全文获取类型
收费全文 | 259055篇 |
免费 | 34417篇 |
国内免费 | 19342篇 |
专业分类
电工技术 | 30338篇 |
技术理论 | 17篇 |
综合类 | 22785篇 |
化学工业 | 24955篇 |
金属工艺 | 7872篇 |
机械仪表 | 17846篇 |
建筑科学 | 16993篇 |
矿业工程 | 7646篇 |
能源动力 | 5065篇 |
轻工业 | 15511篇 |
水利工程 | 5738篇 |
石油天然气 | 10123篇 |
武器工业 | 3052篇 |
无线电 | 35787篇 |
一般工业技术 | 21742篇 |
冶金工业 | 8633篇 |
原子能技术 | 3325篇 |
自动化技术 | 75386篇 |
出版年
2024年 | 1499篇 |
2023年 | 4641篇 |
2022年 | 10138篇 |
2021年 | 11723篇 |
2020年 | 9997篇 |
2019年 | 7998篇 |
2018年 | 7736篇 |
2017年 | 9910篇 |
2016年 | 11510篇 |
2015年 | 13323篇 |
2014年 | 19224篇 |
2013年 | 17520篇 |
2012年 | 19641篇 |
2011年 | 19706篇 |
2010年 | 15153篇 |
2009年 | 14780篇 |
2008年 | 14783篇 |
2007年 | 17694篇 |
2006年 | 15663篇 |
2005年 | 13658篇 |
2004年 | 10596篇 |
2003年 | 9267篇 |
2002年 | 7363篇 |
2001年 | 5666篇 |
2000年 | 4714篇 |
1999年 | 3584篇 |
1998年 | 2639篇 |
1997年 | 2171篇 |
1996年 | 1905篇 |
1995年 | 1548篇 |
1994年 | 1256篇 |
1993年 | 903篇 |
1992年 | 763篇 |
1991年 | 628篇 |
1990年 | 542篇 |
1989年 | 470篇 |
1988年 | 373篇 |
1987年 | 235篇 |
1986年 | 212篇 |
1985年 | 236篇 |
1984年 | 218篇 |
1983年 | 171篇 |
1982年 | 148篇 |
1981年 | 109篇 |
1980年 | 105篇 |
1979年 | 69篇 |
1977年 | 38篇 |
1964年 | 55篇 |
1962年 | 77篇 |
1959年 | 53篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
This paper presents a new design of mobile micro manipulation system for robotic micro assembly where a compliant piezoelectric actuator based micro gripper is designed for handling the miniature parts and compensation of misalignment during peg-in-hole assembly is done because piezoelectric actuator has capability of producing the displacement in micron range and generates high force instantaneously. This adjusts the misalignment of peg during robotic micro assembly. The throughput/speed of mobile micro manipulation system is found for picking and placing the peg from one hole to next hole position. An analysis of piezoelectric actuator based micro gripper has been carried out where voltage is controlled through a proportional-derivative (PD) controller. By developing a prototype, it is demonstrated that compliant piezoelectric actuator based micro gripper is capable of handling the peg-in-hole assembly task in a mobile micro manipulation system. 相似文献
3.
4.
本文以云杉八齿小蠹Ips typographus Linnaeus为例,经标本选取,观察虫体整体形态,绘制整体结构草图,电子显微镜观察局部、得到局部数字图像,分别建立虫体每一部分的高精度细节。把模型每部分拼装在一起组成整体模型,构建出了云杉八齿小蠹三维虚拟昆虫数字化模型。 相似文献
5.
Serena Finco Daria Battini Xavier Delorme Alessandro Persona Fabio Sgarbossa 《国际生产研究杂志》2020,58(4):1255-1270
Ergonomic aspects have a crucial role in manual assembly systems. They impact on the workers’ health, final product quality and productivity. For these reasons, there is the necessity to integrate them into the assembly line balancing phase as, whereas, only time and cost variables are considered. In this study, human energy expenditures are considered as ergonomic aspects and we integrate them, for the first time, into the assembly line balancing problem type 2 through the rest allowance evaluation. We consider as an objective function the minimization of the smoothness index. Firstly, a new optimal method based on mixed integer linear programming and a new linearization methodology are proposed. Then, a heuristic approach is introduced. To complete the study, a computational experimentation is presented to validate the mathematical model and to compare the methodologies proposed in terms of computational time, complexity and solution. Additionally, we provide a detailed analysis of the impact that rest allowance evaluation can have on productivity comparing the results obtained, taking into account the rest allowance integration before, during and after the assembly balancing process. 相似文献
6.
7.
8.
Akira Yamamoto Kentaro Teramura Saburo Hosokawa Tsunehiro Tanaka 《Science and Technology of Advanced Materials》2015,16(2)
The effect of SO2 gas was investigated on the activity of the photo-assisted selective catalytic reduction of nitrogen monoxide (NO) with ammonia (NH3) over a TiO2 photocatalyst in the presence of excess oxygen (photo-SCR). The introduction of SO2 (300 ppm) greatly decreased the activity of the photo-SCR at 373 K. The increment of the reaction temperature enhanced the resistance to SO2 gas, and at 553 K the conversion of NO was stable for at least 300 min of the reaction. X-ray diffraction, FTIR spectroscopy, thermogravimetry and differential thermal analysis, x-ray photoelectron spectroscopy (XPS), elemental analysis and N2 adsorption measurement revealed that the ammonium sulfate species were generated after the reaction. There was a strong negative correlation between the deposition amount of the ammonium sulfate species and the specific surface area. Based on the above relationship, we concluded that the deposition of the ammonium sulfate species decreased the specific surface area by plugging the pore structure of the catalyst, and the decrease of the specific surface area resulted in the deactivation of the catalyst. 相似文献
9.