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   1789篇
  免费   100篇
  国内免费   19篇
耳鼻咽喉   3篇
儿科学   53篇
妇产科学   70篇
基础医学   241篇
口腔科学   22篇
临床医学   100篇
内科学   541篇
皮肤病学   33篇
神经病学   173篇
特种医学   42篇
外科学   183篇
综合类   2篇
预防医学   106篇
眼科学   24篇
药学   157篇
中国医学   4篇
肿瘤学   154篇
  2024年   3篇
  2023年   26篇
  2022年   55篇
  2021年   67篇
  2020年   51篇
  2019年   51篇
  2018年   65篇
  2017年   47篇
  2016年   48篇
  2015年   62篇
  2014年   81篇
  2013年   104篇
  2012年   145篇
  2011年   136篇
  2010年   81篇
  2009年   67篇
  2008年   129篇
  2007年   125篇
  2006年   98篇
  2005年   105篇
  2004年   92篇
  2003年   89篇
  2002年   66篇
  2001年   6篇
  2000年   6篇
  1999年   7篇
  1998年   12篇
  1997年   9篇
  1996年   6篇
  1995年   5篇
  1994年   7篇
  1993年   6篇
  1992年   8篇
  1991年   5篇
  1990年   4篇
  1989年   5篇
  1988年   4篇
  1987年   3篇
  1986年   3篇
  1985年   3篇
  1984年   6篇
  1983年   2篇
  1982年   1篇
  1980年   3篇
  1979年   2篇
  1976年   1篇
  1975年   1篇
排序方式: 共有1908条查询结果,搜索用时 15 毫秒
81.
82.
83.
To investigate the characteristics and clinical course of cerebral vein thrombosis (CVT) in patients with myeloproliferative neoplasms (MPN) we compared 48 patients with MPN and CVT (group MPN‐CVT) to 87 with MPN and other venous thrombosis (group MPN‐VT) and 178 with MPN and no thrombosis (group MPN‐NoT) matched by sex, age at diagnosis of MPN (±5 years) and type of MPN. The study population was identified among 5,500 patients with MPN, from January 1982 to June 2013. Thrombophilia abnormalities were significantly more prevalent in the MPN‐CVT and MPN‐VT than in MPN‐NoT group (P = 0.015), as well as the JAK2 V617F mutation in patients with essential thrombocythemia (P = 0.059). Compared to MPN‐VT, MPN‐CVT patients had a higher rate of recurrent thrombosis (42% vs. 25%, P = 0.049) despite a shorter median follow‐up period (6.1 vs. 10.3 years, P = 0.019), a higher long‐term antithrombotic (94% vs. 84%, P = 0.099) and a similar cytoreductive treatment (79% vs. 70%, P = 0.311). The incidence of recurrent thrombosis was double in MPN‐CVT than in MPN‐VT group (8.8% and 4.2% patient‐years, P = 0.022), and CVT and unprovoked event were the only predictive variables in a multivariate model including also sex, blood count, thrombophilia, cytoreductive, and antithrombotic treatment (HR 1.97, 95%CI 1.05–3.72 and 2.09, 1.09–4.00, respectively). Am. J. Hematol. 89:E200–E205, 2014. © 2014 Wiley Periodicals, Inc.  相似文献   
84.
Monia Marchetti  Arianna Ghirardi  Arianna Masciulli  Alessandra Carobbio  Francesca Palandri  Nicola Vianelli  Elena Rossi  Silvia Betti  Ambra Di Veroli  Alessandra Iurlo  Daniele Cattaneo  Guido Finazzi  Massimiliano Bonifacio  Luigi Scaffidi  Andrea Patriarca  Elisa Rumi  Ilaria Carola Casetti  Clemency Stephenson  Paola Guglielmelli  Elena Maria Elli  Miroslava Palova  Davide Rapezzi  Daniel Erez  Montse Gomez  Kai Wille  Manuel Perez-Encinas  Francesca Lunghi  Anna Angona  Maria Laura Fox  Eloise Beggiato  Giulia Benevolo  Giuseppe Carli  Rossella Cacciola  Mary Frances McMullin  Alessia Tieghi  Valle Recasens  Susanne Isfort  Fabrizio Pane  Valerio De Stefano  Martin Griesshammer  Alberto Alvarez-Larran  Alessandro Maria Vannucchi  Alessandro Rambaldi  Tiziano Barbui 《American journal of hematology》2020,95(3):295-301
One out of ten patients with Philadelphia-negative myeloproliferative neoplasms (MPN) develop a second cancer (SC): in such patients we aimed at assessing the survival impact of SC itself and of MPN-specific therapies. Data were therefore extracted from an international nested case-control study, recruiting 798 patients with SC diagnosed concurrently or after the MPN. Overall, 2995 person-years (PYs) were accumulated and mortality rate (MR) since SC diagnosis was 5.9 (5.1-6.9) deaths for every 100 PYs. A “poor prognosis” SC (stomach, esophagus, liver, pancreas, lung, ovary, head-and-neck or nervous system, osteosarcomas, multiple myeloma, aggressive lymphoma, acute leukemia) was reported in 26.3% of the patients and was the cause of death in 65% of them (MR 11.0/100 PYs). In contrast, patients with a “non-poor prognosis” SC (NPPSC) incurred a MR of 4.6/100 PYs: 31% of the deaths were attributed to SC and 15% to MPN evolution. At multivariable analysis, death after SC diagnosis was independently predicted (HR and 95% CI) by patient age greater than 70 years (2.68; 1.88-3.81), the SC prognostic group (2.57; 1.86-3.55), SC relapse (1.53; 10.6-2.21), MPN evolution (2.72; 1.84-4.02), anemia at SC diagnosis (2.32; 1.49-3.59), exposure to hydroxyurea (1.89; 1.26-2.85) and to ruxolitinib (3.63; 1.97-6.71). Aspirin was protective for patients with a NPPSC (0.60; 0.38-0.95). In conclusion, SC is a relevant cause of death competing with MPN evolution. Prospective data are awaited to confirm the role of cytoreductive and anti-platelet drugs in modulating patient survival after the occurrence of a SC.  相似文献   
85.
86.
87.

Background

The diagnostic and prognostic assessment of newborn infants with hypoxic-ischemic encephalopathy (HIE) comprises, among other tools, diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps.

Objective

To compare the ability of DWI and ADC maps in newborns with HIE to predict the neurodevelopmental outcome at 2 years of age.

Materials and methods

Thirty-four term newborns with HIE admitted to the Neonatal Intensive Care Unit of Modena University Hospital from 2004 to 2008 were consecutively enrolled in the study. All newborns received EEG, conventional MRI and DWI within the first week of life. DWI was analyzed by means of summation (S) score and regional ADC measurements. Neurodevelopmental outcome was assessed with a standard 1–4 scale and the Griffiths Mental Developmental Scales - Revised (GMDS-R).

Results

When the outcome was evaluated with a standard 1–4 scale, the DWI S scores showed very high area under the curve (AUC) (0.89) whereas regional ADC measurements in specific subregions had relatively modest predictive value. The lentiform nucleus was the region with the highest AUC (0.78). When GMDS-R were considered, DWI S scores were good to excellent predictors for some GMDS-R subscales. The predictive value of ADC measurements was both region- and subscale-specific. In particular, ADC measurements in some regions (basal ganglia, white matter or rolandic cortex) were excellent predictors for specific GMDS-R with AUCs up to 0.93.

Conclusions

DWI S scores showed the highest prognostic value for the neurological outcome at 2 years of age. Regional ADC measurements in specific subregions proved to be highly prognostic for specific neurodevelopmental outcomes.  相似文献   
88.
89.
Goal-directed movements involve a series of neural computations that compare the sensory representations of goal location and effector position, and transform these into motor commands. Neurons in posterior parietal cortex (PPC) control several effectors (e.g., eye, hand, foot) and encode goal location in a variety of spatial coordinate systems, including those anchored to gaze direction, and to the positions of the head, shoulder, or hand. However, there is little evidence on whether reference frames depend also on the effector and/or type of motor response. We addressed this issue in macaque PPC area V6A, where previous reports using a fixate-to-reach in depth task, from different starting arm positions, indicated that most units use mixed body/hand-centered coordinates. Here, we applied singular value decomposition and gradient analyses to characterize the reference frames in V6A while the animals, instead of arm reaching, performed a nonspatial motor response (hand lift). We found that most neurons used mixed body/hand coordinates, instead of “pure” body-, or hand-centered coordinates. During the task progress the effect of hand position on activity became stronger compared to target location. Activity consistent with body-centered coding was present only in a subset of neurons active early in the task. Applying the same analyses to a population of V6A neurons recorded during the fixate-to-reach task yielded similar results. These findings suggest that V6A neurons use consistent reference frames between spatial and nonspatial motor responses, a functional property that may allow the integration of spatial awareness and movement control.  相似文献   
90.
Pediatric Surgery International - Since Hirschsprung’s disease (HSCR) already proved to benefit from robotic surgery, we aimed at describing a wider series of patients with this rare disease...  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