全文获取类型
收费全文 | 71801篇 |
免费 | 44293篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 1490篇 |
儿科学 | 4218篇 |
妇产科学 | 525篇 |
基础医学 | 15285篇 |
口腔科学 | 5045篇 |
临床医学 | 12118篇 |
内科学 | 22539篇 |
皮肤病学 | 7418篇 |
神经病学 | 13106篇 |
特种医学 | 2118篇 |
外科学 | 13508篇 |
综合类 | 11篇 |
一般理论 | 21篇 |
预防医学 | 4049篇 |
眼科学 | 1250篇 |
药学 | 5452篇 |
中国医学 | 1017篇 |
肿瘤学 | 6926篇 |
出版年
2024年 | 2篇 |
2023年 | 17篇 |
2022年 | 45篇 |
2021年 | 1252篇 |
2020年 | 5027篇 |
2019年 | 10803篇 |
2018年 | 10022篇 |
2017年 | 11416篇 |
2016年 | 12054篇 |
2015年 | 11895篇 |
2014年 | 11774篇 |
2013年 | 12230篇 |
2012年 | 3979篇 |
2011年 | 3876篇 |
2010年 | 8828篇 |
2009年 | 5180篇 |
2008年 | 1913篇 |
2007年 | 751篇 |
2006年 | 789篇 |
2005年 | 563篇 |
2004年 | 588篇 |
2003年 | 597篇 |
2002年 | 698篇 |
2001年 | 746篇 |
2000年 | 677篇 |
1999年 | 254篇 |
1998年 | 21篇 |
1997年 | 12篇 |
1996年 | 15篇 |
1995年 | 11篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 15篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1978年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Educational tracking based on academic ability accounts for different school dynamics between vocational versus academically‐oriented high schools in Taiwan. Many educational practitioners predict that the settings of vocational schools and academic schools mediate school violence in different ways. Alternatively, some researchers argue the actual mediating mechanism may not vary significantly between the different school types in different cultures. The purpose of this study was to examine how within‐school variables (school engagement, risky peers, and student–teacher interaction) mediate external‐school variables (personal traits, parental monitoring, and victimization) and school violence in Taiwanese vocational and academically‐oriented schools. Structural equation modeling analysis, based on a national representative sample (N=7,841), suggested school violence was mediated through school variables. Similar mediational findings were found between academic and vocational schools as well as between males and females. Findings suggest that school violence is mediated by within‐school variables in similar ways across different school types, genders, and cultures. © 2010 Wiley Periodicals, Inc. 相似文献
992.
993.
994.
Xingchen Wu Seyoum Nerisho Prasun Dastidar Pertti Ryymin Ritva Järvenpää Hannu Pertovaara Hannu Eskola Pirkko‐Liisa Kellokumpu‐Lehtinen 《NMR in biomedicine》2013,26(9):1186-1194
To compare different MRI sequences for the detection of lesions and the evaluation of response to chemotherapy in patients with diffuse large B‐cell lymphoma (DLBCL), 18 patients with histology‐confirmed DLBCL underwent 3‐T MRI scanning prior to and 1 week after chemotherapy. The MRI sequences included T1‐weighted pre‐ and post‐contrast, T2‐weighted with and without fat suppression, and a single‐shot echo‐planar diffusion‐weighted imaging (DWI) with two b values (0 and 800 s/mm2). Conventional MRI sequence comparisons were performed using the contrast ratio between tumor and normal vertebral body instead of signal intensity. The apparent diffusion coefficient (ADC) of the tumor was measured directly on the parametric ADC map. The tumor volume was used as a reference for the evaluation of chemotherapy response. The mean tumor volume was 374 mL at baseline, and decreased by 65% 1 week after chemotherapy (p < 0.01). The T2‐weighted image with fat suppression showed a significantly higher contrast ratio compared with images from all other conventional MRI sequences, both before and after treatment (p < 0.01, respectively). The contrast ratio of the T2‐weighted image with fat suppression decreased significantly (p < 0.01), and that of the T1‐weighted pre‐contrast image increased significantly (p < 0.01), after treatment. However, there was no correlation between the change in contrast ratio and tumor volume. The mean ADC value was 0.68 × 10–3 mm2/s at baseline; it increased by 89% after chemotherapy (p < 0.001), and the change in ADC value correlated with the change in tumor volume (r = 0.66, p < 0.01). The baseline ADC value also correlated inversely with the percentage change in ADC after treatment (r = ?0.62, p < 0.01). In conclusion, this study indicates that T2‐weighted imaging with fat suppression is the best conventional sequence for the detection of lesions and evaluation of the efficacy of chemotherapy in DLBCL. DWI with ADC mapping is an imaging modality with both diagnostic and prognostic value that could complement conventional MRI. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
995.
996.
997.
Adrien Riou Fabien Chauveau Tae‐Hee Cho Marilena Marinescu Serge Nataf Norbert Nighoghossian Yves Berthezène Marlène Wiart 《NMR in biomedicine》2013,26(2):115-123
The broad aim underlying the present research was to investigate the distribution and homing of bone marrow‐derived macrophages in a rodent model of transient middle cerebral artery occlusion using MRI and ultrasmall superparamagnetic iron oxide (USPIO) to magnetically label bone marrow‐derived macrophages. The specific aim was to assess the intra‐carotid infusion route for bone marrow‐derived macrophage delivery at reperfusion. Fifteen Sprague–Dawley rats sustained 1 h of middle cerebral artery occlusion. USPIO‐labeled bone marrow‐derived macrophages were slowly injected for 5 min immediately after reperfusion in ischemic animals (n = 7), 1 h after the end of surgery in sham animals (n = 5) and very shortly after anesthesia in healthy animals (n = 3). Multiparametric MRI was performed at day 0, just after cell administration, and repeated at day 1. Immunohistological analysis included Prussian blue for iron detection and rat endothelial cell antigen‐1 for endothelium visualization. Intra‐carotid cell delivery brought a large number of cells to the ipsilateral hemisphere of the brain, as seen on both MRI and immunohistology. However, it was associated with high mortality (50%). The study of sham animals demonstrated that intra‐carotid cell delivery could induce ischemic lesions and may thus favor additional brain damage. The present study highlights severe drawbacks to the intra‐carotid delivery of macrophages at the time of reperfusion in this rodent model of transient cerebral ischemia. Multiparametric MRI appears to be a method of choice to monitor longitudinally the effects of cell infusion, allowing the assessment of both cell fate with the help of magnetic labeling and of potential tissue damage. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
998.
999.
1000.