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   4233篇
  免费   77篇
  国内免费   2篇
电工技术   6篇
综合类   3篇
化学工业   281篇
金属工艺   18篇
机械仪表   30篇
建筑科学   42篇
矿业工程   8篇
能源动力   53篇
轻工业   135篇
水利工程   10篇
石油天然气   8篇
无线电   41篇
一般工业技术   118篇
冶金工业   3397篇
原子能技术   2篇
自动化技术   160篇
  2024年   5篇
  2023年   18篇
  2022年   46篇
  2021年   67篇
  2020年   28篇
  2019年   39篇
  2018年   55篇
  2017年   59篇
  2016年   45篇
  2015年   31篇
  2014年   31篇
  2013年   83篇
  2012年   60篇
  2011年   72篇
  2010年   36篇
  2009年   42篇
  2008年   31篇
  2007年   37篇
  2006年   19篇
  2005年   22篇
  2004年   13篇
  2003年   17篇
  2002年   17篇
  2001年   5篇
  2000年   8篇
  1999年   106篇
  1998年   999篇
  1997年   605篇
  1996年   378篇
  1995年   244篇
  1994年   177篇
  1993年   214篇
  1992年   36篇
  1991年   65篇
  1990年   52篇
  1989年   66篇
  1988年   60篇
  1987年   46篇
  1986年   36篇
  1985年   36篇
  1983年   7篇
  1982年   20篇
  1981年   16篇
  1980年   21篇
  1979年   2篇
  1978年   6篇
  1977年   94篇
  1976年   129篇
  1975年   6篇
  1955年   1篇
排序方式: 共有4312条查询结果,搜索用时 62 毫秒
61.
62.
63.
64.
PURPOSE: To determine the optimal surgical strategies in reoperative infrainguinal bypass, we reviewed our results in 300 consecutive secondary bypasses in 251 patients operated on between Jan. 1, 1975, and Nov. 1, 1993. METHODS: There were 168 men (67%) and 83 women (33%), with a mean age of 64.8 years and a typical distribution of risk factors including smoking (76.4%), diabetes (33.7%), and coronary artery disease (47.1%). The indications for surgery were limb-threatening ischemia in 83.5% and severe claudication in 16.5% of patients. The majority of conduits (n = 213) were autogenous vein and were composed of a single segment of greater saphenous vein in 121 bypasses (57%) and various alternative veins including composite, arm, and lesser saphenous vein in 92 bypasses (43%). Prosthetic conduits included 69 polytetrafluoroethylene, 16 umbilical vein, and two Dacron grafts. RESULTS: There was one perioperative death (0.3%) and a 25% total morbidity rate including a 1.7% myocardial infarction rate. There was a 28.6% early (< 30 days) graft failure and 10.7% early amputation rate for prosthetic bypass grafts compared with 13.6% early graft failure and 5.6% early amputation rates for vein grafts. Autogenous vein bypasses had higher 5-year secondary patency rates than had prosthetic grafts (51.5% +/- 4.6% vs 27.4% +/- 6.1%, p < 0.001). Results with autogenous vein bypass improved significantly from the 1975 to 1984 to the 1985 to 1993 interval with 5-year secondary patency rates increasing from 38.3% +/- 6.9% to 59.1% +/- 5.8% (p = 0.017) and 5-year limb-salvage rates increasing from 40.4% +/- 7.6% to 72.4% +/- 6.6% (p < 0.001). Vein grafts to the popliteal and tibial outflow levels had equivalent long-term results. Vein grafts completed for claudication demonstrated results superior to those for limb salvage, with a 5-year secondary patency rate of 75.8% +/- 8.1% versus 52.3% +/- 7.9% (p = 0.048). Secondary autogenous vein bypass grafting performed after early primary graft failure (< 3 months) did particularly poorly, with only a 27.2% +/- 7.7% 4-year secondary patency rate. Greater saphenous veins tended to perform better than alternative vein bypasses, with a 5-year secondary patency rate of 68.5% +/- 6.0% compared with 48.3% +/- 10.5% (p = 0.09) and a 5-year limb-salvage rate of 77.8% +/- 7.4% versus 54.2% +/- 11.8% (p = 0.046). CONCLUSIONS: When patients suffer a recurrence of limb-threatening ischemia at the time of infrainguinal graft failure, aggressive attempts at secondary revascularization with autogenous vein are warranted based on the low surgical morbidity and mortality rates and the improved patency and limb salvage rates that are currently attainable.  相似文献   
65.
66.
67.
68.
69.
70.
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