全文获取类型
收费全文 | 1205篇 |
免费 | 50篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 12篇 |
妇产科学 | 20篇 |
基础医学 | 76篇 |
口腔科学 | 31篇 |
临床医学 | 355篇 |
内科学 | 306篇 |
皮肤病学 | 51篇 |
神经病学 | 27篇 |
特种医学 | 3篇 |
外科学 | 137篇 |
综合类 | 17篇 |
一般理论 | 7篇 |
预防医学 | 69篇 |
眼科学 | 24篇 |
药学 | 93篇 |
肿瘤学 | 23篇 |
出版年
2017年 | 9篇 |
2016年 | 17篇 |
2015年 | 19篇 |
2014年 | 21篇 |
2013年 | 43篇 |
2012年 | 10篇 |
2011年 | 6篇 |
2010年 | 52篇 |
2009年 | 36篇 |
2008年 | 11篇 |
2007年 | 7篇 |
2006年 | 16篇 |
2003年 | 8篇 |
2001年 | 23篇 |
2000年 | 15篇 |
1999年 | 47篇 |
1998年 | 58篇 |
1997年 | 74篇 |
1996年 | 68篇 |
1995年 | 69篇 |
1994年 | 53篇 |
1993年 | 49篇 |
1992年 | 50篇 |
1991年 | 40篇 |
1990年 | 41篇 |
1989年 | 34篇 |
1988年 | 35篇 |
1987年 | 19篇 |
1986年 | 19篇 |
1985年 | 14篇 |
1984年 | 15篇 |
1983年 | 19篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1980年 | 9篇 |
1979年 | 12篇 |
1978年 | 12篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1973年 | 4篇 |
1971年 | 5篇 |
1961年 | 5篇 |
1959年 | 15篇 |
1958年 | 22篇 |
1957年 | 19篇 |
1956年 | 15篇 |
1955年 | 19篇 |
1954年 | 15篇 |
1949年 | 5篇 |
1948年 | 6篇 |
排序方式: 共有1255条查询结果,搜索用时 15 毫秒
1.
2.
3.
JOHN P. BOURKE LYNNE HOWELL ALAN MURRAY WILLIAM E. HILL J. CAMPBELL COWAN KEVIN BEATT JOAN ERRINCTON STUART JAMESON RONALD G. GOLD 《Pacing and clinical electrophysiology : PACE》1989,12(8):1419-1425
A randomized prospective study was undertaken to compare the electrical performances of three permanent, endocardial, tined pacing leads with different electrode designs--sintered platinum, vitreous carbon, and porous carbon. Ninety-nine patients received one of the leads (S80 31; 423S 32; S100 36). Acute R wave amplitude and ST elevation of the native endocardial electrogram, voltage threshold, impedance, and current flow at four pulse durations (0.25-1.0 msec) were measured. Voltage thresholds were measured noninvasively at each of four pulse durations at 2 days and 1, 3, and 6 months after implantation. No significant differences were found in sensing properties, or current flow at threshold at 0.5 msec pulse duration. The 423S lead had a significantly higher impedance at threshold and both a higher impedance and lower current flow at 5 V. No significant differences in threshold voltages were found between the three leads at any pulse duration, at any of the assessed times after implantation. Six-month thresholds for the S80, 423S, and S100 leads were 1.18 +/- 0.35, 1.17 +/- 0.29, and 1.06 +/- 0.38 V respectively at 0.5 msec pulse duration. Differences between 'high performance' pacing leads need to be of a greater order of magnitude before they can be exploited to give any real clinical advantage to patients. 相似文献
4.
MARK C FITZGERALD 《Emergency medicine Australasia : EMA》1992,4(2):114-119
Rates of survival horn pre-hospital cardiac arrest are often used to judge the quality of emergency medical systems. Despite many advances in technology and pharmacotherapy over the last two decades, overall survival rates in most systems remain disappointing. Objective analysis of different systems of care and associated outcomes has been hampered by a lack of uniform data reporting. Attempts to improve survival must focus on the key to resuscitation from sudden cardiac death, that is rapid response defibrillation. 相似文献
5.
MARK J. CASTELLANET M.D. JUAN GARZA M.D. STANLEY P. SHANER P.E. JOHN C. MESSENGER M.D. 《Journal of cardiovascular electrophysiology》1987,1(5):360-375
Telemetry of programmed and measured data is an important feature of many pacemakers currently used in clinical practice. The ability to receive non-invasive data from the implanted device constitutes a major advantage for the long-term follow-up of the patients and of device performance. There are numerous types of data retrievable via telemetry: parameters of device characteristics (output, battery longevity, impedance, etc), event recorders or counters, event markers, and endocardial electrograms. Ideally, this information should be beneficial in the longitudinal surveilance of modern pacemakers. 相似文献
6.
7.
8.
Pre-anesthetic hypnosis with rectal pentothal in children 总被引:1,自引:0,他引:1
9.
An Intrapleural Lung Prosthesis: Rationale, Design, and Testing 总被引:1,自引:0,他引:1
FRANCO L. FAZZALARI ROBERT H. BARTLETT MARK R. BONNELL J. PATRICK MONTOYA 《Artificial organs》1994,18(11):801-805
Abstract: Extracorporeal life support (ECLS or ECMO) is standard treatment for severe respiratory failure but poses many contraindications to future lung transplantation. The solution to this dilemma is the implantable gas exchange device (IGED) or artificial lung. Preliminary efforts to create such an artificial lung have been made since 1970 and include designs involving single devices, intravascular devices (i. e., IVOX), and combination heart–lung devices, Stringent requirements govern the design of such a device, the most important of which are high gas exchange efficiency, low resistance to blood flow, and size. This paper describes such a device. It incorporates large diameter inflow and outflow ports in close proximity and a low resistance wound hollow fiber core encapsulated in a compliant outer shell which conserves the work of the right ventricle. In a large animal model (adult sheep) this device was connected in line with the main pulmonary artery in series with the native lungs. This configuration has the advantages of using the lungs as an embolic filter, perfusing the lungs with fully oxygenated blood, and maintaining the integrity of the anatomy necessary for transplant. Laboratory experiments have run >8 h. Preliminary data show that the animals have remained hemodynamically stable while the devices have supported the animals completely by supplying 100% O2 saturation with PO2 values ranging from 250–350 mm Hg. Additionally, this model makes possible the study of respiratory failure without introducing other variables such as extracorporeal circuits or pumps. The other metabolic, endocrine, and reticuloendothelial functions of normal and injured lungs can now be studied more precisely by excluding these variables. Further studies are needed to evaluate this device in chronic (long–term implantation) experiments before clinical application. 相似文献
10.
R.CHARLES HOWELLS II MD MARK K. WAX MD HASSAN H. RAMADAN MD 《Otolaryngology--head and neck surgery》1997,117(6):628-632
OBJECTIVE: Hemorrhage after tonsillectomy is a potentially lethal complication. Preoperative assessment consisting of prothrombin time (PT) and activated partial thromboplastin time (PTT) has been used to identify patients at risk for hemorrhage after tonsillectomy and adenoidectomy. We sought to assess the value of PT/PTT screening as a predictor of posttonsillectomy hemorrhage.DESIGN: A retrospective chart review was carried out with a minimum of 1 month follow-up.SETTING: Tertiary academic referral center.PATIENTS: Between January 1992 and June 1995, 382 patients undergoing tonsillectomy were examined; 339 patients with a minimum of 1 month follow-up were reviewed for this study.MAIN OUTCOME MEASURE: Normal and prolonged PT/PTT values were examined. Bleeding in the intraoperative, immediate postoperative, and delayed phases of healing was examined.RESULTS: Two-hundred and twenty-two patients had normal PT/PTT, 39 had prolonged PT/PTT, and 78 had no preoperative studies performed. Bleeding occurred in 2.7%, 2.6%, and 3.3%, respectively, of patients. Eight patients had positive family histories of bleeding tendencies. One patient [12.5%] with a normal PT/PTT experienced a delayed posttonsillectomy bleed. Of 39 patients with abnormal coagulation studies, 30 were borderline elevations with no repeat studies done; one patient experienced postoperative hemorrhage. Nine abnormal results were repeated; three returned to normal, three remained prolonged but underwent tonsillectomy with no intervention, and three received hematology consultations. One patient had lupus anticoagulant, one had Hageman Factor deficiency, and one was cleared for surgery with no diagnosis. All patients underwent tonsillectomy with no episodes of postoperative bleeding.CONCLUSIONS: Preoperative PT/PTT provides no additional information than does a bleeding history for the general pediatric population undergoing tonsillectomy. This should only be done in selective cases where warranted by history. (Otolaryngol Head Neck Surg 1997;117:628-32.) 相似文献