全文获取类型
收费全文 | 30946篇 |
免费 | 2151篇 |
国内免费 | 1483篇 |
学科分类
工业技术 | 34580篇 |
出版年
2024年 | 87篇 |
2023年 | 370篇 |
2022年 | 597篇 |
2021年 | 802篇 |
2020年 | 847篇 |
2019年 | 641篇 |
2018年 | 614篇 |
2017年 | 891篇 |
2016年 | 1097篇 |
2015年 | 1243篇 |
2014年 | 1962篇 |
2013年 | 1735篇 |
2012年 | 2499篇 |
2011年 | 2764篇 |
2010年 | 2008篇 |
2009年 | 1914篇 |
2008年 | 1677篇 |
2007年 | 2012篇 |
2006年 | 1895篇 |
2005年 | 1571篇 |
2004年 | 1310篇 |
2003年 | 1156篇 |
2002年 | 926篇 |
2001年 | 803篇 |
2000年 | 707篇 |
1999年 | 545篇 |
1998年 | 404篇 |
1997年 | 281篇 |
1996年 | 316篇 |
1995年 | 260篇 |
1994年 | 195篇 |
1993年 | 87篇 |
1992年 | 88篇 |
1991年 | 68篇 |
1990年 | 48篇 |
1989年 | 37篇 |
1988年 | 22篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1982年 | 3篇 |
1981年 | 10篇 |
1980年 | 9篇 |
1979年 | 6篇 |
1977年 | 3篇 |
1964年 | 4篇 |
1957年 | 2篇 |
1956年 | 2篇 |
1955年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
1.
2.
3.
5.
《Journal of dairy science》2022,105(4):3176-3191
Milk concentrates are used in the manufacturing of dairy products such as yogurt and cheese or are processed into milk powder. Processes for the nonthermal separation of water and valuable milk ingredients are becoming increasingly widespread at farm level. The technical barriers to using farm-manufactured milk concentrate in dairies are minimal, hence the suspicion that the practice of on-farm raw milk concentration is still fairly uncommon for economic reasons. This study, therefore, set out to investigate farmers' potential willingness to adopt a raw milk concentration plant. The empirical analysis was based on discrete choice experiments with 75 German dairy farmers to identify preferences and the possible adoption of on-farm raw milk concentration. The results showed that, in particular, farmers who deemed the current milk price to be insufficient viewed on-farm concentration using membrane technology as an option for diversifying their milk sales. We found no indication that adoption would be impeded by a lack of trustworthy information on milk processing technologies or capital. 相似文献
6.
7.
目的研究蛋类礼盒包装结构的缓冲性能。方法以蛋类尺寸为基础,建立可发性聚乙烯(expandable polyethylene. EPE)缓冲单元结构和组合结构,进行静态仿真分析和实验验证,比较结构在形状、叠合层数、组合形式等参数变化时的载荷与位移。结果结构层数变化相同时,单元结构的极限载荷从143N增加到236 N,组合结构的极限载荷从224 N增加到476 N,均呈近线性增长。结论蛋类礼盒包装中,组合结构的承载能力优于单元结构,通过单元结构的组合,可满足不同蛋类的包装要求。 相似文献
8.
This paper analyzes the problems existing in the teaching of data structure course, and puts forward the reform from the as-
pects of strengthening basic programming, visualized explanation of abstract theory, combination of C++, Java programming, ratio-
nal use of online platform, and stratification of exercises, aiming at improving students' practical ability, learning interest and self-
confidence. 相似文献
9.
As suggested by the uncanny valley hypothesis, robots that resemble humans likely elicit feelings of eeriness. Based on the psychological model of meaning maintenance, we expected that the uncanny valley experience could be mitigated through a fictional story, due to the meaning-generating function of narratives. A field experiment was conducted, in which 75 participants interacted with the humanlike robot Telenoid. Prior to the interaction, they either read a short story, a non-narrative leaflet about the robot, or they received no preliminary information. Eeriness ratings were significantly lower in the science fiction condition than in both other conditions. This effect was mediated by higher perceived human-likeness of the robot. Our findings suggest that science fiction may provide meaning for otherwise unsettling future technologies. 相似文献
10.