全文获取类型
收费全文 | 66956篇 |
免费 | 6729篇 |
国内免费 | 3628篇 |
专业分类
电工技术 | 4391篇 |
技术理论 | 5篇 |
综合类 | 5236篇 |
化学工业 | 10819篇 |
金属工艺 | 3620篇 |
机械仪表 | 4367篇 |
建筑科学 | 5756篇 |
矿业工程 | 2150篇 |
能源动力 | 1935篇 |
轻工业 | 5322篇 |
水利工程 | 1270篇 |
石油天然气 | 2943篇 |
武器工业 | 520篇 |
无线电 | 7916篇 |
一般工业技术 | 7974篇 |
冶金工业 | 2972篇 |
原子能技术 | 856篇 |
自动化技术 | 9261篇 |
出版年
2024年 | 307篇 |
2023年 | 1158篇 |
2022年 | 2083篇 |
2021年 | 2899篇 |
2020年 | 2167篇 |
2019年 | 1859篇 |
2018年 | 2004篇 |
2017年 | 2240篇 |
2016年 | 2089篇 |
2015年 | 2717篇 |
2014年 | 3436篇 |
2013年 | 4111篇 |
2012年 | 4441篇 |
2011年 | 4579篇 |
2010年 | 4309篇 |
2009年 | 3997篇 |
2008年 | 3821篇 |
2007年 | 3564篇 |
2006年 | 3481篇 |
2005年 | 2993篇 |
2004年 | 2165篇 |
2003年 | 2333篇 |
2002年 | 2811篇 |
2001年 | 2481篇 |
2000年 | 1752篇 |
1999年 | 1551篇 |
1998年 | 1048篇 |
1997年 | 919篇 |
1996年 | 833篇 |
1995年 | 708篇 |
1994年 | 572篇 |
1993年 | 378篇 |
1992年 | 322篇 |
1991年 | 251篇 |
1990年 | 174篇 |
1989年 | 158篇 |
1988年 | 124篇 |
1987年 | 79篇 |
1986年 | 65篇 |
1985年 | 46篇 |
1984年 | 25篇 |
1983年 | 19篇 |
1982年 | 25篇 |
1981年 | 17篇 |
1980年 | 33篇 |
1979年 | 19篇 |
1977年 | 10篇 |
1962年 | 42篇 |
1961年 | 39篇 |
1960年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Dan Ye Kaiyu Wang Haijiao Yang Xingang Zhao 《International Journal of Adaptive Control and Signal Processing》2020,34(11):1677-1696
In this article, an adaptive fuzzy output feedback control method is presented for nonlinear time-delay systems with time-varying full state constraints and input saturation. To overcome the problem of time-varying constraints, the integral barrier Lyapunov functions (IBLFs) integrating with dynamic surface control (DSC) are applied for the first time to keep the state from violating constraints. The effects of unknown time delays can be removed by using designed Lyapunov-Krasovskii functions (LKFs). An auxiliary design system is introduced to solve the problem of input saturation. The unknown nonlinear functions are approximated by the fuzzy logic systems (FLS), and the unmeasured states are estimated by a designed fuzzy observer. The novel controller can guarantee that all signals remain semiglobally uniformly ultimately bounded and satisfactory tracking performance is achieved. Finally, two simulation examples illustrate the effectiveness of the presented control methods. 相似文献
12.
Yan Jing Zhu Rongying Wu Fan Zhao Ziyin Ye Huan Hou Mengying Liu Yong Yin Lichen 《Nano Research》2020,13(10):2706-2715
Nano Research - Insufficient intratumoral penetration greatly hurdles the anticancer performance of nanomedicine. To realize highly efficient tumor penetration in a precisely and spatiotemporally... 相似文献
13.
14.
15.
Scientometrics - In traditional research, the application of quantitative measurement on the value and influence of uncited papers is not feasible owing to the lack of data. The rapid advancement... 相似文献
16.
Qi Yang Qilong Wu Yang Liu Shuiping Luo Xiaotong Wu Xixia Zhao Haiyuan Zou Baihua Long Wen Chen Yujia Liao Lanxi Li Pei Kang Shen Lele Duan Zewei Quan 《Advanced materials (Deerfield Beach, Fla.)》2020,32(36):2002822
Engineering novel Sn-based bimetallic materials could provide intriguing catalytic properties to boost the electrochemical CO2 reduction. Herein, the first synthesis of homogeneous Sn1−xBix alloy nanoparticles (x up to 0.20) with native Bi-doped amorphous SnOx shells for efficient CO2 reduction is reported. The Bi-SnOx nanoshells boost the production of formate with high Faradaic efficiencies (>90%) over a wide potential window (−0.67 to −0.92 V vs RHE) with low overpotentials, outperforming current tin oxide catalysts. The state-of-the-art Bi-SnOx nanoshells derived from Sn0.80Bi0.20 alloy nanoparticles exhibit a great partial current density of 74.6 mA cm−2 and high Faradaic efficiency of 95.8%. The detailed electrocatalytic analyses and corresponding density functional theory calculations simultaneously reveal that the incorporation of Bi atoms into Sn species facilitates formate production by suppressing the formation of H2 and CO. 相似文献
17.
Loboda P. I. Minitsky A. V. Byba Ye. G. Sysoev M. O. Radchuk S. V. 《Powder Metallurgy and Metal Ceramics》2020,58(11-12):651-656
Powder Metallurgy and Metal Ceramics - The infiltration of aluminum melts into porous metal skeletons produced by powder metallurgy methods, including 3D printing, under a pressure gradient was... 相似文献
18.
As a solid state joining process, ultrasonic spot welding has been proven to be a promising technique for joining copper alloys. However, challenges still remain in employing ultrasonic spot welding to join copper alloys. This article comprehensively reviews the current state of ultrasonic spot welding of copper alloys with a number of critical issues including materials flow, plastic deformation, temperature distribution, vibration, relative motion, vertical displacement, interface friction coefficient, online monitoring technique, coupled with the macrostructure and microstructure, the mechanical properties and electrical conductivity. In addition, the future trends in this field are provided. 相似文献
19.
Effects of different carbon sources and C/N values on nonvolatile taste components of Pleurotus eryngii 下载免费PDF全文
Wen Li Xiaobei Li Yan Yang Feng Zhou Yanfang Liu Shuai Zhou Hailong Yu 《International Journal of Food Science & Technology》2015,50(11):2360-2366
Pleurotus eryngii, the second largest industrial cultivation mushroom in China, is usually cultivated on substrates mainly consisting of sawdust and corncob. In this study, experiments were performed to determine the effects of different carbon sources and C/N values on nonvolatile taste components of P. eryngii. The effects of different carbon sources on nonvolatile taste components levels revealed that sawdust was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while corncob was beneficial to high contents of carbohydrate, polysaccharides and trehalose. At the similar C/N values, relatively higher sawdust content was beneficial to umami amino acid production, while relatively higher corncob content was beneficial to high contents of carbohydrate, polysaccharides and mannitol. Higher C/N value was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while lower C/N value was beneficial to high contents of carbohydrate, polysaccharides and trehalose. These results provided information for P. eryngii fruit body industrial cultivation to obtain specific nonvolatile taste components with high levels. 相似文献
20.