全文获取类型
收费全文 | 1060篇 |
免费 | 115篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 24篇 |
妇产科学 | 16篇 |
基础医学 | 116篇 |
口腔科学 | 7篇 |
临床医学 | 72篇 |
内科学 | 411篇 |
皮肤病学 | 7篇 |
神经病学 | 33篇 |
特种医学 | 39篇 |
外科学 | 269篇 |
综合类 | 15篇 |
预防医学 | 40篇 |
眼科学 | 11篇 |
药学 | 53篇 |
肿瘤学 | 58篇 |
出版年
2021年 | 13篇 |
2020年 | 8篇 |
2019年 | 10篇 |
2018年 | 23篇 |
2017年 | 16篇 |
2016年 | 18篇 |
2015年 | 16篇 |
2014年 | 19篇 |
2013年 | 35篇 |
2012年 | 52篇 |
2011年 | 52篇 |
2010年 | 36篇 |
2009年 | 23篇 |
2008年 | 52篇 |
2007年 | 43篇 |
2006年 | 42篇 |
2005年 | 36篇 |
2004年 | 42篇 |
2003年 | 51篇 |
2002年 | 53篇 |
2001年 | 59篇 |
2000年 | 41篇 |
1999年 | 35篇 |
1998年 | 17篇 |
1997年 | 8篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 43篇 |
1991年 | 39篇 |
1990年 | 38篇 |
1989年 | 27篇 |
1988年 | 26篇 |
1987年 | 14篇 |
1986年 | 11篇 |
1985年 | 13篇 |
1983年 | 9篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1979年 | 12篇 |
1978年 | 5篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1974年 | 8篇 |
1973年 | 9篇 |
1972年 | 10篇 |
1970年 | 5篇 |
1969年 | 13篇 |
1968年 | 5篇 |
排序方式: 共有1175条查询结果,搜索用时 15 毫秒
1.
Hitoshi Ogino Nongchana Klangsuk Wu Jin Christopher T. Bowles Magdi H. Yacoub 《Artificial organs》1995,19(6):525-534
Abstract: The dependence of transient pressure characteristics of a ventricular assist device (VAD) on the compliance of its housing and cannulas was investigated in a mock circulation. The peak rate of change of pressure ( dP/dt max ) values was greater in the cannulas than other compartments and was associated with valve closure-induced pressure oscillations. When cannula compliance was increased from 0.0057 to 0.0129 cm3 /mm Hg, these values decreased by ˜20%, and outflow cannula pressure oscillation frequency decreased from 17.5 Hz by 35%. This trend was also apparent in the inflow. A VAD housing compliance increase from 0.0162 to 0.0483 cm3 /mm Hg caused a dP/dt max decrease of 30% in both the blood chamber and the outflow cannula. The effect of this change on the inflow was weaker implying that housing absorbs the energy associated with outflow deceleration more effectively than the inflow. These findings suggest that increasing VAD housing and cannulas compliance can improve hydrodynamic performance. 相似文献
2.
Selection for donor-specific cytotoxic T lymphocytes within the allografted human heart. 总被引:3,自引:0,他引:3
Lymphocytes were cultured from cardiac biopsies following heart transplantation using interleukin-2-conditioned medium. Using the technique of limiting dilution analysis the frequency of donor specific cytotoxic T lymphocytes was measured in cells cultured from biopsies and compared with that in peripheral blood lymphocytes taken at the same time as the biopsy. The graft cell population showed a considerably higher frequency of donor-specific CTL when compared with the PBL. CTL frequencies in the graft cells were always higher against the donor than against third-party cells. These data demonstrate that there was either selective sequestration or selective expansion of donor-reactive T cells in the heart following cardiac transplantation. These results emphasize the need to investigate more closely the events occurring in the heart, and may explain the lack of specificity and sensitivity in immune monitoring (IM) or cytoimmune monitoring (CIM) seen in many centers. 相似文献
3.
Hilary Eadon Marlene Rose Richard O'Neill Neil Leaver Magdi Yacoub 《Transplant international》1995,8(1):35-40
Pharmacokinetic profiles were obtained for 16 heart or lung recipients following the administration of identical doses of cyclosporin as oral solution and capsules on consecutive days. A comparison of pharmacokinetic parameters (AUC, Cmax, Cmin and tmax) showed that there were no significant differences between the two formulations except for the tmax, which was significantly longer for the capsules. The mean variation in day-to-day trough levels produced by the two different forms was 25.6%. A retrospective study was carried out of consecutive cyclosporin levels in patients at steady state on oral solution. The mean variation in day-to-day trough levels was 32.3%. This was not significantly different from the variation in consecutive trough levels seen in the oral solution/capsule comparison. This study shows that cyclosporin capsules can be substituted for oral solution without causing acute changes in cyclosporin blood levels, and that the pharmacokinetics of the two formulations are similar.This work was carried out in partial fulfillment of the requirements for the Master of Science Degree in Clinical Pharmacy, University of London 相似文献
4.
5.
RASER: a new ultrafast magnetic resonance imaging method. 总被引:1,自引:0,他引:1
Ryan Chamberlain Jang-Yeon Park Curt Corum Essa Yacoub Kamil Ugurbil Clifford R Jack Michael Garwood 《Magnetic resonance in medicine》2007,58(4):794-799
A new MRI method is described to acquire a T(2)-weighted image from a single slice in a single shot. The technique is based on rapid acquisition by sequential excitation and refocusing (RASER). RASER avoids relaxation-related blurring because the magnetization is sequentially refocused in a manner that effectively creates a series of spin echoes with a constant echo time. RASER uses the quadratic phase produced by a frequency-swept chirp pulse to time-encode one dimension of the image. In another implementation the pulse can be used to excite multiple slices with phase-encoding and frequency-encoding in the other two dimensions. The RASER imaging sequence is presented along with single-shot and multislice images, and is compared to conventional spin-echo and echo-planar imaging sequences. A theoretical and empirical analysis of the spatial resolution is presented, and factors in choosing the spatial resolution for different applications are discussed. RASER produces high-quality single-shot images that are expected to be advantageous for a wide range of applications. 相似文献
6.
Emma J. Birks MRCP Magdi H. Yacoub DSc FRS Ani Anyanwu FRCS Rosemary Radley Smith FRCP Nicholas R. Banner FRCP Asghar Khaghani FRCS 《The Journal of heart and lung transplantation》2004,23(12):3688-1344
BACKGROUND: Transplantation for patients with a high pulmonary vascular resistance (PVR) carries an increased risk of mortality and right heart failure following heart transplantation and continues to be a major problem. We evaluated the use of hearts from patients who underwent heart and lung transplantation for primary pulmonary hypertension (PPH) as part of a domino procedure because these hearts have hypertrophied right ventricles used to increased pulmonary pressures, but could have a compromised left ventricle or irreversible damage of the right ventricle. METHODS: We reviewed 12 patients with PVR >4 Wood units who underwent orthotopic heart transplantation between 1989 and 1998 using hearts from donors with PPH as part of a domino procedure. RESULTS: We studied 10 men and 2 women, mean age 42.9 years. Mean PVR was 5.3 (range, 4-9) Wood units. Mean ischemia time was 85.3 minutes, and mean donor age was 32 years. Actuarial survival was 75% at 1 year and 75% at 5 years. In the early post-operative period, 3 patients had temporary arrhythmias, 2 required permanent pacemaker implantation, 1 had atrial fibrillation, and 1 had ventricular tachycardia that required defibrillator implantation. At a mean follow-up of 7.8 years, 2 patients had developed asymptomatic transplant coronary disease (both at 8.5 years after transplantation), 1 moderate and 1 very mild; the rest had none. Mean left ventricular ejection fraction at latest follow-up was 70.1% (range, 63%-78%). Right ventricular function assessed clinically and by echocardiography was adequate in the short and long term. CONCLUSIONS: Our results suggest that heart and lung recipients with PPH can provide useful donor hearts to patients with increased PVR and that these hearts function well in the intermediate and long term. 相似文献
7.
L Boughamoura F Chaabane S Tilouche I Chabchoub N Kabachi K Tlili M Yacoub A-S Essoussi 《Archives de pédiatrie》2007,14(2):173-176
Canavan disease or N-acetyl aspartic aciduria, is an autosomal recessive leukodystrophy characterized by spongy degeneration of brain. The disease is an inborn error of metabolism caused by aspartoacylase deficiency resulting from accumulation of N-acetyl aspartic acid in the brain. The authors report a case in a 10-month-old boy who presented with developmental delay and megalencephaly noticeable after 4 months of age. Magnetic resonance imaging of the brain showed diffuse white matter degeneration. The diagnosis of Canavan disease was confirmed by nuclear magnetic resonance spectroscopy and gas chromatography-mass spectrometry. 相似文献
8.
E S Akl E Ozdogan S K Ohri M Barbir J A Kiti-CheiGaer A G Mitchell M H Yacoub 《British heart journal》1992,68(2):176-180
OBJECTIVE--To define the incidence, possible causes, operative procedure, and early and medium term results of patients undergoing reoperation for coronary artery disease. DESIGN--A retrospective analysis of patients undergoing reoperation in one hospital during a 10 year period. SETTING--A regional cardiothoracic centre. PATIENTS--115 patients had reoperation for recurrent angina, 1-17 years (mean (SD) 7.4 (3.9)) after primary revascularisation. MAIN OUTCOME MEASURES--They received 279 grafts (2.4 grafts per patient); 58% of the grafts were anasatomosed to previously grafted vessels. The internal mammary artery was used in 87% of patients who required grafts to the left anterior descending coronary artery. RESULTS--Reoperation accounted for 8.3% of the total number of patients who underwent coronary bypass grafting. Graft failure alone or in combination with other factors was judged to be the cause of recurrence of symptoms in 87%. 42% of patients had two or more coronary risk factors. The early mortality was 5.2% and the actuarial survival at five and 10 years was 90.4% and 88.4% respectively. 85% of the survivors had initial complete relief of angina and 14% had partial improvement. Freedom from recurrent symptoms at five and 10 years was 66.6% and 34.6% respectively. CONCLUSIONS--Vein graft failure either alone or in combination with progression of native coronary disease is the main cause for symptomatic deterioration after bypass grafting. Reoperation can be performed with slightly increased risk and can give good early and medium term results. 相似文献
9.
10.
Bronchial reactivity to methacholine after combined heart-lung transplantation. 总被引:3,自引:2,他引:1 下载免费PDF全文
The operation of combined heart-lung transplantation results in acute denervation of the heart, lungs, and airways below the level of the trachea. The bronchoconstrictor response to inhaled methacholine of 12 recipients of heart-lung transplants was compared with that of 12 recipients of heart transplants having similar medication and 12 normal subjects. The median dose of methacholine that produced a reduction of at least 20% in the FEV1 (PC20) for the recipients of heart-lung transplants (8 mg/ml) was significantly lower than that for the recipients of heart transplants (64 mg/ml) and normal subjects (greater than 64 mg/ml). The increased airway reactivity may be related to the effects of chronic pulmonary denervation or subclinical inflammation in the airways. The effect of denervation on the response to full inspiration during bronchoconstriction was studied in six patients with heart-lung transplants by means of partial and maximal forced expiratory manoeuvres. Four showed bronchodilation after a deep breath, indicating that this response can occur after extrinsic pulmonary denervation in man. The patients with heart-lung transplants described a "tight" sensation in the anterior chest during bronchoconstriction, indicating that this sensation is not dependent on pulmonary innervation. 相似文献