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   8451篇
  免费   701篇
  国内免费   9篇
耳鼻咽喉   76篇
儿科学   236篇
妇产科学   166篇
基础医学   981篇
口腔科学   144篇
临床医学   1168篇
内科学   1741篇
皮肤病学   108篇
神经病学   812篇
特种医学   235篇
外科学   1327篇
综合类   108篇
一般理论   14篇
预防医学   1078篇
眼科学   142篇
药学   492篇
中国医学   7篇
肿瘤学   326篇
  2023年   54篇
  2022年   57篇
  2021年   135篇
  2020年   117篇
  2019年   155篇
  2018年   165篇
  2017年   105篇
  2016年   135篇
  2015年   150篇
  2014年   223篇
  2013年   343篇
  2012年   440篇
  2011年   466篇
  2010年   239篇
  2009年   240篇
  2008年   471篇
  2007年   458篇
  2006年   447篇
  2005年   451篇
  2004年   451篇
  2003年   417篇
  2002年   403篇
  2001年   216篇
  2000年   219篇
  1999年   187篇
  1998年   105篇
  1997年   76篇
  1996年   56篇
  1995年   65篇
  1994年   65篇
  1993年   60篇
  1992年   161篇
  1991年   151篇
  1990年   115篇
  1989年   119篇
  1988年   118篇
  1987年   114篇
  1986年   112篇
  1985年   88篇
  1984年   96篇
  1983年   70篇
  1982年   56篇
  1981年   54篇
  1980年   52篇
  1979年   60篇
  1978年   56篇
  1977年   57篇
  1975年   53篇
  1974年   57篇
  1972年   56篇
排序方式: 共有9161条查询结果,搜索用时 0 毫秒
11.
12.
Valid classification of stroke is essential to initiate effective acute management and early secondary prevention strategies. To accurately evaluate stroke subtype a number of diagnostic procedures have to be performed. This study sought to investigate variations in use of diagnostic procedures across selected European hospitals. First-ever stroke patients were sampled over a 1-year period through 11 hospital-based registers across 10 European countries. We defined a diagnostic standard for valid aetiological classification of ischemic stroke including brain imaging, vascular imaging and echocardiography. The impact of socio-demographic, clinical and structural characteristics on performance of the diagnostic standard was assessed using multivariate logistic regression analyses. A total of 1721 patients were included in the study. 83.1% received brain imaging, ranging from 32.8% to 100%. The diagnostic standard was performed in 40.4% of stroke patients, ranging from 0% to 77.2%. Patients with increasing age ( P  < 0.001) and with more severe strokes ( P  = 0.001) were less probably to receive the diagnostic standard. Patients treated in stroke units and neurological departments were more frequently investigated with the diagnostic standard ( P  < 0.001). Less than half of hospitalized stroke patients across Europe underwent diagnostic procedures to allow for aetiological classification of stroke, which may hamper the initiation of effective early management and secondary prevention.  相似文献   
13.
14.
R M Saad  M W Wolfe 《Chest》1991,99(2):496-498
In addition to a working knowledge of general complications such as thromboembolism and infective endocarditis, optimal care of the patient with a prosthetic valve requires specific knowledge concerning the characteristics of a given patient's prosthesis. This may need to include the ability to identify the valve roentgenographically when history and records are unavailable. A 53-year-old woman with mitral stenosis secondary to rheumatic heart disease and status post a reported Bjork-Shiley mitral valve (MV) replacement 17 years prior to hospital admission was referred for evaluation of severe hemolytic anemia. Previous cinefluoroscopy in 1986 at the time of a cerebrovascular accident revealed a normally functioning caged disc prosthesis and not the tilting disc of a Bjork-Shiley prosthetic valve. The valve was not further characterized and she continued receiving warfarin therapy until May 1989 when she presented with laboratory findings showing a marked hemolytic anemia with a hemoglobin of 6.5 mg/dl and lactate dehydrogenase (LDH) value of 2100 IU. Echocardiography revealed normal valvular function without evidence of perivalvular leak. The patient was referred for further evaluation with chest roentgenogram at the time of hospital admission revealing a valve configuration characteristic of the Beall model 103/104 series that has been found to manifest progressive disc variance with a high degree of hemolytic anemia (despite normal noninvasive evaluation of MV function), disc tilting with intermittent regurgitation, and catastrophic disc embolization in extreme cases. The precise identification of valvular prosthesis in patients after valve replacement is crucial for optimal management. As in our case, the mere identification of a particular valve may necessitate certain management and therapy based on the natural history of that valve. In the absence of reliable history and/or records, the roentgenographic examination should lead to the precise identification.  相似文献   
15.
16.
Reports suggest that response tointerferon-alpha therapy is influenced by both hepatitisC viral genotype and titer. Our aim was to determine ifdirect, automated, cycle sequencing of the PCR productfrom an HCV RNA detection assay could be used toreliably determine HCV genotype. In addition, theapproach was used to determine the HCV genotypedistribution in our patient population and to learn ifthere was a correlation between HCV genotype and RNAtiter that could be used to predict response totreatment. In all 143 consecutive patients were testedfor both HCV RNA titer and genotype. Automated, cycle sequencing of PCR product was highly effectiveand failed to yield a genotype in only 3 (2%) patients.The distribution of HCV genotypes was: 1a (40%), 1b(39%), 2a (2%), 2b (6%), 3a (4%). There were significant differences in the median HCV RNA titersbetween genotypes 1, 2, and 3. 6 High HCV RNA titers>4.4 × 106 copies/ml were only seenin genotype 1. However, the HCV RNA level should not beused as a surrogate marker of genotype because of a significantoverlap of titers within the genotypes.  相似文献   
17.
We assessed functional disability with the Stanford Health Assessment Questionnaire Functional Disability Index (FDI) in 1,274 patients with rheumatoid arthritis (RA) followed longitudinally for up to 12 years. The rate of functional loss increased sharply after the first clinic visit. Half of patients with RA (median survival time) will reach FDI scores of about 1 in 2 years, 2 in 6 years, and 2.5 in 10 years after the first clinic visit, levels that correspond to moderate, severe and very severe loss of functional ability. Functional outcomes may be predicted by simple demographic and clinical assessments, the best of which are self-assessed measures of global severity, pain and function.  相似文献   
18.
19.
In this study we have assessed the hypothesis that there is a postreceptor defect in glucose metabolism that makes the severely burned patient unable to oxidize glucose efficiently as an energy source. The intracellular pyruvate pool was labeled by the infusion of 3-13C-lactate, and expired CO2 production and isotopic enrichment of both pyruvate and CO2 were determined to calculate the rate of pyruvate production and oxidation. 6,6-d2-Glucose and 15N-alanine were infused simultaneously to relate pyruvate kinetics and oxidation to glucose and alanine kinetics. Five normal volunteers and 10 severely burned patients (mean of 80% +/- 5% body surface burned) were studied in the basal state and during continuous (unlabeled) glucose infusion. Also, the effect of dichloroacetate, which normally stimulates pyruvate dehydrogenase activity, was assessed in both volunteers and patients. The burned patients had many of the classic metabolic responses to severe injury, including significant increases in resting energy expenditure, glucose production, and alanine release from protein breakdown. However, rather than being inhibited, the rate of pyruvate oxidation was increased approximately 300% in burned patients. Although the patients had an elevated mean concentration of lactate, stemming from increased lactate production, no deficit in pyruvate dehydrogenase activity was evident. Rather, the high rate of lactate production was apparently a consequence of the high rate of glycolysis. On the other hand, the direct pathway for synthesis of glycogen from infused glucose appeared to be impaired in burned patients. In both volunteers and patients, dichloroacetate stimulated the percent of pyruvate directed to oxidation, thereby reducing the conversion of pyruvate to other fates, including lactate. However, because there was no deficit in pyruvate dehydrogenase activity in the patients compared with normal volunteers before dichloroacetate treatment, no unique effect of dichloroacetate on glucose or protein kinetics was observed in burned patients. From these results we conclude that if there is a postreceptor defect in glucose metabolism in burned patients, it involves the pathway of direct glycogen synthesis and not the pathway of oxidation.  相似文献   
20.
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