全文获取类型
收费全文 | 2912314篇 |
免费 | 223116篇 |
国内免费 | 32385篇 |
专业分类
耳鼻咽喉 | 36970篇 |
儿科学 | 89472篇 |
妇产科学 | 75497篇 |
基础医学 | 398272篇 |
口腔科学 | 75385篇 |
临床医学 | 282028篇 |
内科学 | 554363篇 |
皮肤病学 | 66168篇 |
神经病学 | 228212篇 |
特种医学 | 112863篇 |
外国民族医学 | 960篇 |
外科学 | 415116篇 |
综合类 | 118986篇 |
现状与发展 | 91篇 |
一般理论 | 993篇 |
预防医学 | 219761篇 |
眼科学 | 66489篇 |
药学 | 226016篇 |
425篇 | |
中国医学 | 29243篇 |
肿瘤学 | 170505篇 |
出版年
2021年 | 33550篇 |
2020年 | 26431篇 |
2019年 | 31860篇 |
2018年 | 40865篇 |
2017年 | 33866篇 |
2016年 | 36447篇 |
2015年 | 45686篇 |
2014年 | 60703篇 |
2013年 | 78689篇 |
2012年 | 107341篇 |
2011年 | 115137篇 |
2010年 | 71773篇 |
2009年 | 66001篇 |
2008年 | 99446篇 |
2007年 | 103947篇 |
2006年 | 104733篇 |
2005年 | 100116篇 |
2004年 | 90661篇 |
2003年 | 87463篇 |
2002年 | 82575篇 |
2001年 | 135588篇 |
2000年 | 138316篇 |
1999年 | 117264篇 |
1998年 | 34574篇 |
1997年 | 30991篇 |
1996年 | 30183篇 |
1995年 | 30818篇 |
1994年 | 27942篇 |
1993年 | 25199篇 |
1992年 | 87146篇 |
1991年 | 83400篇 |
1990年 | 80310篇 |
1989年 | 77365篇 |
1988年 | 70511篇 |
1987年 | 68915篇 |
1986年 | 64295篇 |
1985年 | 61029篇 |
1984年 | 45195篇 |
1983年 | 38070篇 |
1982年 | 22483篇 |
1979年 | 38993篇 |
1978年 | 27421篇 |
1977年 | 23203篇 |
1976年 | 21445篇 |
1975年 | 22779篇 |
1974年 | 26769篇 |
1973年 | 25353篇 |
1972年 | 23761篇 |
1971年 | 21948篇 |
1970年 | 20168篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
45.
Arterial spin labeling (ASL) imaging is a powerful magnetic resonance imaging technique that allows to quantitatively measure blood perfusion non-invasively, which has great potential for assessing tissue viability in various clinical settings. However, the clinical applications of ASL are currently limited by its low signal-to-noise ratio (SNR), limited spatial resolution, and long imaging time. In this work, we propose an unsupervised deep learning-based image denoising and reconstruction framework to improve the SNR and accelerate the imaging speed of high resolution ASL imaging. The unique feature of the proposed framework is that it does not require any prior training pairs but only the subject's own anatomical prior, such as T1-weighted images, as network input. The neural network was trained from scratch in the denoising or reconstruction process, with noisy images or sparely sampled k-space data as training labels. Performance of the proposed method was evaluated using in vivo experiment data obtained from 3 healthy subjects on a 3T MR scanner, using ASL images acquired with 44-min acquisition time as the ground truth. Both qualitative and quantitative analyses demonstrate the superior performance of the proposed txtc framework over the reference methods. In summary, our proposed unsupervised deep learning-based denoising and reconstruction framework can improve the image quality and accelerate the imaging speed of ASL imaging. 相似文献
46.
Chumakov E. M. Petrova N. N. Limankin O. V. Ashenbrenner Yu. V. 《Neuroscience and behavioral physiology》2022,52(1):45-51
Neuroscience and Behavioral Physiology - Objective. To determine the frequency, structure, and severity of cognitive impairments in patients with bipolar affective disorder (BAD) in remission.... 相似文献
47.
Sibylle M. Winter Katja Dittrich Peggy Dörr Judith Overfeld Imke Moebus Elena Murray Gergana Karaboycheva Christian Zimmermann Andrea Knop Manuel Voelkle Sonja Entringer Claudia Buss John-Dylan Haynes Elisabeth B. Binder Christine Heim 《Journal of child psychology and psychiatry, and allied disciplines》2022,63(9):1027-1045
48.
Lin Li Wei Wu Wanchao Zheng Qiao Hui Chunna Zhao 《APMIS : acta pathologica, microbiologica, et immunologica Scandinavica》2022,130(1):21-25
We aimed to explore the correlation between P27 expression and Helicobacter pylori (H. pylori) infection in gastric cancer, so as to provide evidence for understanding the pathogenesis of gastric cancer caused by H. pylori infection. A total of 82 samples of gastric cancer tissues and 56 samples of tumor-adjacent normal tissues collected from the gastrectomy were enrolled in this study. Then, 14C-urease breathing test was carried out to evaluate the infection of H. pylori in gastric cancer tissues, the expression of P27 in the tissue samples was detected by the immunohistochemistry staining, and the correlation between the H. pylori infection and P27 expression in gastric cancer was analyzed. Of 82 gastric cancer patients, there were 53 patients with H. pylori infection (64.63%). Among the patients with highly or moderately differentiated gastric cancer, the expression of P27 was much higher than that of patients with poorly differentiated gastric cancer (p < 0.01). Besides, comparison of the P27 expression between males and females, among different age groups, tumor sizes, TNM stages, tumor infiltration degrees, or lymph node metastasis, showed no significant differences (p > 0.05). Analysis of the correlation revealed that P27 expression was negatively correlated with the infection of H. pylori (p < 0.01). Multifactorial logistics regression analysis indicated that tumor differentiation was a risk factor of P27-positive expression in gastric cancer tissues (p < 0.01). In addition, P27 expression in the gastric cancer tissues was lower than that in the tumor-adjacent normal tissues (p < 0.01). In gastric cancer patients, expression of P27 is correlated with H. pylori infection which, via downregulating P27, can cause the cancerization of gastric mucosa, and P27, for its role in the development and progression of gastric cancer, is a potential auxiliary indicator for clinical diagnosis whether gastric cancer is complicated with H. pylori infection. So, P27 is a key indicator for diagnosis, treatment, and prognostic evaluation of disease in the advanced stage. 相似文献
49.
Improving hyperpolarized 129Xe ADC mapping in pediatric and adult lungs with uncertainty propagation