全文获取类型
收费全文 | 1081篇 |
免费 | 56篇 |
国内免费 | 28篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 8篇 |
妇产科学 | 12篇 |
基础医学 | 121篇 |
口腔科学 | 5篇 |
临床医学 | 97篇 |
内科学 | 187篇 |
皮肤病学 | 19篇 |
神经病学 | 60篇 |
特种医学 | 44篇 |
外科学 | 102篇 |
综合类 | 29篇 |
预防医学 | 105篇 |
眼科学 | 22篇 |
药学 | 155篇 |
中国医学 | 68篇 |
肿瘤学 | 129篇 |
出版年
2023年 | 104篇 |
2022年 | 129篇 |
2021年 | 96篇 |
2020年 | 87篇 |
2019年 | 50篇 |
2018年 | 39篇 |
2017年 | 50篇 |
2016年 | 50篇 |
2015年 | 59篇 |
2014年 | 93篇 |
2013年 | 59篇 |
2012年 | 48篇 |
2011年 | 31篇 |
2010年 | 35篇 |
2009年 | 39篇 |
2008年 | 14篇 |
2007年 | 60篇 |
2006年 | 23篇 |
2005年 | 17篇 |
2004年 | 13篇 |
2003年 | 13篇 |
2002年 | 14篇 |
2001年 | 11篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 13篇 |
1992年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有1165条查询结果,搜索用时 62 毫秒
1.
Diabetic retinopathy (DR) is one of the most important complications of diabetes. Accurate segmentation of DR lesions is of great importance for the early diagnosis of DR. However, simultaneous segmentation of multi-type DR lesions is technically challenging because of 1) the lack of pixel-level annotations and 2) the large diversity between different types of DR lesions. In this study, first, we propose a novel Poisson-blending data augmentation (PBDA) algorithm to generate synthetic images, which can be easily utilized to expand the existing training data for lesion segmentation. We perform extensive experiments to recognize the important attributes in the PBDA algorithm. We show that position constraints are of great importance and that the synthesis density of one type of lesion has a joint influence on the segmentation of other types of lesions. Second, we propose a convolutional neural network architecture, named DSR-U-Net++ (i.e., DC-SC residual U-Net++), for the simultaneous segmentation of multi-type DR lesions. Ablation studies showed that the mean area under precision recall curve (AUPR) for all four types of lesions increased by >5% with PBDA. The proposed DSR-U-Net++ with PBDA outperformed the state-of-the-art methods by 1.7%-9.9% on the Indian Diabetic Retinopathy Image Dataset (IDRiD) and 67.3% on the e-ophtha dataset with respect to mean AUPR. The developed method would be an efficient tool to generate large-scale task-specific training data for other medical anomaly segmentation tasks. 相似文献
2.
BackgroundHeavy metal contamination has become a serious issue in this century especially detected in fish organs. Due to the presence of radioactive compounds in agricultural and sewage effluent, which destroys aquatic ecosystems, threatening human livelihoods. Health hazards associated with low and high consumption consumers assessed in five commercial fish species collected from Hurghada City, Egypt, during winter and summer, 2020. Atomic absorption spectrophotometer technique used for determination heavy meals in different organs and expressed as μg/g wet weight.ResultsHeavy metal concentrations in muscle ranged between:(0.054–0.109), (0.260–1.043), (0.264–0.897), (5.895–11.898), (0.381–0.970), (13.582–29.133) and (0.332–0.589) µg/g for Cd, Pb, Mn, Zn, Cu, Fe and Ni respectively, which were lower than those of gills and liver. These concentrations were within WHO, FAO/WHO, and EU standards. Consumption of edible species was lower than the (TDIs) established by the (JECFA) and Egyptian Standards. Even though THQ and TTHQ values were < 1 while, in children with highly consumer were> 1.ConclusionThis study concluded that intake of Red Sea fish is safe for human health. It is critical for consumers to be aware of the consequences of excessive fish consumption, particularly children with highly consumer, which represent possible health risks. 相似文献
3.
《European journal of surgical oncology》2022,48(1):302
4.
《European journal of surgical oncology》2019,45(11):2143-2150
BackgroundWe aimed to explore whether the anatomic extent of lymph node metastases (AE-LNM) could independently predict prognosis of node-positive major salivary gland carcinoma (MaSGC).MethodsA total of 376 pathologically node-positive MaSGC patients were identified from the Surveillance, Epidemiology and End Results database and constituted the training cohort. Using the X-Tile program, these patients were divided into three groups based on AE-LNM degrees. Discrimination of overall survival (OS) and disease-specific survival (DSS) was evaluated and compared with the 8th American Joint Committee on Cancer (AJCC) pN classification. The results were externally validated by 220 patients in a Chinese multicenter cohort (Validation cohort).ResultsUsing the training cohort, AE-LNM was divided into Extent 1 (spread to parotid LNs or level I), Extent 2 (spread to level II-IV) and Extent 3 (spread to level V or bilateral LNs or rare LNs). Regarding both OS and DSS, the AE-LNM model revealed clear separation of survival curves, while the pN classification failed to discriminate the prognosis of pN1 and pN2 patients. When we incorporated both the AE-LNM model and AJCC pN classification into the same multivariate Cox analyses, AE-LNM was still an independent prognostic factor, while the AJCC pN classification lost its significance. These results were externally validated by the validation cohort.ConclusionAE-LNM is an independent nodal prognosticator for node-positive MaSGC and may have improved discriminative ability over the current AJCC pN classification. Integration of anatomic extent of LNM into the current AJCC N classification could be considered. 相似文献
5.
6.
《Ultrasound in medicine & biology》2020,46(10):2579-2604
The present, updated document describes the fourth iteration of recommendations for the hepatic use of contrast-enhanced ultrasound, first initiated in 2004 by the European Federation of Societies for Ultrasound in Medicine and Biology. The previous updated editions of the guidelines reflected changes in the available contrast agents and updated the guidelines not only for hepatic but also for non-hepatic applications. The 2012 guideline requires updating as, previously, the differences in the contrast agents were not precisely described and the differences in contrast phases as well as handling were not clearly indicated. In addition, more evidence has been published for all contrast agents. The update also reflects the most recent developments in contrast agents, including U.S. Food and Drug Administration approval and the extensive Asian experience, to produce a truly international perspective. These guidelines and recommendations provide general advice on the use of ultrasound contrast agents (UCAs) and are intended to create standard protocols for the use and administration of UCAs in liver applications on an international basis to improve the management of patients. 相似文献
7.
《Vaccine》2016,34(50):6316-6322
ObjectiveAir pollution, weather condition and influenza are known risk factors of acute coronary syndrome (ACS) among elderly people. The influenza vaccine (IV) has been shown to reduce major cardiovascular events. The purpose of this study was to compare resistance to air pollution and weather factors causing ACS between vaccinated and less-vaccinated elderly people.MethodsA case–crossover design was applied to 1835 elderly ACS patients who were obtained from the 1-million sample of Taiwan National Health Insurance Research Data with inclusion criteria: (1) the first diagnosis of ACS was in cold season and at age 68 or more, (2) had received the free IV program at least once during the period 3 years before the ACS. They were stratified into two groups: 707 had received flu vaccinations for all the 3 years and the remaining 1128 had not. The measurements of air pollutants, temperature, and humidity corresponding to each of the 3 days prior to the ACS diagnosis date were retrieved from the data banks of the Taiwan Environmental Protection Administration and Central Weather Bureau.FindingsIncreases in air pollution concentrations of CO, NO2, PM10 or PM2.5 and decreases in temperature significantly influenced the risk of ACS for the non-continuously vaccinated elderly population; however, less significant effects were observed for the continuously vaccinated population.ConclusionConsecutive influenza vaccination may potentially offer resistance against the detrimental effects of air pollution and changes in temperature in frail elderly adults with ACS. Future studies are needed to directly assess the interaction effect between the vaccination and environmental factors on ACS. 相似文献
8.
Chronic inflammatory diseases of the intestinal tract have been known to increase risk of developing a form of colorectal cancer known as inflammation-associated cancer. The roles of inflammation in tumor formation and development in ApcMin/+ mice have been broadly corroborated. The ApcMin/+ mouse model contains a point mutation in the adenomatous polyposis coli (Apc) gene and only develops intestinal precancerous lesions, the benign adenomas. Thus, it provides an excellent in vivo system to investigate the molecular events involved in the inflammatory process which may contribute to multistep tumorigenesis and carcinogenesis. Recent investigations that employ this model studied the effects of gene alterations, intestinal microorganisms, drugs, diet, exercise and sleep on the inflammatory process and tumor development, and revealed the mechanisms involved in the formation, promotion and carcinogenesis of adenomas with the background of inflammation. Herein, we focus our review on the application of the ApcMin/+ mouse model for studying inflammation-associated intestinal tumor and find that anti-inflammation is a possible strategy in combating intestinal tumor, but sometimes anti-inflammation cannot help reduce tumor burden. Moreover, various inflammation-related genes are involved in different mechanistic stages of tumor in ApcMin/+ mice and intricate regulatory effects of inflammation exist in the whole progression of intestinal tumor. 相似文献
9.
《Molecular immunology》2015,63(2):296-304
Regulatory B cells (Bregs) are defined by their ability to restrain inflammatory responses both in vivo and in vitro. Interleukin 10 (IL-10) production by Bregs is thought to be central to their ability to regulate inflammation, largely due to IL-10s’ ability to suppress pro-inflammatory cytokine production by effector lymphocytes and to maintain the differentiation of regulatory T cells (Tregs). However, with an increase in available published data, it has become evident that Bregs utilize a number of suppressive mechanisms in order to alter the activation of a variety of different lymphocytes. Here, we summarize the multiplicity of cellular targets of Breg-mediated suppression and describe the mechanisms employed by Bregs to suppress chronic inflammatory responses. 相似文献
10.