全文获取类型
收费全文 | 81256篇 |
免费 | 6516篇 |
国内免费 | 3101篇 |
专业分类
电工技术 | 4411篇 |
技术理论 | 6篇 |
综合类 | 4915篇 |
化学工业 | 14111篇 |
金属工艺 | 4340篇 |
机械仪表 | 5246篇 |
建筑科学 | 5706篇 |
矿业工程 | 2585篇 |
能源动力 | 2552篇 |
轻工业 | 5537篇 |
水利工程 | 1138篇 |
石油天然气 | 5592篇 |
武器工业 | 523篇 |
无线电 | 8687篇 |
一般工业技术 | 10596篇 |
冶金工业 | 4256篇 |
原子能技术 | 862篇 |
自动化技术 | 9810篇 |
出版年
2024年 | 321篇 |
2023年 | 1363篇 |
2022年 | 2320篇 |
2021年 | 3202篇 |
2020年 | 2440篇 |
2019年 | 2200篇 |
2018年 | 2526篇 |
2017年 | 2764篇 |
2016年 | 2362篇 |
2015年 | 2994篇 |
2014年 | 3903篇 |
2013年 | 4745篇 |
2012年 | 4890篇 |
2011年 | 5490篇 |
2010年 | 4747篇 |
2009年 | 4437篇 |
2008年 | 4332篇 |
2007年 | 4158篇 |
2006年 | 4167篇 |
2005年 | 3826篇 |
2004年 | 2541篇 |
2003年 | 2343篇 |
2002年 | 2148篇 |
2001年 | 1905篇 |
2000年 | 1987篇 |
1999年 | 2204篇 |
1998年 | 1892篇 |
1997年 | 1532篇 |
1996年 | 1470篇 |
1995年 | 1263篇 |
1994年 | 1020篇 |
1993年 | 769篇 |
1992年 | 589篇 |
1991年 | 450篇 |
1990年 | 349篇 |
1989年 | 275篇 |
1988年 | 238篇 |
1987年 | 148篇 |
1986年 | 124篇 |
1985年 | 100篇 |
1984年 | 76篇 |
1983年 | 50篇 |
1982年 | 50篇 |
1981年 | 42篇 |
1980年 | 30篇 |
1979年 | 16篇 |
1977年 | 9篇 |
1976年 | 11篇 |
1975年 | 8篇 |
1970年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
随着FPGA技术和电力电机技术的发展,FPGA+ARM的集成方式已经成为FPGA的发展方向.针对一体化多轴运动控制与驱动的特点,选用了集成双核ARM CPU与FPGA结合的Xilinx Zynq-7020全可编程System-on-chip(SoC)作为硬件平台,一个ARM CPU完成多轴的位置环、速度环和电流环的算法以及多轴轨迹生成,能同时完成伺服高级算法如谐振等,另一个ARM CPU完成交互功能,发挥FPGA高速运算的功能,完成6轴电流环流水线控制以及双采样双更新电流环算法.提高了系统整体带宽,实现多轴ns级同步精度以实现更精确的位置轨迹,驱控一体内部数据通过共享内存以及高速内部总线的方式进行交换,其传输速度更快、传输信息更加丰富. 相似文献
42.
43.
45.
Yong Xu Yun Li Songlin Li Francis Balestra Gerard Ghibaudo Wenwu Li Yen‐Fu Lin Huabin Sun Jing Wan Xinran Wang Yufeng Guo Yi Shi Yong‐Young Noh 《Advanced functional materials》2020,30(20)
Unreliable mobility values, and particularly greatly overestimated values and severely distorted temperature dependences, have recently hampered the development of the organic transistor field. Given that organic field‐effect transistors (OFETs) have been routinely used to evaluate mobility, precise parameter extraction using the electrical properties of OFETs is thus of primary importance. This review examines the origins of the various mobilities that must be determined for OFET applications, the relevant extraction methods, and the data selection limitations, which help in avoiding conceptual errors during mobility extraction. For increased precision, the review also discusses device fabrication considerations, calibration of both the specific gate‐dielectric capacitance and the threshold voltage, the contact effects, and the bias and temperature dependences, which must actually be handled with great care but have mostly been overlooked to date. This review serves as a systematic overview of the OFET mobility extraction process to ensure high precision and will also aid in improving future research. 相似文献
46.
Wei Mengnan Ban Boyuan Li Jingwei Sun Jifei Li Feifei Jiang Xuesong Chen Jian 《SILICON》2020,12(2):327-338
Silicon - A novel green cationic surfactant Poly (propylene glycol) bis (2-aminopropyl ether) (PEA) with multiple amine groups was utilized as a collector for flotation separation of quartz from... 相似文献
47.
Esteban Vera Pingitore María Silvina Juárez Tomás Birgitt Wiese 《Drug development and industrial pharmacy》2015,41(6):942-952
Context: The administration of pharmabiotics is a promising alternative to antimicrobial drugs for the treatment and/or prevention of female urogenital infections.Objective: To design pharmabiotic formulations including bioactive ingredients of microbial origin combined with non-microbial substances and then to evaluate the stability of the combinations during freeze-drying and storage.Materials and methods: Different formulations including Lactobacillus gasseri CRL 1263, Lactobacillus salivarius CRL 1328, salivaricin CRL 1328 (a bacteriocin) and non-microbial compounds (lactose, inulin and ascorbic acid) were assayed, and the ingredients were freeze-dried together or separately. The formulations were stored in gelatin capsules at 4?°C for 360?d.Results: The viability of lactobacilli was affected to different extents depending on the strains and on the formulations assayed. L. salivarius and ascorbic acid were successfully combined only after the freeze-drying process. Salivaricin activity was not detected in formulations containing L. gasseri. However, when combined with ascorbic acid, lactose, inulin or L. salivarius, the bacteriocin maintained its activity for 360?d. The selected microorganisms proved to be compatible for their inclusion in multi-strain formulations together with lactose, inulin and ascorbic acid. Salivaricin could be included only in a L. salivarius CRL 1328 single-strain formulation together with non-microbial substances.Conclusions: This study provides new insights into the design of urogenital pharmabiotics combining beneficial lactobacilli, salivaricin CRL 1328 and compounds with different functionalities. 相似文献
48.
49.
Bing Yang Yu Zhou Wenjie Yu Song Zhang Hongxiang Chen Ju Ye 《Polymer International》2019,68(4):675-683
In order to improve the dispersity and stability of the nano‐SiO2 aqueous system with high solid content, a kind of polyacrylic acid dispersant with methoxysilicon end groups (KH590‐PAA) was synthesized by photopolymerization of acrylic acid (AA) initiated with (3‐mercaptopropyl)trimethoxysilane (KH590). After adding KH590‐PAA into the nano‐SiO2 aqueous dispersion system (20 wt% solid content), the viscosity and the curing time of the system were measured with a rotational viscometer and the inverted bottle method. Moreover, the dispersion mechanism of KH590‐PAA for the nano‐SiO2 aqueous system was researched by measuring the adsorption capacity, the particle size and the zeta potential of the nanoparticles with a conductivity meter, dynamic light scattering, SEM and TEM, respectively. The results showed that the methoxysilicon groups in KH590‐PAA could react with hydroxyl groups on the surface of nano‐SiO2 in the process of stirring, which enhanced the adsorption capacity of the dispersant and then increased the surface charge of the particles. Therefore, electrostatic repulsion and steric hindrance effects between the SiO2 nanoparticles could be further enhanced by adding the KH590‐PAA dispersant, and then the nano‐SiO2 aqueous system exhibited better dispersity and stability. Besides, the dispersion properties of SiO2 nanoparticles in water were closely related to the addition amount and the molecular weight of the KH590‐PAA dispersant. © 2018 Society of Chemical Industry 相似文献
50.