全文获取类型
收费全文 | 431922篇 |
免费 | 26270篇 |
国内免费 | 18958篇 |
专业分类
耳鼻咽喉 | 3405篇 |
儿科学 | 9129篇 |
妇产科学 | 6385篇 |
基础医学 | 46737篇 |
口腔科学 | 5983篇 |
临床医学 | 48044篇 |
内科学 | 67513篇 |
皮肤病学 | 3269篇 |
神经病学 | 30101篇 |
特种医学 | 18667篇 |
外国民族医学 | 155篇 |
外科学 | 53882篇 |
综合类 | 47541篇 |
现状与发展 | 62篇 |
一般理论 | 21篇 |
预防医学 | 34562篇 |
眼科学 | 10452篇 |
药学 | 36661篇 |
226篇 | |
中国医学 | 16466篇 |
肿瘤学 | 37889篇 |
出版年
2024年 | 730篇 |
2023年 | 3733篇 |
2022年 | 9366篇 |
2021年 | 13409篇 |
2020年 | 10200篇 |
2019年 | 8893篇 |
2018年 | 30480篇 |
2017年 | 25276篇 |
2016年 | 26813篇 |
2015年 | 13103篇 |
2014年 | 15650篇 |
2013年 | 13784篇 |
2012年 | 25614篇 |
2011年 | 41541篇 |
2010年 | 31158篇 |
2009年 | 21276篇 |
2008年 | 32327篇 |
2007年 | 34859篇 |
2006年 | 14046篇 |
2005年 | 15396篇 |
2004年 | 12574篇 |
2003年 | 13772篇 |
2002年 | 10552篇 |
2001年 | 7340篇 |
2000年 | 7070篇 |
1999年 | 6727篇 |
1998年 | 4259篇 |
1997年 | 4195篇 |
1996年 | 3235篇 |
1995年 | 3026篇 |
1994年 | 2512篇 |
1993年 | 1600篇 |
1992年 | 2108篇 |
1991年 | 1829篇 |
1990年 | 1548篇 |
1989年 | 1281篇 |
1988年 | 1147篇 |
1987年 | 972篇 |
1986年 | 795篇 |
1985年 | 616篇 |
1984年 | 373篇 |
1983年 | 281篇 |
1982年 | 182篇 |
1981年 | 157篇 |
1980年 | 157篇 |
1979年 | 149篇 |
1975年 | 62篇 |
1974年 | 75篇 |
1938年 | 64篇 |
1932年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
151.
Pengfei Liu 《Remote sensing letters.》2019,10(7):659-668
This letter proposed a new and effective total generalized variation (TGV) induced spatial difference prior model for variational pansharpening problem, which aimed to estimate a high-resolution (HR) multispectral (MS) image from its low-resolution (LR) version and the corresponding HR panchromatic (Pan) image of the same earth scene. In addition to using the local spectral consistency constraint for spectral information preserving, this letter particularly exploited the spatial difference prior between the HR-MS and Pan images, and hence proposed a new TGV-induced spatial difference prior term for spatial information preserving. Then, an efficient optimization algorithm was designed for solving the proposed model under the fast iterative shrinkage-thresholding algorithm (FISTA) framework. Finally, the experimental results validated that the proposed method performed higher spatial and spectral qualities than various methods in both the subjective and objective aspects. 相似文献
152.
153.
154.
155.
156.
Xiaoxuan Liu Ameenat L. Solebo Livia Faes Sophie Beese Tasanee Braithwaite Matthew E. Round 《Ocular immunology and inflammation》2020,28(6):898-907
ABSTRACT
Purpose
New instrument-based techniques for anterior chamber (AC) cell counting can offer automation and objectivity above clinician assessment. This review aims to identify such instruments and its correlation with clinician estimates. 相似文献157.
Quantitative chemical exchange saturation transfer (qCEST) MRI – omega plot analysis of RF‐spillover‐corrected inverse CEST ratio asymmetry for simultaneous determination of labile proton ratio and exchange rate
下载免费PDF全文
![点击此处可从《NMR in biomedicine》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Renhua Wu Gang Xiao Iris Yuwen Zhou Chongzhao Ran Phillip Zhe Sun 《NMR in biomedicine》2015,28(3):376-383
Chemical exchange saturation transfer (CEST) MRI is sensitive to labile proton concentration and exchange rate, thus allowing measurement of dilute CEST agent and microenvironmental properties. However, CEST measurement depends not only on the CEST agent properties but also on the experimental conditions. Quantitative CEST (qCEST) analysis has been proposed to address the limitation of the commonly used simplistic CEST‐weighted calculation. Recent research has shown that the concomitant direct RF saturation (spillover) effect can be corrected using an inverse CEST ratio calculation. We postulated that a simplified qCEST analysis is feasible with omega plot analysis of the inverse CEST asymmetry calculation. Specifically, simulations showed that the numerically derived labile proton ratio and exchange rate were in good agreement with input values. In addition, the qCEST analysis was confirmed experimentally in a phantom with concurrent variation in CEST agent concentration and pH. Also, we demonstrated that the derived labile proton ratio increased linearly with creatine concentration (P < 0.01) while the pH‐dependent exchange rate followed a dominantly base‐catalyzed exchange relationship (P < 0.01). In summary, our study verified that a simplified qCEST analysis can simultaneously determine labile proton ratio and exchange rate in a relatively complex in vitro CEST system. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
158.
159.
160.
This paper reviews the published literature on a group of developmental disorders of the retina and retinal pigment epithelium which result in focal abnormalities in one or both eyes. They are often asymptomatic, found on routine examination and are generally non-progressive. Some are associated with other systemic abnormalities.Subject terms: Retinal diseases, Eye abnormalities 相似文献