全文获取类型
收费全文 | 99919篇 |
免费 | 8088篇 |
国内免费 | 4299篇 |
专业分类
电工技术 | 5651篇 |
技术理论 | 6篇 |
综合类 | 6268篇 |
化学工业 | 16655篇 |
金属工艺 | 6176篇 |
机械仪表 | 6989篇 |
建筑科学 | 8084篇 |
矿业工程 | 3418篇 |
能源动力 | 2915篇 |
轻工业 | 6319篇 |
水利工程 | 1664篇 |
石油天然气 | 7390篇 |
武器工业 | 811篇 |
无线电 | 10732篇 |
一般工业技术 | 11618篇 |
冶金工业 | 4927篇 |
原子能技术 | 1021篇 |
自动化技术 | 11662篇 |
出版年
2024年 | 451篇 |
2023年 | 1782篇 |
2022年 | 3139篇 |
2021年 | 4299篇 |
2020年 | 3338篇 |
2019年 | 2711篇 |
2018年 | 2929篇 |
2017年 | 3309篇 |
2016年 | 3050篇 |
2015年 | 4126篇 |
2014年 | 4929篇 |
2013年 | 5874篇 |
2012年 | 6350篇 |
2011年 | 6767篇 |
2010年 | 5797篇 |
2009年 | 5535篇 |
2008年 | 5381篇 |
2007年 | 5106篇 |
2006年 | 5432篇 |
2005年 | 4722篇 |
2004年 | 2998篇 |
2003年 | 2840篇 |
2002年 | 2665篇 |
2001年 | 2421篇 |
2000年 | 2338篇 |
1999年 | 2648篇 |
1998年 | 2096篇 |
1997年 | 1732篇 |
1996年 | 1702篇 |
1995年 | 1415篇 |
1994年 | 1156篇 |
1993年 | 738篇 |
1992年 | 647篇 |
1991年 | 439篇 |
1990年 | 350篇 |
1989年 | 304篇 |
1988年 | 231篇 |
1987年 | 152篇 |
1986年 | 122篇 |
1985年 | 71篇 |
1984年 | 53篇 |
1983年 | 45篇 |
1982年 | 42篇 |
1981年 | 28篇 |
1980年 | 25篇 |
1979年 | 16篇 |
1978年 | 1篇 |
1965年 | 1篇 |
1959年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
73.
74.
75.
76.
The cardioprotective effects of EGb 761 on the release of nitric oxide (NO), the concentration of serum thiobarbituric acid reaction substance (TBARS), the activity of creatine kinase (CK) and the incidence of ventricular arrhythmias were investigated in myocardial ischemia-reperfusion injury in vivo. Using sodium nitrite (NaNO2) as standard source of nitric oxide (NO), we compared the correlation coefficients of the three measuring methods used currently in the determination of NOFe2+(DETC)2 complex with that of the measuring method suggested in this study. The result showed that measuring the whole height of three splitting signals is the best linear correlation to the concentration of NO comparing with other methods in this system. Using this method, we observed the effects of EGb 761 on NOFe2+(DETC)2 complex in myocardial ischemia-reperfusion injury in vivo. The hearts of the Wistar rats were subjected to 30 min of ischemia and 10 min of reperfusion in vivo. Different doses of EGb 761 (25, 50, 100, 200 mg/kg i.p.), superoxide dismutase (SOD, 10(4) U/kg), l-arginine (50 mg/kg i.p.) and nitric oxide synthase (NOS) inhibitor NG-nitro-l-arginine (NNA, 50 mg/kg i.p.) were administered to the ischemia-reperfusion rats. EGb 761 under the dose of 100 mg/kg increased the signal intensity of NOFe2+(DETC)2 complex, while EGb 761 at 200 mg/kg showed an effect of decreasing the signal intensity of NOFe2+(DETC)2 complex. EGb 761 inhibited the formation of TBARS, the release of CK, and mitigated the incidence of ventricular arrhythmias in a dose dependent way. Both l-arginine and SOD increased the signal intensity of NOFe2+(DETC)2 complex and inhibited the formation of TBARS, the leakage of CK and the incidence of ventricular arrhythmia. NNA not only had no protective effects on myocardial injury, but also increased the incidence of reperfusion-induced arrhythmia. In conclusion, EGb 761 has cardiovascular protective effects by means of adjusting the level of NO and inhibiting oxygen free radicals induced lipid peroxidation in myocardial ischemia-reperfusion injury in vivo. 相似文献
77.
在30CrMnSiA钢中加入不同量的As,Sb,Sn元素,研究了这些元素单独存在及复合存在时对钢的强度,塑性,冲击韧度及韧脆转变温度的影响规律,并用扫描电镜及俄歇能谱分析了As,Sb,Sn导致晶界脆化的机理。 相似文献
78.
79.
将气体动压轴压简化为转化气膜系统后,针对其动力特点,给出气膜在微幅振动下动压轴承的实用数学模型和测定动态参数的方法,并进行了测量误差的修正。 相似文献
80.
Summary Byzantine Agreement is important both in the theory and practice of distributed computing. However, protocols to reach Byzantine Agreement are usually expensive both in the time required as well as in the number of messages exchanged. In this paper, we present a self-adjusting approach to the problem. The Mostly Byzantine Agreement is proposed as a more restrictive agreement problem that requires that in the consecutive attempts to reach agreement, the number of disagreements (i.e., failures to reach Byzantine Agreement) is finite. Fort faulty processes, we give an algorithm that has at mostt disagreements for 4t or more processes. Another algorithm is given forn3t+1 processes with the number of disagreements belowt
2/2. Both algorithms useO(n
3) message bits for binary value agreement.
Yi Zhao is currently working on his Ph.D. degree in Computer Science at University of Houston. His research interests include fault tolerance, distributed computing, parallel computation and neural networks. He obtained his M.S. from University of Houston in 1988 and B.S. from Beijing University of Aeronautics and Astronautics in 1984, both in computer science.
Farokh B. Bastani received the B. Tech. degree in electrical engineering from the Indian Institute of Technology, Bombay, India, and the M.S. and Ph.D. degrees in electrical engineering and computer science from the University of California, Berkeley. He joined the University of Houston in 1980, where he is currently an Associate Professor of Computer Science. His research interests include software design and validation techniques, distributed systems, and fault-tolerant systems. He is a member of the ACM and the IEEE and is on the editorial board of theIEEE Transactions on Software Engineering. 相似文献