全文获取类型
收费全文 | 466761篇 |
免费 | 37767篇 |
国内免费 | 20621篇 |
专业分类
电工技术 | 28014篇 |
技术理论 | 27篇 |
综合类 | 30496篇 |
化学工业 | 75527篇 |
金属工艺 | 25514篇 |
机械仪表 | 28885篇 |
建筑科学 | 38567篇 |
矿业工程 | 12274篇 |
能源动力 | 13098篇 |
轻工业 | 31724篇 |
水利工程 | 8687篇 |
石油天然气 | 24428篇 |
武器工业 | 3621篇 |
无线电 | 55721篇 |
一般工业技术 | 55564篇 |
冶金工业 | 23199篇 |
原子能技术 | 5152篇 |
自动化技术 | 64651篇 |
出版年
2024年 | 1518篇 |
2023年 | 6404篇 |
2022年 | 12016篇 |
2021年 | 17494篇 |
2020年 | 12895篇 |
2019年 | 10627篇 |
2018年 | 11943篇 |
2017年 | 13646篇 |
2016年 | 12510篇 |
2015年 | 17327篇 |
2014年 | 22400篇 |
2013年 | 28124篇 |
2012年 | 29944篇 |
2011年 | 33290篇 |
2010年 | 29271篇 |
2009年 | 28570篇 |
2008年 | 27688篇 |
2007年 | 26626篇 |
2006年 | 26439篇 |
2005年 | 22951篇 |
2004年 | 15499篇 |
2003年 | 13349篇 |
2002年 | 12481篇 |
2001年 | 10971篇 |
2000年 | 10742篇 |
1999年 | 11708篇 |
1998年 | 10373篇 |
1997年 | 8692篇 |
1996年 | 7897篇 |
1995年 | 6634篇 |
1994年 | 5374篇 |
1993年 | 4210篇 |
1992年 | 3296篇 |
1991年 | 2483篇 |
1990年 | 2015篇 |
1989年 | 1693篇 |
1988年 | 1340篇 |
1987年 | 916篇 |
1986年 | 746篇 |
1985年 | 560篇 |
1984年 | 394篇 |
1983年 | 319篇 |
1982年 | 301篇 |
1981年 | 255篇 |
1980年 | 242篇 |
1979年 | 157篇 |
1978年 | 111篇 |
1977年 | 113篇 |
1976年 | 159篇 |
1973年 | 69篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Feng Wenran Li Zhen Chen Yingying Chen Jinyang Lang Haoze Wan Jianghong Gao Yan Dong Haitao 《Journal of Materials Science》2022,57(3):1881-1889
Journal of Materials Science - Although chalcogenide materials continue to generate considerable interest due to great potentials for various optoelectronic devices, annealing for a long time in... 相似文献
2.
Chen Wen-Kuo Chang Jing-Rong Chen Long-Sheng Hsu Rui-Yang 《Multimedia Tools and Applications》2022,81(6):8317-8347
Multimedia Tools and Applications - With the advancement of technology and the spread of the COVID19 epidemic, learning can no longer only be done through face-to-face teaching. Numerous digital... 相似文献
4.
Xiao Zhu Chen Yanxun Jiang Hongbo Hu Zhenzhen Lui John C. S. Min Geyong Dustdar Schahram 《Wireless Networks》2022,28(7):3305-3322
Wireless Networks - Unmanned aerial vehicles (UAV) have been widely used in various fields because of their high mobility and portability. At the same time, due to the rapid development of... 相似文献
5.
7.
8.
Kelin Hu Feipeng Wang Yuyang Yan Hongcheng Liu Zijia Shen 《Ceramics International》2021,47(11):15228-15236
In this paper, a novel hybrid structure of Pd doped ZnO/SnO2 heterojunction nanofibers with hexagonal ZnO columns was one step synthesized from electrospun precursor nanofibers. Due to the synergistic effect of hexagonal ZnO, SnO2 and Pd, the structure exhibited excellent hydrogen (H2) gas sensing properties. At low-temperature of 120 °C, the response (Ra/Rg) to 100 ppm H2 gas exceeded 160, the response/recovery time was only 20 s and 6 s respectively and the limit of detection was only 0.5 ppm. Meanwhile, it also had good selectivity for H2 gas and excellent linearity. In addition, the materials were characterized by XRD, FESEM, HRTEM, XPS, and the synthesis mechanism and gas sensing mechanism were proposed. 相似文献
9.
Shanshan Zhuang Wenxiong Zheng Yunong Na Naiyi Chen Fan Gong Bingxuan Huang Stephen Brennan Charles Congyi Liu Jian Cheng Lukai Ma Huifan Liu 《International Journal of Food Science & Technology》2022,57(2):1093-1103
The β-Carotene (BC), an important precursor of vitamin A (VA), possesses antioxidant activity but is fat-soluble and has low bioavailability. In previous in-vitro assays evaluating antioxidant and 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) free radical scavenging, both BC and VA showed a strong ability to scavenge radicals and protected cells from oxidative stress. Here, we used artificially simulated gastrointestinal digestion and Caco-2 cell absorption models to evaluate the bioavailability of the BC during gastrointestinal digestion and absorption using high-performance liquid chromatography (HPLC) analysis. We observed high absorptive and transfer rates of BC and detected retinol metabolites (Vitamin A). Therefore, BC can be detected in the acidic gastrointestinal environment using HPLC. Optimised method provided better separation of BC and VA in the column, improving the accuracy of the test results. 相似文献
10.
This paper investigates PID control design for a class of planar nonlinear uncertain systems in the presence of actuator saturation. Based on the bounds on the growth rates of the nonlinear uncertain function in the system model, the system is placed in a linear differential inclusion. Each vertex system of the linear differential inclusion is a linear system subject to actuator saturation. By placing the saturated PID control into a convex hull formed by the PID controller and an auxiliary linear feedback law, we establish conditions under which an ellipsoid is contractively invariant and hence is an estimate of the domain of attraction of the equilibrium point of the closed-loop system. The equilibrium point corresponds to the desired set point for the system output. Thus, the location of the equilibrium point and the size of the domain of attraction determine, respectively, the set point that the output can achieve and the range of initial conditions from which this set point can be reached. Based on these conditions, the feasible set points can be determined and the design of the PID control law that stabilizes the nonlinear uncertain system at a feasible set point with a large domain of attraction can then be formulated and solved as a constrained optimization problem with constraints in the form of linear matrix inequalities (LMIs). Application of the proposed design to a magnetic suspension system illustrates the design process and the performance of the resulting PID control law. 相似文献