全文获取类型
收费全文 | 4277篇 |
免费 | 229篇 |
国内免费 | 13篇 |
专业分类
耳鼻咽喉 | 87篇 |
儿科学 | 119篇 |
妇产科学 | 144篇 |
基础医学 | 582篇 |
口腔科学 | 225篇 |
临床医学 | 363篇 |
内科学 | 712篇 |
皮肤病学 | 78篇 |
神经病学 | 403篇 |
特种医学 | 176篇 |
外科学 | 594篇 |
综合类 | 11篇 |
一般理论 | 1篇 |
预防医学 | 323篇 |
眼科学 | 123篇 |
药学 | 250篇 |
中国医学 | 4篇 |
肿瘤学 | 324篇 |
出版年
2023年 | 36篇 |
2022年 | 56篇 |
2021年 | 108篇 |
2020年 | 78篇 |
2019年 | 94篇 |
2018年 | 114篇 |
2017年 | 63篇 |
2016年 | 125篇 |
2015年 | 107篇 |
2014年 | 143篇 |
2013年 | 210篇 |
2012年 | 279篇 |
2011年 | 269篇 |
2010年 | 158篇 |
2009年 | 149篇 |
2008年 | 300篇 |
2007年 | 276篇 |
2006年 | 304篇 |
2005年 | 250篇 |
2004年 | 230篇 |
2003年 | 232篇 |
2002年 | 212篇 |
2001年 | 39篇 |
2000年 | 28篇 |
1999年 | 44篇 |
1998年 | 60篇 |
1997年 | 35篇 |
1996年 | 30篇 |
1995年 | 36篇 |
1994年 | 34篇 |
1993年 | 39篇 |
1992年 | 25篇 |
1991年 | 21篇 |
1990年 | 19篇 |
1989年 | 28篇 |
1988年 | 22篇 |
1987年 | 21篇 |
1986年 | 22篇 |
1985年 | 22篇 |
1984年 | 24篇 |
1983年 | 23篇 |
1982年 | 20篇 |
1981年 | 17篇 |
1980年 | 13篇 |
1979年 | 24篇 |
1978年 | 17篇 |
1977年 | 8篇 |
1976年 | 13篇 |
1974年 | 11篇 |
1972年 | 8篇 |
排序方式: 共有4519条查询结果,搜索用时 0 毫秒
51.
52.
An in vitro degradation study of three bioresorbable glass fiber-reinforced poly(l-lactide-co-dl-lactide) (PLDLA) composites was carried out in simulated body fluid (SBF), to simulate body conditions, and deionized water, to evaluate the nature of the degradation products. The changes in mechanical and chemical properties were systematically characterized over 52 weeks dissolution time to determine the degradation mechanism and investigate strength retention by the bioresorbable glass fiber-reinforced PLDLA composite. The degradation mechanism was found to be a combination of surface and bulk erosion and does not follow the typical core-accelerated degradation mechanism of poly(α-hydroxyacids). Strength retention by bioresorbable glass fiber-reinforced PLDLA composites can be tailored by changing the oxide composition of the glass fibers, but the structure–property relationship of the glass fibers has to be understood and controlled so that the phenomenon of ion leaching can be utilized to control the degradation rate. Therefore, these high performance composites are likely to open up several new possibilities for utilizing resorbable materials in clinical applications which could not be realized in the past. 相似文献
53.
Short DNA sequences and bacterial DNA induce esophageal,gastric, and colorectal cancer cell invasion
Joonas H. Kauppila Tuomo J. Karttunen Juha Saarnio Pia Nyberg Tuula Salo David E. Graves Katri S. Selander 《APMIS : acta pathologica, microbiologica, et immunologica Scandinavica》2013,121(6):511-522
Toll‐like receptor 9 (TLR9) recognizes both bacterial and self‐DNA and it is abundantly expressed in the gastrointestinal tract. In this study, we investigated the influences of both bacterial DNA and specific short DNA sequences on TLR9‐mediated gastrointestinal cancer cell invasion. We assessed the effect of various DNA ligands on cellular invasion and on TLR9 and matrix metalloproteinase expression of three gastrointestinal cancer cell lines. DNA‐ligands described in this study include CpG‐ODN M362, 9‐mer (hairpin), human telomeric sequence h‐Tel22 G‐quadruplex, and bacterial DNAs from Escherichia coli and Helicobacter pylori. All of the DNAs studied were demonstrated to induce invasion in the studied cells. The DNA‐induced invasion was inhibited with a broad‐spectrum MMP inhibitor and partly also with chloroquine suggesting that it could be mediated via MMP activation, endosomal signaling, and TLR9. Interestingly, H. pylori DNA was shown to induce a more pronounced invasion in a gastric cancer cell line than in the other cell lines. Our results suggest that bacterial DNA as well as deoxynucleotides having stable secondary structures (i.e. hairpins or G‐quadruplex structures) may serve as endogenous, invasion‐inducing TLR9‐ligands and promote local progression and metastasis of cancers in the alimentary tract. 相似文献
54.
Jaana I. Halonen Jussi Vahtera Stephen Stansfeld Tarja Yli-Tuomi Paula Salo Jaana Pentti Mika Kivim?ki Timo Lanki 《Environmental health perspectives》2012,120(10):1391-1396
Background: Associations between traffic noise and sleep problems have been detected in experimental studies, but population-level evidence is scarce.Objectives: We studied the relationship between the levels of nighttime traffic noise and sleep disturbances and identified vulnerable population groups.Methods: Noise levels of nighttime–outdoor traffic were modeled based on the traffic intensities in the cities of Helsinki and Vantaa, Finland. In these cities, 7,019 public sector employees (81% women) responded to postal surveys on sleep and health. We linked modeled outdoor noise levels to the residences of the employees who responded to the postal survey. We used logistic regression models to estimate associations of noise levels with subjectively assessed duration of sleep and symptoms of insomnia (i.e., difficulties falling asleep, waking up frequently during the night, waking up too early in the morning, nonrestorative sleep). We also used stratified models to investigate the possibility of vulnerable subgroups.Results: For the total study population, exposure to levels of nighttime–outside (Lnight, outside) traffic noise > 55 dB was associated with any insomnia symptom ≥ 2 nights per week [odds ratio (OR) = 1.32; 95% confidence interval (CI): 1.05, 1.65]. Among participants with higher trait anxiety scores, which we hypothesized were a proxy for noise sensitivity, the ORs for any insomnia symptom at exposures to Lnight, outside traffic noises 50.1–55 dB and > 55 dB versus ≤ 45 dB were 1.34 (95% CI: 1.00, 1.80) and 1.61 (95% CI: 1.07, 2.42), respectively.Conclusions: Nighttime traffic noise levels > 50 dB Lnight, outside was associated with insomnia symptoms among persons with higher scores for trait anxiety. For the total study population, Lnight, outside > 55 dB was positively associated with any symptoms. 相似文献
55.
Aleksi Reito Antti Eskelinen Timo Puolakka Jorma Pajamäki 《Archives of orthopaedic and trauma surgery》2013,133(2):267-273
The prevalence of total hip arthroplasty in young patients is small but increasing. We analyzed the results of metal-on-metal hip resurfacing (MMHR) in patients aged 40 years or less. In total 74 operations were performed on 64 patients. Mean age at operation was 33.2 years. HHS averaged 92.3 points at latest follow-up, mean UCLA activity was 8.2. Patients with comorbidity evinced lower scores in HHS, in UCLA activity and in quality of life than patients without comorbidities. Eight revisions (10.8 %) were performed, of which seven due to adverse reaction to metal debris. Seven-year survival was 90.5 %. The functional outcome of hip resurfacing in this cohort was excellent, but overall survival was unsatisfactory. Further analysis is required to verify the role of hip resurfacing among young and active patients. 相似文献
56.
57.
58.
Kuronen Moona Kokki Hannu Nyyssönen Timo Savolainen Sakari Kokki Merja 《Quality of life research》2018,27(11):3013-3020
Quality of Life Research - Pain has a negative impact on life satisfaction (LS). Our primary aims were to compare LS in on-opioid and opioid-naïve spine surgery patients and to evaluate... 相似文献
59.
60.