全文获取类型
收费全文 | 3657篇 |
免费 | 231篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 27篇 |
儿科学 | 97篇 |
妇产科学 | 98篇 |
基础医学 | 703篇 |
口腔科学 | 175篇 |
临床医学 | 324篇 |
内科学 | 552篇 |
皮肤病学 | 118篇 |
神经病学 | 393篇 |
特种医学 | 133篇 |
外科学 | 576篇 |
综合类 | 27篇 |
一般理论 | 2篇 |
预防医学 | 185篇 |
眼科学 | 77篇 |
药学 | 185篇 |
中国医学 | 5篇 |
肿瘤学 | 217篇 |
出版年
2023年 | 22篇 |
2022年 | 25篇 |
2021年 | 60篇 |
2020年 | 51篇 |
2019年 | 45篇 |
2018年 | 83篇 |
2017年 | 55篇 |
2016年 | 77篇 |
2015年 | 100篇 |
2014年 | 110篇 |
2013年 | 130篇 |
2012年 | 212篇 |
2011年 | 222篇 |
2010年 | 128篇 |
2009年 | 137篇 |
2008年 | 174篇 |
2007年 | 165篇 |
2006年 | 171篇 |
2005年 | 142篇 |
2004年 | 165篇 |
2003年 | 122篇 |
2002年 | 114篇 |
2001年 | 85篇 |
2000年 | 114篇 |
1999年 | 106篇 |
1998年 | 23篇 |
1997年 | 25篇 |
1996年 | 24篇 |
1995年 | 22篇 |
1993年 | 21篇 |
1992年 | 53篇 |
1991年 | 39篇 |
1990年 | 55篇 |
1989年 | 54篇 |
1988年 | 41篇 |
1987年 | 28篇 |
1986年 | 22篇 |
1985年 | 44篇 |
1984年 | 26篇 |
1979年 | 25篇 |
1978年 | 19篇 |
1977年 | 20篇 |
1974年 | 26篇 |
1971年 | 26篇 |
1885年 | 18篇 |
1880年 | 32篇 |
1879年 | 21篇 |
1877年 | 21篇 |
1876年 | 21篇 |
1875年 | 18篇 |
排序方式: 共有3894条查询结果,搜索用时 15 毫秒
61.
62.
63.
Julia M. Kröpfl Fernando G. Beltrami Markus Rehm Hans-Jürgen Gruber Ingeborg Stelzer Christina M. Spengler 《Journal of Science and Medicine in Sport》2021,24(7):689-695
ObjectivesRegular physical exercise is known to protect endothelial integrity. It has been proposed that acute exercise-induced changes of the (anti-)oxidative system influence early (glycocalyx shedding) and sustained endothelial activation (shedding of endothelial cells, ECs) as well as endothelial-cell repair by circulating hematopoietic stem and progenitor cells (HPCs). However, results are not conclusive and data in trained participants performing different exercise modalities is lacking.DesignEighteen healthy, well-trained participants (9 runners, 9 cyclists; age: 29.7 ± 4.2 yrs) performed a strenuous acute exercise session consisting of 4 bouts of 4-min high-intensity with decreasing power profile and 3-min low-intensity in-between.MethodsAverage power/speed of intense phases was 85% of the peak achieved in a previous incremental test. Before and shortly after exercise, total oxidative and antioxidative capacities (TAC), shedding of syndecan-1, heparan sulfate, hyaluronan, ECs, and circulating HPCs were investigated.ResultsTAC decreased from 1.81 ± 0.42 nmol/L to 1.47 ± 0.23 nmol/L post-exercise (p = 0.010) only in runners. Exercise-induced early and sustained endothelial activation were enhanced post-exercise- syndecan-1: 103.2 ± 63.3 ng/mL to 111.3 ± 71.3 ng/mL, heparan sulfate: from 2637.9 ± 800.1 ng/mL to 3197.1 ± 1416.3 ng/mL, both p < 0.05; hyaluronan: 84.3 ± 21.8 ng/mL to 121.4 ± 29.4 ng/mL, ECs: from 6.6 ± 4.5 cells/μL to 9.5 ± 6.2 cells/μL, both p < 0.01; results were not different between exercise modalities and negatively related to TAC concentrations post-exercise. HPC proportions and self-renewal ability were negatively, while EC concentrations were positively associated with circulating hyaluronan concentrations.ConclusionsThese results highlight the importance of the antioxidative system to prevent the endothelium from acute exercise-induced vascular injury – independent of exercise modality – in well-trained participants. Endothelial-cell repair is associated with hyluronan signaling, possibly a similar mechanism as in wound repair. 相似文献
64.
65.
66.
67.
68.
69.
70.
Long-Term Enteral Feeding: A Retrospective Comparison of Delivery via Percutaneous Endoscopic Gastrostomy and Nasoenteric Tubes 总被引:2,自引:0,他引:2
David E. Fay M.D. Maurice Poplausky M.D. Marcia Gruber R.N. Peter Lance M.D. 《The American journal of gastroenterology》1991,86(11):1604-1609
The use of percutaneous endoscopic gastrostomy (PEG) tubes for enteral feeding is widespread, although their superiority to other feeding devices, such as nasoenteric tubes (NET), has not been substantiated. We retrospectively compared clinical outcomes in patients who received enteral feeding via PEG (n = 80) or NET (n = 29) from 1984 to 1988. Mean follow-up was 192 days in the PEG group and 141 days in the NET group. Changes in nutritional and performance status were similar in both groups. Aspiration pneumonia occurred within 14 days of tube placement in 6% and 24% (p = 0.01) of the PEG and NET patients, respectively. With the exception of tube replacement, cumulative rates of minor and major complications (including aspiration pneumonia) were similar in both groups during follow-up. None of the clinical variables that were assessed correlated with the development of aspiration pneumonia. Mortality was similar in both groups. These results suggest that, for long-term enteral feeding, PEG offers no substantial advantages over NET with respect to patient nutrition, performance, or survival. The reasons for the observed difference in short-term aspiration pneumonia rates are unknown, and must be investigated prospectively. 相似文献