全文获取类型
收费全文 | 2392篇 |
免费 | 5篇 |
国内免费 | 17篇 |
专业分类
电工技术 | 6篇 |
综合类 | 5篇 |
化学工业 | 58篇 |
金属工艺 | 26篇 |
机械仪表 | 19篇 |
建筑科学 | 7篇 |
矿业工程 | 4篇 |
能源动力 | 1篇 |
轻工业 | 25篇 |
石油天然气 | 6篇 |
武器工业 | 1篇 |
无线电 | 150篇 |
一般工业技术 | 45篇 |
冶金工业 | 2026篇 |
自动化技术 | 35篇 |
出版年
2021年 | 3篇 |
2016年 | 3篇 |
2014年 | 3篇 |
2013年 | 17篇 |
2011年 | 25篇 |
2010年 | 10篇 |
2009年 | 7篇 |
2008年 | 10篇 |
2007年 | 14篇 |
2006年 | 22篇 |
2005年 | 19篇 |
2004年 | 42篇 |
2003年 | 26篇 |
2002年 | 20篇 |
2001年 | 11篇 |
2000年 | 9篇 |
1999年 | 59篇 |
1998年 | 574篇 |
1997年 | 302篇 |
1996年 | 218篇 |
1995年 | 126篇 |
1994年 | 102篇 |
1993年 | 136篇 |
1992年 | 34篇 |
1991年 | 44篇 |
1990年 | 38篇 |
1989年 | 49篇 |
1988年 | 47篇 |
1987年 | 38篇 |
1986年 | 37篇 |
1985年 | 25篇 |
1984年 | 5篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 17篇 |
1980年 | 27篇 |
1979年 | 11篇 |
1978年 | 7篇 |
1977年 | 61篇 |
1976年 | 143篇 |
1975年 | 5篇 |
1974年 | 2篇 |
1971年 | 3篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1961年 | 3篇 |
1959年 | 2篇 |
1958年 | 3篇 |
1956年 | 3篇 |
1955年 | 4篇 |
排序方式: 共有2414条查询结果,搜索用时 484 毫秒
41.
GJ Wetscher G Perdikis DH Kretchmar RG Stinson D Bagchi EJ Redmond TE Adrian RA Hinder 《Canadian Metallurgical Quarterly》1995,40(6):1297-1305
Free radical-mediated esophagitis was studied during duodenogastroesophageal reflux (mixed reflux) or acid reflux in rats. The influence of reflux on esophageal glutathione levels was also examined. Mixed reflux caused more gross mucosal injury than acid reflux. Gross mucosal injury occurred in the mid-esophagus. Total glutathione (GSH) in the esophageal mucosa of control rats was highest in the distal esophagus. The time course of esophageal GSH in rats treated by mixed reflux showed a significant decrease 4 hr after initiation of reflux, followed by a significant increase from the 12th hour on. Mucosal GSH was increased in both reflux groups after 24 hr but significantly more so in the mixed than in the acid reflux group. The free radical scavenger superoxide dismutase (SOD) prevented esophagitis and was associated with decreased GSH levels. GSH depletion by buthionine sulfoximine (BSO) prevented esophagitis and stimulated SOD production in the esophageal mucosa. It is concluded that gastroesophageal reflux is associated with oxidative stress in the esophageal mucosa. The lower GSH levels in the mid-esophagus may predispose to damage in this area. Duodenogastroesophageal reflux causes more damage than pure acid reflux. Oxidative stress leads to GSH depletion of the esophageal mucosa in the first few hours following damage but then stimulates GSH production. GSH depletion by BSO does not worsen esophagitis since it increases the esophageal SOD concentration. 相似文献
42.
43.
TS Bocanegra AL Weaver EA Tindall DH Sikes JA Ball CB Wallemark GS Geis JG Fort 《Canadian Metallurgical Quarterly》1998,25(8):1602-1611
44.
OBJECTIVES: To compare gastric tonometry (pHi) with estimates of pHi in ill injured patients, and to correlate pHi with haemodynamic variables. DESIGN: Prospective, non-interventional study. SETTING: ICU of Level I trauma centre, USA. MAIN OUTCOME MEASURES: 154 gastric tonometry measurements were compared with physicians' estimates of adequacy of resuscitation. Resuscitation was categorised as inadequate (pHi < 7.35) or adequate (pHi> or = 7.35). Measured and estimated pHi were also compared with oxygen delivery, oxygen consumption, cardiac index, mixed venous O2 saturation, and critical illness scores. RESULTS: Estimated pHi was often higher than measured pHi in the judgement of all four surgical intensive care physicians. Measured pHi correlated positively with mixed venous O2 tension (r = 0.21). There were significant negative correlations between measured pHi and both oxygen delivery (r = -0.25) and oxygen consumption (r = 0.28). Estimated pHi correlated positively with mean arterial pressure (r = 0.21) and hospital day (r = 0.26); it correlated negatively with pulmonary arterial elastance (r = -0.35). CONCLUSION: Experienced intensive care physicians tended to overestimate visceral perfusion, which suggests that gastric tonometry adds useful information over and above routine haemodynamic indices. Arterial blood pressure and mixed venous oxygen saturation correlated better with measured pHi than with other indices of perfusion. 相似文献
45.
46.
介绍了利用北京正负对撞机(BEPC)同步辐射X射线光刻装置,进行LIGA工艺技术深结构光刻实验研究,详细论述了X射线光刻使用的掩模制备过程及掩模镀金工艺,在国内最早曝光出直径为400μm、厚为27~45μm的三维立体齿轮胶图形。 相似文献
47.
48.
49.
SC Shim DH Yoo JK Lee HK Koh SR Lee SH Oh SY Kim 《Canadian Metallurgical Quarterly》1998,25(12):2464-2468
Ankylosing spondylitis (AS) results in disease-specific inflammation at the site of ligamentous insertion into the bone. Atlantoaxial joint subluxation and vertical subluxation of the axis may occur as a consequence of instability resulting from the inflammatory process. Spontaneous anterior atlantoaxial subluxation is a well recognized complication in about 2% of patients with AS, and presents with or without signs of spinal cord compression. Vertical subluxation may follow anterior or posterior subluxation. It was noted in 3-8% of patients with rheumatoid arthritis, but is an exceedingly rare complication of AS. Moreover, it has never been reported that multiple cerebellar infarction and bulbar symptoms developed spontaneously due to atlanto-occipital subluxation and vertical subluxation in a patient with a long [corrected] history of AS. We describe a man with AS who developed multiple cerebellar infarction due to vertebral artery obstruction and bulbar symptoms associated with atlanto-occipital subluxation and vertical subluxation. 相似文献
50.