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   4908篇
  免费   403篇
  国内免费   60篇
耳鼻咽喉   38篇
儿科学   151篇
妇产科学   209篇
基础医学   629篇
口腔科学   76篇
临床医学   427篇
内科学   1267篇
皮肤病学   113篇
神经病学   611篇
特种医学   157篇
外科学   446篇
综合类   6篇
一般理论   3篇
预防医学   282篇
眼科学   54篇
药学   336篇
中国医学   9篇
肿瘤学   557篇
  2024年   14篇
  2023年   130篇
  2022年   215篇
  2021年   432篇
  2020年   250篇
  2019年   273篇
  2018年   320篇
  2017年   204篇
  2016年   232篇
  2015年   257篇
  2014年   265篇
  2013年   314篇
  2012年   414篇
  2011年   346篇
  2010年   189篇
  2009年   141篇
  2008年   232篇
  2007年   239篇
  2006年   199篇
  2005年   166篇
  2004年   144篇
  2003年   130篇
  2002年   100篇
  2001年   16篇
  2000年   8篇
  1999年   22篇
  1998年   24篇
  1997年   14篇
  1996年   11篇
  1995年   11篇
  1994年   12篇
  1993年   9篇
  1992年   2篇
  1991年   5篇
  1990年   4篇
  1989年   3篇
  1988年   6篇
  1987年   4篇
  1986年   3篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1981年   3篇
  1979年   3篇
排序方式: 共有5371条查询结果,搜索用时 15 毫秒
101.
Purpose

To compare the accuracy of Contrast-Enhanced Spectral Mammography (CESM), MG, US, and breast MRI in estimating the size of breast lesions requiring surgery. The postoperative histology size of the lesion was used as the gold standard.

Material and methods

Two hundred thirty-three non-benign lesions in 189 patients were included in the analyses. All the selected patients underwent CESM and at least one other conventional diagnostic exam (US, MG, or MRI). Subsequently, all the patients underwent surgery preceded by cytological/histological examination. The largest diameter of the lesion at imaging was measured by a radiologist with more than 10 years’ experience and then compared with the size of the lesion in the histological sample at the surgery (gold standard).

Results

Among the 233 breast lesions, 196 were evaluated with US, 206 with MG and 160 with MRI. We found no statistically significant differences between size measurements using CESM and MRI compared with the measurements at the surgery (p value 0.63 and 0.51), whereas a significant difference was found for MG and US (p?<?0.001).

Conclusion

CESM is a reliable method for estimating the size of breast lesions: its performance seems superior to US and MG and comparable to MRI.

  相似文献   
102.
OBJECTIVE: Studies of memory T cells transferred with the graft are relevant to better understand the early immune reconstitution of patients given autologous bone marrow transplantation (A-BMT). A critical question is whether memory T cells resident in bone marrow (BM) of patients with hematological malignancies are resistant to either pretransplant chemotherapy or ex vivo pharmacological purging. PATIENTS AND METHODS: To address these issues, we evaluated the frequency of tetanus-toxoid (TT)-specific proliferating T-cell precursors (TT-PTCp) in BM and peripheral blood (PB) of eight patients with acute myeloid leukemia (AML) given A-BMT after in vitro purging of BM with mafosfamide. Patients were studied at the time of BM harvesting and five of them also after A-BMT. RESULTS: The range of TT-PTCp frequencies found after A-BMT were comparable with those observed in PB and in BM at the time of harvesting and did not differ significantly from those of eight age-matched healthy subjects who donated BM for a human leukocyte antigen-identical sibling. TT-PTCp frequencies in BM, studied before and after ex vivo purging, appeared not to be affected by incubation with mafosfamide. We also compared the T-cell receptor (TCR)-Vbeta-repertoire usage of TT-specific T-cell lines (TT-TCL) in BM of patients at the time of harvesting and in their PB 2 months after transplantation. The same TCR-clonotypes were detected in TT-TCL at time of harvesting and after A-BMT. CONCLUSION: These data indicate that BM-resident memory T cells of patients with AML are resistant to both pretransplant chemotherapy and ex vivo pharmacological purging and may contribute to immune reconstitution after A-BMT.  相似文献   
103.
INTRODUCTION: Surgical repair of tetralogy of Fallot is complicated by the occurrence of ventricular tachycardia (VT). Among different indexes proposed to assess prognosis of these patients, the study of QRS and repolarization provided useful information. Controversial results come from the analysis of signal-averaging ECG (SAECG). The aim of our study was to identify patients operated for tetralogy of Fallot at higher risk of sudden death by means of SAECG. METHODS AND RESULTS: Sixty-six consecutive patients, mean age 26 +/- 10 years, were studied 17.7 +/- 5.8 years after total correction for tetralogy of Fallot using standard ECG, 24-hour Holter recordings, SAECG, and echocardiography. The following variables were measured: standard QRS duration, filtered QRS duration (fQRS), high-frequency and low-amplitude signal duration (HFLA), root mean square of the mean voltage in the terminal portion of filtered QRS (RMS), left and right end-diastolic volumes, and ejection fractions. During a mean follow-up period of 7.3 +/- 3.1 years, 12 patients had episodes of sustained VT and two of them suddenly died. All patients had complete right bundle branch block. Patients with VT were characterized by a significantly longer fQRS duration at all filter settings. On the contrary, there was no difference in standard QRS duration in patients with or without VT. At a multivariate analysis, left ventricular ejection fraction and fQRS were independent predictors for VT. CONCLUSIONS: A longer fQRS duration is associated with an increased risk in developing malignant ventricular arrhythmias in asymptomatic patients after total correction of tetralogy of Fallot.  相似文献   
104.
105.
Humans are quicker to detect reflectional than rotational or translational symmetry, despite the fact that these patterns are equally regular. We were interested in the neural correlates of these perceptual effects. Participants viewed random, reflection, rotation, and translation patterns while we recorded EEG from the scalp. Half the participants classified the pattern regularity overtly, the other half did not explicitly attend to pattern regularity but reported rare oddball trials, where two squares were embedded among the dots. The amplitude of a symmetry‐related ERP known as the sustained posterior negativity was most pronounced for reflection, then rotation and translation. We suggest that reflectional symmetry, despite its biological significance, may not be processed by unique visual mechanisms, but instead it could be a preferred stimulus for a more general regularity‐sensitive network in the extrastriate visual cortex.  相似文献   
106.
107.
In pathogenic simian immunodeficiency virus (SIV) and human immunodeficiency virus (HIV) infections, the translocation of microbial products from the gastrointestinal (GI) tract to portal and systemic circulation has been proposed as a major driver of the chronic immune activation that is associated with disease progression. Consistently, microbial translocation is not present in nonpathogenic SIV infections of natural host species. In vivo studies demonstrated that HIV/SIV-associated microbial translocation results from a series of immunopathological events occurring at the GI mucosa: (i) early and severe mucosal CD4+ depletion, (ii) mucosal immune hyperactivation/persistent inflammation; (iii) damage to the integrity of the intestinal epithelium with enterocyte apoptosis and tight junction disruption; and (iv) subverted the gut microbiome, with a predominance of opportunistic bacteria. Direct in situ evidence of microbial translocation has been provided for SIV-infected rhesus macaques showing translocated microbial products in the intestinal lamina propria and distant sites. While the mechanisms by which microbial translocation causes immune activation remain controversial, a key pathogenic event appears to be innate immunity activation via Toll-like receptors and other pathogen recognition receptors. Accumulating clinical observations suggest that microbial translocation might affect HIV disease progression, response to therapy, and non-AIDS comorbidities. Given its detrimental effect on overall immunity, several interventions to prevent/block microbial translocation are currently under investigation as novel therapeutic agents for HIV/AIDS.  相似文献   
108.
Journal of Neurology - Diagnostic delay of hereditary transthyretin amyloidosis (ATTRv, v for variant) prevents timely treatment and, therefore, concurs to the mortality of the disease. The aim of...  相似文献   
109.
Bucello  Sebastiano  Annovazzi  Pietro  Ragonese  Paolo  Altieri  Marta  Barcella  Valeria  Bergamaschi  Roberto  Bianchi  Alessia  Borriello  Giovanna  Buscarinu  Maria Chiara  Callari  Graziella  Capobianco  Marco  Capone  Fioravante  Cavalla  Paola  Cavarretta  Rosella  Cortese  Antonio  De Luca  Giovanna  Di Filippo  Massimiliano  Dattola  Vincenzo  Fantozzi  Roberta  Ferraro  Elisabetta  Filippi  Maria Maddalena  Gasperini  Claudio  Grimaldi  Luigi Maria Edoardo  Landi  Doriana  Re  Marianna Lo  Mallucci  Giulia  Manganotti  Paolo  Marfia  Girolama Alessandra  Mirabella  Massimiliano  Perini  Paola  Pisa  Marco  Realmuto  Sabrina  Russo  Margherita  Tomassini  Valentina  Torri-Clerici  Valentina Liliana Adriana  Zaffaroni  Mauro  Zuliani  Cristina  Zywicki  Sofia  Filippi  Massimo  Prosperini  Luca 《Journal of neurology》2021,268(8):2922-2932
Journal of Neurology - To identify baseline factors associated with disease activity in patients with relapsing–remitting multiple sclerosis (RRMS) under teriflunomide treatment. This was an...  相似文献   
110.
Female pelvic floor is a complex functional unit involved in multiple functions that extend beyond the sole support of pelvic organs. Pelvic floor dysfunction globally affects micturition, defecation and sexual activity. Evolutionary modifications such ad adaptation to upright standing, walking and the need to deliver fetuses with larger head diameters made the fascial and muscle support of the pelvic floor vulnerable, therefore predisposing women to pelvic organ prolapse and incontinence. Different than in males, the female pelvic floor undergoes a number of adaptive changes related to life and endocrine events. Most of the clinical manifestations of these changes become apparent after menopause and throughout aging in women. This review article summarizes the key aspects of the pathophysiology and the clinics of the modifications of the pelvic floor in women through midlife and beyond. A particular focus is given to the relationship between urinary and bowel dysfunction.  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