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   911篇
  免费   78篇
  国内免费   6篇
耳鼻咽喉   4篇
儿科学   36篇
妇产科学   8篇
基础医学   80篇
口腔科学   35篇
临床医学   87篇
内科学   238篇
皮肤病学   12篇
神经病学   14篇
特种医学   250篇
外科学   93篇
综合类   17篇
预防医学   32篇
眼科学   16篇
药学   27篇
肿瘤学   46篇
  2023年   6篇
  2022年   6篇
  2021年   7篇
  2020年   15篇
  2019年   2篇
  2018年   14篇
  2017年   21篇
  2016年   17篇
  2015年   18篇
  2014年   31篇
  2013年   26篇
  2012年   33篇
  2011年   28篇
  2010年   42篇
  2009年   34篇
  2008年   17篇
  2007年   25篇
  2006年   13篇
  2005年   17篇
  2004年   16篇
  2003年   5篇
  2002年   9篇
  2001年   6篇
  2000年   4篇
  1999年   8篇
  1998年   46篇
  1997年   57篇
  1996年   53篇
  1995年   48篇
  1994年   46篇
  1993年   30篇
  1992年   13篇
  1991年   11篇
  1990年   11篇
  1989年   20篇
  1988年   31篇
  1987年   15篇
  1986年   40篇
  1985年   36篇
  1984年   17篇
  1983年   21篇
  1982年   18篇
  1981年   10篇
  1980年   10篇
  1979年   2篇
  1978年   7篇
  1977年   11篇
  1976年   16篇
  1975年   4篇
  1969年   1篇
排序方式: 共有995条查询结果,搜索用时 15 毫秒
21.

Background  

The purpose of the present investigation was to determine if the salivary counts of 40 common oral bacteria in subjects with an oral squamous cell carcinoma (OSCC) lesion would differ from those found in cancer-free (OSCC-free) controls.  相似文献   
22.
Dual-energy X-ray absorptiometry (DXA)-derived appendicular lean mass/height2 (ALM/ht2) is the most commonly used estimate of muscle mass in the assessment of sarcopenia, but its predictive value for fracture is substantially attenuated by femoral neck (fn) bone mineral density (BMD). We investigated predictive value of 11 sarcopenia definitions for incident fracture, independent of fnBMD, fracture risk assessment tool (FRAX®) probability, and prior falls, using an extension of Poisson regression in US, Sweden, and Hong Kong Osteoporois Fractures in Men Study (MrOS) cohorts. Definitions tested were those of Baumgartner and Delmonico (ALM/ht2 only), Morley, the International Working Group on Sarcopenia, European Working Group on Sarcopenia in Older People (EWGSOP1 and 2), Asian Working Group on Sarcopenia, Foundation for the National Institutes of Health (FNIH) 1 and 2 (using ALM/body mass index [BMI], incorporating muscle strength and/or physical performance measures plus ALM/ht2), and Sarcopenia Definitions and Outcomes Consortium (gait speed and grip strength). Associations were adjusted for age and time since baseline and reported as hazard ratio (HR) for first incident fracture, here major osteoporotic fracture (MOF; clinical vertebral, hip, distal forearm, proximal humerus). Further analyses adjusted additionally for FRAX-MOF probability (n = 7531; calculated ± fnBMD), prior falls (y/n), or fnBMD T-score. Results were synthesized by meta-analysis. In 5660 men in USA, 2764 Sweden and 1987 Hong Kong (mean ages 73.5, 75.4, and 72.4 years, respectively), sarcopenia prevalence ranged from 0.5% to 35%. Sarcopenia status, by all definitions except those of FNIH, was associated with incident MOF (HR = 1.39 to 2.07). Associations were robust to adjustment for prior falls or FRAX probability (without fnBMD); adjustment for fnBMD T-score attenuated associations. EWGSOP2 severe sarcopenia (incorporating chair stand time, gait speed, and grip strength plus ALM) was most predictive, albeit at low prevalence, and appeared only modestly influenced by inclusion of fnBMD. In conclusion, the predictive value for fracture of sarcopenia definitions based on ALM is reduced by adjustment for fnBMD but strengthened by additional inclusion of physical performance measures. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).  相似文献   
23.
24.
A 54-year-old man was treated with weekly 24-h infusion of high-dose 5-fluorouracil (2600 mg/m2) and leucovorin (100 mg/m2) for metastatic colon cancer. At first, he tolerated the treatment well and no significant toxicity was identified. After a total of eight courses of treatment, a stable disease was observed, but mild shortness of breath was found on occasion. The patient had no previous history of cardiac disease and the heart performance assessed by left ventricular ejection fraction before treatment was normal. Unfortunately, acute pulmonary edema with lethal cardiogenic shock occurred during the ninth course of treatment, in spite of intensive medical treatment. The chest X-ray showed extreme cardiomegaly. Repeated assessment of his heart function by echocardiogram and ventricular ejection fraction revealed a very poor cardiac performance. Toxic cardiogenic shock during weekly 24-h infusion of high-dose 5-fluorouracil and leucovorin is extremely rare. To the best of our knowledge, no case has been reported in the English literature. We report a case and the relevant literature about the incidence, clinical picture and possible pathophysiology on 5-fluorouracil-related cardioxicity is reviewed.   相似文献   
25.
The aim of this study was to explore the role of self-beliefs in predicting postschool outcomes for deaf young adults in transition from secondary settings. Three self-level constructs were explored: self-concept, self-determination, and expectations about the future. This study utilized data from the National Longitudinal Transition Study-2 (NLTS2) that collected longitudinal data from youths with disabilities across the nation, 550 of which were deaf or hard of hearing and met the selection criteria in this study. This study examined the relationships between these deaf adolescents’ self-beliefs and actual future achievements that were reached as they transitioned to adult life, in three domains: life, employment, and education. Despite the generally positive self-beliefs of deaf individuals, which were, in some cases, related to postschool outcomes, the self-beliefs assessed in this study did not emerge as comprehensive predictors of postschool attainments. Findings suggest that for deaf individuals, successfully navigating transitions to adult life involves dimensions beyond individual agency. Positive self-beliefs are clearly a part of successfully attaining postschool outcomes, but deaf individuals may not have full access to equitable opportunities to capitalize on these beliefs.  相似文献   
26.
27.
28.
29.
30.
To characterize the heterogeneity of severe (type III) von Willebrand disease (vWD), plasma and platelet von Willebrand factor antigen (vWF:Ag) and ristocetin cofactor activity (Ricof) were measured in 28 obligatory heterozygotes (ie, parents or children of probands from 15 different kindreds with severe vWD). On the average, heterozygotes had low levels of vWF in both platelets and plasma. There was, however, considerable heterogeneity, with four distinct patterns. Eleven heterozygotes had concordant reduction of vWF:Ag and Ricof in both plasma and platelets; five had low levels of vWF:Ag and Ricof in plasma contrasting with normal levels in platelets; eight had a peculiar pattern, the reverse of the above (ie, low levels in platelets and normal levels in plasma); and in one, both vWF measurements were normal in plasma and platelets. These patterns were genetically determined: they were consistent in four couples of consanguineous heterozygotes and in two couples carrying the same gene deletion. Only the remaining three heterozygotes had no clearly identifiable pattern. Other findings of this study were that although most of the heterozygotes had normal bleeding times, the 7 of 28 who had prolonged bleeding times had concordantly low levels of vWF measurements in both plasma and platelets. In conclusion, this large series of obligatory heterozygotes provides evidence for phenotypic and genotypic heterogeneity of severe vWD.  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