全文获取类型
收费全文 | 56824篇 |
免费 | 5040篇 |
国内免费 | 1516篇 |
专业分类
耳鼻咽喉 | 423篇 |
儿科学 | 894篇 |
妇产科学 | 398篇 |
基础医学 | 3423篇 |
口腔科学 | 722篇 |
临床医学 | 10175篇 |
内科学 | 5744篇 |
皮肤病学 | 145篇 |
神经病学 | 8933篇 |
特种医学 | 16785篇 |
外国民族医学 | 12篇 |
外科学 | 4152篇 |
综合类 | 5624篇 |
现状与发展 | 1篇 |
一般理论 | 1篇 |
预防医学 | 1010篇 |
眼科学 | 450篇 |
药学 | 2009篇 |
15篇 | |
中国医学 | 433篇 |
肿瘤学 | 2031篇 |
出版年
2024年 | 132篇 |
2023年 | 819篇 |
2022年 | 1706篇 |
2021年 | 2634篇 |
2020年 | 2330篇 |
2019年 | 2123篇 |
2018年 | 2058篇 |
2017年 | 2259篇 |
2016年 | 2344篇 |
2015年 | 2208篇 |
2014年 | 3953篇 |
2013年 | 3482篇 |
2012年 | 3338篇 |
2011年 | 3708篇 |
2010年 | 3184篇 |
2009年 | 3235篇 |
2008年 | 3173篇 |
2007年 | 2968篇 |
2006年 | 2726篇 |
2005年 | 2501篇 |
2004年 | 1992篇 |
2003年 | 1589篇 |
2002年 | 1236篇 |
2001年 | 1152篇 |
2000年 | 946篇 |
1999年 | 774篇 |
1998年 | 739篇 |
1997年 | 690篇 |
1996年 | 673篇 |
1995年 | 552篇 |
1994年 | 472篇 |
1993年 | 377篇 |
1992年 | 309篇 |
1991年 | 235篇 |
1990年 | 169篇 |
1989年 | 136篇 |
1988年 | 114篇 |
1987年 | 84篇 |
1986年 | 60篇 |
1985年 | 56篇 |
1984年 | 32篇 |
1983年 | 26篇 |
1982年 | 25篇 |
1981年 | 14篇 |
1980年 | 15篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1971年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
《Modern rheumatology / the Japan Rheumatism Association》2013,23(3):273-282
AbstractA rare case of an inflammatory pseudotumor (IPT) of the liver with reactive arthritis (ReA) is herein described. A 34-year-old woman presented with post-infectious ReA in the bilateral knees and foot joints. As the primary infected site for ReA could not be determined, a systemic survey revealed an IPT in her liver, which was diagnosed histologically. The arthritis and the tumor regressed simultaneously after being treated by indomethacin farnesil 400 mg/day. Although the exact etiology of IPT or ReA still remains unknown, it is hypothesized that the same pathogenetic mechanisms may be involved in the development of IPT and ReA. 相似文献
992.
《International journal of hyperthermia》2013,29(8):801-809
AbstractWe review the most recent and significant results published in the field of magnetotactic bacteria (MTB), in particular data relating to the use of bacterial magnetosomes in magnetic hyperthermia for the treatment of tumours. We review different methods for cultivating MTB and preparing suspensions of bacterial magnetosomes. As well as the production of magnetosomes, we also review key data on the toxicity of the magnetosomes as well as their heating and anti-tumour efficiencies. The toxicity and efficiency of magnetosomes needs to be understood and the risk–benefit ratio with which to evaluate their use in the magnetic hyperthermia treatment of tumours needs to be measured. 相似文献
993.
994.
Magnetic resonance (MR) arthrography is currently the gold standard radiological investigation for shoulder joint instability. Not only does this investigation allow for identification of important disease processes, but the reduced slice thickness and increased in‐plane resolution allowed by the latest imaging sequences also gives excellent demonstration of shoulder joint internal anatomy. This article describes the technique of MR arthrography of the shoulder practiced at our institution, briefly outlining features of the FIESTA (fast imaging employing steady state acquisition) MR sequence employed, including its advantages and limitations. A pictorial review of shoulder MR arthrography performed with this technique is presented, concentrating on normal shoulder joint internal anatomy and anatomical variants that may mimic pathology. Clin. Anat., 2013. © 2012 Wiley Periodicals, Inc. 相似文献
995.
H. De Praetere J. Vandesande F. Rega W. Daenen G. Marc B. Eyskens 《Acta chirurgica Belgica》2013,113(2):92-98
Background : Arterial switch operation became the golden treatment for simple transposition of the great arteries (sTGA). We describe our experience with the arterial switch operation regarding long-term outcome and the need for re-intervention. Nevertheless, supravalvular pulmonary stenosis (SPS) remains a concern in the long run. We assess the evolution of SPS over time and evaluate the effect of technical modifications on SPS during our experience. Methods : We performed a retrospective study on 133 patients operated with ASO for TGA between October 1991 and November 2009. Last report method was used. We reviewed our pediatric cardiology and cardiac surgery database to examine the echocardiography data and electrocardiograms. A mean follow-up of 9.2 years (± 5.83 SD) was reached. Results : One (0.8%) patient deceased postoperatively due to cardiogenic shock. The overall actuarial freedom from reoperation (open and percutaneous) was 88.1%, 78.5% and 76.9% at 1, 5 and 10 years. SPS needed to be treated in 17 patients. Valve regurgitation at final investigation was maximal moderate in 5 patients for the aortic valve, 10 for pulmonary valve and 3 in tricuspid valve.Conclusions : ASO shows excellent long-term results in sTGA with a very low morbidity and mortality and is therefore the procedure of choice. Re-intervention rate is determined by SPS. Since the extensive mobilization of the pulmonary arteries and the creation of a longer neo-pulmonary root, reduction in SPS was seen with no re-interventions in the second half of the group. To obtain a final comparison with the atrial switch operation, a longer Follow-up is necessary. 相似文献
996.
Accelerated ferumoxytol‐enhanced 4D multiphase,steady‐state imaging with contrast enhancement (MUSIC) cardiovascular MRI: validation in pediatric congenital heart disease
下载免费PDF全文
![点击此处可从《NMR in biomedicine》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ziwu Zhou Fei Han Stanislas Rapacchi Kim‐Lien Nguyen Daniel Z. Brunengraber Grace‐Hyun J. Kim J. Paul Finn Peng Hu 《NMR in biomedicine》2017,30(1)
The purpose of this work was to validate a parallel imaging (PI) and compressed sensing (CS) combined reconstruction method for a recently proposed 4D non‐breath‐held, multiphase, steady‐state imaging technique (MUSIC) cardiovascular MRI in a cohort of pediatric congenital heart disease patients. We implemented a graphics processing unit accelerated CS‐PI combined reconstruction method and applied it in 13 pediatric patients who underwent cardiovascular MRI after ferumoxytol administration. Conventional breath‐held contrast‐enhanced magnetic resonance angiography (CE‐MRA) was first performed during the first pass of ferumoxytol injection, followed by the original MUSIC and the proposed CS‐PI MUSIC during the steady‐state distribution phase of ferumoxytol. Qualities of acquired images were then evaluated using a four‐point scale. Left ventricular volumes and ejection fractions calculated from the original MUSIC and the CS‐PI MUSIC were also compared with conventional multi‐slice 2D cardiac cine MRI. The proposed CS‐PI MUSIC reduced the imaging time of the MUSIC acquisition to 4.6 ± 0.4 min from 8.9 ± 1.2 min. Computationally intensive image reconstruction was completed within 5 min without interruption of sequential clinical scans. The proposed method (mean 3.3–4.0) provided image quality comparable to that of the original MUSIC (3.2–4.0) (all P ≥ 0.42), and better than conventional breath‐held first‐pass CE‐MRA (1.1–3.3) for 13 anatomical structures (all P ≤ 0.0014) with good inter‐observer agreement (κ > 0.46). The calculated ventricular volumes and ejection fractions from both original MUSIC (r > 0.90) and CS‐PI MUSIC (r > 0.85) correlated well with 2D cine imaging. In conclusion, PI and CS were successfully incorporated into the 4D MUSIC acquisition to further reduce scan time by approximately 50% while maintaining highly comparable image quality in a clinically practical reconstruction time. 相似文献
997.
Asif Padiyath M.D. Paul Gribben B.S. Joseph R. Abraham B.S. Ling Li M.D. Ph.D. Sheela Rangamani M.D. Andreas Schuster M.D. David A. Danford M.D. Gianni Pedrizzetti Ph.D. Shelby Kutty M.D. 《Echocardiography (Mount Kisco, N.Y.)》2013,30(2):203-210
We investigated intermodality agreements of strains from two‐dimensional echocardiography (2DE) and cardiac magnetic resonance (CMR) feature tracking (FT) in the assessment of right (RV) and left ventricular (LV) mechanics in tetralogy of Fallot (TOF). Patients were prospectively studied with 2DE and CMR performed contiguously. LV and RV strains were computed separately using 2DE and CMR‐FT. Segmental and global longitudinal strains (GLS) for the LV and RV were measured from four‐chamber views; LV radial (global radial strain [GRS]) and circumferential strains (GCS) measured from short‐axis views. Intermodality and interobserver agreements were examined. In 40 patients (20 TOF, mean age 23 years and 20 adult controls), LV, GCS showed narrowest intermodality limits of agreement (mean percentage error 9.5%), followed by GLS (16.4%). RV GLS had mean intermodality difference of 25.7%. GLS and GCS had acceptable interobserver agreement for the LV and RV with both 2DE and CMR‐FT, whereas GRS had high interobserver and intermodality variability. In conclusion, myocardial strains for the RV and LV derived using currently available 2DE and CMR‐FT software are subject to considerable intermodality variability. For both modalities, LV GCS, LV GLS, and RV GLS are reproducible enough to warrant further investigation of incremental clinical merit. 相似文献
998.
《Scandinavian cardiovascular journal : SCJ》2013,47(5):241-248
AbstractAims. The relationship between the heart rate of ventricular tachycardia (VT) and the transmurality of ischemic scars was assessed by a new semiautomatic coordinate-based analysis of late gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) images. Methods and results. Twenty patients assessed by LGE-CMR before implantation of implantable cardioverter defibrillator (ICD) with verified VT during the first year following ICD implantation were included. Scar was defined by pixels with a signal intensity ≥ 50% of maximum signal intensity. All pixels were assigned a coordinate position between endo- and epicardium (λ) and the angle of the heart axis (φ). Based upon the λ and φ values, multiple scar features were computed for all scarred areas. These features were correlated to VT heart rate across the complete range of transmurality. The strongest correlation with univariate regression was found between VT heart rate and the sum of transmurality when the maximum transmurality of these features was ≥ 90% (R-square = 0.47). In multiple regressions analysis, the strongest relationship with VT heart rate was found with a maximum transmurality ≥ 90% and by a combination of scar size, transmurality, and endocardial extent of infarction (R-square = 0.64). Conclusion. Transmurality is the strongest predictor of VT heart rate both in univariate and multivariate models. The strongest relationships were found at a transmurality level > 90%. 相似文献
999.
《Radiography》2017,23(1):e8-e13
The purpose of the study was to survey MRI qualification and certification frameworks in the major English-speaking countries (Australia, New Zealand, US, Canada, UK, Ireland) with the aim of identifying elements of good practice. The intention is to incorporate these elements in a national framework that could be used in supporting an MRI specialist register. The study was conducted using document analysis of MRI qualification and certification documents from these states with data triangulated through a web-based questionnaire amongst an expert group of MRI radiographers (n = 59) from the same states. Based on the results of the study, recommendations have been put forward for those countries that are in the process of developing such frameworks. The main recommendations include that a professional or regulatory body externally accredits MRI programmes and that learning outcomes be based on an MRI competence profile that addresses current and forecasted needs of the particular country. The MRI competence profile should encompass a novice-to expert continuum and be referenced directly to a national qualification framework. Ideally each level of expertise should be assessed and evidenced by a portfolio of CPD activities, including clinical and management case studies appropriate to that level. 相似文献
1000.
Ping Liu Xi-Ze Jia Yi Chen Yang Yu Kan Zhang Ya-Jie Lin Bao-Hong Wang Guo-Ping Peng 《CNS Neuroscience & Therapeutics》2021,27(2):163-173
AimsTo explore the potential relationships among gut microbiota (GM), local brain spontaneous activity, and neuropsychological characteristics in amnestic mild cognitive impairment (aMCI) patients.MethodsTwenty aMCI and 22 healthy control (HC) subjects were recruited. The GM composition was determined by 16S ribosomal RNA gene sequencing. Resting‐state functional magnetic resonance imaging scans were performed, and fractional amplitude of low‐frequency fluctuations (fALFF) was calculated across different frequencies. The Spearman or Pearson correlation analysis was used to analyze the relationship between spontaneous brain activity and cognitive function, and GM composition.ResultsaMCI patients had altered GM state and local spontaneous brain activity as compared with HC subjects. Correlation analysis showed that aMCI and HC groups had different “GM‐intrinsic brain activity interaction” patterns. In aMCI group, at the typical band (0.01‐0.08 Hz), the relative abundance (RA) of Bacteroides from phylum to genus level was negatively correlated with fALFF value of cerebellar vermis IV‐V, and the Ruminococcaceae RA was negatively correlated with fALFF values of left lenticular nucleus and pallidum. The Clostridiaceae RA and Blautia RA were positively correlated with the left cerebellum lobules IV‐V at the slow‐4 band (0.027‐0.073 Hz). The Veillonellaceae RA was positively correlated with fALFF values of left precentral gyrus at the slow‐5 band (0.073‐0.08 Hz). Correlation analysis showed that Clostridium members (Lachnospiraceae and Blautia) were positively, while Veillonellaceae was negatively, correlated with cognition test. Bacteroides was positively correlated with attention and computation, and negatively correlated with the three‐stage command score.ConclusionsaMCI patients have a specific GM‐intrinsic brain activity‐cognitive function interaction pattern. 相似文献