全文获取类型
收费全文 | 8718篇 |
免费 | 988篇 |
国内免费 | 395篇 |
专业分类
电工技术 | 648篇 |
技术理论 | 3篇 |
综合类 | 602篇 |
化学工业 | 1478篇 |
金属工艺 | 433篇 |
机械仪表 | 571篇 |
建筑科学 | 704篇 |
矿业工程 | 321篇 |
能源动力 | 275篇 |
轻工业 | 653篇 |
水利工程 | 190篇 |
石油天然气 | 554篇 |
武器工业 | 68篇 |
无线电 | 901篇 |
一般工业技术 | 1074篇 |
冶金工业 | 375篇 |
原子能技术 | 96篇 |
自动化技术 | 1155篇 |
出版年
2024年 | 59篇 |
2023年 | 220篇 |
2022年 | 413篇 |
2021年 | 565篇 |
2020年 | 388篇 |
2019年 | 313篇 |
2018年 | 335篇 |
2017年 | 368篇 |
2016年 | 330篇 |
2015年 | 434篇 |
2014年 | 447篇 |
2013年 | 503篇 |
2012年 | 541篇 |
2011年 | 592篇 |
2010年 | 503篇 |
2009年 | 462篇 |
2008年 | 404篇 |
2007年 | 395篇 |
2006年 | 409篇 |
2005年 | 376篇 |
2004年 | 220篇 |
2003年 | 250篇 |
2002年 | 242篇 |
2001年 | 208篇 |
2000年 | 204篇 |
1999年 | 195篇 |
1998年 | 133篇 |
1997年 | 99篇 |
1996年 | 104篇 |
1995年 | 87篇 |
1994年 | 67篇 |
1993年 | 45篇 |
1992年 | 45篇 |
1991年 | 41篇 |
1990年 | 25篇 |
1989年 | 25篇 |
1988年 | 14篇 |
1987年 | 12篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1975年 | 1篇 |
1959年 | 2篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
2.
Wesley P. Chan Hiroto Mizohana Xiangyu Chen Yasuto Shiigi Yoshiyuki Yamanoue Masaki Nagatsuka Masayuki Inaba 《野外机器人技术杂志》2019,36(1):17-33
The use of field robots can greatly decrease the amount of time, effort, and associated risk compared to if human workers were to carryout certain tasks such as disaster response. However, transportability and reliability remain two main issues for most current robot systems. To address the issue of transportability, we have developed a lightweight modularizable platform named AeroArm. To address the issue of reliability, we utilize a multimodal sensing approach, combining the use of multiple sensors and sensor types, and the use of different detection algorithms, as well as active continuous closed‐loop feedback to accurately estimate the state of the robot with respect to the environment. We used Challenge 2 of the 2017 Mohammed Bin Zayed International Robotics Competition as an example outdoor manipulation task, demonstrating the capabilities of our robot system and approach in achieving reliable performance in the fields, and ranked fifth place internationally in the competition. 相似文献
3.
Lu Zhang Junjie Shang Tim Pelton Leslee Francis Pelton 《Journal of Computer Assisted Learning》2020,36(4):540-548
With the advent of mobile technologies, well-designed fraction apps can be used to help children gain fraction knowledge, a challenging topic for both teachers and students. The present pilot study adopted a quasi-experimental design to investigate whether children can learn fraction concepts equally well if half of the lesson time (20 min) is replaced with game-based learning. Keeping the total lesson time (40 min) identical, the control group (N = 33) received traditional instruction, and the experimental group (N = 32) was presented with a blended learning approach spending half of the class time (20 min) playing tablet-based fraction games, where each of the learners had their own tablet. The results suggested that in the posttest, the experimental group achieved similar learning gains to the control group and appear to have achieved better performance in the transfer test than the control group. This paper also discusses the efficiency of game-based learning, the mechanism of how fraction games might enhance learning, and the potential of integrating game-based learning in educational settings. 相似文献
4.
5.
6.
Zhen Wu Jing Yao Pengfei Zhu Fusheng Yang Xiangyu Meng Sandra Kurko Zaoxiao Zhang 《International Journal of Hydrogen Energy》2021,46(19):11183-11198
Advanced biogas power generation technology has been attracting attentions, which contributes to the waste disposal and the mitigation of greenhouse gas emissions. This work proposes and models a novel biogas-fed hybrid power generation system consisting of solid oxide fuel cell, water gas shift reaction, thermal swing adsorption and proton exchange membrane fuel cell (SOFC-WGS-TSA-PEMFC). The thermodynamic, exergetic, and thermo-economic analyses of this hybrid system for power generation were conducted to comprehensively evaluate its performance. It was found that the novel biogas-fed hybrid system has a gross energy conversion efficiency of 68.63% and exergy efficiency of 65.36%, indicating high efficiency for this kind of hybrid power technology. The market sensitivity analysis showed that the hybrid system also has a low sensitivity to market price fluctuation. Under the current subsidy level for the distributed biogas power plant, the levelized cost of energy can be lowered to 0.02942 $/kWh for a 1 MW scale system. Accordingly, the payback period and annual return on investment can reach 1.4 year and about 20%, respectively. These results reveal that the proposed hybrid system is promising and economically feasible as a distributed power plant, especially for the small power scale (no more than 2 MW). 相似文献
7.
8.
研究了具有新型结构的双膦胺镍配合物N,N-双(二苯膦基)-对甲氧基苯胺二氯化镍-甲基铝氧烷(PNP-N i-MAO)催化体系对苯乙烯聚合的催化性能,考察了聚合温度、n(A l)∶n(PNP-N i)、PNP-N i的浓度和苯乙烯的浓度对催化活性、苯乙烯转化率、聚苯乙烯相对分子质量及其分布的影响,并用核磁共振和凝胶色谱对聚苯乙烯的结构进行了表征。实验结果表明,在聚合温度25℃、聚合时间1h、n(A l)∶n(PNP-N i)=300、c(苯乙烯)=2.3m ol/L、c(PNP-N i)=0.4mm ol/L、甲苯为溶剂的适宜条件下,苯乙烯的转化率可达95%以上,催化活性达到5×105g/(m ol.h)左右。核磁共振和凝胶色谱表征结果显示,所得聚苯乙烯为无规结构,重均相对分子质量约为1×104,相对分子质量分布Mw/Mn约为2。 相似文献
9.
10.
Weijia Shang O'Keefe M.T. Fortes J.A.B. 《Parallel and Distributed Systems, IEEE Transactions on》1994,5(2):193-204
This paper describes several loop transformation techniques for extracting parallelism from nested loop structures. Nested loops can then be scheduled to run in parallel so that execution time is minimized. One technique is called selective cycle shrinking, and the other is called true dependence cycle shrinking. It is shown how selective shrinking is related to linear scheduling of nested loops and how true dependence shrinking is related to conflict-free mappings of higher dimensional algorithms into lower dimensional processor arrays. Methods are proposed in this paper to find the selective and true dependence shrinkings with minimum total execution time by applying the techniques of finding optimal linear schedules and optimal and conflict-free mappings proposed by W. Shang and A.B. Fortes 相似文献