全文获取类型
收费全文 | 57787篇 |
免费 | 2658篇 |
国内免费 | 204篇 |
专业分类
电工技术 | 868篇 |
综合类 | 97篇 |
化学工业 | 10837篇 |
金属工艺 | 2068篇 |
机械仪表 | 3073篇 |
建筑科学 | 1238篇 |
矿业工程 | 52篇 |
能源动力 | 2158篇 |
轻工业 | 4080篇 |
水利工程 | 252篇 |
石油天然气 | 211篇 |
武器工业 | 1篇 |
无线电 | 10018篇 |
一般工业技术 | 11227篇 |
冶金工业 | 6983篇 |
原子能技术 | 631篇 |
自动化技术 | 6855篇 |
出版年
2023年 | 531篇 |
2022年 | 833篇 |
2021年 | 1403篇 |
2020年 | 991篇 |
2019年 | 1009篇 |
2018年 | 1335篇 |
2017年 | 1327篇 |
2016年 | 1651篇 |
2015年 | 1303篇 |
2014年 | 2033篇 |
2013年 | 3491篇 |
2012年 | 3195篇 |
2011年 | 3903篇 |
2010年 | 2971篇 |
2009年 | 3165篇 |
2008年 | 2918篇 |
2007年 | 2470篇 |
2006年 | 2244篇 |
2005年 | 1939篇 |
2004年 | 1854篇 |
2003年 | 1700篇 |
2002年 | 1653篇 |
2001年 | 1291篇 |
2000年 | 1206篇 |
1999年 | 1212篇 |
1998年 | 2537篇 |
1997年 | 1627篇 |
1996年 | 1354篇 |
1995年 | 1015篇 |
1994年 | 792篇 |
1993年 | 754篇 |
1992年 | 497篇 |
1991年 | 508篇 |
1990年 | 430篇 |
1989年 | 422篇 |
1988年 | 335篇 |
1987年 | 288篇 |
1986年 | 262篇 |
1985年 | 243篇 |
1984年 | 200篇 |
1983年 | 154篇 |
1982年 | 160篇 |
1981年 | 136篇 |
1980年 | 137篇 |
1979年 | 102篇 |
1978年 | 99篇 |
1977年 | 161篇 |
1976年 | 253篇 |
1975年 | 82篇 |
1974年 | 74篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
Su-gil Cho Junyong Jang Shinyu Kim Sanghyun Park Tae Hee Lee Minuk Lee Jong-Su Choi Hyung-Woo Kim Sup Hong 《Structural and Multidisciplinary Optimization》2016,54(6):1671-1688
Uncertainty-based multidisciplinary design optimization (UMDO) has been widely acknowledged as an advanced methodology to address competing objectives and reliable constraints of complex systems by coupling relationship of disciplines involved in the system. UMDO process consists of three parts. Two parts are to define the system with uncertainty and to formulate the design optimization problem. The third part is to quantitatively analyze the uncertainty of the system output considering the uncertainty propagation in the multidiscipline analysis. One of the major issues in the UMDO research is that the uncertainty propagation makes uncertainty analysis difficult in the complex system. The conventional methods are based on the parametric approach could possibly cause the error when the parametric approach has ill-estimated distribution because data is often insufficient or limited. Therefore, it is required to develop a nonparametric approach to directly use data. In this work, the nonparametric approach for uncertainty-based multidisciplinary design optimization considering limited data is proposed. To handle limited data, three processes are also adopted. To verify the performance of the proposed method, mathematical and engineering examples are illustrated. 相似文献
942.
This study developed a droplet biochip driven with a single vacuum module to produce droplets from small sample volumes. The vacuum module is composed of a shape memory polymer, which releases prestored energy for shape recovery when subjected to heat trigger, and works as an easy-to-attach vacuum source. The three-layer Teflon mold is designed to manufacture a vacuum module with a favorable yield (>95%). The water-in-oil emulsion droplets can be produced by attaching a single vacuum module with a microfluidic chip. The diameter of the vacuum module has been successfully reduced to 6 mm. The maximum driving pressure provided by the 15-mm diameter vacuum module attached with a 2 μL chip is approximately 9653 Pa. The produced flow rate varies with the deformation rate of the vacuum module and becomes stable at 2.4 µL/min during the droplet generation. The droplet diameters range from 180 to 240 µm. The developed disposable vacuum module is easy to attach, easy to use, easy to make, cost-effective, and automatically controllable for driving fluids on a chip for handling small sample volumes. 相似文献
943.
944.
The Double‐Edged Sword: The Effects of Journalists' Social Media Activities on Audience Perceptions of Journalists and Their News Products 下载免费PDF全文
Jayeon Lee 《Journal of Computer-Mediated Communication》2015,20(3):312-329
As social media become popular news platforms, journalists and news organizations have been keen to capitalize on their potential to build and maintain audiences. However, little is known about the extent to which these efforts may have adverse implications. Based on normative theories, the present study investigates the influence of journalists' social media activities (specifically, self‐disclosure and interaction with other users) on audience perceptions of journalists. An experiment (N = 267) revealed that: Although both journalists' self‐disclosure and interaction positively influenced audience perceptions of the journalists in the personal dimension, interaction negatively influenced audience perceptions in the professional dimension; and the perceptions transferred to perceptions of news products, thereby mediating the relationship between journalists' social media activities and audience news perceptions. 相似文献
945.
946.
947.
948.
949.
950.