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   595篇
  免费   37篇
  国内免费   14篇
耳鼻咽喉   10篇
儿科学   35篇
妇产科学   10篇
基础医学   57篇
口腔科学   10篇
临床医学   40篇
内科学   165篇
皮肤病学   8篇
神经病学   24篇
特种医学   7篇
外科学   154篇
综合类   6篇
预防医学   24篇
眼科学   5篇
药学   33篇
中国医学   3篇
肿瘤学   55篇
  2024年   2篇
  2023年   5篇
  2022年   24篇
  2021年   33篇
  2020年   16篇
  2019年   31篇
  2018年   24篇
  2017年   19篇
  2016年   13篇
  2015年   19篇
  2014年   25篇
  2013年   31篇
  2012年   61篇
  2011年   54篇
  2010年   23篇
  2009年   25篇
  2008年   37篇
  2007年   37篇
  2006年   33篇
  2005年   23篇
  2004年   27篇
  2003年   18篇
  2002年   16篇
  2001年   9篇
  2000年   13篇
  1999年   4篇
  1998年   3篇
  1997年   3篇
  1993年   1篇
  1992年   4篇
  1991年   2篇
  1988年   1篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1984年   1篇
  1971年   1篇
  1967年   1篇
  1966年   1篇
  1965年   1篇
排序方式: 共有646条查询结果,搜索用时 15 毫秒
61.
Among the many sites for primary small cell cancer is the genitourinary system. The majority of cases have been observed in the bladder and prostate. Small cell carcinoma accounts for less than 1% of all bladder tumors. Definitive predisposing factors are unknown; however, small cell carcinoma of the bladder has been associated with cigarette smoking, long-standing cystitis, bladder calculus, and augmented cystoplasty. Contrary to the early theory of derivation from Kulchitsky cells, it is now believed that small cell carcinoma of the bladder originates from the totipotent stem cells present in the submucosa of the bladder wall. A number of chromosomal aberrations have been reported in small cell cancer of the bladder. There are no specific clinical features that differentiate these patients from transitional cell carcinoma of the bladder; however, some patients may have associated paraneoplastic conditions. Diagnosis is established by cystoscopic-assisted biopsy. Like small cell carcinoma of the lung, small cell carcinoma of the bladder has a propensity for early metastases. There is no standard therapy for small cell carcinoma of the bladder and the prognosis is poor; however, patients treated with cisplatin-based chemotherapy regimens seem to have a better prognosis.  相似文献   
62.
Small cell carcinoma of the breast (SCCB) is an uncommon neoplasm that accounts for less than 1% of primary breast cancers. Histologically, these tumors have striking similarities to small call carcinoma of the lung, usually with evidence of associated ductal carcinoma-in-situ (DCIS) with areas of ductal, lobular, or papillary differentiation. Immunoreactivity for neuroendocrine markers is documented in two thirds of cases, while 33% to 50% are positive for estrogen receptor (ER) or progesterone receptor (PR). Her2/neu expression has not been reported in SCCB. Treatment, which may include surgery, radiotherapy, and combination chemotherapy, is based on clinical stage and the presence of metastases. Prognosis is variable and is dependent on the initial stage of disease.  相似文献   
63.
64.
Ultra-fine surface features are commonly used to modulate cellular activity on a variety of materials. The continuing challenge for materials in contact with bone is the development of a material with both favorable surface and bulk properties to modulate not only the cell-substrate interactions, but also to ensure the long-term stability of the implant. In a combined approach involving material sciences and cell and molecular biology, the nature and mechanism of cell-substrate interaction, in particular, the molecular machinery controlling cell response to the surface of the nanostructured titanium based material produced by the high pressure torsion (HPT) process is assessed. The degree of pre-osteoblast attachment and rate of growth, which are regulated through the activity and interaction of proteins present in the extracellular matrix and associated with cytoskeleton and focal adhesion, are notably increased on the HPT-processed titanium substrates. The improved cell activity is attributed to the nanostructured feature of these substrates consisting of ultra-fine crystals (<50 nm) and a distinct surface oxide layer which provide higher degree of surface wettability. These findings demonstrate the advantages of HPT-processed titanium over the conventional and coated titanium implants, as both mechanical properties and cellular response are improved.  相似文献   
65.
Context: The investigations have shown that patients with diabetes have the elevated levels of glucose and oxLDL. These two play an important role in increased expression levels of oxLDL scavenger receptors on the surface of macrophages and endothelial cells that leads to deposition of oxLDL and macrophages in vascular walls.

Objective: The present study intends to show the effects of β-d-mannuronic acid (M2000) on the expression profile of ox-LDL scavenger receptors (including SR-A, LOX-1, CD36, and CD68) in an experimental model of diabetes.

Materials and methods: Eighteen Sprague-Dawley rats were randomly divided into three 6-member groups of the healthy control, diabetic control, and treated rats by M2000. Diabetes was induced in rats by intraperitoneal (IP) administration of 60?mg/kg streptozotocin. The treated rats were given daily intraperitoneal injections of M2000 with a dose of 25?mg/kg for 28 days and at the end of the 28th day, their aortas were removed. The qRT-PCR technique was then used to evaluate the expression levels of the proposed gene.

Results: The gene expression levels of the SR-A, LOX-1, CD36, and CD68 significantly declined in the diabetic group that received M2000 compared with untreated diabetic rats.

Conclusions: The M2000, as a novel NSAID is able to modify by lowering the gene expression levels of SR-A, LOX-1, CD36, and CD68 in treated rats compared to the untreated diabetic group, which may play an important role in preventing the complications that could lead to a cardioprotective efficacy.  相似文献   
66.
67.

Objectives

The aim of the study was to evaluate the right ventricular (RV) performance during exercise in patients who underwent mitral valve repair for chronic mitral valve insufficiency relative to healthy individuals and to assess exercise capacity using a semisupine ergometer.

Methods

We studied 56 patients who underwent mitral valve repair for degenerative posterior mitral leaflet prolapse between 2005 and 2014 and a control group of 13 healthy individuals. Clinical data were collected prospectively, and echocardiographic measurements of RV function were obtained at rest and at peak exercise.

Results

One-third of the study patients had RV systolic dysfunction as indicated by tricuspid annular plane excursion (TAPSE) at rest. Resting TAPSE was lower in the study group (16.7?±?3.3 mm) than in the control group (24.4?±?4.3 mm), p?<?0.001. TAPSE increased in both groups during exercise and exercise was shown to have a significant main effect on TAPSE F(1, 52)?=?80, p?<?0.001. TAPSE increased more in the control group and an interaction was detected between the participant groups (study group vs. control group) and exercise, F(1, 52)?=?24, p?<?0.001. In the study group, Poor postoperative RV function was associated with preoperative left ventricular dilatation but was not correlated with impaired maximum exercise capacity.

Conclusions

Despite the excellent clinical outcome during rest and exercise after mitral valve repair, our results suggest patients that have undergone mitral valve repair due to posterior leaflet prolapse have significantly reduced RV function at rest and during exercise compared to healthy controls at long-term follow-up, as measured by TAPSE.
  相似文献   
68.
Autologous stem cell transplantation (ASCT) has enabled the use of high-dose alkylating agents either as a single agent or in combination with other cytotoxic agents and/or total body irradiation (TBI) for the treatment of multiple myeloma. Despite improved complete remission rates, relapse and regimen-related toxicities remain challenging. In an effort to increase event-free survival and decrease the high incidence of regimen-related toxicity, we have studied the use of etoposide in combination with reduced-dose busulfan and cyclophosphamide as a conditioning regimen for ASCT in a group of 26 patients with advanced multiple myeloma. Median follow-up for the group was 30 months. There was no early treatment-related mortality. The main toxicity was mucositis. Otherwise, there was 1 case of reversible, clinically diagnosed hepatic veno-occlusive disease. Post-engraftment, 10 patients (38%) achieved CR, 15 (58%) patients achieved PR or SD, and 1 patient developed progressive disease (4%). Five patients in PR and 1 with progressive disease before transplant attained a CR post-transplant. The median times for event-free survival and overall survival after transplantation were 24 and 43 months, respectively. In conclusion, conditioning with busulfan, cyclophosphamide, and etoposide followed by ASCT is a safe regimen with comparable effectiveness to other previously used preparative regimens, thus providing another approach of non-TBI containing high-dose chemotherapy for patients with multiple myeloma.  相似文献   
69.
Rationalizing has become a new trend in the world of science and technology. Nanotechnology has ascended to become one of the most favorable technologies, and one which will change the application of materials in different fields. The quality of dental biomaterials has been improved by the emergence of nanotechnology. This technology manufactures materials with much better properties or by improving the properties of existing materials. The science of nanotechnology has become the most popular area of research, currently covering a broad range of applications in dentistry. This review describes the basic concept of nanomaterials, recent innovations in nanomaterials and their applications in restorative dentistry. Advances in nanotechnologies are paving the future of dentistry, and there are a plenty of hopes placed on nanomaterials in terms of improving the health care of dental patients.  相似文献   
70.
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