全文获取类型
收费全文 | 5969篇 |
免费 | 505篇 |
国内免费 | 100篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 66篇 |
妇产科学 | 26篇 |
基础医学 | 279篇 |
口腔科学 | 38篇 |
临床医学 | 886篇 |
内科学 | 2406篇 |
皮肤病学 | 18篇 |
神经病学 | 138篇 |
特种医学 | 435篇 |
外科学 | 422篇 |
综合类 | 515篇 |
预防医学 | 195篇 |
眼科学 | 21篇 |
药学 | 505篇 |
2篇 | |
中国医学 | 387篇 |
肿瘤学 | 233篇 |
出版年
2024年 | 16篇 |
2023年 | 217篇 |
2022年 | 346篇 |
2021年 | 488篇 |
2020年 | 397篇 |
2019年 | 480篇 |
2018年 | 435篇 |
2017年 | 212篇 |
2016年 | 160篇 |
2015年 | 192篇 |
2014年 | 438篇 |
2013年 | 354篇 |
2012年 | 282篇 |
2011年 | 301篇 |
2010年 | 197篇 |
2009年 | 190篇 |
2008年 | 225篇 |
2007年 | 252篇 |
2006年 | 152篇 |
2005年 | 143篇 |
2004年 | 95篇 |
2003年 | 88篇 |
2002年 | 68篇 |
2001年 | 72篇 |
2000年 | 52篇 |
1999年 | 60篇 |
1998年 | 60篇 |
1997年 | 54篇 |
1996年 | 27篇 |
1995年 | 42篇 |
1994年 | 45篇 |
1993年 | 29篇 |
1992年 | 43篇 |
1991年 | 37篇 |
1990年 | 32篇 |
1989年 | 28篇 |
1988年 | 31篇 |
1987年 | 34篇 |
1986年 | 27篇 |
1985年 | 32篇 |
1984年 | 31篇 |
1983年 | 24篇 |
1982年 | 23篇 |
1981年 | 18篇 |
1980年 | 10篇 |
1979年 | 9篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1973年 | 3篇 |
排序方式: 共有6574条查询结果,搜索用时 31 毫秒
101.
Victor Manuel Zamora-Gasga Alicia Paulina Cárdenas-Castro Efigenia Montalvo-González María Guadalupe Flavia Loarca-Piña Vázquez-Landaverde Pedro Alberto Juscelino Tovar 《International journal of food sciences and nutrition》2018,69(6):718-728
The indigestible fraction (IF) isolated from three lunch menus: Modified Mexican Lunch (MM-L), Traditional Mexican Lunch (TM-L) and Alternative Mexican Lunch (AM-L), was studied in terms of antioxidant capacity (AOX) and metabolites produced through fermentation by human intestinal microbiota. IFs were isolated after withstanding in vitro gastrointestinal digestion and total soluble polyphenols (TSP), condensed tannins (CT), hydrolysable polyphenols (HP) and AOX (DPPH, FRAP) were evaluated. AOX, pH and bacterial metabolites profile changes were also monitored during in vitro colonic fermentation. Lunch menus showed differences in IF, TSP, CT and FRAP values (p<.05). TM-L had the highest TSP and CT contents (0.84 and 1.89?g/100?g DW, respectively). Changes in pH and AOX during fermentation were time-dependent and substrate-dependent (p<.05). Butyric acid production was not significantly modified by the IFs (p>.05). Fifty-seven microbiota-produced volatile compounds were detected by SPME-GC–MS. This study shows the potential effects of food habits on bacterial metabolite production. 相似文献
102.
《Journal of immunotoxicology》2013,10(1):43-55
Many immunosuppressive drugs are associated with an increased risk of neoplasia, principally non-melanoma skin cancers and B-cell lymphomas. However, only 6 of the 13 immunosuppressive drugs tested in 2 year bioassays increased the incidence of neoplasia. For example, the 2-year bioassays conducted with cyclosporine (CSA), an International Agency for Research on Cancer (IARC) Group 1 human carcinogen, were negative. The purpose of these investigations was to use transplanted tumor models in immunocompetent, syngeneic mice to gain insight into the failure of the 2-year bioassay to show an increased incidence of neoplasia with CSA. C3H HeN mice were used in a battery of assays with a transplanted squamous cell carcinoma (SCC VII cells) or a B-cell, lymphoma (38C13 cells) cells to study effects of CSA on local growth and metastases, experimental metastases, and progression of established metastases. Mice received CSA twice weekly by subcutaneous (SC) injection at doses of 0.5, 5, or 50?mg/kg; controls received the CSA vehicle. CSA had a modest inhibitory effect on SC tumors initiated by 38C13 cells and on intramuscular tumors initiated by SCC VII cells. CSA also decreased the number of lung colonies and decreased the size, growth fraction and vascularity of established lung metastases initiated by SCC VII cells. In contrast, CSA increased progressive growth of metastases to the sentinel lymph node from an intramuscular SCC VII tumor, but had no effect cellular traffic to the node. In conclusion, CSA at doses up to 50?mg/kg did not facilitate tumor progression and it partially inhibited tumor growth, suggesting that suppression of tumor progression may partially explain the failure of CSA to act as a carcinogen in 2 year bioassays. 相似文献
103.
Response stratification and survival analysis of hepatocellular carcinoma patients treated with intra‐arterial therapy using MR imaging‐based arterial enhancement fraction 下载免费PDF全文
104.
105.
106.
Accuracy of an automated transthoracic echocardiographic tool for 3D assessment of left heart chamber volumes 下载免费PDF全文
107.
Can T1w/T2w ratio be used as a myelin‐specific measure in subcortical structures? Comparisons between FSE‐based T1w/T2w ratios,GRASE‐based T1w/T2w ratios and multi‐echo GRASE‐based myelin water fractions 下载免费PDF全文
Md Nasir Uddin Teresa D. Figley Ruth Ann Marrie Chase R. Figley for the CCOMS Study Group 《NMR in biomedicine》2018,31(3)
Given the growing popularity of T1‐weighted/T2‐weighted (T1w/T2w) ratio measurements, the objective of the current study was to evaluate the concordance between T1w/T2w ratios obtained using conventional fast spin echo (FSE) versus combined gradient and spin echo (GRASE) sequences for T2w image acquisition, and to compare the resulting T1w/T2w ratios with histologically validated myelin water fraction (MWF) measurements in several subcortical brain structures. In order to compare these measurements across a relatively wide range of myelin concentrations, whole‐brain T1w magnetization prepared rapid acquisition gradient echo (MPRAGE), T2w FSE and three‐dimensional multi‐echo GRASE data were acquired from 10 participants with multiple sclerosis at 3 T. Then, after high‐dimensional, non‐linear warping, region of interest (ROI) analyses were performed to compare T1w/T2w ratios and MWF estimates (across participants and brain regions) in 11 bilateral white matter (WM) and four bilateral subcortical grey matter (SGM) structures extracted from the JHU_MNI_SS ‘Eve’ atlas. Although the GRASE sequence systematically underestimated T1w/T2w values compared to the FSE sequence (revealed by Bland–Altman and mountain plots), linear regressions across participants and ROIs revealed consistently high correlations between the two methods (r2 = 0.62 for all ROIs, r2 = 0.62 for WM structures and r2 = 0.73 for SGM structures). However, correlations between either FSE‐based or GRASE‐based T1w/T2w ratios and MWFs were extremely low in WM structures (FSE‐based, r2 = 0.000020; GRASE‐based, r2 = 0.0014), low across all ROIs (FSE‐based, r2 = 0.053; GRASE‐based, r2 = 0.029) and moderate in SGM structures (FSE‐based, r2 = 0.20; GRASE‐based, r2 = 0.17). Overall, our findings indicated a high degree of correlation (but not equivalence) between FSE‐based and GRASE‐based T1w/T2w ratios, and low correlations between T1w/T2w ratios and MWFs. This suggests that the two T1w/T2w ratio approaches measure similar facets of subcortical tissue microstructure, whereas T1w/T2w ratios and MWFs appear to be sensitized to different microstructural properties. On this basis, we conclude that multi‐echo GRASE sequences can be used in future studies to efficiently elucidate both general (T1w/T2w ratio) and myelin‐specific (MWF) tissue characteristics. 相似文献
108.
《山东中医药大学学报》2018,(1)
目的:探讨自拟参苓养心颗粒治疗射血分数保留的心力衰竭的临床疗效。方法:将60例气阴两虚、血瘀水停型射血分数保留的心力衰竭患者按随机数字表法分为对照组与治疗组。对照组给予常规西药治疗。治疗组在对照组治疗基础上加用参苓养心颗粒。治疗4周后观察两组治疗前后心脏彩超、脑钠肽(BNP)、综合疗效等指标。结果:参苓养心颗粒可以明显改善患者症状,并降低BNP、二尖瓣口舒张早期血流峰值/二尖瓣环舒张早期运动速度(E/E’),与对照组比较差异有统计学意义。对左房容积指数(LAVI)未见明显的改善。结论:参苓养心颗粒能够改善射血分数保留的心力衰竭左心舒张功能,且无明显不良反应。 相似文献
109.
110.