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   1748篇
  免费   92篇
  国内免费   20篇
耳鼻咽喉   21篇
儿科学   47篇
妇产科学   78篇
基础医学   130篇
口腔科学   63篇
临床医学   109篇
内科学   393篇
皮肤病学   35篇
神经病学   28篇
特种医学   74篇
外国民族医学   2篇
外科学   483篇
综合类   19篇
一般理论   2篇
预防医学   69篇
眼科学   49篇
药学   107篇
中国医学   4篇
肿瘤学   147篇
  2024年   1篇
  2023年   32篇
  2022年   67篇
  2021年   114篇
  2020年   62篇
  2019年   80篇
  2018年   112篇
  2017年   67篇
  2016年   58篇
  2015年   55篇
  2014年   81篇
  2013年   99篇
  2012年   152篇
  2011年   174篇
  2010年   99篇
  2009年   74篇
  2008年   78篇
  2007年   67篇
  2006年   54篇
  2005年   69篇
  2004年   70篇
  2003年   55篇
  2002年   46篇
  2001年   7篇
  2000年   13篇
  1999年   7篇
  1998年   6篇
  1997年   3篇
  1996年   6篇
  1995年   2篇
  1994年   2篇
  1991年   2篇
  1989年   2篇
  1988年   5篇
  1987年   1篇
  1986年   7篇
  1985年   9篇
  1984年   7篇
  1983年   4篇
  1982年   3篇
  1981年   1篇
  1980年   2篇
  1977年   2篇
  1976年   1篇
  1965年   2篇
排序方式: 共有1860条查询结果,搜索用时 23 毫秒
51.
52.
Objectives:To explore the changing patterns of long-stay patients (LSP) to improve the utilization of pediatric intensive care units (PICUs) resources.Methods:This is a 2-points cross-sectional study (5 years apart; 2014-2019) conducted among PICUs and SCICUs in Riyadh, Saudi Arabia. Children who have stayed in PICU for more than 21 days were included.Results:Out of the 11 units approached, 10 (90%) agreed to participate. The prevalence of LSP in all these hospitals decreased from 32% (48/150) in 2014 to 23.4% (35/149) in 2019. The length of stay ranged from 22 days to 13.5 years. The majority of LSP had a neuromuscular or cardiac disease and were admitted with respiratory compromise. Ventilator-associated pneumonia was the most prevalent complication (37.5%). The most commonly used resources were mechanical ventilation (93.8%), antibiotics (60.4%), and blood-products transfusions (35.4%). The most common reason for the extended stay was medical reasons (51.1%), followed by a lack of family resources (26.5%) or lack of referral to long-term care facilities (22.4%).Conclusion:A long-stay is associated with significant critical care bed occupancy, complications, and utilization of resources that could be otherwise utilized as surge capacity for critical care services. Decreasing occupancy in this multicenter study deserves further engagement of the healthcare leaders and families to maximize the utilization of resources.  相似文献   
53.
A series of 1,2,4‐triazolo[1,5‐a]pyrimidine derivatives was designed, synthesized, and screened for their phosphodiesterase (PDE 4B) inhibitory activity and bronchodilation ability. Compound 7e showed 41.80% PDE 4B inhibition at 10 µM. Eight compounds were screened for their bronchodilator activity, where compounds 7f and 7e elicited promising bronchodilator activity with EC50 values of 18.6 and 57.1 µM, respectively, compared to theophylline (EC50 = 425 µM). Molecular docking at the PDE 4B active site revealed a binding mode and docking scores comparable to those of a reference ligand, consistent with their PDE 4B inhibition activity.  相似文献   
54.
55.
Purpose: The aim of this study was to determine effect of compressive cyclic loading on fatigue resistance and microleakage of monolithic CAD/CAM molar ceramic and composite crowns. Materials and Methods: Thirty‐two extracted molars were prepared to receive CEREC crowns according to manufacturer's guidelines using a special paralleling device (Parallel‐A‐Prep). Sixteen feldspathic ceramic crowns (VITABLOCS Mark II) (VMII) and 16 resin‐composite crowns (Paradigm‐MZ100 blocks) (PMZ) were milled using a CEREC‐3D machine. Eight crowns of each group were cemented to their respective teeth using self‐etching resin cement (Panavia‐F‐2.0) (PAN), and eight were cemented using self‐adhesive resin cement (RelyX‐Unicem‐Clicker) (RXU). Following storage for 1 week in water, specimens were subjected to uniaxial compressive cyclic loading in an Instron testing machine at 12 Hz for 1,000,000 cycles. Load was applied at the central fossa, and the cycle range was 60–600 N. Specimens were then subjected to microleakage testing. Data were statistically analyzed using factorial ANOVA and Post Hoc (Tukey HSD) tests. Results: All composite crowns survived compressive cyclic loading without fracture, while three ceramic crowns from the subgroup cemented with RXU developed surface cracks at the center of occlusal surfaces, extending laterally. Microleakage scores of ceramic crowns cemented with PAN were significantly lower than those of the other three subgroups (p < 0.05). Conclusions: After 1,000,000 cycles of compressive cyclic loading, PMZ composite molar crowns were more fatigue‐resistant than VMII ceramic crowns. Cement type had a significant effect on fatigue resistance of the ceramic crowns but not the composite ones. Microleakage scores of ceramic crowns cemented with PAN were significantly lower than those of the other subgroups (p < 0.05).  相似文献   
56.
Percutaneous management of valvular heart disease is becoming a reality, with multicenter trials supporting minimally invasive procedures for both aortic and mitral valve disease. Historically, the treatment of choice has been aortic valve replacement with conventional surgery for patients with severe aortic stenosis, as the prognosis of untreated patients is poor, particularly if the patient is symptomatic. Transcatheter aortic valve replacement is now available as a minimally invasive option to treat select high-risk patients with severe aortic stenosis. At present more than 30,000 procedures have been performed worldwide, mostly confined to patients at high surgical risk. The short- and medium-term outcomes have been promising.  相似文献   
57.
Little is known about the impact of thrombolytic agents on in-hospital outcomes in the Middle East. The objective of this study was to evaluate the impact of thrombolytic agents on in-hospital outcomes in ST-segment elevation myocardial infarction (STEMI) patients in six Middle Eastern countries. Gulf Registry of Acute Coronary Events was a prospective, multinational, multicentre, observational survey of consecutive acute coronary syndrome patients admitted to 65 hospitals in 2006 and 2007. Out of 1,765 STEMI patients admitted to hospitals within 12 h of symptoms onset, 25, 43, and 30% were treated with streptokinase, reteplase, and tenecteplase, respectively. Median age of the study cohort was 50 (45–59) years and majority were males (89%). The overall median symptom onset-to-presentation and median door-to-needle times were 130 min (65–240) and 45 min (30–75), respectively. Streptokinase patients had worse GRACE risk scores compared to patients who received fibrin specific thrombolytics. Academic hospitals and cardiologists as admitting physicians were associated with the use of fibrin specific thrombolytics. After significant covariate adjustment, both reteplase [odds ratio (OR), 0.38; 95% CI: 0.18–0.79; P = 0.009] and tenecteplase (OR, 0.30; 95% CI: 0.12–0.77; P = 0.012) were associated with lower all-cause in-hospital mortality compared with streptokinase. No significant differences in other in-hospital outcomes were noted between the thrombolytic agents. In conclusion, in light of the study’s limitations, fibrin specific agents, reteplase and tenecteplase, were associated with lower all-cause in-hospital mortality compared to the non-specific fibrin agent, streptokinase. However, the type of thrombolytic agent used did not influence other in-hospital outcomes.  相似文献   
58.
Aim of the workTo assess the high sensitivity C-reactive protein (hs-CRP level) in systemic lupus erythematosus (SLE) patients without cardiac involvement and find its relation with clinical and laboratory findings, disease activity, damage index and intima-media thickness (IMT).Patients and methodsForty-five female SLE patients were recruited in the present study without any cardiac involvement. History taking, examination and laboratory investigations were performed for patients. Disease activity was evaluated by the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) and damage by the Systemic Lupus International Collaborating Clinics (SLICC) index. Thirty age matched female healthy subjects were considered as a control group. hs-CRP was measured quantitatively by microplate immunoenzymometric assay and the IMT measured by ultrasonography.ResultsThe hs-CRP in the patients was significantly higher (4.84 ± 3.91 mg/l) compared to the control (1.74 ± 0.61 mg/l) (p < 0.001). The IMT in the patients was significantly increased (0.72 ± 0.37 mm) compared to the control (0.54 ± 0.15 mm) (p 0.004). There was no difference in the level of hs-CRP according to the presence or absence of clinical manifestations. However, it was significantly higher in those with positive DNA (5.71 ± 4.36 mg/L) compared to those with negative results (3.12 ± 1.97 mg/L) (p 0.009). There was a significant correlation of the hs-CRP level with the IMT (r 0.49, p 0.001) and SLEDAI (r 0.67, p < 0.001).ConclusionsThese findings suggest that SLE patients without traditional major cardiovascular risk factors may have increased risk of future cardiac events. Measuring hs-CRP may be useful as a marker of disease activity, increased IMT and subclinical atherosclerosis in SLE especially those with positive ds-DNA.  相似文献   
59.
60.
Cardiac involvement in patients with sarcoidosis has been reported in up to 25-39% of patients and is responsible for up to 85% of deaths attributed to the disease, often due to sudden cardiac death. An established diagnosis of cardiac sarcoidosis (CS) portends an ominous prognosis, with an estimated five year-survival of 44%. We report a case that was initially diagnosed as arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C), but extra-cardiac biopsies later on were consistent with sarcoidosis and a final diagnosis of CS was made. The patient received an implantable cardioverter defibrillator (ICD) with a subcutaneous lead array implant for high defibrillation threshold (DFT). Exclusive right ventricular (RV) involvement is atypical for CS. The predominant RV involvement based on echocardiogram, cardiac magnetic resonance imaging (MRI) and right precordial electrocardiogram changes can lead to misdiagnosis as ARVD/C based on the modified task force criteria. Cardiac sarcoidosis is an under-diagnosed disease and the delay in its diagnosis and appropriate therapy can lead to a fatal outcome. High defibrillation thresholds have not been previously reported in patients with CS, but given the natural progression of the disease and the limitations in current pharmacotherapy, implanters who diagnose and treat such patients must be prepared to deal with this issue.  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