全文获取类型
收费全文 | 107467篇 |
免费 | 12114篇 |
国内免费 | 6970篇 |
专业分类
电工技术 | 8449篇 |
技术理论 | 8篇 |
综合类 | 8966篇 |
化学工业 | 15766篇 |
金属工艺 | 6330篇 |
机械仪表 | 7363篇 |
建筑科学 | 8800篇 |
矿业工程 | 3807篇 |
能源动力 | 3272篇 |
轻工业 | 7943篇 |
水利工程 | 2522篇 |
石油天然气 | 4897篇 |
武器工业 | 1207篇 |
无线电 | 13291篇 |
一般工业技术 | 11477篇 |
冶金工业 | 4291篇 |
原子能技术 | 1485篇 |
自动化技术 | 16677篇 |
出版年
2024年 | 496篇 |
2023年 | 1832篇 |
2022年 | 3794篇 |
2021年 | 5444篇 |
2020年 | 4016篇 |
2019年 | 3155篇 |
2018年 | 3501篇 |
2017年 | 3863篇 |
2016年 | 3433篇 |
2015年 | 5179篇 |
2014年 | 6474篇 |
2013年 | 7604篇 |
2012年 | 8770篇 |
2011年 | 8956篇 |
2010年 | 8134篇 |
2009年 | 7478篇 |
2008年 | 7142篇 |
2007年 | 6427篇 |
2006年 | 5750篇 |
2005年 | 4716篇 |
2004年 | 3272篇 |
2003年 | 2810篇 |
2002年 | 3166篇 |
2001年 | 2639篇 |
2000年 | 1842篇 |
1999年 | 1537篇 |
1998年 | 969篇 |
1997年 | 822篇 |
1996年 | 688篇 |
1995年 | 609篇 |
1994年 | 480篇 |
1993年 | 321篇 |
1992年 | 267篇 |
1991年 | 236篇 |
1990年 | 154篇 |
1989年 | 123篇 |
1988年 | 104篇 |
1987年 | 61篇 |
1986年 | 49篇 |
1985年 | 30篇 |
1984年 | 18篇 |
1983年 | 7篇 |
1982年 | 25篇 |
1981年 | 20篇 |
1980年 | 42篇 |
1979年 | 25篇 |
1978年 | 7篇 |
1977年 | 7篇 |
1959年 | 20篇 |
1951年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
42.
Wei-Li Xie Xiao-Dong Zhang Wen-Hui Liu Qi Xie Guang-Wu Wen Xiao-Xiao Huang Jian-Dong Zhu Fei-Xiang Ma 《稀有金属(英文版)》2019,(3)
SiC nano wires were fabricated on the silicon substrate dipped with a layer of Ni catalyst at 900 ℃ by gas pressure annealing processing. The morphologies and crystal structures were determined by scanning electron microscopy(SEM), transmission electron microscopy(TEM)and X-ray diffraction(XRD). The results show that the assynthesized nanowires are β-SiC single crystalline with diameter range of 50-100 nm, and length of tens of micron by directly annealing at 900 ℃. The SiC nano wires grow along the [111] direction with highly uniform morphology. And the possible growth mechanism of SiC nano wires is proposed.The present work provides an efficient strategy for the production of high-quality SiC nano wires. 相似文献
43.
44.
45.
Liyan Wen Gang Tao Bin Jiang 《International Journal of Adaptive Control and Signal Processing》2021,35(3):373-400
In this article, adaptive compensation designs are developed for nonlinear systems with uncertainties from the system functions and persistent actuator failures of characterizations that (i) some unknown system inputs are stuck at some unknown fixed or varying values at unknown time instants and (ii) the failure pattern always switches from one to another and the switching does not stop. Such a controlled plant is described by an uncertain time-varying nonlinear system, and some robust adaptive feedback linearization based failure compensation results are studied for closed-loop system stabilization and bounded output tracking for some specific conditions. To improve the tracking performance in the presence of persistent actuator failures, a new adaptive control scheme is developed, using the failure indicator function which contains the failure pattern and failure time in the formulation. Detailed stability and tracking performance are shown. Simulation results are shown to verify the effectiveness of the proposed adaptive actuator failure compensation method. 相似文献
46.
Wen Cao Zhonghua Zhou Chenyu Li Qun Wang Yue Huang Shirley Shen 《Ceramics International》2021,47(2):1807-1818
Sodalime float (SF) glass is widely used in our societies and industries. Hydrothermal corrosion method is one of the effective ways to prepare a superhydrophobic glass, but there is still lack of knowledge about hydrothermal corrosion behavior and mechanism of SF glass. We have hydrothermally treated SF glass at 180 °C for different time, and tried to reveal the aqueous corrosion process of SF glass. We have characterized the morphologies and chemical compositions of samples, and found that (1) the two sides of SF glass have different corrosion resistances, and (2) a multilayer structural coating with a nanoflake layer (Mg-rich gel layer), a nanowire layer (Ca-rich gel layer), and a porous layer (etched layer) is formed on the air-side of SF glass. Based on the experimental results, we have proposed an aqueous corrosion mechanism of SF glass. The insights of the hydrothermal corrosion behaviors and mechanism provide helpful guidelines to glass surface structural control and functionalization. 相似文献
47.
针对领域自适应问题中源域和目标域的联合分布差异最小化问题,提出两阶段领域自适应学习方法.在第一阶段考虑样本标签和数据结构的判别信息,通过学习一个共享投影变换,使投影后的共享空间中边缘分布的差异最小.第二阶段利用源域标记数据和目标域非标记数据学习一个带结构风险的自适应分类器,不仅能最小化源域和目标域条件分布差异,还能进一步保持源域和目标域边缘分布的流形一致性.在3个基准数据集上的实验表明,文中方法在平均分类准确率和Kappa系数两项评价指标上均表现较优. 相似文献
48.
49.
50.
Huimin Zhao Wensi Wang Yunmei Du Yu Yang Minghui Wang Shaoxiang Li Ruixin Chen Yanru Liu Lei Wang 《International Journal of Hydrogen Energy》2021,46(18):10763-10772
In this work, we synthesized Se doped MoS2@Ni3S2 with nanosheets coated nanorods structure supported on Ni foam (MoNiSeS). Firstly, MoS2@Ni3S2 (MoNiS) nanorods was synthesized by hydrothermal method. After selenization treatment, MoSe2 successfully formed on the edge of MoS2 nanosheets and particle Ni3S2 transformed into NiSe, in which MoSe2 and NiSe acted as new phase in MoNiSeS. The obtained MoNiSeS only needs a low overpotential of 68 mV to reach the current density of 10 mA cm?2, and has a low Tafel plots of 72.77 mV dec?1 and good electrochemical durability, whose electrochemical activity is much better than that of MoNiS and NiSeS, implying the introduction of Mo and Se is beneficial to improve the electrocatalytic performance of NiS for HER. In addition, the proper amount of Mo source, which has an effect on the morphology of product, has also been investigated. For MoNiSeS, the typical nanosheets coated nanarods expose more active sites and the synergic effects is good to the improvement of the catalytic activity. Meanwhile, WNiSeS has also been prepared using the same method and the corresponding results show that the electrochemical activity of WNiSeS is much better than that of NiSeS, proving the universality of this strategy. 相似文献