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   341篇
  免费   30篇
耳鼻咽喉   5篇
儿科学   3篇
妇产科学   16篇
基础医学   78篇
口腔科学   4篇
临床医学   19篇
内科学   41篇
皮肤病学   16篇
神经病学   14篇
特种医学   7篇
外科学   25篇
预防医学   12篇
眼科学   2篇
药学   28篇
肿瘤学   101篇
  2022年   2篇
  2021年   5篇
  2020年   1篇
  2019年   2篇
  2018年   2篇
  2017年   2篇
  2016年   10篇
  2015年   6篇
  2014年   7篇
  2013年   18篇
  2012年   16篇
  2011年   11篇
  2010年   11篇
  2009年   10篇
  2008年   12篇
  2007年   21篇
  2006年   15篇
  2005年   15篇
  2004年   23篇
  2003年   21篇
  2002年   25篇
  2001年   16篇
  2000年   32篇
  1999年   21篇
  1998年   8篇
  1997年   6篇
  1996年   3篇
  1995年   4篇
  1994年   5篇
  1993年   1篇
  1992年   16篇
  1991年   8篇
  1990年   3篇
  1989年   2篇
  1988年   1篇
  1987年   6篇
  1986年   1篇
  1985年   2篇
  1984年   1篇
排序方式: 共有371条查询结果,搜索用时 703 毫秒
231.
Matrix metalloproteinases in skin   总被引:18,自引:0,他引:18  
Abstract Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases collectively capable of degrading essentially all extracellular matrix components. These enzymes can be produced by several different types of cells in skin such as fibroblasts, keratinocytes. macro-phages, endothelial cells, mast cells, and eosinophils and their activity can be specifically inhibited by TIMPs (tissue inhibitors of metalloproteinases), which bind to active MMPs with 1:1 stoichiometry. In general, MMPs are not constitutively expressed in skin but are induced temporarily in response to exogenous signals such as various cytokines. growth factors, cell-matrix interactions and altered cell-cell contacts. At present, more evidence is accumulating thai MMPs play an important role in proteolytic remodeling of extracellular matrix in various physiologic situations, including developmental tissue morphogenesis, tissue repair, and angiogenesis. On the other hand, MMPs play an important pathogenetic role in excessive breakdown of connective tissue components, e.g. in rheumatoid arthritis, oslteoarthritis, chronic ulcers, dermal photoageing, and periodontitis, as well as in tumor cell invasion and metastasis. In this review we discuss the role of MMPs and TIMPs in human skin based on new observations on the regulation of the expression of MMPs, on their substrate specificily, and MMP expression in physiologic and pathologic conditions of skin involving matrix remodeling. Furthermore, therapeutic modalities based on regulating MMP activity will be reviewed.  相似文献   
232.
233.
234.
Primary serous ovarian carcinoma (OVCA) and serous Fallopian tube carcinoma (FTC), both belonging to the BRCA-linked tumour spectrum, share many properties and are treated similarly. However, a detailed molecular comparison has been lacking. We hypothesized that comparative genomic studies of serous OVCAs and FTCs should point to gene regions critically involved in their tumorigenesis. Array comparative genomic hybridization (array CGH) analysis indicated that serous OVCAs and serous FTCs displayed common but also more distinctive patterns of recurrent changes. Targeted gene identification using a dedicated multiplex ligation-dependent probe amplification (MLPA) probe set directly identified EIF2C2 on 8q as a potentially important driver gene. Other previously unappreciated gained/amplified genes included PSMB4 on 1q, MTSS1 on 8q, TEAD4 and TSPAN9 on 12p, and BCAS4 on 20q. SPINT2 and ACTN4 on 19q were predominantly found in FTCs. Gains/amplifications of CCNE1 and MYC, often in conjunction with changes in genes of the AKT pathway, EVI1 and PTK2, seemed to be involved at earlier stages, whereas changes of ERBB2 were associated with advanced stages. The only BRCA1-mutated FTC shared common denominators with the sporadic tumours. In conclusion, the data suggest that serous OVCAs and FTCs, although related, exhibit differences in genomic profiles. In addition to known pathways, new genes/pathways are likely to be involved, with changes in an miRNA-associated gene, EIF2C2, as one important new feature. Dedicated MLPA sets constitute potentially important tools for differential diagnosis and may provide footholds for tailored therapy.  相似文献   
235.
Breast cancer (BC) is a heterogeneous disease, and different tumor characteristics and genetic variation may affect the clinical outcome. The FANCM c.5101C > T nonsense mutation in the Finnish population associates with increased risk of breast cancer, especially for triple‐negative breast cancer patients. To investigate the association of the mutation with disease prognosis, we studied tumor phenotype, treatment outcome, and patient survival in 3,933 invasive breast cancer patients, including 101 FANCM c.5101C > T mutation carriers and 3,832 non‐carriers. We also examined association of the mutation with nuclear immunohistochemical staining of DNA repair markers in 1,240 breast tumors. The FANCM c.5101C > T mutation associated with poor 10‐year breast cancer‐specific survival (hazard ratio (HR)=1.66, 95% confidence interval (CI) 1.09–2.52, p = 0.018), with a more pronounced survival effect among familial cases (HR = 2.93, 95% CI 1.5–5.76, p = 1.80 × 10?3). Poor disease outcome of the carriers was also found among the estrogen receptor (ER) positive subgroup of patients (HR = 1.8, 95% CI 1.09–2.98, p = 0.021). Reduced survival was seen especially among patients who had not received radiotherapy (HR = 3.43, 95% CI 1.6–7.34, p = 1.50 × 10?3) but not among radiotherapy treated patients (HR = 1.35, 95% CI 0.82–2.23, p = 0.237). Significant interaction was found between the mutation and radiotherapy (p = 0.040). Immunohistochemical analyses show that c.5101C > T carriers have reduced PAR‐activity. Our results suggest that FANCM c.5101C > T nonsense mutation carriers have a reduced breast cancer survival but postoperative radiotherapy may diminish this survival disadvantage.  相似文献   
236.
Non-germinal center (non-GC) phenotype is an adverse prognostic factor in chemotherapy (CT)-treated diffuse large B-cell lymphoma (DLBCL) patients. To determine how high-dose therapy (HDT) supported with auto-SCT as first line therapy influences GC-associated outcome in young high-risk DLBCL patients GC and non-GC phenotypes were determined immunohistochemically from 63 patients. Of these, 29 primary high-risk DLBCL patients were treated with auto-SCT, whereas 34 CT-treated patients served as a control group. Consistent with previous studies, non-GC phenotype was associated with adverse outcome in CT-treated high-risk patients. In contrast, immunohistochemical classification by cell of origin did not associate with survival after auto-SCT. When the impact of treatment on the predictive value of cell of origin was analyzed, the non-GC patients, who received HDT, had a better failure-free survival (FFS) and overall survival (OS) than the patients treated with CT alone. In multivariate analyses, both age-adjusted International Prognostic Index (aaIPI) and treatment were independent prognostic factors for FFS and OS. For the patients with GC phenotype, the influence of auto-SCT on survival was not significant. The data imply that auto-SCT can overcome the adverse prognostic impact of the non-GC phenotype in patients with high-risk DLBCL and warrant additional prospective studies.  相似文献   
237.
238.
KDM4A, KDM4B and KDM4D are lysine demethylases which demethylate H3 at lysine K9 and K36 sites, additionally KDM4D also the H1.4 linker histone at K26 lysine. Lysine methylation changes can repress or induce gene expression at specific sites thus influencing cellular functions. We analysed the immunohistochemical expression of KDM4A, KDM4B and KDM4D in a clinical material of 188 patients with lung carcinomas. There were 132 (70%) squamous cell carcinomas, 53 (28%) adenocarcinomas and 3 (2%) large cell carcinomas in the study. Additionally, the trimethylated state of chromatin was detected with an antibody to trimethylated H3K9 residue. Nuclear KDM4A and KDM4D were associated with the presence of lymph node metastases in tumors. Cytoplasmic KDM4A was associated with poor survival of the patients (P = 0.015) and with a shorter recurrence free interval (P = 0.028). KDM4A and KDM4D appear to have a significant role in the metastatic spread of lung carcinomas. The findings are also in line with their proposed involvement in mechanisms associated with cell proliferation, apoptosis and DNA repair.  相似文献   
239.

Background

Blood supplies in Greece are insufficient to meet the high transfusion needs arising from car accidents and treatment of thalassaemia. This study was designed to determine Greeks’ opinions about blood donation, in order to identify the reasons for the lack of motivation to donate and allow experts to establish better recruitment campaigns for the enrichment of the donor pool, based on our findings.

Materials and methods

The opinions of randomly selected Greek citizens (n=800) about volunteer blood donation were assessed by means of a standardised, anonymous questionnaire. The results were analysed using the χ2 test and Spearman’s correlation coefficient.

Results

With regards to attitudes towards intention to donate, only 7.1% were indifferent, while 88.0% of the individuals believed that donating blood was an “offer”. Reasons for not donating mainly involved safety (36.0%) and fear (24.0%), whereas need (77.9%) was the most fundamental positive motivation. Of the people enrolled in the present study, 10.0% were active donors, 31.3% occasional donors, 15.0% rare donors and 36.6% non-donors.

Discussion

The considerable percentages of occasional and rare donors in comparison with the low proportion of active donors in the Greek donor pool indicates that “need” is a more important motivation for blood donation than altruism in Greece. These results could be useful for establishing advertising campaigns on blood donation and for a more direct approach to the population, aiming for a change in mentality in favour of active blood donation.  相似文献   
240.
Merkel cell carcinoma is a rare, although increasingly recognized, malignant tumor of the skin. The most common site of occurrence is the head and neck (50%). Only five cases of this tumor on the auricle have been reported previously. We present a further such case. The incidence, clinical features, diagnosis, prognosis, and treatment of the Merkel cell carcinoma are discussed. Received: 21 August 2000 / Accepted: 18 September 2000  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