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   5480篇
  免费   276篇
  国内免费   31篇
耳鼻咽喉   93篇
儿科学   282篇
妇产科学   35篇
基础医学   583篇
口腔科学   126篇
临床医学   385篇
内科学   1236篇
皮肤病学   192篇
神经病学   279篇
特种医学   115篇
外科学   898篇
综合类   173篇
一般理论   1篇
预防医学   245篇
眼科学   194篇
药学   425篇
  1篇
中国医学   19篇
肿瘤学   505篇
  2024年   4篇
  2023年   36篇
  2022年   85篇
  2021年   196篇
  2020年   104篇
  2019年   142篇
  2018年   190篇
  2017年   124篇
  2016年   162篇
  2015年   186篇
  2014年   258篇
  2013年   319篇
  2012年   498篇
  2011年   509篇
  2010年   292篇
  2009年   243篇
  2008年   363篇
  2007年   344篇
  2006年   327篇
  2005年   297篇
  2004年   267篇
  2003年   245篇
  2002年   208篇
  2001年   30篇
  2000年   29篇
  1999年   37篇
  1998年   40篇
  1997年   40篇
  1996年   29篇
  1995年   13篇
  1994年   13篇
  1993年   12篇
  1992年   7篇
  1991年   8篇
  1990年   7篇
  1989年   15篇
  1988年   17篇
  1987年   10篇
  1986年   5篇
  1985年   10篇
  1984年   6篇
  1983年   11篇
  1982年   11篇
  1981年   6篇
  1980年   3篇
  1976年   2篇
  1975年   2篇
  1958年   11篇
  1957年   4篇
  1952年   2篇
排序方式: 共有5787条查询结果,搜索用时 15 毫秒
21.
22.
The etiologic role of Malassezia furfur in onychomycosis is a contentious diagnostic problem because its keratinolytic ability has never been verified. This case report describes the isolation of M. furfur from the infected nails of a child clinically diagnosed with onychomycosis, and discusses the role of this organism as an etiologic agent/colonizer. The patient presented with subungual hyperkeratosis and onycholysis without associated paronychia. Budding yeast cells compatible with M. furfur were repeatedly demonstrated in KOH wet mounts of damaged nails, histopathology of hematoxylin and eosin (H&E) and periodic acid-Schiff (PAS) stained sections showed penetration of fungal elements between deeper layers of keratin, and numerous colonies of M. furfur were isolated on three consecutive occasions from nail specimens collected from different areas of hand and toenail lesions. No evidence of nail invasion by dermatophytic or nondermatophytic filamentous fungi were found by direct microscopy or culture. Microscopy and culture were negative following 12 weeks of ketoconazole treatment, which resulted in growth of healthy nail plates with normal beds. We can infer from these observations that M.furfur was an etiologic agent rather than a colonizer in the patient's nails even though direct keratinolytic character of this fungus was not demonstrated.  相似文献   
23.
24.
In a previous study of phyllodes tumours, it has been shown that both the stroma and the epithelium can exhibit distinct molecular changes, suggesting that both are part of the neoplastic process. In view of this finding, it was decided to study stromal-epithelial interactions in these tumours by examining the Wnt-APC-beta-catenin pathway. Beta-catenin and cyclin D1 immunohistochemistry was performed on 119 phyllodes tumours. Eighty-six (72%) showed stromal nuclear beta-catenin localization and in 57% the staining was moderate or strong; however, of the eight malignant tumours in the series, seven showed absent or weak nuclear staining (p<0.025). In no tumour was nuclear beta-catenin staining seen in the epithelial component. Moderate or strong stromal cyclin D1 staining correlated with nuclear stromal beta-catenin staining (p<0.05). Forty-five of the tumours, including two malignant lesions, were screened for beta-catenin exon 3 mutations using SSCP and sequencing, but none was found. Loss of heterozygosity (LOH) of the marker D5S346 was used to infer APC mutation, but only one (benign) tumour showed LOH. Wnt2 and Wnt5a mRNA was localized by in situ hybridization in 13 cases (three malignant) chosen to reflect the different beta-catenin staining patterns. There was an association between strong nuclear beta-catenin staining of stromal cells and epithelial Wnt5a expression (p<0.0015). These data suggest that stromal proliferation in benign phyllodes tumours relies on abnormalities in the Wnt pathway which result not from mutation, but from Wnt5a expression in the epithelium. In the progression to malignancy, the stromal proliferation appears to become independent of the Wnt pathway and, presumably, of the epithelial component of these tumours.  相似文献   
25.
26.
27.
Although interest in the role of donor-specific antibodies (DSAs) in kidney transplant rejection, graft survival, and histopathological outcomes is increasing, their impact on steroid avoidance or minimization in renal transplant populations is poorly understood. Primary outcomes of graft survival, rejection, and histopathological findings were assessed in 188 patients who received transplants between 2012 and 2015 at the Scripps Center for Organ Transplantation, which follows a steroid avoidance protocol. Analyses were performed using data from the United Network for Organ Sharing. Cohorts included kidney transplant recipients with de novo DSAs (dnDSAs; n = 27), preformed DSAs (pfDSAs; n = 15), and no DSAs (nDSAs; n = 146). Median time to dnDSA development (classes I and II) was shorter (102 days) than in previous studies. Rejection of any type was associated with DSAs to class I HLA (P < .05) and class II HLA (P < .01) but not with graft loss. Although mean fluorescence intensity (MFI) independently showed no association with rejection, an MFI >5000 showed a trend toward more antibody-mediated rejection (P < .06), though graft loss was not independently associated. Banff chronic allograft nephropathy scores and a modified chronic injury score were increased in the dnDSA cohort at 6 months, but not at 2 years (P < .001 and P < .08, respectively). Our data suggest that dnDSAs and pfDSAs impact short-term rejection rates but do not negatively impact graft survival or histopathological outcomes at 2 years. Periodic protocol post-transplant DSA monitoring may preemptively identify patients who develop dnDSAs who are at a higher risk for rejection.  相似文献   
28.
Pro-inflammatory cytokine and chemokines genes drive prostate cancer progression and metastasis: molecular mechanism update and the science that underlies racial disparity. comprehensive review article.Isaac J. Powell, S. Chinni, S.S. Reddy, Alexander Zaslavsky, Navnath Gavande Introduction: In 2013 we reported that with the use of bioinformatics and ingenuity pathway network analysis we were able to identify functional driver genes that were differentially expressed among a large population of African American men (AAM) and European American men (EAM). Pro-inflammatory cytokine genes were found to be more interactive and more expressed among AAM and have been found to be functional drivers of aggressive prostate cancer (CaP) and aggressiveness in other solid tumors. We examined these genes and biological pathways initiated by these cytokines in primary CaP tissue.Method We unravel the gene network and identified biologic pathways that impacted activation of the androgen receptor, mesenchymal epithelial transition (invasion) and chemokines associated with metastasis in the CaP tissue from 639 radical prostatectomy specimens.Results Biologic pathways identified by unraveling pro-inflammatory genes from our network, more expressed among AAM compared to EAM, were tumor necrosis factor (TNF), IL1b, IL6, and IL8. IL6 and IL8 are downstream of TNF activity and are known activators of androgen receptor and through mediators promote CaP cell proliferation. TNF and IL1b mediate tumor cell invasiveness through the activation of MMP (matrix metalloproteinase) which down regulates E-Cadherin to initiate epithelial mesenchymal transition which allows cells to become invasive in the microenvironment. Ultimately our network analysis indicates that TNF and IL1b activate CXCR4 receptor on CaP cells, which facilitates metastatic progression reportedly by binding to CXCL12 on lipid rafts and tumor implantation in the bone marrow.Conclusion Our retrospective biologic mechanistic model reveals a set of pro-inflammatory cytokines and chemokines that drive CaP aggressiveness, tumor heterogeneity, progression and metastasis. A prospective multi-institutional study needs to be conducted for clinical validation as well consideration of targeted therapy.  相似文献   
29.
BackgroundThe long-term safety results of the REALIZE (Ethicon Endo-Surgery, Inc., Cincinnati, OH) adjustable gastric band collected in this prospective, multicenter study in patients with morbid obesity are presented.ObjectivesTo determine the reoperation rate, including band revisions, replacements, and explants, resulting from a serious adverse device-related event through years 4 and 5. Various efficacy measures were also assessed as secondary objectives.SettingNine academic and/or private institutions.MethodsThe participating institutions enrolled 303 patients, who were then assessed on an annual basis, with 231 patients completing 5 years of follow-up. The study parameters included reoperation rates, changes in percentage of excess weight loss (%EWL), and changes in body mass index (BMI), as well as parameters of diabetes and dyslipidemia. Quality of life was assessed using the Short Form (SF)-36 and the Impact of Weight on Quality of Life-Lite questionnaires.ResultsThe reoperation rate due to a serious adverse event in this population at 5 years after implantation with the REALIZE gastric band was 8.9%. The most common serious adverse event was band slippage, which affected 6.9% of the study population. The mean %EWL was 35.6% ± 26.84%, and the decrease in mean BMI was ?7.01 ± 5.45 kg/m2 at 5 years. Patients experienced improvements in mean glycated hemoglobin and serum lipid levels, in addition to improvements in the quality of life measures.ConclusionNo new safety concerns were identified during the 5 years of follow-up. Although the results of this study did not meet the predefined safety criteria of 8% or less, the safety profile and long-term effectiveness observed in this study are consistent with those in the current literature.  相似文献   
30.
An interesting case of anhidrotic Ectoderml Dysplasia (A.E.D.) which came with epistaxix, headache and maggots in nose is presented. Histopathology of forearm shin, scalp and Exercise test helped to confirm the diagnosis, AED is an X-linked recessive condition and has no cure but symptomatic treatment along with heat protection and protection of eyes especially in summer season has a role to play in the management of these cases.  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