全文获取类型
收费全文 | 735篇 |
免费 | 49篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 6篇 |
妇产科学 | 5篇 |
基础医学 | 80篇 |
口腔科学 | 24篇 |
临床医学 | 210篇 |
内科学 | 112篇 |
皮肤病学 | 10篇 |
神经病学 | 22篇 |
特种医学 | 13篇 |
外科学 | 28篇 |
综合类 | 99篇 |
一般理论 | 1篇 |
预防医学 | 83篇 |
眼科学 | 17篇 |
药学 | 48篇 |
4篇 | |
中国医学 | 21篇 |
肿瘤学 | 8篇 |
出版年
2023年 | 8篇 |
2022年 | 7篇 |
2021年 | 27篇 |
2020年 | 22篇 |
2019年 | 27篇 |
2018年 | 29篇 |
2017年 | 21篇 |
2016年 | 24篇 |
2015年 | 17篇 |
2014年 | 44篇 |
2013年 | 51篇 |
2012年 | 37篇 |
2011年 | 52篇 |
2010年 | 38篇 |
2009年 | 39篇 |
2008年 | 51篇 |
2007年 | 35篇 |
2006年 | 36篇 |
2005年 | 21篇 |
2004年 | 30篇 |
2003年 | 14篇 |
2002年 | 19篇 |
2001年 | 19篇 |
2000年 | 18篇 |
1999年 | 19篇 |
1998年 | 24篇 |
1997年 | 7篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 4篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 6篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1976年 | 1篇 |
排序方式: 共有803条查询结果,搜索用时 31 毫秒
1.
Nabil El-Sherif 《The International Journal of Cardiac Imaging》1991,7(3-4):141-150
In this work the electrophysiologic mechanisms of ventricular arrhythmias have been briefly summarized. Ventricular arrhytmias can be caused either by pacemaker activity or by reentrant excitation. Enhancement of normal automaticy can generate a parasystolic rhythm in normal fibers. Abnormal automaticity may arise fom fibers in which maximum diastolic potential has been reduced by a variety of interventions. Triggered activity is caused by either an early (EAD) or delayed (DAD) afterdepolarization and requires a prior normal action potential for initiation. While there is growing evidence that EAD-induced triggered activity plays a significant role in the Long QTU syndrome and Torsade de Pointes, no clinical arrhythmias has definitely been ascribed to DADs, although DADs have been recorded in man after acute digoxin intoxication.Ventricular arrhytmias can be also caused by reentrant excitation, which can be subdivided into reflection or circus movement reentry (CMR). In the reflection model impulses in both directions are transmitted over the same pathway. In the CMR three models can be differentiated: the ring model, which requires a fixed anatomical obstacle; the figure-eight model and the leading circle model, where functional rather than fixed anatomical obstacles are involved.Abbreviations AV
atrio-ventricular
- CMR
circus movement reentry
- DAD
delayed afterdepolarization
- EAD
early afterdepolarization
- ECG
electrocardiogram
- LV
left ventricle
- MAP
monophasic action potential
- MF
muscle fiber
- PF
Purkinje fiber
- RV
right ventricle
- TdP
Torsade de Pointes 相似文献
2.
3.
Margaret A. Chambers 《Journal of clinical nursing》1998,7(3):201-208
? This paper focuses on some issues in the assessment of clinical practice of particular interest to the author. ? The assessment of students of nursing in clinical practice is acknowledged as a long-standing and difficult problem. ? There is little consensus as to what is meant by the term competence when applied to clinical nursing practice, making the assessment of clinical practice a mainly subjective process. ? The English National Board (1989) has distinguished the term mentor as meaning counsellor and guide, nevertheless the roles of mentor and assessor are frequently confused. ? It is suggested that nurses are equally accountable for the accurate assessment of student nurses' clinical skills as they are for their own practice. ? The validity and reliability of tools used to assess clinical practice are difficult to establish, making objective assessment complex at best, and impossible at worst. ? The assessment of the reflective process has been suggested as one way out of the dilemma, but the ability to think and to write does not necessarily translate into competent clinical practice. 相似文献
4.
介绍一种新型激光治疗装置.它利用超声波产生的雾化气体通道作为光学传导媒介,将激光束汇同雾化药雾通过患者的深呼吸一起传导至患者的呼吸道及肺部,进行治疗. 相似文献
5.
6.
Transport of molecules across tumor vasculature 总被引:16,自引:0,他引:16
Rakesh K. Jain 《Cancer metastasis reviews》1987,6(4):559-593
The vascular-extravascular exchange of fluid and solute molecules in a tissue is determined by three transport parameters (vascular permeability, P, hydraulic conductivity, Lp, and reflection coefficient, ); the surface area for exchange, A; and the transluminal concentration and pressure gradients. The transport parameters and the exchange area for a given molecule are governed by the structure of the vessel wall. In general, tumor vessels have wide interendothelial junctions; large number of fenestrae and transendothelial channels formed by vesicles; and discontinuous or absent basement membrane. While these factors favor movement of molecules across tumor vessels, high interstitial pressure and low microvascular pressure may retard extravasation of molecules and cells, especially in large tumors. These characteristics of the transvascular transport have significant implications in tumor growth, metastasis, detection and treatment. 相似文献
7.
8.
Thomas Kenner 《Pflügers Archiv : European journal of physiology》1976,364(3):285-289
Summary The contours of pressure and flow of a pulse wave arriving at the entrance of a collapsed segment of an elastic tube can be described by application of the basic laws of reflection. The collapsed segment acts like a valve. It is opened by the pressure of the pulse wave when the pressure within the tube becomes higher than the collapse pressure, i.e. the pressure exerted on the segment from outside. This opening of the collapsed segment suddenly changes the sign of the pulse wave reflection from positive to negative; thus a typical contour change of the pulse proximal to the segment is observed. The most obvious effect is a reduction of the pulse pressure. The extent of this reduction is a function of the collapse pressure.A typical example of this phenomenon can be observed in an artery proximal to the segment which is collapsed due to the pressure exerted by an inflated Riva-Rocci cuff. The effect is explained by the assumption that the sign of reflection changes when the pressure of the pulse wave crosses the level of the cuff pressure. This explanation is supported by the results of model experiments. 相似文献
9.
Ranald M. Sutherland Claus Dähne John F. Place Anthony R. Ringrose 《Journal of immunological methods》1984,74(2):253-265
The theoretical basis and instrumental requirements of an optical detection technique for monitoring antibody-antigen reactions at a quartz-liquid interface are described. The antibody is covalently immobilized on the optical surface of a planar, fused-quartz waveguide and reacted with antigen solution. A light beam is internally reflected within the waveguide and penetrates into the solution only a fraction of the wavelength of the incident light. This is the evanescent wave which interacts optically with the growing number of antigen-antibody complexes but minimally with the bulk solution. A two-site immunofluorescent assay for human IgG measurement is described using fluorescein as the label. The assay detection limit is approximately 0.8 micrograms/ml and individual fluorescence measurements are completed within 10 min. It is expected that this evanescent wave immunoassay should have wide applicability in both routine and research fields. 相似文献
10.
根据薄膜理论基础,分析了受抑全内反射(FTIR)的理论机制,并导出相应的光线透过率及反射率公式,绘制出透射率、反射率随棱镜相对间隙d/λ、入射角θ。的变化曲线。并建立了一套FTIR组合测试原理实验装置,得到了透过及发射光脉冲曲线,通过实验地其特性进行了具体分析。 相似文献