全文获取类型
收费全文 | 205676篇 |
免费 | 49118篇 |
国内免费 | 3291篇 |
专业分类
耳鼻咽喉 | 2214篇 |
儿科学 | 6950篇 |
妇产科学 | 1374篇 |
基础医学 | 32467篇 |
口腔科学 | 8177篇 |
临床医学 | 20177篇 |
内科学 | 35483篇 |
皮肤病学 | 5989篇 |
神经病学 | 28929篇 |
特种医学 | 15323篇 |
外国民族医学 | 19篇 |
外科学 | 21113篇 |
综合类 | 12339篇 |
现状与发展 | 3篇 |
一般理论 | 8篇 |
预防医学 | 13431篇 |
眼科学 | 2150篇 |
药学 | 27464篇 |
25篇 | |
中国医学 | 8602篇 |
肿瘤学 | 15848篇 |
出版年
2024年 | 245篇 |
2023年 | 1332篇 |
2022年 | 2349篇 |
2021年 | 4674篇 |
2020年 | 8961篇 |
2019年 | 13809篇 |
2018年 | 13487篇 |
2017年 | 14943篇 |
2016年 | 14186篇 |
2015年 | 14124篇 |
2014年 | 16458篇 |
2013年 | 17341篇 |
2012年 | 15406篇 |
2011年 | 15951篇 |
2010年 | 13386篇 |
2009年 | 10073篇 |
2008年 | 10727篇 |
2007年 | 9105篇 |
2006年 | 8436篇 |
2005年 | 7646篇 |
2004年 | 7071篇 |
2003年 | 6301篇 |
2002年 | 5636篇 |
2001年 | 4545篇 |
2000年 | 3071篇 |
1999年 | 1798篇 |
1998年 | 1595篇 |
1997年 | 1489篇 |
1996年 | 1308篇 |
1995年 | 1210篇 |
1994年 | 1068篇 |
1993年 | 879篇 |
1992年 | 819篇 |
1991年 | 741篇 |
1990年 | 712篇 |
1989年 | 649篇 |
1988年 | 590篇 |
1987年 | 536篇 |
1986年 | 538篇 |
1985年 | 790篇 |
1984年 | 727篇 |
1983年 | 536篇 |
1982年 | 540篇 |
1981年 | 501篇 |
1980年 | 459篇 |
1979年 | 320篇 |
1978年 | 239篇 |
1977年 | 193篇 |
1976年 | 167篇 |
1975年 | 117篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
1.
2.
Noninvasive imaging of cardiac fibrosis is important for early diagnosis and intervention in chronic heart diseases. Here, we investigated whether noninvasive, contrast agent-free MRI T2-mapping can quantify myocardial fibrosis in preclinical models of aging and pressure overload. Myocardial fibrosis and remodeling were analyzed in two animal models: (i) aging (15-month-old male CF-1 mice vs. young 6- to 8-week-old mice), and (ii) pressure overload (PO; by transverse aortic constriction in 4- to 5-month-old male C57BL/6 mice vs. sham-operated for 14 days). In vivo T2-mapping was performed by acquiring data during the isovolumic and early diastolic phases, with a modified respiratory and ECG-triggered multiecho TurboRARE sequence on a 7-T MRI. Cine MRI provided cardiac morphology and function. A quantitative segmentation method was developed to analyze the in vivo T2-maps of hearts at midventricle, apex, and basal regions. The cardiac fibrosis area was analyzed ex vivo by picro sirius red (PSR) staining. Both aged and pressure-overloaded hearts developed significant myocardial contractile dysfunction, cardiac hypertrophy, and interstitial fibrosis. The aged mice had two phenotypes, fibrotic and mild-fibrotic. Notably, the aged fibrotic subgroup and the PO mice showed a marked decrease in T2 relaxation times (25.3 ± 0.6 in aged vs. 29.9 ± 0.7 ms in young mice, p = 0.002; and 24.3 ± 1.7 in PO vs. 28.7 ± 0.7 ms in shams, p = 0.05). However, no significant difference in T2 was detected between the aged mild-fibrotic subgroup and the young mice. Accordingly, an inverse correlation between myocardial fibrosis percentage (FP) and T2 relaxation time was derived (R2 = 0.98): T2 (ms) = 30.45 – 1.05 × FP. Thus, these results demonstrate a statistical agreement between T2-map–quantified fibrosis and PSR staining in two different clinically relevant animal models. In conclusion, T2-mapping MRI is a promising noninvasive contrast agent-free quantitative technique to characterize myocardial fibrosis. 相似文献
3.
4.
Sports Imaging has dramatically increased in the past decade with increasing number of adolescents, young and middle-aged adults participating in non-competitive/hobby sports. Therefore, sports injuries are no longer confined to elite athletes. Furthermore, newer forms of sports such as mountain climbing, pickle ball and curling etc. are gaining popularity. Majority of the injuries in sports medicine are from musculoskeletal trauma. Therefore, it is imperative that the musculoskeletal radiologist becomes familiar with various sports related injury patterns as these are commonly encountered in daily practice. This update aims to briefly encapsulate the major aspects of sports imaging. It includes the imaging manifestations of various types of musculoskeletal injuries on different modalities (commonly US and MRI) and briefly mentions the various image guided interventions, performed both on the sports field and in the hospital setting. 相似文献
5.
6.
《Cancer cell》2021,39(9):1214-1226.e10
- Download : Download high-res image (204KB)
- Download : Download full-size image
7.
8.
Major depressive disorder and other neuropsychiatric disorders are often managed with long-term use of antidepressant medication. Fluoxetine, an SSRI antidepressant, is widely used as a first-line treatment for neuropsychiatric disorders. However, fluoxetine has also been shown to increase the risk of metabolic diseases such as non-alcoholic fatty liver disease. Fluoxetine has been shown to increase hepatic lipid accumulation in vivo and in vitro. In addition, fluoxetine has been shown to alter the production of prostaglandins which have also been implicated in the development of non-alcoholic fatty liver disease. The goal of this study was to assess the effect of fluoxetine exposure on the prostaglandin biosynthetic pathway and lipid accumulation in a hepatic cell line (H4-II-E-C3 cells). Fluoxetine treatment increased mRNA expression of prostaglandin biosynthetic enzymes (Ptgs1, Ptgs2, and Ptgds), PPAR gamma (Pparg), and PPAR gamma downstream targets involved in fatty acid uptake (Cd36, Fatp2, and Fatp5) as well as production of 15-deoxy-Δ12,14PGJ2 a PPAR gamma ligand. The effects of fluoxetine to induce lipid accumulation were attenuated with a PTGS1 specific inhibitor (SC-560), whereas inhibition of PTGS2 had no effect. Moreover, SC-560 attenuated 15-deoxy-Δ12,14PGJ2 production and expression of PPAR gamma downstream target genes. Taken together these results suggest that fluoxetine-induced lipid abnormalities appear to be mediated via PTGS1 and its downstream product 15d-PGJ2 and suggest a novel therapeutic target to prevent some of the adverse effects of fluoxetine treatment. 相似文献
9.
Weina Cheng Yazhi Wang Jingxian Liu Xiaofei Li Ming Yu Cancan Duan Liu Liu Jianyong Zhang 《Journal of applied toxicology : JAT》2022,42(6):970-980
Cantharidin (CTD) is an effective antitumor agent. However, it exhibits significant hepatotoxicity, the mechanism of which remains unclear. In this study, biochemical and histopathological analyses complemented with ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS)-based targeted metabolomic analysis of bile acids (BAs) were employed to investigate CTD-induced hepatotoxicity in rats. Sixteen male and female Sprague–Dawley rats were randomly divided into two groups: control and CTD (1.0 mg/kg) groups. Serum and liver samples were collected after 28 days of intervention. Biochemical, histopathological, and BA metabolomic analyses were performed for all samples. Further, the key biomarkers of CTD-induced hepatotoxicity were identified via multivariate and metabolic pathway analyses. In addition, metabolite–gene–enzyme network and Kyoto Encyclopedia of Genes and Genomes pathway analyses were used to identify the signaling pathways related to CTD-induced hepatotoxicity. The results revealed significantly increased levels of biochemical indices (alanine aminotransferase, aspartate aminotransferase, and total bile acid). Histopathological analysis revealed that the hepatocytes were damaged. Further, 20 endogenous BAs were quantitated via UHPLC-MS/MS, and multivariate and metabolic pathway analyses of BAs revealed that hyocholic acid, cholic acid, and chenodeoxycholic acid were the key biomarkers of CTD-induced hepatotoxicity. Meanwhile, primary and secondary BA biosynthesis and taurine and hypotaurine metabolism were found to be associated with the mechanism by which CTD induced hepatotoxicity in rats. This study provides useful insights for research on the mechanism of CTD-induced hepatotoxicity. 相似文献
10.