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   5332篇
  免费   361篇
  国内免费   22篇
耳鼻咽喉   30篇
儿科学   56篇
妇产科学   50篇
基础医学   812篇
口腔科学   40篇
临床医学   589篇
内科学   1137篇
皮肤病学   84篇
神经病学   880篇
特种医学   310篇
外科学   744篇
综合类   15篇
预防医学   222篇
眼科学   40篇
药学   311篇
中国医学   6篇
肿瘤学   389篇
  2023年   61篇
  2022年   127篇
  2021年   279篇
  2020年   150篇
  2019年   240篇
  2018年   253篇
  2017年   175篇
  2016年   174篇
  2015年   212篇
  2014年   249篇
  2013年   317篇
  2012年   497篇
  2011年   473篇
  2010年   252篇
  2009年   219篇
  2008年   276篇
  2007年   252篇
  2006年   240篇
  2005年   207篇
  2004年   169篇
  2003年   120篇
  2002年   97篇
  2001年   44篇
  2000年   40篇
  1999年   40篇
  1998年   23篇
  1997年   12篇
  1996年   16篇
  1995年   19篇
  1994年   12篇
  1992年   34篇
  1991年   34篇
  1990年   31篇
  1989年   43篇
  1988年   34篇
  1987年   27篇
  1986年   22篇
  1985年   23篇
  1984年   19篇
  1983年   22篇
  1982年   12篇
  1981年   15篇
  1980年   16篇
  1979年   20篇
  1977年   11篇
  1976年   9篇
  1975年   10篇
  1974年   16篇
  1973年   16篇
  1972年   10篇
排序方式: 共有5715条查询结果,搜索用时 0 毫秒
41.
Journal of Neurology - Evidence of immune-mediated neurological syndromes associated with the severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection is limited. We therefore...  相似文献   
42.
With the multiplication of electronic devices in our daily life, there is a need for tailored wideband electromagnetic (EM) absorbers that could be conformed on any type of surface-like antennas for interference attenuation or military vehicles for stealth applications. In this study, a wideband flexible flat electromagnetic absorber compatible with additive manufacturing has been studied in the X-Ku frequency bands. A multilayer structure has been optimized using a genetic algorithm (GA), adapting the restrictions of additive manufacturing and exploiting the EM properties of loaded and non-loaded filaments, of which the elaboration is described. After optimization, a bi-material multilayer absorber with a thickness of 4.1 mm has been designed to provide a reflectivity below −12 dB between 8 and 18 GHz. Finally, the designed multilayer structure was 3D-printed and measured in an anechoic chamber, achieving −11.8 dB between 7 and 18 GHz. Thus, the development of dedicated materials has demonstrated the strong potential of additive technologies for the manufacturing of thin wideband flexible EM absorbers.  相似文献   
43.
The World Health Organization 2008 Classification emphasizes myeloperoxidase (MPO) detection as sufficient for assigning a blast population to the myeloid lineage. Published MPO positivity thresholds are 10% for flow cytometry (FCM) but 3% for cytochemistry. Here we re‐evaluated the FCM‐MPO threshold by comparing retrospectively 128 acute lymphoblastic leukaemias and 75 acute myeloid leukaemias without maturation, all assessed by benzidine‐based cytochemistry. A 13% threshold was found to be relevant using an isotype control as background‐reference (sensitivity 95·1%, specificity 91·7%). Residual normal lymphocytes proved to be an advantageous alternative reference, a threshold of 28% yielding improved 97·4% sensitivity and 96·1% specificity.  相似文献   
44.
Mesenchymal stem cells (MSCs) display immunomodulatory properties mediated by various factors, including inducible nitric oxide synthase (iNOS). Since heme oxygenase-1 (HO-1) is a potent immunosuppressive enzyme, we tested the hypothesis that HO-1 could mediate the immunosuppressive effects of MSCs. We generated adult rat MSCs that inhibited T-cell proliferation in vitro. These MSCs expressed both HO-1 and iNOS. In vitro, whereas neither HO-1 nor iNOS inhibition alone could interfere with the immunosuppressive properties of rat MSCs, simultaneous inhibition of both enzymes restored T-cell proliferation. In vivo, injection of MSCs significantly delayed heart allograft rejection, and inhibition of either HO-1 or iNOS totally reversed the protective activity of MSCs, inducing rejection. Adult human MSCs also expressed HO-1; in these cells, HO-1 inhibition was sufficient to completely block their immunosuppressive capacity. In conclusion, we show, for the first time, that HO-1 mediates the immunosuppressive properties of rat and human MSCs.  相似文献   
45.
Background To compare RCB (Residual Cancer Burden) and Neo-Bioscore in terms of prognostic performance and see if adding pathological variables improve these scores.Methods We analysed 750 female patients with invasive breast cancer (BC) treated with neoadjuvant chemotherapy (NAC) at Institut Curie between 2002 and 2012. Scores were compared in global population and by BC subtype using Akaike information criterion (AIC), C-Index (concordance index), calibration curves and after adding lymphovascular invasion (LVI) and pre-/post-NAC TILs levels.Results RCB and Neo-Bioscore were significantly associated to disease-free and overall survival in global population and for triple-negative BC. RCB had the lowest AICs in every BC subtype, corresponding to a better prognostic performance. In global population, C-Index values were poor for RCB (0.66; CI [0.61–0.71]) and fair for Neo-Bioscore (0.70; CI [0.65–0.75]). Scores were well calibrated in global population, but RCB yielded better prognostic performances in each BC subtype. Concordance between the two scores was poor. Adding LVI and TILs improved the performance of both scores.Conclusions Although RCB and Neo-Bioscore had similar prognostic performances, RCB showed better performance in BC subtypes, especially in luminal and TNBC. By generating fewer prognostic categories, RCB enables an easier use in everyday clinical practice.Subject terms: Breast cancer, Breast cancer, Chemotherapy  相似文献   
46.
47.
48.
Upper extremity digital ischaemia (UEDI) is a rare heterogeneous condition whose frequency is 40 times less than that of toe ischaemia. Using a large cohort, the aim of this study was to evaluate aetiologies, prognosis and midterm clinical outcomes of UEDI.All patients with UEDI with or without cutaneous necrosis in a university hospital setting between January 2000 to December 2016 were included. Aetiologies, recurrence of UEDI, digital amputation and survival were analyzed retrospectively.Three hundred twenty three patients were included. UEDI due to cardio-embolic disease (DICE) was the highest occurring aetiology with 59 patients (18.3%), followed by DI due to Systemic Sclerosis (SSc) (16.1%), idiopathic causes (11.7%), Thromboangiitis obliterans (TAO) (9.3%), iatrogenic causes (9.3%), and cancer (6.2%). DICE patients tended to be older and featured more cases with arterial hypertension whereas TAO patients smoked more tobacco and cannabis. During follow-up, recurrences were significantly more frequent in SSc than in all other tested groups (P < .0001 vs idiopathic and DICE, P = .003 vs TAO) and among TAO patients when compared to DICE patients (P = .005). The cumulated rate of digital amputation was higher in the SSc group (n = 18) (P = .02) and the TAO group (n = 7) (P = .03) than in DICE (n = 2).This retrospective study suggests that main aetiologies of UEDI are DICE, SSc and idiopathic. This study highlights higher frequency of iatrogenic UEDI than previous studies. UEDI associated with SSc has a poor local prognosis (amputations and recurrences) and DICE a poor survival. UEDI with SSc and TAO are frequently recurrent.  相似文献   
49.
50.
Digestive Diseases and Sciences - Abdominal pain is a cardinal sign of functional bowel disorders (FBD), in favor of irritable bowel syndrome (IBS). However, the determinants of abdominal pain...  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