全文获取类型
收费全文 | 905763篇 |
免费 | 57581篇 |
国内免费 | 2309篇 |
专业分类
耳鼻咽喉 | 12515篇 |
儿科学 | 28681篇 |
妇产科学 | 26143篇 |
基础医学 | 126721篇 |
口腔科学 | 24709篇 |
临床医学 | 74866篇 |
内科学 | 183481篇 |
皮肤病学 | 19004篇 |
神经病学 | 71527篇 |
特种医学 | 36472篇 |
外国民族医学 | 336篇 |
外科学 | 142212篇 |
综合类 | 19037篇 |
一般理论 | 247篇 |
预防医学 | 64613篇 |
眼科学 | 20112篇 |
药学 | 63947篇 |
13篇 | |
中国医学 | 1800篇 |
肿瘤学 | 49217篇 |
出版年
2018年 | 9072篇 |
2017年 | 7208篇 |
2016年 | 7737篇 |
2015年 | 8737篇 |
2014年 | 12376篇 |
2013年 | 19212篇 |
2012年 | 25650篇 |
2011年 | 27260篇 |
2010年 | 16577篇 |
2009年 | 15787篇 |
2008年 | 26129篇 |
2007年 | 27737篇 |
2006年 | 27919篇 |
2005年 | 27453篇 |
2004年 | 26308篇 |
2003年 | 25471篇 |
2002年 | 25065篇 |
2001年 | 41363篇 |
2000年 | 42556篇 |
1999年 | 36271篇 |
1998年 | 9967篇 |
1997年 | 9148篇 |
1996年 | 9082篇 |
1995年 | 8445篇 |
1994年 | 8082篇 |
1993年 | 7584篇 |
1992年 | 28199篇 |
1991年 | 26980篇 |
1990年 | 26408篇 |
1989年 | 25348篇 |
1988年 | 23556篇 |
1987年 | 23172篇 |
1986年 | 22251篇 |
1985年 | 21152篇 |
1984年 | 15806篇 |
1983年 | 13478篇 |
1982年 | 8087篇 |
1979年 | 14592篇 |
1978年 | 10208篇 |
1977年 | 8629篇 |
1976年 | 8148篇 |
1975年 | 8963篇 |
1974年 | 10704篇 |
1973年 | 10186篇 |
1972年 | 9664篇 |
1971年 | 8921篇 |
1970年 | 8585篇 |
1969年 | 8029篇 |
1968年 | 7687篇 |
1967年 | 7087篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Otavio Berwanger Renato D. Lopes Diogo D.F. Moia Francisco A. Fonseca Lixin Jiang Shaun G. Goodman Stephen J. Nicholls Alexander Parkhomenko Oleg Averkov Carlos Tajer Germán Malaga Jose F.K. Saraiva Helio P. Guimaraes Pedro G.M. de Barros e Silva Lucas P. Damiani Renato H.N. Santos Denise M. Paisani Tamiris A. Miranda Jose C. Nicolau 《Journal of the American College of Cardiology》2019,73(22):2819-2828
BackgroundThe efficacy of ticagrelor in the long-term post–ST-segment elevation myocardial infarction (STEMI) treated with fibrinolytic therapy remains uncertain.ObjectivesThe purpose of this study was to evaluate the efficacy of ticagrelor when compared with clopidogrel in STEMI patients treated with fibrinolytic therapy.MethodsThis international, multicenter, randomized, open-label with blinded endpoint adjudication trial enrolled 3,799 patients (age <75 years) with STEMI receiving fibrinolytic therapy. Patients were randomized to ticagrelor (180-mg loading dose, 90 mg twice daily thereafter) or clopidogrel (300- to 600-mg loading dose, 75 mg daily thereafter). The key outcomes were cardiovascular mortality, myocardial infarction, or stroke, and the same composite outcome with the addition of severe recurrent ischemia, transient ischemic attack, or other arterial thrombotic events at 12 months.ResultsThe combined outcome of cardiovascular mortality, myocardial infarction, or stroke occurred in 129 of 1,913 patients (6.7%) receiving ticagrelor and in 137 of 1,886 patients (7.3%) receiving clopidogrel (hazard ratio: 0.93; 95% confidence interval: 0.73 to 1.18; p = 0.53). The composite of cardiovascular mortality, myocardial infarction, stroke, severe recurrent ischemia, transient ischemic attack, or other arterial thrombotic events occurred in 153 of 1,913 patients (8.0%) treated with ticagrelor and in 171 of 1,886 patients (9.1%) receiving clopidogrel (hazard ratio: 0.88; 95% confidence interval: 0.71 to 1.09; p = 0.25). The rates of major, fatal, and intracranial bleeding were similar between the ticagrelor and clopidogrel groups.ConclusionAmong patients age <75 years with STEMI, administration of ticagrelor after fibrinolytic therapy did not significantly reduce the frequency of cardiovascular events when compared with clopidogrel. (Ticagrelor in Patients With ST Elevation Myocardial Infarction Treated With Pharmacological Thrombolysis [TREAT]; NCT02298088) 相似文献
22.
C. Ludes A. Labani F. Severac M.Y. Jeung P. Leyendecker C. Roy M. Ohana 《Diagnostic and interventional imaging》2019,100(2):85-93
Purpose
To qualitatively and quantitatively compare unenhanced ultra-low-dose chest computed tomography (ULD-CT) acquired at 80 kVp and 135 kVp.Materials and methods
Fifty-one patients referred for unenhanced chest CT were prospectively included. There were 29 men and 22 women, with a mean age of 64.7 ± 11.6 (SD) years (range: 35–91 years) and a mean body mass index of 26.2 ± 6.3 (SD) (range: 17–54.9). All patients underwent two different ULD-CT protocols (80 kVp-40 mA and 135 kVp-10 mA). Image quality of both ULD-CT examinations using a 5-level scale as well as assessability of 6 predetermined lung parenchyma lesions were blindly evaluated by three radiologists and compared using a logistic regression model. Image noise of the two protocols was compared with Wilcoxon signed-rank test.Results
The mean dose-length product at 80 kVp and at 135 kVp were 14.7 ± 1.8 (SD) mGy.cm and 15.6 ± 1.9 (SD) mGy.cm, respectively (P < 0.001). Image noise was significantly lower at 135 kVp (58.9 ± 12.4) than at 80 kVp (74.7 ± 14.5) (P < 0.001). For all readers and for all examinations, the 135 kVp protocol yielded better image quality than 80 kVp protocol, with a mean qualitative score of 4.5 ± 0.7 versus 3.9 ± 0.8 (P < 0.001). The 135 kVp protocol was significantly more often of diagnostic quality than the 80 kvp protocol (92.3% versus 77.8%, respectively) (P < 0.001) and was less prone to image quality deterioration in obese patients. Parenchymal lesions were never better depicted on the 80 kVp protocol than with the 135 kVp protocol.Conclusion
Unenhanced chest ULD-CT should be acquired at a high kilovoltage and low current, such as 135 kVp-10 mA, over a low kilovoltage and high current protocol. 相似文献23.
24.
25.
26.
27.
Iman M.N. Hamdan Ismaiel A. Tekko Kyle B. Matchett Luis G. Arnaut Claudia S. Silva Helen O. McCarthy Ryan F. Donnelly 《Journal of pharmaceutical sciences》2018,107(9):2439-2450
Nodular basal cell carcinoma is a deep skin lesion and one of the most common cancers. Conventional photodynamic therapy is limited to treatment of superficial skin lesions. The parenteral administration of near-IR preformed photosensitizers suffers from poor selectivity and may result in prolonged skin photosensitivity. Microneedles (MNs) can provide localized drug delivery to skin lesions. Intradermal delivery of the preformed near-IR photosensitizer; 5,10,15,20-tetrakis(2,6-difluoro-3-N-methylsulfamoylphenyl bacteriochlorin (Redaporfin?) using dissolving MN was successful in vitro and in vivo. MN demonstrated complete dissolution 30 min after skin application and showed sufficient mechanical strength to penetrate the skin to a depth of 450 μm. In vitro deposition studies illustrated that the drug was delivered and detected down to 5 mm in skin. In vivo biodistribution studies in athymic nude mice Crl:NU(NCr)-Foxn1nu showed both fast initial release and localized drug delivery. The MN-treated mice showed a progressive decrease in the fluorescence intensity at the application site over the 7-day experiment period, with the highest and lowest fluorescence intensities measured being 9.2 × 1010 ± 2.5 × 1010 and 3.8 × 109 ± 1.6 × 109 p/s, respectively. By day 7, there was some migration of fluorescence away from the site of initial MN application. However, the majority of the body surfaces showed fluorescence levels that were comparable to those seen in the negative control group. This work suggests utility for polymeric MN arrays in minimally invasive intradermal delivery to enhance photodynamic therapy of deep skin lesions. 相似文献
28.
29.
Birke J. Benedikter Emiel F. M. Wouters Paul H. M. Savelkoul Gernot G. U. Rohde 《Journal of toxicology and environmental health. Part B, Critical reviews》2018,21(3):142-160
Extracellular vesicles (EV) are secreted signaling entities that enhance various pathological processes when released in response to cellular stresses. Respiratory exposures such as cigarette smoke and air pollution exert cellular stresses and are associated with an increased risk of several chronic diseases. The aim of this review was to examine the evidence that modifications in EV contribute to respiratory exposure-associated diseases. Publications were searched using PubMed and Google Scholar with the search terms (cigarette smoke OR tobacco smoke OR air pollution OR particulate matter) AND (extracellular vesicles OR exosomes OR microvesicles OR microparticles OR ectosomes). All original research articles were included and reviewed. Fifty articles were identified, most of which investigated the effect of respiratory exposures on EV release in vitro (25) and/or on circulating EV in human plasma (24). The majority of studies based their main observations on the relatively insensitive scatter-based flow cytometry of EV (29). EV induced by respiratory exposures were found to modulate inflammation (19), thrombosis (13), endothelial dysfunction (11), tissue remodeling (6), and angiogenesis (3). By influencing these processes, EV may play a key role in the development of cardiovascular diseases and chronic obstructive pulmonary disease and possibly lung cancer and allergic asthma. The current findings warrant additional research with improved methodologies to evaluate the contribution of respiratory exposure-induced EV to disease etiology, as well as their potential as biomarkers of exposure or risk and as novel targets for preventive or therapeutic strategies. 相似文献
30.
Aisha F. Badr Sawsan Kurdi Samah Alshehri Claire McManus Jeannie Lee 《Saudi Pharmaceutical Journal》2018,26(8):1204-1207