全文获取类型
收费全文 | 68472篇 |
免费 | 5113篇 |
国内免费 | 2826篇 |
专业分类
电工技术 | 3631篇 |
技术理论 | 7篇 |
综合类 | 4229篇 |
化学工业 | 11014篇 |
金属工艺 | 3570篇 |
机械仪表 | 3937篇 |
建筑科学 | 5458篇 |
矿业工程 | 1855篇 |
能源动力 | 1876篇 |
轻工业 | 4058篇 |
水利工程 | 1158篇 |
石油天然气 | 4508篇 |
武器工业 | 450篇 |
无线电 | 7072篇 |
一般工业技术 | 8021篇 |
冶金工业 | 7157篇 |
原子能技术 | 719篇 |
自动化技术 | 7691篇 |
出版年
2024年 | 227篇 |
2023年 | 1039篇 |
2022年 | 1723篇 |
2021年 | 2442篇 |
2020年 | 1894篇 |
2019年 | 1644篇 |
2018年 | 1864篇 |
2017年 | 2094篇 |
2016年 | 1906篇 |
2015年 | 2370篇 |
2014年 | 3214篇 |
2013年 | 3670篇 |
2012年 | 4087篇 |
2011年 | 4426篇 |
2010年 | 3880篇 |
2009年 | 3685篇 |
2008年 | 3610篇 |
2007年 | 3513篇 |
2006年 | 3565篇 |
2005年 | 3087篇 |
2004年 | 2091篇 |
2003年 | 1883篇 |
2002年 | 1646篇 |
2001年 | 1599篇 |
2000年 | 1653篇 |
1999年 | 1899篇 |
1998年 | 2747篇 |
1997年 | 1930篇 |
1996年 | 1505篇 |
1995年 | 1208篇 |
1994年 | 999篇 |
1993年 | 791篇 |
1992年 | 462篇 |
1991年 | 390篇 |
1990年 | 350篇 |
1989年 | 263篇 |
1988年 | 222篇 |
1987年 | 152篇 |
1986年 | 139篇 |
1985年 | 105篇 |
1984年 | 42篇 |
1983年 | 33篇 |
1982年 | 43篇 |
1981年 | 43篇 |
1980年 | 43篇 |
1979年 | 3篇 |
1978年 | 9篇 |
1977年 | 80篇 |
1976年 | 134篇 |
1975年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
对溢洪闸门自动监控系统中几个问题的探讨 总被引:1,自引:1,他引:0
结合某水电站介绍了溢洪闸门自动监控系统的结构、功能,讨论了该研制过程中的几个问题的解决办法. 相似文献
102.
103.
104.
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
105.
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
106.
In this paper the modelling, analysis and optimization of millimeter wave oscillatorsare investigated by using the a frequency-domain harmonic balance technique (FDHB), where theexternal-circuit impedances looking outside from the active device are calculated with a combinedtechnique of modes expansion, Galerkin, and collocation methods. The optimization results arein agreement with the experimental ones, which show the reliability of the presented model andoptimization. 相似文献
107.
Haining Yang Mingyuan Gu Weiji Jiang Guoding Zhang 《Journal of Materials Science》1996,31(7):1903-1907
The interface structure in Gr/Al composites fabricated with liquid metal infiltration has been studied using transmission electron microscopy (TEM). Morphologies of interfacial reaction product, aluminium carbide Al4C3, formed at different manufacturing parameters were compared and, the growth mechanism of the carbide was studied by means of high resolution electron microscopy (HREM). It has been shown that the morphology of the carbide is intimately related to the processing parameters with which the composites were produced. There are two kinds of interfaces between the carbide and the aluminium matrix. They have different growth mechanisms and relative growth rates under different growth driving forces. Several crystal orientation relationships between the carbide and the aluminium matrix have been observed. 相似文献
108.
109.