篇
基础医学   134篇
口腔科学   66篇
临床医学   113篇
内科学   293篇
皮肤病学   15篇
神经病学   59篇
特种医学   23篇
外科学   277篇
综合类   39篇
预防医学   70篇
眼科学   62篇
药学   114篇
中国医学   7篇
肿瘤学   28篇
  2023年   10篇
  2022年   35篇
  2021年   56篇
  2020年   24篇
  2019年   38篇
  2018年   46篇
  2017年   27篇
  2016年   23篇
  2015年   24篇
  2014年   38篇
  2013年   40篇
  2012年   62篇
  2011年   92篇
  2010年   31篇
  2009年   41篇
  2008年   75篇
  2007年   80篇
  2006年   74篇
  2005年   73篇
  2004年   61篇
  2003年   42篇
  2002年   43篇
  2001年   25篇
  2000年   28篇
  1999年   15篇
  1998年   8篇
  1996年   10篇
  1995年   7篇
  1993年   8篇
  1992年   23篇
  1991年   19篇
  1990年   22篇
  1989年   18篇
  1988年   9篇
  1987年   7篇
  1986年   10篇
  1985年   10篇
  1984年   7篇
  1983年   7篇
  1981年   8篇
  1979年   14篇
  1978年   7篇
  1975年   10篇
  1974年   14篇
  1973年   15篇
  1972年   8篇
  1970年   6篇
  1969年   7篇
  1968年   7篇
  1966年   6篇
排序方式: 共有1412条查询结果,搜索用时 15 毫秒
141.
Idiopathic interstitial pneumonias are diseases of the lung interstitium where the etiology is unknown. They constitute the largest group of interstitial lung diseases. Making a diagnosis can be challenging due to the diversity of clinical presentations and frequently, non-specific radiological and pathological findings. The most common form, idiopathic pulmonary fibrosis, has a poor prognosis with median survival of 3 years from diagnosis. There have been changes in the nomenclature of different individual entities over the years. Moreover, there is paucity of data on the best treatments available to manage this group of lung diseases. The nomenclature, clinical features, pathophysiology, diagnostic techniques, and prognosis of the idiopathic interstitial pneumonias are discussed in this review.  相似文献   
142.
Radiofrequency ablation for cure of atrial flutter   总被引:1,自引:0,他引:1  
Abstract Background: Atrial flutter is a common arrhythmia which frequently recurs after cardioversion and is relatively difficult to control with antiarrhythmic agents.
Aims: To evaluate the success rate, recurrence rate and safety of radiofrequency (RF) ablation for atrial flutter in a consecutive series of patients with drug refractory chronic or paroxysmal forms of the arrhythmia.
Methods: Electrophysiologic evaluation of atrial flutter included activation mapping with a 20 electrode halo cadieter placed around the tricuspid annulus and entrainment mapping from within the low right atrial isthmus. After confirmation of the arrhythmia mechanism with these techniques, an anatomic approach was used to create a linear lesion between the inferior tricuspid annulus and the eustachian ridge at the anterior margin of the inferior vena cava. In order to demonstrate successful ablation, mapping techniques were employed to show that bi-directional conduction block was present in the low right atrial isthmus.
Results: Successful ablation was achieved in 26/27 patients (96%). In one patient with a grossly enlarged right atrium, isthmus block could not be achieved. Of the 26 patients with successful ablation, mere has been one recurrence of typical flutter (4%) during a mean follow-up period of 5.5±2.7 months. This patient underwent a successful repeat ablation procedure. Of eight patients with documented clinical atrial fibrillation (in addition to atrial flutter) prior to the procedure, five continued to have atrial fibrillation following the ablation. There were no procedural complications and all patients had normal AV conduction at the completion of the ablation.
Conclusions: RF ablation is a highly effective and safe procedure for cure of atrial flutter. In patients with chronic or recurrent forms of atrial flutter RF ablation should be considered as a first line therapeutic option.  相似文献   
143.
IntroductionEgypt has established different types of surveillance systems to monitor influenza activities, early detect outbreaks, and tailor efficient prevention and control strategies. This is the first study to describe epidemiology and outcome of influenza‐associated infections among hospitalized patients using the National Electronic Disease Surveillance System (NEDSS) data, 2016‐2019.MethodsData reported from 284 hospitals all over Egypt were extracted from the NEDSS. Data of hospitalized patients with Acute Respiratory Infections (ARI), 2016‐2019, were included in the analysis. Laboratory testing for influenza by RT‐PCR according to US CDC testing protocol was used to confirm influenza type and subtype.ResultsOverall 46 417 patients hospitalized with ARI were identified, their mean age was 30.9 ± 26 and 52.9% were males. Among 41 512 (89.4%) laboratory‐tested patients, 7167 (17.3%) were positive for one or more types of influenza viruses. Influenza viruses circulated in all ages and throughout the year, with higher rates in winter, late childhood, and middle ages. Mortality from influenza was significantly higher than other causes of ARIs (5.0% vs 3.8%, P < .001), and it was associated with older ages, December‐May, delay in hospital admission, residence in urban and frontier governorates and infection with A/H1N1 virus. The distribution of influenza subtype by time shows alternate pattern between A/H1N1 and H3N2, each subtype peaks every other year with a high peak of A/H1N1 in 2016.ConclusionsThe national Egyptian surveillance succeeded to describe the epidemiology of hospitalized patients with ARIs and influenza in Egypt over time. Surveillance with strain‐specific laboratory testing and annual assessment of associated severity might be useful to guide influenza prevention and control strategies including vaccination and case management.  相似文献   
144.
145.

Background

Drug‐coated balloons (DCB) have been used to treat de novo small vessel coronary disease (SVD), with promising results and shorter dual antiplatelet therapy (DAPT) duration compared to drug‐eluting stents (DES). We compared safety and effectiveness of the two treatments at 1 year.

Methods

We reviewed 3,613 angioplasty cases retrospectively from 2011 to 2013 and identified 335 patients with SVD treated with device diameter of ≤2.5 mm. DCB‐only angioplasty was performed in 172 patients, whereas 163 patients were treated with second‐generation DES.

Results

DCB patients had smaller reference vessel diameter (2.22 ± 0.30 vs. 2.44 ± 0.19 mm, P < 0.001) and received smaller devices (median diameter 2.25 vs. 2.50 mm, P < 0.001) compared to the DES group. DES‐treated vessels had larger acute lumen gain (1.71 ± 0.48 mm) than DCB (1.00 ± 0.53 mm, P < 0.001). Half the patients had diabetes mellitus. While there were more patients presenting with acute coronary syndrome (ACS) in the DCB group (77.9% vs. 62.2%, P = 0.013), they received shorter DAPT (7.4 ± 4.7 vs. 11.8 ± 1.4 months, P < 0.001) than the DES group. The 1‐year composite major adverse cardiac event rate was 11.6% in the DCB arm and 11.7% in the DES arm (P = 1.000), with target lesion revascularization rate of 5.2% and 3.7%, respectively, (P = 0.601).

Conclusions

In this high‐risk cohort of patients, DCB‐only angioplasty delivered good clinical outcome at 1 year. The results were comparable with DES‐treated patients, but had the added benefit of a shorter DAPT regime.
  相似文献   
146.

Objective

Prediabetes is defined by elevations of plasma glucose concentration, and is aimed at identifying individuals at increased risk of type 2 diabetes and coronary heart disease (CHD). However, since these individuals are also insulin resistant and hyperinsulinemic, we evaluated the association between several facets of carbohydrate metabolism and CHD risk profile in apparently healthy, nondiabetic individuals.

Methods

Plasma glucose and insulin concentrations were measured before and at hourly intervals for eight hours after two test meals in 281 nondiabetic individuals. Insulin action was quantified by determining the steady-state plasma glucose (SSPG) concentration during the insulin suppression test. CHD risk was assessed by measurements of blood pressure and fasting lipoprotein profile.

Results

For purposes of analysis, the population was divided into tertiles, and the results demonstrated that the greater the 1) fasting plasma glucose (FPG) concentration, 2) incremental plasma insulin response to meals, and 3) SSPG concentration, the more adverse the CHD risk profile (p < 0.05). In contrast, the CHD risk profile did not significantly worsen with increases in the incremental plasma glucose response to meals.

Conclusions

In nondiabetic individuals, higher FPG concentrations, accentuated daylong incremental insulin responses to meals, and greater degrees of insulin resistance are each associated with worse CHD risk profile (higher blood pressures, higher triglycerides, and lower high density lipoprotein cholesterol concentrations). Interventional efforts aimed at decreasing CHD in such individuals should take these abnormalities into consideration.  相似文献   
147.
OBJECTIVE: To compare the frequency of acute stress ulceration and secondary pneumonia caused by aerobic Gram-negative bacilli in ICU patients treated with either sucralfate or ranitidine. DESIGN: Prospective, randomized study. SETTING: ICU, university hospital. PATIENTS: Sixty adult patients who were mechanically ventilated and at risk of developing stress ulceration. INTERVENTION: The patients were randomized to receive either sucralfate (1 g every 6 hrs) via the nasogastric tube or iv ranitidine (50 mg every 6 hrs). If the gastric pH was less than 3.5 in the latter group, 30 mL of 0.3M sodium citrate was given via the nasogastric tube. MEASUREMENTS AND MAIN RESULTS: On admission, the frequency rate of erosion/ulceration (assessed with the endoscope) was 13.5%. After 4 days, this rate had increased to 18% in sucralfate-treated patients and 36% in ranitidine-treated patients (NS). Mean gastric pH was more alkaline in the ranitidine-treated patients (5.50) compared with the sucralfate-treated patients (4.26) (p less than .01). This pH permitted a higher occurrence rate of gastric colonization by aerobic Gram-negative bacilli in ranitidine-treated patients (64.3%) compared with sucralfate-treated patients (23.8%) (p less than .01). Retrograde bacterial colonization from the stomach to oropharynx and trachea occurred more frequently in ranitidine-treated patients compared with sucralfate-treated patients. Ultimately, the occurrence rate of pneumonia was greater in the ranitidine-treated (35.7%) than in the sucralfate-treated patients (10.3%) (p less than .05). CONCLUSION: Based on our findings, we recommend the adoption of sucralfate for routine prophylaxis against stress ulceration.  相似文献   
148.
BACKGROUND: Incomplete concordance for psychosis in monozygotic (MZ) twins has been interpreted as indicative of non-genetic cofactors in transmission of the illness. In this case study, we consider childbirth a landmark in the onset of psychotic symptoms, leading to the diagnosis of puerperal psychosis and then to bipolar/schizoaffective disorder. At the end of the third trimester, there is a sudden drop in estrogen, which exerts prominent effects on the serotonergic system in the orbitofrontal cortex (OFC). OBJECTIVES: The purpose of the present study was to investigate OFC activation during emotional processing in MZ twins discordant for affective psychosis. METHODS: Blood-oxygen-level-dependent activation using functional magnetic resonance imaging was measured during the passive viewing of emotional film excerpts. RESULTS: Consistent with our hypothesis, a significant locus of activation was found in the left OFC in the normal MZ twin, but not in the psychosis MZ twin. CONCLUSIONS: The personality changes noted in the psychosis MZ twin (postpartum psychosis) may be related to dysfunctional OFC. Ms J's childbirth may have triggered the onset of psychotic symptoms, leading to the diagnosis of bipolar or schizoaffective disorder.  相似文献   
149.
The effect of histamine on adrenergic neurotransmission in the mouse isolated vas deferens preparation was investigated. Concentrations of histamine ranging from 0.2 to 650 M depressed, in a dose-related manner, not only the contractile response elicited by field stimulation but also the response caused by the addition of exogenous noradrenaline and acetylcholine. However, the release of [3H]-NA evoked by field stimulation or by high K+ remained unchanged in the presence of these concentrations of histamine. The inhibitory effect of histamine on the contractile responses caused by various stimuli was reduced or completely antagonized by cimetidine, a histamine H2-receptor antagonist but not by mepyramine, a conventional antihistamine. The inhibitory effect of histamine was found to be inversely proportional to both the Ca2+ concentration in the bathing medium and to the frequency of field stimulation. Further, the inhibitory effect of histamine was markedly reduced when Mg2+ was omitted from the bathing medium. It is concluded that the mouse vas deferens preparation contains a post-junctional inhibitory H2-receptor. The stimulation of H2-receptors by histamine inhibits the contractile response of the vas deferens, possibly by decreasing the availability of Ca2+ required for contraction by depressing the influx of Ca2+.  相似文献   
150.
Seventy-two patients with acute myocardial infarction complicated by atrioventricular or bundle-branch block or a combination of both had His bundle electrogram studies performed during their stay in the coronary care unit. In 19 of the 72 patients a repeat His bundle electrogram was performed before discharge from hospital. These studies demonstrated that 30 of the 32 patients with atrioventricular block and narrow QRS complexes had a block above the origin othe His spike (proximal block). Eleven patients in this group had repeat His bundle electrograms performed before discharge and in 3 patients there was evidence of residual atrioventricular nodal dysfunction. Both the hospital and follow-up mortality in this group was low and there was no evidence to suggest that permanent pacing would benefit these patients. Of the 18 patients with bundle-branch block and a normal PR interval, 9 had prolongation of the HV interval, but there was no difference in mortality in patients with normal or prolonged HV intervals. Twenty-two patients with bundle-branch block also developed atrioventricular block. In 5 of these patients the site of the AV block was proximal and in 14 it was distal, while 3 patients had both proximal and distal block. The hospital mortality in those patients who progressed to second- or third-degree atrioventricular block was considerably higher than in those patients who remained in first-degree atrioventricular block.  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