全文获取类型
收费全文 | 1360篇 |
免费 | 40篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 26篇 |
儿科学 | 57篇 |
妇产科学 | 47篇 |
基础医学 | 178篇 |
口腔科学 | 44篇 |
临床医学 | 95篇 |
内科学 | 218篇 |
皮肤病学 | 10篇 |
神经病学 | 166篇 |
特种医学 | 49篇 |
外科学 | 178篇 |
综合类 | 7篇 |
预防医学 | 88篇 |
眼科学 | 31篇 |
药学 | 121篇 |
肿瘤学 | 88篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 10篇 |
2020年 | 8篇 |
2019年 | 25篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 19篇 |
2015年 | 18篇 |
2014年 | 30篇 |
2013年 | 70篇 |
2012年 | 74篇 |
2011年 | 82篇 |
2010年 | 50篇 |
2009年 | 41篇 |
2008年 | 82篇 |
2007年 | 86篇 |
2006年 | 100篇 |
2005年 | 94篇 |
2004年 | 112篇 |
2003年 | 87篇 |
2002年 | 105篇 |
2001年 | 20篇 |
2000年 | 8篇 |
1999年 | 15篇 |
1998年 | 23篇 |
1997年 | 18篇 |
1996年 | 10篇 |
1995年 | 19篇 |
1994年 | 11篇 |
1993年 | 14篇 |
1992年 | 8篇 |
1991年 | 16篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 7篇 |
1963年 | 3篇 |
排序方式: 共有1403条查询结果,搜索用时 0 毫秒
31.
Mikko Jormalainen Risto Kesvuori Peter Raivio Antti Vento Caius Mustonen Hannu-Pekka Honkanen Stefano Rosato Jarmo Simpanen Kari Teittinen Fausto Biancari Tatu Juvonen 《Interactive Cardiovascular and Thoracic Surgery》2022,34(3):453
Open in a separate windowOBJECTIVESWe investigated whether the selective use of supracoronary ascending aorta replacement achieves late outcomes comparable to those of aortic root replacement for acute Stanford type A aortic dissection (TAAD).METHODSPatients who underwent surgery for acute type A aortic dissection from 2005 to 2018 at the Helsinki University Hospital, Finland, were included in this analysis. Late mortality was evaluated with the Kaplan–Meier method and proximal aortic reoperation, i.e. operation on the aortic root or aortic valve, with the competing risk method.RESULTSOut of 309 patients, 216 underwent supracoronary ascending aortic replacement and 93 had aortic root replacement. At 10 years, mortality was 33.8% after aortic root replacement and 35.2% after ascending aortic replacement (P = 0.806, adjusted hazard ratio 1.25, 95% confidence interval, 0.77–2.02), and the cumulative incidence of proximal aortic reoperation was 6.0% in the aortic root replacement group and 6.2% in the ascending aortic replacement group (P = 0.65; adjusted subdistributional hazard ratio 0.53, 95% confidence interval 0.15–1.89). Among 71 propensity score matched pairs, 10-year survival was 34.4% after aortic root replacement and 36.2% after ascending aortic replacement surgery (P = 0.70). Cumulative incidence of proximal aortic reoperation was 7.0% after aortic root replacement and 13.0% after ascending aortic replacement surgery (P = 0.22). Among 102 patients with complete imaging data [mean follow-up, 4.7 (3.2) years], the estimated growth rate of the aortic root diameter was 0.22 mm/year, that of its area 7.19 mm2/year and that of its perimeter 0.43 mm/year.CONCLUSIONSWhen stringent selection criteria were used to determine the extent of proximal aortic reconstruction, aortic root replacement and ascending aortic replacement for type A aortic dissection achieved comparable clinical outcomes. 相似文献
32.
Grönroos JM Gullichsen R Karvonen J Salminen P 《Surgical laparoscopy, endoscopy & percutaneous techniques》2011,21(3):e107-e109
Even in experienced hands, a common problem at endoscopic retrograde cholangiopancreatography (ERCP) is difficulty in reaching a selective cannulation of the common bile duct or pancreatic duct. The success rate of biliary cannulation has improved markedly in many centers after the adoption of double-guidewire-assisted cannulation technique in cases in which the guidewire repeatedly passes into the pancreatic duct although the common bile duct is intended. Here, we describe 2 novel applications of the double-guidewire technique for difficult cannulation in ERCP. In particular, we emphasize that in addition to difficult biliary cannulation, double-guidewire technique may prove useful in difficult pancreatic cannulation. The double-guidewire technique is feasible also in cases in which the guidewire repeatedly passes into the cystic duct instead of the intended common hepatic duct and intrahepatic radicals. ERCP endoscopists should be aware of all modifications of double-guidewire technique to further increase the success rates of selective cannulations in ERCP. 相似文献
33.
Maarit Jaana Korhonen Pekka Tiittanen Helena Kastarinen Arja Helin‐Salmivaara Milka Hauta‐aho Maria Rikala Risto Huupponen 《Basic & clinical pharmacology & toxicology》2018,123(2):195-201
Clinical significance of potential interaction between warfarin and statins is unclear. Our objective was to determine whether use of statins as a class or use of simvastatin modulates the rate of bleeding requiring hospitalization among new warfarin users. Using Finnish healthcare databases, we identified a cohort of 101,588 warfarin initiators between 1 January 2009 and 30 June 2012. By the end of 2012, these patients accumulated 92,695 person‐years of exposure to warfarin‐only and 60,253 years of exposure to warfarin‐with‐statin. The outcome was a composite of gastrointestinal, intracranial or other bleeding leading to hospitalization. A Poisson generalized estimating equation model was employed to estimate rate ratios (RR) and their 95% confidence intervals (CI) for exposure to warfarin‐with‐statin compared to warfarin‐only and to allow multiple episodes per patient and time‐dependent covariates. In multivariable models, we found no difference in the bleeding rate in association with exposure to any statin (multivariable‐adjusted RR = 0.98, 95% CI 0.89–1.07) or to simvastatin (RR = 1.01, 95% CI 0.91–1.11) with warfarin compared to exposure to warfarin‐only. We conclude that concomitant use of statins and warfarin was not associated with an increased rate of bleeding requiring hospitalization. 相似文献
34.
35.
Timing of different virus neutralizing 19S and 7S antibodies in natural Coxsackie infections of newborn babies and adults 总被引:1,自引:0,他引:1 下载免费PDF全文
Neutralizing Coxsackie antibodies arising from natural infections with Coxsackie virus type B3 or B5 were studied in adults and newborn babies. No differences could be found between the antibody response of the newborn babies and that of the adults.
The antibody titres rose approximately as rapidly in the babies as in the adult patients, and the means of the peak titres did not differ significantly in the two groups. Early in the infection the neutralizing antibodies of both newborn babies and adults were exclusively IgM. There was a gradual shift to IgG in the course of 3 months, and this shift was as rapid in babies as in adults.
相似文献36.
Nikulin VV Kicić D Kähkönen S Ilmoniemi RJ 《The European journal of neuroscience》2003,18(5):1206-1212
Transcranial magnetic stimulation (TMS) and multichannel electroencephalography (EEG) were used for the investigation of cortical excitability preceding voluntary movement in human subjects. The study showed the practical value of the combined TMS-EEG approach in differentiating between cortical and spinal-cord mechanisms, which is difficult with conventional electromyographic measures alone. TMS induced a pronounced negativity (N100) lasting for 150-200 ms, with the amplitude maximum in the stimulated hemisphere. When TMS was applied just before the onset of the visually triggered movement, N100 was markedly attenuated, although motor evoked potentials (MEPs) became larger. We suggest that the N100 component represents an inhibitory response following TMS. This interpretation is in agreement with intracellular recordings in animals, paired-pulse TMS studies and experiments showing increased premovement excitability on the basis of MEPs. N100 was not affected only by the subsequent movement, but also by the switching from rest to the motor-task condition, which caused a slight attenuation of the N100 component; no changes, however, were found in the amplitude of MEPs, suggesting that modified excitability did not affect the output of the corticospinal pyramidal cells. By contrast to MEPs, N100 was modulated also by the presentation of the visual stimulus alone, i.e. when no movement was required. This attenuation suggests that even in a rest condition visual stimuli have an access to the sensorimotor regions of the cortex, most probably through ascending arousal brain systems. 相似文献
37.
Cerebral White Matter Maturation Patterns in Preterm Infants: An MRI T2 Relaxation Anisotropy and Diffusion Tensor Imaging Study 下载免费PDF全文
Michael J. Knight Adam Smith‐Collins Sarah Newell Mark Denbow Risto A. Kauppinen 《Journal of neuroimaging》2018,28(1):86-94
BACKGROUND AND PURPOSE
Preterm birth is associated with worse neurodevelopmental outcome, but brain maturation in preterm infants is poorly characterized with standard methods. We evaluated white matter (WM) of infant brains at term‐equivalent age, as a function of gestational age at birth, using multimodal magnetic resonance imaging (MRI).METHODS
Infants born very preterm (<32 weeks gestation) and late preterm (33‐36 weeks gestation) were scanned at 3 T at term‐equivalent age using diffusion tensor imaging (DTI) and T2 relaxometry. MRI data were analyzed using tract‐based spatial statistics, and anisotropy of T2 relaxation was also determined. Principal component analysis and linear discriminant analysis were applied to seek the variables best distinguishing very preterm and late preterm groups.RESULTS
Across widespread regions of WM, T2 is longer in very preterm infants than in late preterm ones. These effects are more prevalent in regions of WM that myelinate earlier and faster. Similar effects are obtained from DTI, showing that fractional anisotropy (FA) is lower and radial diffusivity higher in the very preterm group, with a bias toward earlier myelinating regions. Discriminant analysis shows high sensitivity and specificity of combined T2 relaxometry and DTI for the detection of a distinct WM development pathway in very preterm infants. T2 relaxation is anisotropic, depending on the angle between WM fiber and magnetic field, and this effect is modulated by FA.CONCLUSIONS
Combined T2 relaxometry and DTI characterizes specific patterns of retarded WM maturation, at term equivalent age, in infants born very preterm relative to late preterm. 相似文献38.
Factors related to postmenopausal muscle performance: a cross-sectional population-based study 总被引:2,自引:0,他引:2
Sirola J Rikkonen T Kröger H Honkanen R Tuppurainen M Airaksinen O Saarikoski S 《European journal of applied physiology》2004,93(1-2):102-107
The aim of the present study was to investigate cross-sectionally the association of postmenopausal muscle strength with simple performance tests. A random sample of 1,166 naturally postmenopausal women (born 1932–1941) was selected from the Kuopio Osteoporosis Risk Factor and Prevention (OSTPRE) study cohort. Grip and quadriceps strength were measured with strain gauge dynamometers and reported in both absolute values (KPa and kg) and per kilogram of body mass (N cm–2 kg–1 and N kg–1). In addition, two performance tests, ability to stand on one foot and ability to squat down to touch the floor were carried out. A five-category self-assessment of overall health (very good, good, moderate, bad, and very bad) was obtained by postal questionnaire. The women that were able to stand on one foot and able to squat down to touch the floor had greater grip and quadriceps strength than their counterparts (P<0.001 and P<0.03 in ANOVA, respectively). In addition, self-assessed health had a strong positive association with muscle strength in the grip and leg extensor muscles in ANOVA (P<0.001 between very good and moderate or poorer state of health) and regression model (P<0.001). Adjustment for age, duration of menopause, body mass, height, physical activity level, use of HRT, and number of diseases and medications did not change any of the main effects. Also, there were no differences in results between absolute measurement values and values reported per kilogram of body mass. According to the present study, a simple performance test may be useful in the prediction of postmenopausal muscle strength. Furthermore, self-assessed state of health is strongly associated with muscle strength in postmenopausal women. 相似文献
39.
Kunnas TA Lehtimäki T Laaksonen R Ilveskoski E Janatuinen T Vesalainen R Nuutila P Karhunen PJ Knuuti J Nikkari ST 《Journal of molecular medicine (Berlin, Germany)》2002,80(12):802-807
The objective was to study whether coronary blood flow or its response to pravastatin are affected by genetic variation in the endothelial nitric oxide synthase (eNOS) gene. Vascular endothelial nitric oxide maintains endothelium-dependent vasodilatation and also mediates antithrombotic actions. Its formation is catalyzed by eNOS, a constitutive enzyme, which has a polymorphic site in intron 4 (4a/b). Some clinical studies have suggested an association of the rare a-allele of eNOS with coronary artery disease and myocardial infarction. We carried out a double-blind placebo-controlled study involving 43 men (aged 35+/-4 years), who were randomized to receive either 40 mg/day pravastatin ( n=21) or placebo ( n=22) for 6 months. Myocardial blood flow was measured by positron emission tomography (PET) using (15)O-labeled water. PET was performed at rest and after stimulation by adenosine infusion. PET and lipid analyses were carried out at baseline and after 6 months. eNOS genotyping was done by PCR. At baseline there were no differences in basal or adenosine-stimulated coronary blood flow between subjects with either eNOS bb or ba genotypes. At the end of the study genotypes reacted differently between pravastatin and placebo groups with respect to the change in adenosine-stimulated flow (ANCOVA P=0.008). More specifically, after pravastatin treatment the adenosine-stimulated flow increased by 54.5% in men with the eNOS ba genotype, whereas in the men with the bb genotype no significant change in flow was observed ( P=0.002 for ba versus bb). In the placebo group there were no significant changes in blood flow from the baseline values ( P=0.916 for ba versus bb). After pravastatin treatment both genotype groups showed a similar decrease in serum total cholesterol and low-density lipoprotein cholesterol ( P<0.00001 for both). Our results suggest that adenosine-stimulated myocardial perfusion improves after treatment with pravastatin in subjects with the eNOS ba genotype but not in those with the bb genotype. This effect is not dependent on the decrease of serum cholesterol. 相似文献
40.