全文获取类型
收费全文 | 2886篇 |
免费 | 374篇 |
国内免费 | 50篇 |
专业分类
耳鼻咽喉 | 21篇 |
儿科学 | 142篇 |
妇产科学 | 32篇 |
基础医学 | 298篇 |
口腔科学 | 49篇 |
临床医学 | 475篇 |
内科学 | 808篇 |
皮肤病学 | 98篇 |
神经病学 | 279篇 |
特种医学 | 311篇 |
外科学 | 357篇 |
综合类 | 51篇 |
一般理论 | 2篇 |
预防医学 | 126篇 |
眼科学 | 25篇 |
药学 | 129篇 |
中国医学 | 5篇 |
肿瘤学 | 102篇 |
出版年
2023年 | 56篇 |
2022年 | 17篇 |
2021年 | 34篇 |
2020年 | 102篇 |
2019年 | 26篇 |
2018年 | 108篇 |
2017年 | 79篇 |
2016年 | 83篇 |
2015年 | 70篇 |
2014年 | 115篇 |
2013年 | 134篇 |
2012年 | 91篇 |
2011年 | 101篇 |
2010年 | 110篇 |
2009年 | 132篇 |
2008年 | 95篇 |
2007年 | 102篇 |
2006年 | 99篇 |
2005年 | 78篇 |
2004年 | 57篇 |
2003年 | 51篇 |
2002年 | 85篇 |
2001年 | 81篇 |
2000年 | 89篇 |
1999年 | 68篇 |
1998年 | 98篇 |
1997年 | 112篇 |
1996年 | 93篇 |
1995年 | 86篇 |
1994年 | 68篇 |
1993年 | 67篇 |
1992年 | 61篇 |
1991年 | 46篇 |
1990年 | 47篇 |
1989年 | 74篇 |
1988年 | 63篇 |
1987年 | 41篇 |
1986年 | 38篇 |
1985年 | 40篇 |
1984年 | 27篇 |
1983年 | 26篇 |
1982年 | 21篇 |
1981年 | 19篇 |
1980年 | 19篇 |
1979年 | 25篇 |
1978年 | 19篇 |
1977年 | 17篇 |
1976年 | 19篇 |
1975年 | 14篇 |
1971年 | 12篇 |
排序方式: 共有3310条查询结果,搜索用时 15 毫秒
81.
Narrow QRS tachycardia with apparent concentric atrial activation pattern: What is the mechanism?
下载免费PDF全文
![点击此处可从《Pacing and clinical electrophysiology : PACE》网站下载免费的PDF全文](/ch/ext_images/free.gif)
82.
83.
Monique Lhussier HND MSc PhD Simon Eaton BMedSci BMBS FRCP DM CertMEd Natalie Forster BA PGCert Mathew Thomas BA Sue Roberts MBBS MSc FRCP Susan M Carr BA MSc PhD 《Health expectations》2015,18(5):605-624
Objective
This article focuses on approaches within clinical practice that seek to actively involve patients with long‐term conditions (LTCs) and how professionals may understand and implement them. Personalized care planning is one such approach, but its current lack of conceptual clarity might have impeded its widespread implementation to date. A variety of overlapping concepts coexist in the literature, which have the potential to impair both clinical and research agendas. The aim of this article is therefore to explore the meaning of the concept of care planning in relation to other overlapping concepts and how this translates into clinical practice implementation.Methods
Searches were conducted in the Cochrane database for systematic reviews, CINHAL and MEDLINE. A staged approach to conducting the concept mapping was undertaken, by (i) an examination of the literature on care planning in LTCs; (ii) identification of related terms; (iii) locating reviews of those terms. Retrieved articles were subjected to a content analysis, which formed the basis of our concept maps. (iv) We then appraised these against knowledge and experience of the implementation of care planning in clinical practice.Results and Conclusions
Thirteen articles were retrieved, in which the core importance of patient‐centredness, shared decision making and self‐management was highlighted. Literature searches on these terms retrieved a further 24 articles. Our concept mapping exercise shows that whilst there are common themes across the concepts, the differences between them reflect the context and intended outcomes within clinical practice. We argue that this clarification exercise will allow for further development of both research and clinical implementation agendas. 相似文献84.
85.
Identification of an oncogenic form of the thrombopoietin receptor MPL using retrovirus-mediated gene transfer 总被引:3,自引:3,他引:3
Onishi M; Mui AL; Morikawa Y; Cho L; Kinoshita S; Nolan GP; Gorman DM; Miyajima A; Kitamura T 《Blood》1996,88(4):1399-1406
Thrombopoietin and its receptor (MPL) are important regulators of megakaryopoiesis. We have identified an activating mutation of MPL using a combination of a retrovirus-mediated gene transfer and polymerase chain reaction-driven random mutagenesis. This point mutation causes a single amino acid substitution from Ser498 to Asn498 in the transmembrane region and abrogates factor-dependency of all interleukin-3-dependent cell lines tested. Murine interleukin-3- dependent Ba/F3 cells expressing the mutated but not the normal form of MPL were tumorigenic when transduced into syngeneic mice. Analysis of intracellular signaling pathways indicated that the mutant MPL protein constitutively activated two distinct signaling pathways, SHC-Raf-MAPK and JAK2-STAT3/STAT5. 相似文献
86.
Role of copper in mitochondrial iron metabolism 总被引:1,自引:1,他引:1
Heme synthesis by copper-deficient cells was investigated to elucidate the nature of the defect in intracellular iron metabolism. Iron uptake from transferrin by copper-deficient reticulocytes was 52% of normal, and the rate of heme synthesis was 33% of normal. Hepatic mitochondria isolated from copper-deficient animals were deficient in cytochrome oxidase activity and failed to synthesize heme from ferric iron (Fe III) and protoporphyrin at the normal rate. The rate of heme synthesis correlated with the cytochrome oxidase activity. Heme synthesis from Fe(III) and protoporphyrin by normal mitochondria was enhanced by succinate and inhibited by malonate, antimycin A, azide, and cyanide. It is proposed that an intact electron transport system is required for the reduction of Fe(III), thereby providing a pool of ferrous iron (Fe II) for protoheme and heme a synthesis. 相似文献
87.
Does continuous positive airway pressure by face mask improve patients with acute cardiogenic pulmonary edema due to left ventricular diastolic dysfunction? 总被引:10,自引:0,他引:10
OBJECTIVE: Continuous positive airway pressure (CPAP) by face mask is an effective method of treating severe cardiogenic pulmonary edema (CPE). However, to our knowledge, no study has provided a precise evaluation of the effects of CPAP on cardiac function in patients presenting with CPE and preserved left ventricular (LV) function. DESIGN: Prospective observational clinical study. SETTING: A 14-bed, medical ICU at a university hospital. PATIENTS: Nine consecutive patients presenting with hypoxemic acute CPE. INTERVENTIONS: All patients were selected for 30 min of CPAP with 10 cm H(2)O by mask with fraction of inspired oxygen adjusted for a cutaneous saturation > 90%. Doppler echocardiography was performed before CPAP application and during the last 10 min of breathing with CPAP. Two-tailed, paired t-tests were used to compare data recorded at baseline (oxygen alone) and after CPAP. MEASUREMENTS AND RESULTS: Four patients presented CPE with preserved left ventricular (LV) function (a preserved LV ejection fraction [LVEF] > 45%, and/or aortic velocity time integral > 17 cm in the absence of aortic stenosis or hypertrophic cardiomyopathy). Oxygenation and ventilatory parameters were improved by CPAP in all patients. Hemodynamic monitoring and Doppler echocardiographic analysis demonstrated that in patients with preserved LV systolic function, mean arterial pressure and LV end-diastolic volume were decreased significantly by CPAP (p < 0.04). In patients with LV systolic dysfunction, CPAP improved LVEF (p < 0.05) and decreased LV end-diastolic volume (p = 0.001) significantly. CONCLUSION: CPAP improves oxygenation and ventilatory parameters in all kinds of CPE. In patients with preserved LV contractility, the hemodynamic benefit of CPAP results from a decrease in LV end-diastolic volume (preload). 相似文献
88.
The molluscicidal activity of crushed seed pods of Swartzia madagascariensis was assessed by laboratory and field trials. Mature dry seed pods were ground and extracted in tap water for 24 h. Water extracts exerted a significant molluscicidal activity against Bulinus globosus up to dilutions of 100 mg of ground pods per litre. The chromatographically isolated saponin (1) responsible for the molluscicidal activity showed a toxicity of LC 100 at 3 mg/l after exposure of B. globosus and Biomphalaria glabrata for 24 h. Saponin (1) could be identified by FAB-MS and 13C-NMR-spectroscopy as oleanolic acid-3-O-beta-D-glucuronopyranosyl (1----3)-alpha-L-rhamnopyranoside. Two field trials with S. madagascariensis pod extracts in ponds (60 and 160 m3) harbouring dense populations of B. globosus compared well with the laboratory findings and showed the efficiency of the molluscicide in a natural habitat. A single application of the plant molluscicide significantly reduced the populations of B. globusus. The toxicity of S. madagascariensis pod extracts to non-target organisms remains an obstacle for its use in certain situations where schistosomiasis control is envisaged and where S. madagascariensis is found. However, S. madagascariensis is a valid candidate molluscicide which may be applied in selected epidemiological settings as part of integrated schistosomiasis control measures. 相似文献
89.
90.
DM Clarkson 《Journal of medical engineering & technology》2013,37(3):125-131
An overview is provided of the scope and application of IEC TR 60825-9 in determination of hazards of non coherent optical radiation sources. Specific areas reviewed in detail include those relating to hazards of ultraviolet radiation, retinal thermal hazard and blue light photochemical hazard. The effect of spectral temperature on relative risk relating to retinal thermal hazard and blue light photochemical hazard are outlined. Assessment of risk factors of these hazards was determined using a range of measurement devices including spectral radiometer, broad band power meter and a locally developed device for determination of pulse profile of pulsed light sources. 相似文献