收费全文 | 79210篇 |
免费 | 6112篇 |
国内免费 | 3425篇 |
耳鼻咽喉 | 745篇 |
儿科学 | 1536篇 |
妇产科学 | 1556篇 |
基础医学 | 9036篇 |
口腔科学 | 1366篇 |
临床医学 | 8631篇 |
内科学 | 15618篇 |
皮肤病学 | 1054篇 |
神经病学 | 6061篇 |
特种医学 | 2944篇 |
外国民族医学 | 26篇 |
外科学 | 9225篇 |
综合类 | 8508篇 |
现状与发展 | 12篇 |
一般理论 | 1篇 |
预防医学 | 4390篇 |
眼科学 | 1674篇 |
药学 | 7306篇 |
34篇 | |
中国医学 | 2811篇 |
肿瘤学 | 6213篇 |
2024年 | 160篇 |
2023年 | 965篇 |
2022年 | 2538篇 |
2021年 | 3395篇 |
2020年 | 2395篇 |
2019年 | 2285篇 |
2018年 | 2444篇 |
2017年 | 2189篇 |
2016年 | 2064篇 |
2015年 | 2902篇 |
2014年 | 3674篇 |
2013年 | 3829篇 |
2012年 | 5432篇 |
2011年 | 5566篇 |
2010年 | 3330篇 |
2009年 | 2869篇 |
2008年 | 3961篇 |
2007年 | 4097篇 |
2006年 | 3920篇 |
2005年 | 3817篇 |
2004年 | 2997篇 |
2003年 | 2687篇 |
2002年 | 2391篇 |
2001年 | 2195篇 |
2000年 | 2140篇 |
1999年 | 2171篇 |
1998年 | 1040篇 |
1997年 | 990篇 |
1996年 | 845篇 |
1995年 | 687篇 |
1994年 | 604篇 |
1993年 | 415篇 |
1992年 | 941篇 |
1991年 | 804篇 |
1990年 | 738篇 |
1989年 | 727篇 |
1988年 | 623篇 |
1987年 | 547篇 |
1986年 | 500篇 |
1985年 | 392篇 |
1984年 | 293篇 |
1983年 | 230篇 |
1982年 | 143篇 |
1979年 | 220篇 |
1978年 | 128篇 |
1977年 | 110篇 |
1974年 | 122篇 |
1973年 | 125篇 |
1972年 | 122篇 |
1971年 | 110篇 |
Physical activity brings significant health benefits to middle-aged adults, although the research to date has been focused on late adulthood. This study aims to examine how ageing affects the self-reported and accelerometer-derived measures of physical activity levels in middle-aged adults. We employed the data recorded in the UK Biobank and analysed the physical activity levels of 2,998 participants (1381 men and 1617 women), based on self-completion questionnaire and accelerometry measurement of physical activity. We also assessed the musculoskeletal health of the participants using the dual-energy X-ray absorptiometry (DXA) measurements provided by the UK Biobank. Participants were categorised into three groups according to their age: group I younger middle-aged (40 to 49 years), group II older middle-aged (50 to 59 years), and group III oldest middle-aged (60 to 69 years). Self-reported physical activity level increased with age and was the highest in group III, followed by group II and I (P?<?0.05). On the contrary, physical activity measured by accelerometry decreased significantly with age from group I to III (P?<?0.05), and the same pertained to the measurements of musculoskeletal health (P?<?0.05). It was also shown that middle-aged adults mostly engaged in low and moderate intensity activities. The opposing trends of the self-reported and measured physical activity levels may suggest that middle-aged adults over-report their activity level as they age. They should be aware of the difference between their perceived and actual physical activity levels, and objective measures would be useful to prevent the decline in musculoskeletal health.
相似文献Area covered: The current review is provided to update recent developments in the clinical application of cyclin/CDK inhibitors to breast cancer with a focus on the anti-tumor immune response.
Expert opinion: The cyclin D1 gene encodes the regulatory subunit of a proline-directed serine-threonine kinase that phosphorylates several substrates. CDKs possess phosphorylation site selectivity, with the phosphate-acceptor residue preceding a proline. Several important proteins are substrates including all three retinoblastoma proteins, NRF1, GCN5, and FOXM1. Over 280 cyclin D3/CDK6 substrates have b\een identified. Given the diversity of substrates for cyclin/CDKs, and the altered thresholds for substrate phosphorylation that occurs during the cell cycle, it is exciting that small molecular inhibitors targeting cyclin D/CDK activity have encouraging results in specific tumors. 相似文献