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   45527篇
  免费   2224篇
  国内免费   172篇
耳鼻咽喉   661篇
儿科学   1101篇
妇产科学   970篇
基础医学   5930篇
口腔科学   3736篇
临床医学   2826篇
内科学   10449篇
皮肤病学   1265篇
神经病学   4095篇
特种医学   981篇
外国民族医学   1篇
外科学   5416篇
综合类   231篇
一般理论   11篇
预防医学   4027篇
眼科学   1111篇
药学   3226篇
中国医学   323篇
肿瘤学   1563篇
  2023年   393篇
  2022年   859篇
  2021年   1648篇
  2020年   927篇
  2019年   1365篇
  2018年   1748篇
  2017年   1119篇
  2016年   1208篇
  2015年   1436篇
  2014年   1902篇
  2013年   2357篇
  2012年   3610篇
  2011年   3945篇
  2010年   2053篇
  2009年   1635篇
  2008年   2902篇
  2007年   2823篇
  2006年   2504篇
  2005年   2259篇
  2004年   2089篇
  2003年   1734篇
  2002年   1591篇
  2001年   854篇
  2000年   863篇
  1999年   689篇
  1998年   240篇
  1997年   153篇
  1996年   145篇
  1995年   110篇
  1994年   123篇
  1993年   87篇
  1992年   251篇
  1991年   250篇
  1990年   217篇
  1989年   174篇
  1988年   180篇
  1987年   159篇
  1986年   122篇
  1985年   119篇
  1984年   99篇
  1983年   92篇
  1982年   41篇
  1981年   47篇
  1980年   47篇
  1979年   74篇
  1978年   60篇
  1975年   45篇
  1973年   43篇
  1971年   51篇
  1967年   60篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
ObjectivesDuring the last decade, some changes in the epidemiology of invasive infections have been reported; however, specific studies with patient-level data are scarce. The aim of this study was to describe and evaluate the epidemiologic changes in bloodstream infections (BSI) during the last decade in Andalucía, Spain.MethodsData from two prospective cohorts of BSI in adults with the same methodology performed 10 years apart in 11 hospitals (eight tertiary and three community) in Andalucía, Spain, were compared; the 2006–7 cohort study was performed between October 2006 and March 2007, and the 2016–17 cohort study was performed between October 2016 and March 2017. Population-based incidence rates were calculated and extrapolated for 1 year. Relative risk ratios were calculated between the 2 periods. Multivariate analyses were performed by logistic regression.ResultsOverall, 1262 episodes of BSI were included, 563 (44.6%) in 2006–7 and 699 (55.3%) in 2016–17. Multivariate models selected the following changes in patients' features in 2016–17, after controlling for type of acquisition: higher age (odds ratio (OR) = 1.02; 95% confidence interval [CI] 1.01–1.03), lower urinary catheter (OR = 0.37; 95% CI, 0.26–0.48) and lower Pitt score (OR = 0.76; 95% CI, 0.71–0.82). Adjusted estimations considering patients' features and exposure to procedures showed a reduction in coagulase-negative staphylococci (OR = 0.47; 95% CI, 0.32–0.69), and an increase in Proteus spp. (OR = 3.12; 95% CI, 1.18–8.23) and Candida spp. (OR = 3.01; 95% CI, 1.03–8.86).ConclusionsWe found relevant epidemiologic changes in BSI in our area, including rates, frequency of acquisition types, changes in patient's profiles and aetiologic agents.  相似文献   
942.
ObjectivesThe objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters.MethodsA cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs).ResultsIn all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22–0.47; p < 0.001) for tocilizumab, 0.82 (0.71–1.30; p 0.82) for IHDC, 0.61 (0.43–0.86; p 0.006) for PDC, and 1.17 (0.86–1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02–0.17; p < 0.001).ConclusionsTocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situation.  相似文献   
943.
944.
Patients with mucopolysaccharidosis type VI (MPS VI) present with a wide range of disease severity and clinical manifestations, with significant functional impairment and shortened lifespan. Enzyme replacement therapy (ERT) with galsulfase has been shown to improve clinical and biochemical parameters including patient survival, quality of life and growth. The present study is a resurvey of 34 Brazilian MPS VI patients with rapidly progressive disease (classical phenotype) who initiated ERT with galsulfase under five years of age and had been on ERT until data collection in 2019, with few exceptions (n = 4 patients who died before 2019).Anthropometric measures, urinary glycosaminoglycans, and data regarding cardiac, orthopedic, neurologic, sleep apnea, hearing and ophthalmologic outcomes were filled in by specialists. Pubertal development, clinical complications, hospitalizations, and surgeries were also assessed.In this resurvey study, treatment with galsulfase has shown to be safe and well tolerated in MPS VI patients who initiated ERT under the age of 5 years and who have been undergoing ERT for approximately 10 years. Mortality rate suggests that early initiation of ERT may have a positive impact on patients' survival, improving but not preventing disease progression and death. MPS VI patients on ERT also showed improved growth velocity and the pubertal development was normal in all surviving patients.Follow-up data on pneumonia and hospitalization suggest that early ERT may have a protective effect against major respiratory complications. Cardiac valve disease progressed since their prior evaluation and spinal cord compression was observed in a large number of patients, suggesting that these disease complications were not modified by ERT.  相似文献   
945.
946.
947.
948.
The morphological study of limbs is important for the understanding of tetrapod biology, where it can be applied to taxonomy and phylogeny, as well ecology and behavior. In this study area, osteogenesis is a subject in Kinosternidae, which has been little researched. The main aim of this study was to characterize the skeletogenesis of Kinosternon scorpioides limbs. Samples were histologically processed, and the embryos were cleared with potassium hydroxide and stained with alcian blue and alizarin red. It was observed that the limbs arose in embryonic Stage 10 as mesenchymal condensate cells. The first stylopodium chondrification centers were noted at Stage 14. Zeugopodium chondrification centers appeared at Stage 15; carpal, metacarpal, tarsal, and metatarsal regions were observed at Stage 16, and the cartilage molds of all bones limbs were present at Stage 18. Ossification began in the humerus and femur at Stage 20, and continued into the radius, ulna, tibia, and fibula bones. By Stage 23, it was already effectively directed toward the bone epiphyses in both limbs. At Stage 26 and hatching, only articular cartilages remained, and in the majority of samples the carpal region showed no affinity for alcian blue or alizarin red staining. This study acts as an indicative parameter of the taxon's normal development and can contribute to the phylogenetic understanding of this group.  相似文献   
949.
950.
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