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   6004篇
  免费   341篇
  国内免费   31篇
耳鼻咽喉   188篇
儿科学   339篇
妇产科学   230篇
基础医学   563篇
口腔科学   148篇
临床医学   566篇
内科学   1153篇
皮肤病学   122篇
神经病学   541篇
特种医学   226篇
外科学   1132篇
综合类   72篇
一般理论   1篇
预防医学   362篇
眼科学   159篇
药学   245篇
中国医学   2篇
肿瘤学   327篇
  2024年   4篇
  2023年   53篇
  2022年   92篇
  2021年   181篇
  2020年   103篇
  2019年   193篇
  2018年   197篇
  2017年   157篇
  2016年   208篇
  2015年   244篇
  2014年   289篇
  2013年   379篇
  2012年   474篇
  2011年   424篇
  2010年   281篇
  2009年   202篇
  2008年   417篇
  2007年   449篇
  2006年   401篇
  2005年   397篇
  2004年   324篇
  2003年   280篇
  2002年   253篇
  2001年   65篇
  2000年   54篇
  1999年   50篇
  1998年   28篇
  1997年   21篇
  1996年   21篇
  1995年   14篇
  1994年   8篇
  1993年   9篇
  1992年   13篇
  1991年   13篇
  1990年   12篇
  1989年   7篇
  1988年   5篇
  1987年   3篇
  1986年   5篇
  1985年   6篇
  1984年   10篇
  1983年   4篇
  1982年   3篇
  1981年   2篇
  1980年   3篇
  1979年   3篇
  1978年   5篇
  1977年   4篇
  1966年   2篇
  1907年   1篇
排序方式: 共有6376条查询结果,搜索用时 15 毫秒
51.
52.
53.
Background: The widespread use of percutaneous mitral commissurotomy (PMC) has led to an increase in restenosis cases. The data regarding follow‐up results of repeat PMC are quite limited. The aim of this retrospective analysis is to evaluate the immediate and midterm results of the second PMC, in patients with symptomatic mitral restenosis after a succesful first procedure. Methods: Twenty patients (95% female, mean age 37 ± 4 years) who have undergone a second PMC, 6.3 ± 2.5 years after a first successful intervention built the study group. All were in sinus rhythm, with a mean Wilkins score of 8.5 ± 1.2. Results: The valve area increased from 1.2 ± 0.2 to 1.9 ± 0.2 cm2 and mean gradient decreased from 10.5 ± 3.4 to 6.1 ± 1.1 mmHg. There were no complications except for a transient embolic event without sequela (5%) and two cases (10%) of severe mitral regurgitation. The immediate success rate was 90%. The mean follow‐up was 70 ± 29 months (36–156 months). The 5‐year restenosis and intervention (repeat PMC or valve replacement) rates were 9.1 ± 5.2% and 3.6 ± 3.3%, respectively. The intervention free 5‐year survival in good functional capacity (New York Heart Association [NYHA] I–II) was 95.1 ± 5.5% and restenosis and intervention free 5‐year survival with good functional capacity was 89.7 ± 6.8%. Conclusions: Although from a limited number of selected patients, these findings indicate that repeat PMC is a safe and effective method, with follow‐up results similar to a first intervention and should be considered as the first therapeutic option in suitable patients. (Echocardiography 2010;27:765‐769)  相似文献   
54.
55.
Three clusters of Chryseobacterium meningosepticum infections in a tertiary health center in July 2006 and January 2007 involving 8 newborns and 5 older children were investigated. The index patient was from the neonatal intensive care unit, and the older patients were from other pediatric wards. Cultures were obtained from the environment and from health care workers' hands as part of an outbreak investigation. C meningosepticum was isolated from hand cultures obtained from a senior resident and from environmental cultures obtained from powdered infant formula, an electrical button, a computer keyboard, phone, a doorknob, and an Ambu bag. Antibiogram typing and enterobacterial repetitive intergenic consensus sequence polymerase chain reaction indicated that all of the isolates were epidemiologically related. Nine patients improved on antimicrobial treatment, and 4 premature infants died after the infection. C meningosepticum is a well-known etiologic agent for nosocomial infections involving newborns and immunocompromised patients. Wet and dry environmental surfaces and equipment may act as a source or play a role in disseminating the microorganism. Outbreaks may be controlled with strong emphasis on infection control measures.  相似文献   
56.
57.
BACKGROUND: Light-induced fluorescence endoscopy (LIFE) may improve the detection of high-grade dysplasia (HGD) and early stage cancer (EC) in Barrett's esophagus (BE). The aim of this study was to compare LIFE with standard endoscopy (SE) in a randomized crossover study. METHODS: Fifty patients with BE underwent SE and LIFE in a randomized sequence (4 to 6-week interval between procedures). The two procedures were performed by two different endoscopists who were blinded to the findings of the other examination. Targeted biopsy specimens were taken from detected lesions, followed by random biopsy specimens with a 2-cm interval, 4-quadrant protocol. Biopsy specimens were routinely evaluated and subsequently reviewed by a single, blinded expert GI pathologist. RESULTS: Targeted biopsy specimens had a sensitivity for the diagnosis of HGD/EC of 62% (8/13) for both techniques. The overall sensitivity (all biopsy specimens) was 85% for SE and 69% for LIFE (p = 0.69). All targeted biopsy specimens had a positive predictive value (PPV) for HGD/EC of 41% for SE and 28% for LIFE (p = 0.40); autofluorescence-targeted biopsy specimens had a PPV of 13%. False-positive lesions had a significantly higher rate of acute inflammation than random biopsy specimens. CONCLUSIONS: In this study, LIFE did not improve the detection of HGD or EC in patients with BE compared with SE.  相似文献   
58.
BACKGROUND/AIMS: The aim of the study is to clarify the effects of octreotide and propranolol, agents used in the treatment of portal hypertension, on mucosal changes in portal hypertensive colopathy. METHODOLOGY: Portal hypertension was induced in all rats by partial portal vein ligation, and after the operation all rats were caged for a 10-week period. Then, animals were divided into three groups and for two weeks medical treatment were administered to the individual groups as follows: Control group, saline 0.5 mL/day, intraperitoneally. Octreotide group, octreotide 100 micrograms/kg/12 hours, subcutaneously. Propranolol group, propranolol 20 mg/kg/day, intraperitoneally. In order to assess the portal hypertensive colopathy, criteria such as mean diameters of dilated vessels in colonic mucosa, and the existence of mucosal edema, capillary ectasia, hyperemia and hemorrhage, inflammation were used. RESULTS: When parameters were compared for the control versus propranolol groups, mucosal edema and hyperemia and hemorrhage criteria were found to be significant for the propranolol group; control versus octreotide groups, mucosal edema, capillary ectasia, and hyperemia and hemorrhage criteria were found to be significant for the octreotide group; octreotide versus propranolol groups, capillary ectasia and mucosal edema criteria were found to be significant for the octreotide group. CONCLUSIONS: The mucosal changes in portal hypertensive colopathy could be corrected by drugs modifying portal blood flow, octreotide may find a place in the treatment of portal hypertensive colopathy.  相似文献   
59.
60.
OBJECTIVES: This study sought to identify whether obesity and obstructive sleep apnea (OSA) independently predict incident atrial fibrillation/flutter (AF). BACKGROUND: Obesity is a risk factor for AF, and OSA is highly prevalent in obesity. Obstructive sleep apnea is associated with AF, but it is unknown whether OSA predicts new-onset AF independently of obesity. METHODS: We conducted a retrospective cohort study of 3,542 Olmsted County adults without past or current AF who were referred for an initial diagnostic polysomnogram from 1987 to 2003. New-onset AF was assessed and confirmed by electrocardiography during a mean follow-up of 4.7 years. RESULTS: Incident AF occurred in 133 subjects (cumulative probability 14%, 95% confidence interval [CI] 9% to 19%). Univariate predictors of AF were age, male gender, hypertension, coronary artery disease, heart failure, smoking, body mass index, OSA (hazard ratio 2.18, 95% CI 1.34 to 3.54) and multiple measures of OSA severity. In subjects <65 years old, independent predictors of incident AF were age, male gender, coronary artery disease, body mass index (per 1 kg/m2, hazard ratio 1.07, 95% CI 1.05 to 1.10), and the decrease in nocturnal oxygen saturation (per 0.5 U log change, hazard ratio 3.29, 95% CI 1.35 to 8.04). Heart failure, but neither obesity nor OSA, predicted incident AF in subjects > or =65 years of age. CONCLUSIONS: Obesity and the magnitude of nocturnal oxygen desaturation, which is an important pathophysiological consequence of OSA, are independent risk factors for incident AF in individuals <65 years of age.  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