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   8134篇
  免费   472篇
  国内免费   35篇
耳鼻咽喉   68篇
儿科学   282篇
妇产科学   192篇
基础医学   1245篇
口腔科学   173篇
临床医学   719篇
内科学   1683篇
皮肤病学   246篇
神经病学   860篇
特种医学   167篇
外科学   623篇
综合类   67篇
一般理论   3篇
预防医学   668篇
眼科学   185篇
药学   770篇
中国医学   11篇
肿瘤学   679篇
  2024年   8篇
  2023年   65篇
  2022年   215篇
  2021年   350篇
  2020年   203篇
  2019年   215篇
  2018年   280篇
  2017年   195篇
  2016年   275篇
  2015年   273篇
  2014年   318篇
  2013年   462篇
  2012年   688篇
  2011年   668篇
  2010年   351篇
  2009年   301篇
  2008年   481篇
  2007年   524篇
  2006年   500篇
  2005年   459篇
  2004年   481篇
  2003年   407篇
  2002年   382篇
  2001年   48篇
  2000年   45篇
  1999年   43篇
  1998年   50篇
  1997年   51篇
  1996年   39篇
  1995年   23篇
  1994年   26篇
  1993年   22篇
  1992年   17篇
  1991年   17篇
  1990年   10篇
  1989年   17篇
  1988年   10篇
  1987年   6篇
  1986年   7篇
  1985年   9篇
  1984年   9篇
  1983年   12篇
  1982年   13篇
  1981年   9篇
  1980年   6篇
  1978年   6篇
  1977年   7篇
  1976年   4篇
  1975年   4篇
  1974年   6篇
排序方式: 共有8641条查询结果,搜索用时 15 毫秒
991.
992.
Epithelioid hemangioendothelioma (EHE) is a rare, vascular sarcoma. Visceral forms arise in the liver/ lungs. We review the clinical and molecular phenotype of pediatric visceral EHE based on the case of a 9‐year‐old male child with EHE of the liver/lungs. His tumor expressed the EHE‐specific fusion oncogene WWTR1‐CAMTA1. Molecular characterization revealed a low somatic mutation rate and activated interferon signaling, angiogenesis regulation, and blood vessel remodeling. After polychemotherapy and resection of lung tumors, residual disease remained stable on oral lenalidomide. Literature review identified another 24 children with EHE of the liver/lungs. Most presented with multifocal, systemic disease. Only those who underwent complete resection achieved complete remission. Four children experienced rapid progression and died. In six children, disease remained stable for years without therapy. Two patients died from progressive EHE 21 and 24 years after first diagnosis. Natural evolution of pediatric visceral EHE is variable, and long‐term prognosis remains unclear.  相似文献   
993.
Plasma vitamins C, E, retinol and carotene were measured in 1971–1973 in 2,974 men working in Basel Switzerland. In 1990, the vital status of all participants was assessed. A total of 290 men had died from cancer during the 17 years of follow-up, including 87 with lung cancer, 30 with prostate cancer, 28 with stomach cancer and 22 with colon cancer. Overall mortality from cancer was associated with low mean plasma levels of carotene (adjusted for cholesterol) and of vitamin C. Lung and stomach cancers were associated with a low mean plasma carotene level. After calculation of the relative risk, using the Cox model, with exclusion of mortality during the first 2 years of follow-up, simultaneously low levels of plasma carotene (below quartile I) and lipid-adjusted retinol were related to a significantly increased mortality risk for all cancers and for lung cancer. Simultaneously, low levels of plasma vitamin C and lipid-adjusted vitamin E also were associated with a significantly increased risk for lung cancer. Additionally, low vitamin E levels in smokers were related to an increased risk for prostate cancer. It is concluded that low plasma levels of the vitamins C, E, retinol and carotene are related to increased risk of subsequent overall and lung-cancer mortality and that low levels of vitamin E in smokers are related to an increased risk of prostate-cancer mortality. © 1996 Wiley-Liss, Inc.  相似文献   
994.
Background Receptor activator of NF‐κB ligand (RANKL), a member of the tumor necrosis factor superfamily, is a key mediator of osteoclast formation, activation, and survival. Thus, it is reasonable to hypothesize that there might be a functional relationship between RANKL expression and peri‐implantitis. Purpose This pilot study was performed to determine the reference levels for soluble RANKL (sRANKL) in peri‐implant crevicular fluid and to correlate them with the clinical parameters associated with inflammatory reactions and bone destruction. Materials and Methods The clinical parameters probing depth (PD), modified bleeding index (MBI), and modified plaque index (MPI) served as indicators for bone resorption and inflammation. Exclusion criteria for calculations were the detection limit of the immunoassay and the minimum acceptable crevicular volume for measurement. From the 84 collected samples of 16 patients, 30–84 years of age, with a total of 19 implants, 29 met these criteria. The absolute amount of sRANKL within crevicular fluid adsorbed to filter strips was a median of 0.18 femtomol (fmol; range, 0.08–0.53) and 0.26 nM (range, 0.09–1.21) when normalized by volume. PD was 4 mm in median and varied within a range between 2 and 12 mm. Results Absolute amounts of sRANKL showed no correlation with the adsorbed volume and the clinical parameters PD, MBI, and MPI. When sRANKL was normalized by volume, no correlation with the clinical parameters PD, MBI, and MPI was observed either. The patients’ age was not associated with total sRANKL and the concentration of RANKL within crevicular fluid. Absolute levels of sRANKL and sRANKL concentration did not show any differences based on the sampling sites buccal and lingual, or on the patients’ gender. A significant difference in sRANKL concentration was detectable when samples from maxillary implants (0.31 nM median; range, 0.12–1.21) were compared with samples from mandibular implants (0.21 nM median; range, 0.09–0.6) (p=.03). Absolute levels of sRANKL were not different between the maxilla and the mandible. Conclusion Given the limited sample size, our data provide a basis for future prospective longitudinal studies on the possible relevance of sRANKL as a prognostic marker in peri‐implantitis, and for an understanding of the pathophysiologic process of the disease as a prerequisite for the design of treatment strategies.  相似文献   
995.
996.
997.
998.
999.
BACKGROUND: Adult data suggest that urinary tract infections occur frequently after renal transplantation (RTx) and contribute to mortality and graft loss; data in children are limited. Therefore, we evaluated prevalence, short and long-term morbidity and confounding factors of febrile UTI (fUTI) after paediatric RTx. METHODS: In a retrospective cross-sectional study of three centres, we analysed data on 110 children followed for 4.9+/-3.4 years after successful transplantation. RESULTS: 40/110 (36%) patients had at least one fUTI at a median time of 0.98 years (range 0.02-8.96) after RTx; 11 patients (28%) had recurrent fUTI. Serum creatinine (SCr) rose significantly from 1.15+/-1.13 to 1.83+/-1.69 mg/dl, (P<0.001) during the fUTI, declining to baseline values after treatment. At the last followed-up calculated mean, GFR was comparable between fUTI and non-fUTI groups (75+/-26 vs 71+/-22 ml/min/1.73 m2). During fUTI mean, C-reactive protein (CRP) increased to 123+/-75 mg/l. Febrile UTI were significantly more frequent in girls compared to boys (22/44 vs 18/66, P<0.05) but occurred significantly earlier in boys than in girls [median 0.63 (range 0.02-4.15) vs 1.07 (0.04-8.96) years after RTx; P<0.02]. Also, patients with urinary tract malformations (UTMs) and neurogenic bladder as underlying diagnosis and those with urological surgery prior to transplantation had an increased risk for fUTI. CONCLUSION: fUTI is a frequent complication with significant short-term morbidity especially in girls and children with UTMs, neurogenic bladder and those with urological surgery. Long-term follow-up and prospective studies confirming specific risk factors, preventive measures and impact on graft survival are necessary.  相似文献   
1000.
BACKGROUND: Cognitive dysfunction is increasingly considered to be the strongest clinical predictor of poor long-term outcome in schizophrenia. Associations have been found between the severity of cognitive deficits and social dysfunction, impairments in independent living, occupational limitations, and disturbances in quality of life (QOL). METHODS: In this cross-sectional study, the relationships of cognitive deficits and treatment outcomes in terms of QOL, needs, and psychosocial functioning were examined in 60 outpatients with schizophrenia who had a duration of illness over 2 years and had been treated with either clozapine or olanzapine for at least 6 months. RESULTS: The present study suggests that cognitive functioning might be a predictor of work functioning/independent living outcome in stabilized patients with schizophrenia: deficits of visual memory and working memory were negatively associated with occupational functioning, and older patients lived independently and/or in a stable partnership more often. The patients' assessments of QOL and needs for care did not show any significant associations with cognitive functioning. DISCUSSION: These findings suggest that cognitive functioning is a key determinant of work functioning/independent living for stable outpatients with schizophrenia.  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