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   1513896篇
  免费   120376篇
  国内免费   3590篇
耳鼻咽喉   19926篇
儿科学   49683篇
妇产科学   43436篇
基础医学   215043篇
口腔科学   41538篇
临床医学   132645篇
内科学   310058篇
皮肤病学   36734篇
神经病学   125221篇
特种医学   56161篇
外国民族医学   464篇
外科学   223355篇
综合类   33348篇
现状与发展   3篇
一般理论   522篇
预防医学   120609篇
眼科学   33843篇
药学   105857篇
  1篇
中国医学   3863篇
肿瘤学   85552篇
  2021年   13116篇
  2019年   14194篇
  2018年   20833篇
  2017年   15161篇
  2016年   16509篇
  2015年   18538篇
  2014年   25432篇
  2013年   37818篇
  2012年   53224篇
  2011年   56213篇
  2010年   32387篇
  2009年   29989篇
  2008年   50912篇
  2007年   53910篇
  2006年   53797篇
  2005年   52225篇
  2004年   49429篇
  2003年   46980篇
  2002年   45188篇
  2001年   75505篇
  2000年   77496篇
  1999年   63741篇
  1998年   17395篇
  1997年   15694篇
  1996年   15836篇
  1995年   14987篇
  1994年   13572篇
  1993年   12735篇
  1992年   46706篇
  1991年   44213篇
  1990年   42208篇
  1989年   40130篇
  1988年   36667篇
  1987年   35839篇
  1986年   33370篇
  1985年   31700篇
  1984年   24135篇
  1983年   20270篇
  1982年   12328篇
  1981年   10891篇
  1979年   20992篇
  1978年   14766篇
  1977年   12268篇
  1976年   11543篇
  1975年   11860篇
  1974年   14263篇
  1973年   13843篇
  1972年   12893篇
  1971年   11750篇
  1970年   11177篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
DNA methylation at CpG dinucleotides is an important epigenetic regulator common to virtually all mammalian cell types, but recent evidence indicates that during early postnatal development neuronal genomes also accumulate uniquely high levels of two alternative forms of methylation, non-CpG methylation and hydroxymethylation. Here we discuss the distinct landscape of DNA methylation in neurons, how it is established, and how it might affect the binding and function of protein readers of DNA methylation. We review studies of one critical reader of DNA methylation in the brain, the Rett syndrome protein methyl CpG-binding protein 2 (MeCP2), and discuss how differential binding affinity of MeCP2 for non-CpG and hydroxymethylation may affect the function of this methyl-binding protein in the nervous system.  相似文献   
93.
Background A high Mandard score implies a non-response to chemotherapy in oesophageal adenocarcinoma. However, some patients exhibit tumour volume reduction and a nodal response despite a high score. This study examines survival and recurrence patterns in these patients.Methods Clinicopathological factors were analysed using multivariable Cox regression assessing time to death and recurrence. Computed tomography-estimated tumour volume change was examined in a subgroup of consecutive patients.Results Five hundred and fifty-five patients were included. Median survival was 55 months (Mandard 1–3) and 21 months (Mandard 4 and 5). In the Mandard 4 and 5 group (332 patients), comparison between complete nodal responders and persistent nodal disease showed improved survival (90 vs 18 months), recurrence rates (locoregional 14.75 vs 28.74%, systemic 24.59 vs 48.42%) and circumferential resection margin positivity (22.95 vs 68.11%). Complete nodal response independently predicted improved survival (hazard ratio 0.34 (0.16–0.74). Post-chemotherapy tumour volume reduction was greater in patients with a complete nodal response (−16.3 vs −7.7 cm3, p = 0.033) with no significant difference between Mandard groups.Conclusion Patients with a complete nodal response to chemotherapy have significantly improved outcomes despite a poor Mandard score. High Mandard score does not correspond with a non-response to chemotherapy in all cases and patients with nodal downstaging may still benefit from adjuvant chemotherapy.Subject terms: Oesophageal cancer, Surgical oncology  相似文献   
94.
95.

Background

Refractory acute myeloid leukemia (AML) includes AML includes failure of disease to respond to standard induction chemotherapy, relapse within 6 months after first CR, and 2 or more relapses. The outcome of these patients is usually very poor; only a small proportion can be rescued by allogenic hematopoietic stem-cell transplantation (allo-HSCT). The aim of this study was to evaluate the efficacy and feasibility of allo-HSCT in patients with refractory AML.

Patients and Methods

We retrospectively analyzed the clinical outcome of 91 patients who were diagnosed with treatment-refractory AML at Hacettepe University Hospital between January 2002 and June 2018. Patients' disease status included refractory AML, defined as failure to respond to standard induction chemotherapy and relapse within 6 months after first complete remission.

Results

The median follow-up was 12 months (range, 0.5-184 months) for the entire group. Kaplan-Meier estimates of the 3-year overall survival for patients who underwent allo-HSCT and patients who received only salvage chemotherapy were 67% and 12%, respectively. Additionally, the Kaplan-Meier estimates of 5-year overall survival for patients who underwent allo-HSCT and patients who received only salvage chemotherapy were 44% and 4%, respectively (P < .001). Complete remission was obtained in 25 patients (83.3%) who underwent allo-HSCT; however, the disease of only 3 patients (3.8%) exhibited complete response after salvage chemotherapy.

Conclusion

Allo-HSCT is still the best-known treatment option with curative potential in patients with treatment-refractory AML. Therefore, all efforts should be made in an attempt to find a suitable matched donor in order to perform allo-HSCT.  相似文献   
96.
97.
98.
99.
100.
Guidelines and consensus on the management of patients with acne aim to give evidence-based, expert-group recommendations. This review compares current guidelines and consensus articles to provide a compilation of recommendations on the treatment of acne with oral isotretinoin. Ten common, relevant, clinical questions are addressed, based on published recommendations, including the indications of isotretinoin, the proposed daily dose, the cumulative isotretinoin dose and the laboratory monitoring needed. Recommendations on special considerations are also addressed, including the timing of procedures and the question of an association of depression or inflammatory bowel disease with isotretinoin. A major limitation is the use of different classification systems for acne across guidelines. The recommended daily dose ranges from 0.3 to 0.5 mg/kg in the European guidelines to up to 1 mg/kg in the US guidelines. A specific duration of treatment of at least 6 months is only recommended in the European guidelines. All guidelines report the need of strict pregnancy prevention measures. The European, French and US guidelines recommend to monitor for symptoms of depression. Important clinical questions that are inconsistently addressed in guidelines include the age indication, the recommendation for a cumulative dose, the timing of procedures, the association of isotretinoin with IBD, the recommendation for preventing acne flares and for appropriate laboratory monitoring. These topics should be clearly included in the recommendations of guidelines as they are often raised in everyday clinical practice.  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