全文获取类型
收费全文 | 1776篇 |
免费 | 122篇 |
国内免费 | 24篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 60篇 |
妇产科学 | 19篇 |
基础医学 | 141篇 |
口腔科学 | 30篇 |
临床医学 | 212篇 |
内科学 | 529篇 |
皮肤病学 | 233篇 |
神经病学 | 49篇 |
特种医学 | 104篇 |
外科学 | 200篇 |
综合类 | 21篇 |
预防医学 | 145篇 |
眼科学 | 4篇 |
药学 | 109篇 |
中国医学 | 4篇 |
肿瘤学 | 57篇 |
出版年
2022年 | 12篇 |
2021年 | 24篇 |
2020年 | 15篇 |
2019年 | 13篇 |
2018年 | 28篇 |
2017年 | 19篇 |
2016年 | 45篇 |
2015年 | 42篇 |
2014年 | 50篇 |
2013年 | 89篇 |
2012年 | 38篇 |
2011年 | 50篇 |
2010年 | 59篇 |
2009年 | 71篇 |
2008年 | 35篇 |
2007年 | 44篇 |
2006年 | 42篇 |
2005年 | 28篇 |
2004年 | 31篇 |
2003年 | 24篇 |
2002年 | 35篇 |
2001年 | 27篇 |
2000年 | 44篇 |
1999年 | 51篇 |
1998年 | 77篇 |
1997年 | 57篇 |
1996年 | 60篇 |
1995年 | 53篇 |
1994年 | 56篇 |
1993年 | 39篇 |
1992年 | 62篇 |
1991年 | 20篇 |
1990年 | 45篇 |
1989年 | 49篇 |
1988年 | 59篇 |
1987年 | 44篇 |
1986年 | 34篇 |
1985年 | 18篇 |
1984年 | 49篇 |
1983年 | 18篇 |
1982年 | 21篇 |
1981年 | 22篇 |
1980年 | 17篇 |
1978年 | 12篇 |
1976年 | 13篇 |
1975年 | 10篇 |
1973年 | 12篇 |
1971年 | 11篇 |
1966年 | 11篇 |
1964年 | 14篇 |
排序方式: 共有1922条查询结果,搜索用时 20 毫秒
61.
Jingkai Wei Ruixue Hou Liyang Xie Eeshwar K. Chandrasekar Haidong Lu Tiansheng Wang Changwei Li Hanzhang Xu 《Journal of Science and Medicine in Sport》2021,24(2):189-194
ObjectivesWe aimed to estimate the association of sleep, sedentary activity and physical activity with cognitive function among older adults, with consideration of the competing nature between variables of activity status.DesignCross-sectional study.MethodsA total of 3086 older adults (60 years or older) in the 2011–2014 National Health and Nutrition Examination Survey were included. The Global Physical Activity Questionnaire was used to measure self-reported time for sedentary activity, walking/bicycling and moderate-to-vigorous physical activity (MVPA). Cognitive function was examined using the CERAD Word Learning subtest (memory), Digit Symbol Substitution Test (executive function/processing speed), and Animal Fluency Test (language). Sleep duration was obtained via interview. Isotemporal substitution models using multivariable linear regression were applied to examine the associations of replacing sleep, sedentary activity, walking/bicycling, MVPA with each other and cognitive function, stratified by sleep duration per night (≤7 h, >7 h).ResultsAmong participants with sleep duration ≤7 h/night, replacing 30 min/day of sedentary activity with 30 min/day of MVPA or 30 min/day was associated with better cognition. Among participants with sleep duration >7 h/night, replacing 30 min/day of sleep with 30 min/day of sedentary activity, walking/bicycling, or MVPA was associated with better cognition.ConclusionsReplacing sedentary activities with MVPA was associated with favorable cognitive function among older adults sleeping no longer than 7 h/night, and replacing excessive sleep with sedentary or physical activities was associated with favorable cognition. Future research is expected to examine the associations of replacing different activity status on long-term cognitive outcomes in longitudinal studies. 相似文献
62.
Involvement of guanine nucleotide binding proteins in neutrophil activation and priming by GM-CSF 总被引:4,自引:0,他引:4
Pre-incubation of human neutrophils with pertussis toxin significantly inhibited the neutrophil-directed biologic actions of granulocyte- macrophage colony-stimulating factor (GM-CSF) in three separate assays: the induction of c-fos mRNA, the enhancement of both platelet- activating factor-induced mobilization of intracellular calcium, and stimulation of leukotriene synthesis by the calcium ionophore A23187. Cholera toxin did not have an effect on the latter two assays. Pre- treatment of human neutrophils with pertussis toxin did not affect the binding of GM-CSF to its surface receptor. These results provide the first evidence that a pertussis toxin substrate plays an important mediatory role in the mechanism of action of GM-CSF. 相似文献
63.
Local delivery of 17-beta-estradiol decreases neointimal hyperplasia after coronary angioplasty in a porcine model 总被引:4,自引:0,他引:4
BACKGROUND: Neointimal hyperplasia is an important mechanism of restenosis after percutaneous transluminal coronary angioplasty (PTCA). Systemically administered estrogen is known to inhibit neointimal formation after arterial injury. OBJECTIVES: We sought to assess the efficacy of locally delivered 17-beta-estradiol (BE) in inhibiting neointimal hyperplasia after PTCA. METHODS: Eighteen juvenile farm pigs were studied. Coronary angioplasty was performed in all three coronary arteries of each animal. After PTCA, each coronary artery in each pig was randomized to receive either local delivery of 600 microg BE, vehicle alone or PTCA only. Twelve animals were euthanized at 28 days for morphometric analysis, and four animals were euthanized at seven days for immunohistochemical analysis of vascular smooth muscle cell (SMC) proliferative activity. Two animals died a few days after PTCA and were excluded. RESULTS: On morphometric study, the arterial segments treated with BE demonstrated significantly less neointimal proliferation. Arteries treated with BE had reductions in several indexes of restenosis compared with arteries treated with vehicle alone or PTCA only: neointimal area (0.4+/-0.09 mm2 for BE vs. 1.14+/-0.33 mm2 for vehicle alone vs. 0.88+/-0.2 mm2 for PTCA only, p<0.05), percent neointima (12.16+/-2.57% vs. 25.46+/-4.73% vs. 23.02+/-3.97%, p<0.025), neointima/media area (0.59+/-0.14 vs. 1.75+/-0.41 vs. 1.67+/-0.43, p<0.01) and restenotic index (1.3+/-0.14 vs. 2.42+/-0.22 vs. 2.4+/-0.23, p<0.005). Immunohistochemistry showed decreased SMC proliferative activity in BE-treated arteries compared with the other two treatment groups (p<0.05). CONCLUSIONS: Local delivery of BE significantly decreases neointimal hyperplasia after PTCA in pigs, probably by the inhibition of SMC proliferation. 相似文献
64.
Time‐Dependent Changes in QT Dynamics after Initiation and Termination of Paroxysmal Atrial Fibrillation 下载免费PDF全文
65.
66.
Flower‐like/clover leaf lymphocytes appear in various diseases: Cerebrospinal fluid cytology case with review of the literature 下载免费PDF全文
67.
68.
Simona Attardo Viveksandeep Thoguluva Chandrasekar Marco Spadaccini Roberta Maselli Harsh K Patel Madhav Desai Antonio Capogreco Matteo Badalamenti Piera Alessia Galtieri Gaia Pellegatta Alessandro Fugazza Silvia Carrara rea Anderloni Pietro Occhipinti Cesare Hassan Prateek Sharma Alessandro Repici 《World journal of gastroenterology : WJG》2020,26(37):5606-5616
Several studies have shown a significant adenoma miss rate up to 35% during screening colonoscopy, especially in patients with diminutive adenomas. The use of artificial intelligence(AI) in colonoscopy has been gaining popularity by helping endoscopists in polyp detection, with the aim to increase their adenoma detection rate(ADR) and polyp detection rate(PDR) in order to reduce the incidence of interval cancers. The efficacy of deep convolutional neural network(DCNN)-based AI system for polyp detection has been trained and tested in ex vivo settings such as colonoscopy still images or videos. Recent trials have evaluated the real-time efficacy of DCNN-based systems showing promising results in term of improved ADR and PDR. In this review we reported data from the preliminary ex vivo experiences and summarized the results of the initial randomized controlled trials. 相似文献
69.
70.
Maoxin Wu M.D. PH.D. Hua Chen M.D. Ph.D. XiaoYong Zheng M.D. Ph.D. David E. Burstein M.D. Dara Aisner M.D. Ph.D. 《Diagnostic cytopathology》2013,41(12):1100-1106
Ultrasound‐guided fine needle aspiration (USG‐FNA) has enabled cytopathologists to accurately diagnose smaller or non‐palpable lymph nodes (LN) on a regular basis. Pre‐FNA clinical and ultrasonographic factors, such as a patient's age, ratio of short to long axis diameter (S/L ratio), internal echogenicity, and the vascular pattern of a LN, are reported to be able to predict the benign or malignant nature of a LN. This study is designed to test the formula “0.06 × (age) + 4.76 × (S/L ratio) + 2.15 × (internal echo) + 1.80 × (vascular pattern)” generated from the study of Liao et al. as a scoring system for predicting LN malignancy in a cytopathologist operated USG‐FNA practice. Eighty‐three reports of USG‐FNA of LNs issued between 7/1/2008 and 4/28/2010 were reviewed. Patient's age, S/L ratio, internal echo, and vascular pattern were used to generate scores based on the aforementioned formula. A score of seven was used as a cutoff for predicting benign (<7) and malignant (>7) LNs. FNA cytology diagnosis, flow cytometric analysis as well as subsequent surgical diagnosis in some cases served as gold standard for statistical analysis. Among 46 USG‐FNA of LNs with scores > 7, 38 were malignant and eight were benign. All 37 USG‐FNA of LNs with scores < 7 were proven to be benign. The scoring system achieved 100% sensitivity, 82% specificity, 83% positive predictive value, 100% negative predictive value, and 90% accuracy. Further study of the eight “false‐positive” cases revealed that three of them (37.5%) were found to be malignant in follow‐up FNA and/or surgical biopsy. This scoring system may serve as a complementary tool in determining how aggressive a FNA procedure should be performed, how a FNA sample of LN should be triaged for ancillary study, and how closely a patient with lymphadenopathy should be followed up. Diagn. Cytopathol. 2013;41:1100–1106. © 2011 Wiley Periodicals, Inc. 相似文献