全文获取类型
收费全文 | 89579篇 |
免费 | 7046篇 |
国内免费 | 3487篇 |
专业分类
电工技术 | 4954篇 |
技术理论 | 5篇 |
综合类 | 5751篇 |
化学工业 | 15744篇 |
金属工艺 | 5502篇 |
机械仪表 | 5543篇 |
建筑科学 | 7878篇 |
矿业工程 | 2580篇 |
能源动力 | 2378篇 |
轻工业 | 5369篇 |
水利工程 | 1570篇 |
石油天然气 | 5270篇 |
武器工业 | 687篇 |
无线电 | 9387篇 |
一般工业技术 | 10665篇 |
冶金工业 | 4545篇 |
原子能技术 | 1069篇 |
自动化技术 | 11215篇 |
出版年
2024年 | 366篇 |
2023年 | 1496篇 |
2022年 | 2428篇 |
2021年 | 3366篇 |
2020年 | 2635篇 |
2019年 | 2192篇 |
2018年 | 2553篇 |
2017年 | 2877篇 |
2016年 | 2464篇 |
2015年 | 3275篇 |
2014年 | 4144篇 |
2013年 | 5085篇 |
2012年 | 5578篇 |
2011年 | 5952篇 |
2010年 | 5054篇 |
2009年 | 4983篇 |
2008年 | 4788篇 |
2007年 | 4596篇 |
2006年 | 4902篇 |
2005年 | 4353篇 |
2004年 | 2903篇 |
2003年 | 2508篇 |
2002年 | 2304篇 |
2001年 | 2029篇 |
2000年 | 2311篇 |
1999年 | 2694篇 |
1998年 | 2199篇 |
1997年 | 1787篇 |
1996年 | 1834篇 |
1995年 | 1495篇 |
1994年 | 1216篇 |
1993年 | 863篇 |
1992年 | 707篇 |
1991年 | 558篇 |
1990年 | 407篇 |
1989年 | 338篇 |
1988年 | 272篇 |
1987年 | 187篇 |
1986年 | 123篇 |
1985年 | 89篇 |
1984年 | 57篇 |
1983年 | 36篇 |
1982年 | 40篇 |
1981年 | 34篇 |
1980年 | 23篇 |
1979年 | 6篇 |
1978年 | 2篇 |
1965年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Xueli Chen Ke Liu Qianwan Qin Zhenlu Yu Meiqing Li Xingyu Qu Yu Zhou Aichun Dou Mingru Su Yunjian Liu 《Ceramics International》2021,47(11):15400-15407
With excellent specific capacity, superior cycle stability, safety and strong practical, Nb2O5 has been considered as one of the prospective anode materials for lithium-ion batteries (LIBs). However, current study suggests that Nb2O5 electrode materials for LIBs still face the vital issues of low electrical conductivity and poor rate performance. Therefore, carbon-coated TT-Nb2O5 materials are designed and synthesized through solid state method in this work, which present high specific capacity (228 mA h g?1 at 0.2C), satisfactory rate properties (107 mA h g?1 at 20 C). The outstanding electrochemical property can not only give the credit to the pseudocapacitance effect of TT-Nb2O5, but also attribute to introduction of carbon. The homogeneous carbon-coated materials enhance the electrical conductivity, increase the electron transmission speed and alleviate particle crushing. This research not only offers a new method for preparing excellent electrode materials, but also provides a kind of excellent anode material with prospective application for LIBs. 相似文献
52.
53.
Pyrochlore-type WO_3 powder was synthesized via hydrothermal method using aqueous sodium tungstate solution and oxalic acid as raw materials. The as-prepared powder was made into a soliquoid,from which films were made by dip coating process with indium-tin oxide(ITO).The obtained films were characterized by thermogravimetric and differential thermal analysis(TG-DTA), X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM), cyclic voltammetry(CV), chronoamperometry(CA) and ultravioletvisible(UV-Vis) absorption. Results show that the crystal of the pyrochlore-type WO_3 powder is perfect. When the calcination temperature rises from room temperature to500 ℃,the pyrochlore-type structure first becomes deformed, then it is destroyed and turns into amorphous phase,finally it will completely convert to WO_3 with a monoclinic structure. Electrochemical and optical tests demonstrate that the film calcined at 300 ℃ exhibits the best electrochromic performance and has a coloration efficiency of up to 68.5 cm~2 C~(-1) at 884 nm. 相似文献
54.
55.
Sumeng Wei Yuling Yang Xiao Feng Shanshan Li Lei Zhou Jingyu Wang Xiaozhi Tang 《International Journal of Food Science & Technology》2020,55(7):2691-2699
Structures and properties of myofibrillar protein gel prepared at different power (300–800 W) were evaluated. Amino acid analysis demonstrated that changes in microwave power did not alter primary structure of gel. However, an increase in microwave power could change higher structures of gel. As microwave power increased, α-helix content decreased and β-sheet content increased. Increased microwave power probably facilitated protein to unfold and expose the internal groups, causing surface hydrophobicity and the formation of disulphide bonds were enhanced, which indicated changes in tertiary and quaternary structures of protein. At 500 W, gel had the best ultrastructure where surface morphology, springiness and water holding capacity reached the optimum. Our findings suggested that microwave at an appropriate power (500 W) could change higher structures of myofibrillar protein gel to achieve desired processing and quality protein gel characteristics. 相似文献
56.
Pattern Analysis and Applications - A novel image segmentation model is proposed to improve the stability of existing segmentation methods. In the proposed model, we introduce two factors into the... 相似文献
57.
58.
59.
Guankui Long Yecheng Zhou Mingtao Zhang Randy Sabatini Abdullah Rasmita Li Huang Girish Lakhwani Weibo Gao 《Advanced materials (Deerfield Beach, Fla.)》2019,31(17)
Hybrid organic–inorganic perovskites (HOIPs), in particular 3D HOIPs, have demonstrated remarkable properties, including ultralong charge‐carrier diffusion lengths, high dielectric constants, low trap densities, tunable absorption and emission wavelengths, strong spin–orbit coupling, and large Rashba splitting. These superior properties have generated intensive research interest in HOIPs for high‐performance optoelectronics and spintronics. Here, 3D hybrid organic–inorganic perovskites that implant chirality through introducing the chiral methylammonium cation are demonstrated. Based on structural optimization, phonon spectra, formation energy, and ab initio molecular dynamics simulations, it is found that the chirality of the chiral cations can be successfully transferred to the framework of 3D HOIPs, and the resulting 3D chiral HOIPs are both kinetically and thermodynamically stable. Combining chirality with the impressive optical, electrical, and spintronic properties of 3D perovskites, 3D chiral perovskites is of great interest in the fields of piezoelectricity, pyroelectricity, ferroelectricity, topological quantum engineering, circularly polarized optoelectronics, and spintronics. 相似文献
60.
Wang Lu-di Zhou Wei Xing Ying Liu Na Movahedipour Mahmood Zhou Xiao-guang 《浙江大学学报:C卷英文版》2019,20(3):405-413
Frontiers of Information Technology & Electronic Engineering - Reconstruction of a 12-lead electrocardiogram (ECG) from a serial 3-lead ECG has been researched in the past to satisfy the need... 相似文献