全文获取类型
收费全文 | 7663篇 |
免费 | 77篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 61篇 |
综合类 | 2篇 |
化学工业 | 573篇 |
金属工艺 | 59篇 |
机械仪表 | 61篇 |
建筑科学 | 81篇 |
矿业工程 | 29篇 |
能源动力 | 43篇 |
轻工业 | 314篇 |
水利工程 | 19篇 |
石油天然气 | 8篇 |
无线电 | 538篇 |
一般工业技术 | 457篇 |
冶金工业 | 5066篇 |
原子能技术 | 35篇 |
自动化技术 | 396篇 |
出版年
2021年 | 27篇 |
2020年 | 23篇 |
2018年 | 40篇 |
2017年 | 28篇 |
2016年 | 20篇 |
2015年 | 26篇 |
2014年 | 43篇 |
2013年 | 208篇 |
2012年 | 78篇 |
2011年 | 104篇 |
2010年 | 72篇 |
2009年 | 102篇 |
2008年 | 111篇 |
2007年 | 127篇 |
2006年 | 113篇 |
2005年 | 96篇 |
2004年 | 84篇 |
2003年 | 105篇 |
2002年 | 69篇 |
2001年 | 78篇 |
2000年 | 66篇 |
1999年 | 224篇 |
1998年 | 1645篇 |
1997年 | 954篇 |
1996年 | 583篇 |
1995年 | 380篇 |
1994年 | 324篇 |
1993年 | 329篇 |
1992年 | 89篇 |
1991年 | 118篇 |
1990年 | 93篇 |
1989年 | 79篇 |
1988年 | 99篇 |
1987年 | 73篇 |
1986年 | 67篇 |
1985年 | 75篇 |
1984年 | 34篇 |
1983年 | 49篇 |
1982年 | 53篇 |
1981年 | 63篇 |
1980年 | 68篇 |
1979年 | 34篇 |
1978年 | 34篇 |
1977年 | 135篇 |
1976年 | 183篇 |
1975年 | 43篇 |
1974年 | 18篇 |
1973年 | 24篇 |
1972年 | 29篇 |
1966年 | 19篇 |
排序方式: 共有7742条查询结果,搜索用时 46 毫秒
81.
Lactate clearance and survival following injury 总被引:1,自引:0,他引:1
D Abramson TM Scalea R Hitchcock SZ Trooskin SM Henry J Greenspan 《Canadian Metallurgical Quarterly》1993,35(4):584-8; discussion 588-9
Previous reports cite optimization of O2 delivery (DO2) to 660 mL/min/m2, O2 consumption (VO2) to 170 mL/min/m2, and cardiac index (CI) of 4.5 L/min as predicting survival. We prospectively evaluated 76 consecutive patients with multiple trauma admitted directly to the ICU from the operating room or emergency department. Patients had serum lactate levels and oxygen transport measured on ICU admission and at 8, 16, 24, 36, and 48 hours. Patients were analyzed with respect to survival (S) versus nonsurvival (NS), lactate clearance to normal (< or = 2 mmol/L) by 24 and 48 hours, hemodynamic optimization as defined above, as well as Injury Severity Score (ISS), ICU stay (LOS), and admission blood pressure. All patients achieved non-flow-dependent VO2. There was no difference in CI, DO2, VO2, or ISS when S was compared with NS. All 27 patients whose lactate level normalized in 24 hours survived. If lactate levels cleared to normal between 24 and 48 hours, the survival rate was 75%. Only 3 of the 22 patients who did not clear their lactate level to normal by 48 hours survived. Ten of the 25 nonsurvivors (40%) achieved the above arbitrary optimization criteria. Fifteen of the survivors never achieved any of these criteria. Optimization alone does not predict survival. However, the time needed to normalize serum lactate levels is an important prognostic factor for survival in severely injured patients. 相似文献
82.
83.
A simple method was developed for the determination of dietary fiber in multicomponent foods. The method involves dispersing the sample into pH 7.4 phosphate buffer and adding bile and pancreatic enzyme as described. Results were comparable to AOAC methods with correlation coefficients of 86% for multicomponent dinners and 89% for breakfast foods. Coefficients of variation ranged from 7.4 to 20.0% for multicomponent foods and 1.0 to 3.6% for single component foods. In addition, blind duplicate samples had a correlation of 0.99. The described method required less time, labor, and manipulation than AOAC methods. 相似文献
84.
85.
86.
Yokoyama A. King R.W.P. Sandler S.S. 《Antennas and Propagation, IEEE Transactions on》1995,43(5):541-544
Yokoyama makes some comments on the “numerical distance” contained in the surface wave term in the paper by King and Sandler (see ibid., vol.42, p.383, 1994) comparing it with the one obtained by former authors. He comments on the parameter P in the Fresnel-integral term in the paper. Yokoyama concludes that for the calculation of such a problem in a semi-sphere, the spherical polar coordinate system is preferable to the cylindrical coordinate system including the case of lateral waves. King and Sandler reply to the Comment 相似文献
87.
88.
89.
90.