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   70篇
  免费   2篇
基础医学   10篇
临床医学   5篇
内科学   14篇
神经病学   5篇
特种医学   7篇
外科学   19篇
药学   7篇
肿瘤学   5篇
  2023年   2篇
  2022年   2篇
  2020年   1篇
  2019年   2篇
  2018年   2篇
  2017年   4篇
  2015年   1篇
  2014年   3篇
  2013年   3篇
  2012年   8篇
  2011年   6篇
  2010年   2篇
  2009年   1篇
  2008年   1篇
  2007年   1篇
  2006年   3篇
  2005年   2篇
  2004年   5篇
  2003年   3篇
  2002年   5篇
  2001年   2篇
  2000年   1篇
  1998年   1篇
  1997年   2篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1987年   2篇
  1982年   1篇
  1977年   1篇
  1975年   1篇
  1970年   1篇
排序方式: 共有72条查询结果,搜索用时 187 毫秒
51.
Cancer cell invasion takes place at the cancer–host interface and is a prerequisite for distant metastasis. The relationships between current biological and clinical concepts such as cell migration modes, tumour budding and epithelial–mesenchymal transition (EMT) remains unclear in several aspects, especially for the 'real' situation in human cancer. We developed a novel method that provides exact three‐dimensional (3D) information on both microscopic morphology and gene expression, over a virtually unlimited spatial range, by reconstruction from serial immunostained tissue slices. Quantitative 3D assessment of tumour budding at the cancer–host interface in human pancreatic, colorectal, lung and breast adenocarcinoma suggests collective cell migration as the mechanism of cancer cell invasion, while single cancer cell migration seems to be virtually absent. Budding tumour cells display a shift towards spindle‐like as well as a rounded morphology. This is associated with decreased E‐cadherin staining intensity and a shift from membranous to cytoplasmic staining, as well as increased nuclear ZEB1 expression. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.  相似文献   
52.
Prostate cancer is the most frequently diagnosed cancer and the second most common cause of cancer death in men in the United States. Such men can experience a continuum of disease presentations from indolent to highly aggressive. For physicians who care for these men, a significant challenge has been and continues to be identifying and treating those men with localized cancer who are at a higher risk of dying from their disease. We discuss the risk stratification of patients in order to better identify those patients at higher risk of progression. A comprehensive review of the literature was then performed reviewing the roles of surgery, radiotherapy, hormone therapy, and chemotherapy, as well as combinations of these modalities, in treating these challenging patients. An integrated approach combining local and systemic therapies can be beneficial in the management of high-risk localized prostate cancer. The choice of therapy or combination of therapies is dependant upon many considerations, including patient preference and quality of life aspects. It is becoming clearer that the addition of hormonal therapies or chemotherapies to established therapies, such as radiotherapy or surgery, will have significant benefits. As evidence accumulates regarding the efficacy of these new regimens, our hope is that the challenge of optimizing the management of high-risk prostate cancer will be delivered. However, many important questions remain unresolved regarding the optimal type, combination, timing of therapy, and duration of therapy. Such questions will only be answered with large, well-designed prospective clinical trials.  相似文献   
53.
54.

Background

Tissue-engineered vascular grafts (TEVGs) offer potential to overcome limitations of current approaches for reconstruction in congenital heart disease by providing biodegradable scaffolds on which autologous cells proliferate and provide physiologic functionality. However, current TEVGs do not address the diverse anatomic requirements of individual patients. This study explores the feasibility of creating patient-specific TEVGs by combining 3-dimensional (3D) printing and electrospinning technology.

Methods

An electrospinning mandrel was 3D-printed after computer-aided design based on preoperative imaging of the ovine thoracic inferior vena cava (IVC). TEVG scaffolds were then electrospun around the 3D-printed mandrel. Six patient-specific TEVGs were implanted as cell-free IVC interposition conduits in a sheep model and explanted after 6 months for histologic, biochemical, and biomechanical evaluation.

Results

All sheep survived without complications, and all grafts were patent without aneurysm formation or ectopic calcification. Serial angiography revealed significant decreases in TEVG pressure gradients between 3 and 6 months as the grafts remodeled. At explant, the nanofiber scaffold was nearly completely resorbed and the TEVG showed similar mechanical properties to that of native IVC. Histological analysis demonstrated an organized smooth muscle cell layer, extracellular matrix deposition, and endothelialization. No significant difference in elastin and collagen content between the TEVG and native IVC was identified. There was a significant positive correlation between wall thickness and CD68+ macrophage infiltration into the TEVG.

Conclusions

Creation of patient-specific nanofiber TEVGs by combining electrospinning and 3D printing is a feasible technology as future clinical option. Further preclinical studies involving more complex anatomical shapes are warranted.  相似文献   
55.

Purpose

Whole brain radiation therapy (WBRT) is historically the standard of care for patients with brain metastases (BM) from small-cell lung cancer (SCLC), although locally ablative treatments are the standard of care for patients with 1–4 BM from other solid tumors. The objective of this analysis was to find prognostic factors influencing overall survival (OS) and intracranial progression-free survival (iPFS) in SCLC patients with single BM (SBM) treated with WBRT.

Methods

A total of 52 patients were identified in the authors’ cancer center database with histologically confirmed SCLC and contrast-enhanced magnet resonance imaging (MRI) or computed tomography (CT), which confirmed SBM between 2006 and 2015 and were therefore treated with WBRT. A Kaplan-Meier survival analysis was performed for OS analyses. The log-rank (Mantel-Cox) test was used to compare survival curves. Univariate Cox proportional-hazards ratios (HRs) were used to assess the influence of cofactors on OS and iPFS.

Results

The median OS after WBRT was 5 months and the median iPFS after WBRT 16 months. Patients that received surgery prior to WBRT had a significantly longer median OS of 19 months compared to 5 months in the group receiving only WBRT (p = 0.03; HR 2.24; 95% confidence interval [CI] 1.06–4.73). Patients with synchronous disease had a significantly longer OS compared to patients with metachronous BM (6 months vs. 3 months, p = 0.005; HR 0.27; 95% CI 0.11–0.68). Univariate analysis for OS revealed a statistically significant effect for metachronous disease (HR 2.25; 95% CI 1.14–4.46; p = 0.019), initial response to first-line chemotherapy (HR 0.58; 95% CI 0.35–0.97; p = 0.04), and surgical resection (HR 0.36; 95% CI 0.15–0.88; p = 0.026). OS was significantly affected by metachronous disease in multivariate analysis (HR 2.20; 95% CI 1.09–4.45; p = 0.028).

Conclusions

Univariate analysis revealed that surgery followed by WBRT can improve OS in patients with SBM in SCLC. Furthermore, synchronous disease and response to initial chemotherapy appeared to be major prognostic factors. Multivariate analysis revealed metachronous disease as a significantly negative prognostic factor on OS. The value of WBRT, stereotactic radiosurgery (SRS), or surgery alone or in combination for patients with a limited number of BM in SCLC should be evaluated in further prospective clinical trials.
  相似文献   
56.
With the advent of off-pump coronary artery bypass grafting and minimally invasive coronary artery bypass grafting, significant efforts have been made to facilitate construction of the graft to coronary anastomosis. As a result, a number of anastomotic devices have been developed. While the ideal anastomotic device should be easy to use, to produce a geometrically optimal anastomosis with minimal endothelial damage and minimal blood-exposed non-intimal surface, a number of design constraints apply. This review collects the available pre-clinical and clinical data for some of the devices with special regard for surgical outcome, patency rate and the need for additional perioperative anticoagulation treatment.  相似文献   
57.

Background

Despite advances in the Fontan procedure, there is an unmet clinical need for patient-specific graft designs that are optimized for variations in patient anatomy. The objective of this study is to design and produce patient-specific Fontan geometries, with the goal of improving hepatic flow distribution (HFD) and reducing power loss (Ploss), and manufacturing these designs by electrospinning.

Methods

Cardiac magnetic resonance imaging data from patients who previously underwent a Fontan procedure (n = 2) was used to create 3-dimensional models of their native Fontan geometry using standard image segmentation and geometry reconstruction software. For each patient, alternative designs were explored in silico, including tube-shaped and bifurcated conduits, and their performance in terms of Ploss and HFD probed by computational fluid dynamic (CFD) simulations. The best-performing options were then fabricated using electrospinning.

Results

CFD simulations showed that the bifurcated conduit improved HFD between the left and right pulmonary arteries, whereas both types of conduits reduced Ploss. In vitro testing with a flow-loop chamber supported the CFD results. The proposed designs were then successfully electrospun into tissue-engineered vascular grafts.

Conclusions

Our unique virtual cardiac surgery approach has the potential to improve the quality of surgery by manufacturing patient-specific designs before surgery, that are also optimized with balanced HFD and minimal Ploss, based on refinement of commercially available options for image segmentation, computer-aided design, and flow simulations.  相似文献   
58.
Since a few years more and more products have appeared on the market for dietary supplements containing steroids that had never been marketed as approved drugs, mostly without proper labeling of the contents. Syntheses and few data on pharmacological effects are available dated back mainly to the 1950s or 1960s. Only little knowledge exists about effects and side effects of these steroids in humans.The present study reports the identification of Δ6-methyltestosterone in a product named “Jungle Warfare”, which was obtained from a web-based supplement store.The main urinary metabolites, 17α-hydroxy-17β-methylandrosta-4,6-dien-3-one (Δ6-epimethyl-testosterone), 17α-methyl-5β-androstane-3α,17β-diol (3α,5β-THMT), and 17β-methyl-5β-androstane-3α,17α-diol, as well as the parent compound excreted after a single oral administration were monitored by GC-MS/MS. Δ6-Epimethyltestosterone and 3α,5β-THMT served for long-term detection (still present in the 181-189 h urine). 17α-Methyltestosterone and its 17-epimer were not detected in the urines (LOD 0.3 ng/mL). The highest concentrations were found in the 14-20.5 h urine for Δ6-epimethyltestosterone (600 ng/mL), and 3α,5β-THMT (240 ng/mL) and in the 36-44.5 h urine for 17β-methyl-5β-androstane-3α,17α-diol (7 ng/mL).For reference methyltestosterone and epimethyltestosterone were dehydrogenated with chloranil. The characterization of the products was performed by GC-MS(/MS) and NMR.  相似文献   
59.

Background

Pancreatic cancer is among the most dismal of human malignancies. The 5-year survival rate is lower than 5%. The identification of precursor lesions would be the main step to improve this fatal outcome. One precursor lesions are called pancreatic intraepithelial neoplasia (PanIN) and are graduated in grade 1 to 3, whereas grade 3 is classified as carcinoma in situ. Currently, no reliable, noninvasive imaging technique (e.g., ultrasound, computed tomography, magnet resonance imaging) exists to verify PanINs.

Methods

Recently, a transgenic mouse model of pancreatic cancer was established in which the tumor progression of human pancreatic carcinoma is reproduced. These so-called Pdx-1-Cre; LSL-KrasG12D/+; LSL-Trp53R172H/+mice develop PanINs, which transform to invasive growing pancreatic carcinoma. The pancreata of mice of different ages were immunohistochemically stained using α-GLUT-2 antibodies. Furthermore, mice underwent positron emission tomography (PET)-computed tomography (CT) with 18F-fluorodeoxyglucose (FDG) to evaluate early detection of PanIN lesions.

Results

An expression of GLUT-2 in murine PanINs was found in PanINs of grade 1B and higher. This finding is associated with an elevated glucose metabolism, leading to the detection of precursor lesions of pancreatic cancer in the FDG PET-CT scan. In addition, immunohistochemical staining of GLUT-2 was detectable in 45 (75%) of 60 human PanINs, whereas PanINs of grade 1B and higher showed a very extensive expression.

Conclusions

In conclusion, we demonstrate for the first time that an elevated glucose metabolism occurs already in precursor lesions of murine and human pancreatic carcinoma. These findings are the basis for the detection of precursor lesions by PET-CT, thereby helping improving the prognosis of this devastating disease.  相似文献   
60.

Purpose

The chick embryo is a well-known economical in vivo model system and is widely applied in preclinical research, e.g., bone development studies. It is therefore surprising that no studies concerning the application of 18F-fluoride microPET to bone metabolism have been reported so far. This may be due to motion artifacts or the lack of convenient tracer injection sites.

Methods

We resolved the above problems using a combination of sample preparation, anesthesia, microPET imaging, and computational processing, and describe a convenient way of visualizing three- and four- dimensional features of bone metabolism in living chick embryos.

Results

The application of 18F-fluoride microPET facilitates repeat measurements, highly reproducible and motion-artifact-free skeletal imaging, and provides quantitative measurements of in ovo metabolic activities in the bones of developing chick. During microPET measurement, radio tracer was injected intravascularly using a custom-made catheter system, allowing us to additionally investigate early time points in tracer kinetics and uptake.

Conclusions

Our results show that bone metabolism in living chick embryos can be reproducibly studied and quantified in ovo, even for multiple tracer injections over a longer time period. The use of dynamic 18F-fluoride microPET imaging made it possible to visualize and analyze even small bone structures with excellent quality. Moreover, as our data are comparable to data from corresponding rodent experiments, the use of embryonated chicken eggs is a convenient and economical alternative to other animal models.  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