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   4329篇
  免费   354篇
  国内免费   31篇
耳鼻咽喉   29篇
儿科学   149篇
妇产科学   180篇
基础医学   567篇
口腔科学   206篇
临床医学   472篇
内科学   892篇
皮肤病学   198篇
神经病学   302篇
特种医学   114篇
外科学   381篇
综合类   66篇
一般理论   7篇
预防医学   356篇
眼科学   85篇
药学   346篇
中国医学   47篇
肿瘤学   317篇
  2024年   9篇
  2023年   104篇
  2022年   207篇
  2021年   314篇
  2020年   205篇
  2019年   309篇
  2018年   348篇
  2017年   222篇
  2016年   218篇
  2015年   222篇
  2014年   277篇
  2013年   300篇
  2012年   422篇
  2011年   386篇
  2010年   174篇
  2009年   133篇
  2008年   204篇
  2007年   163篇
  2006年   144篇
  2005年   99篇
  2004年   83篇
  2003年   53篇
  2002年   60篇
  2001年   10篇
  2000年   2篇
  1999年   11篇
  1998年   5篇
  1997年   3篇
  1996年   1篇
  1995年   1篇
  1994年   3篇
  1993年   4篇
  1992年   1篇
  1989年   4篇
  1987年   4篇
  1986年   1篇
  1984年   3篇
  1983年   1篇
  1982年   1篇
  1981年   2篇
  1965年   1篇
排序方式: 共有4714条查询结果,搜索用时 19 毫秒
991.
To assess the presence of genetic imbalances in patients with myeloproliferative neoplasms (MPNs), 38 patients with chronic eosinophilia were studied by array comparative genomic hybridization (aCGH): seven had chronic myelogenous leukaemia (CML), BCR‐ABL1 positive, nine patients had myeloproliferative neoplasia Ph? (MPN‐Ph?), three had a myeloid neoplasm associated with a PDGFRA rearrangement, and the remaining two cases were Lymphoproliferative T neoplasms associated with eosinophilia. In addition, 17 patients had a secondary eosinophilia and were used as controls. Eosinophilic enrichment was carried out in all cases. Genomic imbalances were found in 76% of all MPN patients. Losses on 20q were the most frequent genetic abnormality in MPNs (32%), affected the three types of MPN studied. This study also found losses at 11q13.3 in 26% of patients with MPN‐Ph? and in 19p13.11 in two of the three patients with an MPN associated with a PDGFRA rearrangement. In addition, 29% of patients with CML had losses on 8q24. In summary, aCGH revealed clonality in eosinophils in most MPNs, suggesting that it could be a useful technique for defining clonality in these diseases. The presence of genetic losses in new regions could provide new insights into the knowledge of these MPN associated with eosinophilia.  相似文献   
992.
993.
994.
995.
The dangerous dose-dependent side effects of anticancer agents triggered the finding of new approaches for elevated chemotherapy efficacy. This study investigated the potential application of nanostructured lipid careers (NLCs) in increasing vitamin D3 (VitD) effectiveness in breast cancer cell (MCF-7) in concurrent administration with doxorubicin (Dox). VitD-loaded NLCs were characterized by particle size, zeta potential, Fourier transform infrared spectroscopy, and scanning electron microscope. Cytotoxicity and molecular effects of formulation were evaluated by MTT, DAPI staining, flow cytometry, and real-time quantitative PCR assays. The formulation revealed mean particle size of 87±5 nm with a polydispersity index of 0.24 confirmed by SEM images. The IC50 values for VitD and Dox were 1.3 ± 0.04 and 0.65 ± 0.05 µM, respectively. VitD-loaded NLCs decreased the percentage of cell proliferation from 49 ± 7.2% to 37 ± 5.1% (P < 0.05). Cotreatment of the cells with VitD-loaded NLCs and Dox caused over a twofold increase in the percentage of apoptosis (P < 0.05). Gene expression profile demonstrated a significant decrease in antiapoptotic factor survivin along with increase in proapoptotic factor Bax mRNA levels. Overall, our results introduced the NLC technology as a novel strategy to elevate the efficacy of chemotherapeutics in breast cancer.  相似文献   
996.
Background Skin tags are common benign lesion occurring mainly on the neck and major flexures as a small soft pedunculated protrusion. This study evaluate insulin and insulin‐like growth factor‐I (IGF‐I) in non‐diabetic ones. Methods and materials A case–control study was conducted in non‐diabetic persons. Comparing insulin and IGF‐I between matched cases (n = 40) and controls (n = 40) by radioimmunoassay test. Cases and controls were recruited from patients consecutively seen at an academic outpatient dermatology clinic. Results The insulin level in patients with skin tags was significantly higher than controls (P = 0.00) but IGF‐I level was not significantly different (P = 0.43). Conclusion These results show an increased insulin level in non‐diabetics ones and overall importance of insulin effect in pathogenesis of skin tags.  相似文献   
997.
BackgroundBreast cancer among older women is a major and increasing public health issue. No clear recommendation has been established in France after 74 years, the age limit for state-organised screening program. A survey was performed among all regional agencies in charge of the breast screening to analyse which information is delivered to women reaching the age of 75 years.MethodsA postal survey sent to 91 French organised cancer screening agencies.ResultsAmong the 89 agencies that answered, only 22 deliver a systematic written information. Twelve suggest that mammographic screening should be continued, and five mention clinical examination. Twenty agencies dispatch the screening to general practitionners or gynaecologists. Two information letters insist on the ongoing risk of breast cancer. Most of the written information is given with the last mammography report. No impact study has ever been performed.ConclusionIn our study, only 25% of the screening agencies give systematic information to women. The modalities and the substance of this information are heterogeneous. A better information seems to be a key-point for earlier clinical breast cancer diagnosis among older women, for whom there is little direct evidence of the benefit of systematic mammographic screening.  相似文献   
998.
Pulmonary agenesis is characterized by undeveloped pulmonary vessels, bronchi as well as lung parenchyma and is a rare congenital anomaly with unknown etiology. It is usually diagnosed during childhood. Nearly, one third of these patients have concomitant congenital heart diseases. While more than 50% of these patients die before the age of 5 years, some other patients may be asymptomatic throughout their life. On the other hand, common atrium, another rare congenital anomaly, is characterized by complete absence of the atrial septum and is usually accompanied by atrioventricular valve malformations. An 18‐year‐old male presented with concomitant pulmonary agenesis and common atrium and had not undergone surgery due to high risk for mortality.  相似文献   
999.
1000.
Thymidine phosphorylase/platelet-derived endothelial cell growth factor (TPase/PD-ECGF) is a catabolic enzyme that has been shown to be chemotactic for endothelial cells in vitro and angiogenic in vivo. TPase/PD-ECGF expression is increased in a variety of tumors. In the skin, TPase is active in normal keratinocytes in vitro and in vivo. Our objective was to study the expression and localization of TPase/PD-ECGF by immunohistochemical analysis in normal skin and cutaneous tumors and to correlate this information with enzymatic activity of TPase. TPase/PD-ECGF expression was observed in keratinocytes with intense staining of the infundibulum of hair follicles but no staining of hair bulbs. Expression localized primarily to the nucleus of keratinocytes in the basal layer but was more intense and cytoplasrmic in suprabasal keratinocytes. Increased expression of TPase/PD-ECGF in differentiated cells was confirmed by in vitro studies of TPase activity. In cutaneous tumors, there was positive staining for TPase/ PD-ECGF in squamous cell carcinomas (10/10), eccrine poromas (3/4), eccrine syringomas (4/4), trichoepitheliomas (1/3), and tumors of the follicular infundibulum (2/3) and melanomas (5/8). There was no staining of any intradermal nevi (0/2), basal cell carcinomas (0/10) or Merkel cell carcinoma (0/1). We conclude TPase/PD-ECGF is found throughout the epidermis and its expression increases with differentiation of keratinocytes. In cutaneous tumors, expression of TPase/PD-ECGF may be linked to the cell of origin of the tumor as well as the tumor's degree of differentiation.  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