首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6296篇
  免费   629篇
  国内免费   3篇
  2023年   39篇
  2022年   71篇
  2021年   211篇
  2020年   117篇
  2019年   127篇
  2018年   166篇
  2017年   120篇
  2016年   218篇
  2015年   403篇
  2014年   415篇
  2013年   488篇
  2012年   626篇
  2011年   572篇
  2010年   325篇
  2009年   284篇
  2008年   413篇
  2007年   389篇
  2006年   362篇
  2005年   299篇
  2004年   281篇
  2003年   240篇
  2002年   206篇
  2001年   51篇
  2000年   30篇
  1999年   35篇
  1998年   56篇
  1997年   32篇
  1996年   25篇
  1995年   20篇
  1994年   23篇
  1993年   20篇
  1992年   18篇
  1991年   16篇
  1990年   10篇
  1989年   7篇
  1988年   11篇
  1987年   10篇
  1986年   7篇
  1985年   6篇
  1984年   13篇
  1982年   15篇
  1981年   19篇
  1980年   22篇
  1979年   21篇
  1978年   14篇
  1977年   7篇
  1976年   15篇
  1974年   10篇
  1973年   5篇
  1972年   7篇
排序方式: 共有6928条查询结果,搜索用时 671 毫秒
41.
Among a consecutive series of 9,279 sternotomies performed during a period of 2(1/2) years, 61 (0.66%) patients developed significant wound complications. Of these, 58 (95.1%) survived. Sternal infection occurred in 36 patients (0.39%). Predisposing factors included chronic obstructive pulmonary disease, diabetes mellitus, obesity, closed chest massage, prolonged assisted ventilation, and excessive bleeding after operation. Positive end expiratory pressure (PEEP) did not, in itself, predispose to sternal dehiscence. Intermittent positive pressure breathing (IPPB) treatments caused excessive coughing, which may have increased the likelihood of dehiscence. Disposable drapes and expeditious surgery probably contributed to the low incidence of wound infection. Early diagnosis, surgical debridement, rewiring and primary closure with substernal drainage, without continuous antibiotic irrigation, resulted in satisfactory resolution in most patients.  相似文献   
42.
Persistent atrial paralysis in a patient with complete heart block and mild mitral insufficiency is presented. Left atrial specimens obtained during implantation of a permanent cardiac pulse generator showed evidence of hypertrophy and fibrosis; subcellular degenerative changes ranged from near normal to irreversible, thus suggesting that atrial paralysis may be due to the replacement of normal atrial muscle with nonfunctional fibrous tissue.  相似文献   
43.
Dissatisfaction with the hemodynamic characteristics of available porcine valves prompted a clinical trial of the Ionescu-Shiley percardial xenograft (ISPX) valve. Three hundred fifty-six ISPX valves were implanted consecutively in 326 patients. Operative mortality was 2.6% (2/75) for aortic valve replacement alone and 7.7% (12/155) for aortic valve replacements that included reoperations and combined procedures such as mitral commissurotomy, annuloplasty, and coronary artery bypass. Operative mortality for all patients who underwent mitral valve replacement was 9.5% (14/147). The mean peak systolic gradient pressure in the aortic position was 5.4 mm Hg overall and 4.27 mm Hg with the size 19 mm valve. There were no embolic episodes in patients who received the ISPX valve in the aortic position. The available data indicate that the rate of peripheral embolism with the ISPX valve compares favorably with that of porcine valves. Considering its hemodynamic advantage, if the longterm durability of the full-orifice Ionescu-Shiley pericardial xenograft valve continues to be confirmed by follow-up studies, it is our opinion that it is the biologic valve of choice.  相似文献   
44.
45.
46.
47.
48.
Two bacteriophage T4-induced, nucleic acid-modifying activities, 5′ polynucleotide kinase and 3′ phosphatase, are both coded by the pseT gene. Therefore, the product of this gene is an enzyme which can remove phosphates from 3′ termini and add them to 5′-hydroxyl termini and thus could be said to “shuttle” phosphates on polynucleotides. This enzyme is sometimes required for T4 true-late gene expression, probably by helping establish the required intracellular DNA structure. Our data suggest that a host gene product normally can substitute for the product of the pseT gene, making it non-essential for phage multiplication on most laboratory strains of Escherichia coli.  相似文献   
49.
A 10-month-old infant was found to have an isolated congenital arteriovenous fistula between the right subclavian artery and vein. Ligation of the fistula resulted in complete anatomic correction and rapid resolution of cardiomegaly.  相似文献   
50.
A 66-year-old woman developed chronic congestive heart failure after myocardial infarction of the anterior wall of the left ventricle. Angiographic studies revealed total proximal occlusion of the left anterior descending coronary artery and a large saccular aneurysm located on the anteroapical aspect of the left ventricle. Resection of a false aneurysm at operation resulted in improved cardiac function, and the patient made an uneventful recovery. Repeat evaluation six months later confirmed normal cardiac hemodynamics and left ventricular angiographic characteristics. To our knowledge, this is the first documented case of normalized heart function resulting from resection of a false aneurysm of the left ventricle. Functional classification according to the New York Heart Association improved dramatically, rising from Class IV preoperatively to Class I after operation.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号