全文获取类型
收费全文 | 1235篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 15篇 |
金属工艺 | 2篇 |
建筑科学 | 1篇 |
能源动力 | 2篇 |
轻工业 | 9篇 |
无线电 | 8篇 |
一般工业技术 | 3篇 |
冶金工业 | 1189篇 |
自动化技术 | 7篇 |
出版年
2022年 | 2篇 |
2021年 | 1篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 6篇 |
2012年 | 3篇 |
2011年 | 2篇 |
2010年 | 1篇 |
2009年 | 1篇 |
2008年 | 2篇 |
2007年 | 1篇 |
2006年 | 4篇 |
2005年 | 1篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1999年 | 44篇 |
1998年 | 343篇 |
1997年 | 204篇 |
1996年 | 143篇 |
1995年 | 62篇 |
1994年 | 59篇 |
1993年 | 77篇 |
1992年 | 12篇 |
1991年 | 15篇 |
1990年 | 21篇 |
1989年 | 22篇 |
1988年 | 21篇 |
1987年 | 21篇 |
1986年 | 20篇 |
1985年 | 8篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 9篇 |
1978年 | 3篇 |
1977年 | 32篇 |
1976年 | 66篇 |
1975年 | 5篇 |
1973年 | 1篇 |
排序方式: 共有1240条查询结果,搜索用时 328 毫秒
101.
102.
103.
104.
JJ Hoballah RT Chalmers MM Nazzal CR Mohan J Corson 《Canadian Metallurgical Quarterly》1997,63(11):970-974
The coexistence of infrarenal aortic aneurysm and internal iliac artery aneurysm may represent a management problem with regard to preservation of the pelvic blood supply. In this article, we review the methods available for maintaining the pelvic blood flow and describe a useful technique that we have successfully utilized in seven patients to preserve the hypogastric artery blood flow. 相似文献
105.
106.
107.
108.
109.
110.
The metabolic effects during myocardial ischemia and sustained reperfusion of the antianginal agents diltiazem (n = 10) and propranolol (n = 10) were monitored with noninvasive phosphorus nuclear magnetic resonance spectroscopy to establish any correlation between metabolic changes and infarct size. Spectroscopy followed changes in high-energy phosphate concentrations and myocardial intracellular pH during 2 h of left anterior descending coronary artery occlusion and 3 subsequent weeks of reperfusion, in a closed chest canine infarct model. Gadolinium-DTPA enhanced magnetic resonance imaging was used to assess the extent of myocardial injury (infarct size). Microspheres were used to document the zone at risk and the success of reperfusion. Whereas diltiazem appeared to reduce the derangement in high-energy phosphates during coronary occlusion, there was no significant change in infarct size when compared with a previously studied control group. Propranolol, which produced a lesser decline in pH during occlusion and smaller pH changes during early reperfusion, was associated with a significant reduction in the degree of tissue necrosis (compared with controls). There was an inverse correlation (r = -0.51) between the change in myocardial pH (occlusion end to immediate reperfusion) and the recovery index (an index of myocardial salvage). By 1 h into reperfusion, there was a stronger inverse correlation between pH and infarct size (r = -0.75), implying a protective effect of delaying pH recovery during early reperfusion and indicating the potential use of this parameter as a predictor of tissue viability. 相似文献