全文获取类型
收费全文 | 50899篇 |
免费 | 4236篇 |
国内免费 | 1815篇 |
专业分类
电工技术 | 2634篇 |
技术理论 | 6篇 |
综合类 | 2835篇 |
化学工业 | 9109篇 |
金属工艺 | 3056篇 |
机械仪表 | 2912篇 |
建筑科学 | 3772篇 |
矿业工程 | 1295篇 |
能源动力 | 1695篇 |
轻工业 | 3520篇 |
水利工程 | 760篇 |
石油天然气 | 3144篇 |
武器工业 | 274篇 |
无线电 | 5706篇 |
一般工业技术 | 6448篇 |
冶金工业 | 2813篇 |
原子能技术 | 608篇 |
自动化技术 | 6363篇 |
出版年
2024年 | 167篇 |
2023年 | 901篇 |
2022年 | 1376篇 |
2021年 | 2159篇 |
2020年 | 1598篇 |
2019年 | 1408篇 |
2018年 | 1548篇 |
2017年 | 1698篇 |
2016年 | 1527篇 |
2015年 | 1986篇 |
2014年 | 2515篇 |
2013年 | 3271篇 |
2012年 | 3257篇 |
2011年 | 3507篇 |
2010年 | 2936篇 |
2009年 | 2910篇 |
2008年 | 2742篇 |
2007年 | 2555篇 |
2006年 | 2746篇 |
2005年 | 2366篇 |
2004年 | 1581篇 |
2003年 | 1431篇 |
2002年 | 1379篇 |
2001年 | 1047篇 |
2000年 | 1089篇 |
1999年 | 1276篇 |
1998年 | 1139篇 |
1997年 | 894篇 |
1996年 | 858篇 |
1995年 | 680篇 |
1994年 | 558篇 |
1993年 | 381篇 |
1992年 | 325篇 |
1991年 | 223篇 |
1990年 | 178篇 |
1989年 | 121篇 |
1988年 | 151篇 |
1987年 | 86篇 |
1986年 | 65篇 |
1985年 | 53篇 |
1984年 | 54篇 |
1983年 | 29篇 |
1982年 | 37篇 |
1981年 | 21篇 |
1980年 | 22篇 |
1979年 | 24篇 |
1978年 | 8篇 |
1976年 | 11篇 |
1974年 | 6篇 |
1965年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
1.
Yarn-dyed fabric is often woven from warp and weft yarns in the same color depth to ensure a uniform color appearance. The difference in color depth between warp and weft tends to result in the uneven color of the yarn-dyed fabric. This article aims to establish a color tolerance for yarn-dyed fabric that can be woven with a qualified color appearance but from the warp and weft yarns in different color depths. A total of 27 yarn-dyed fabric samples in three color series (red, yellow, and blue) were evaluated by using the yarn-dyed fabric from warp and weft yarns in the same color depth of 2% (on weight of fabric, owf) as the standard. Visual assessment and instrumental measurement of color were carried out to establish the color tolerance ellipse that was defined as CMC (Color Measurement Committee) color differences (2:1) of no more than 1.00. It was found that the color strengths (K/S) and color differences (ΔECMC(2:1)) of these fabric samples for each color series had linear relationships with the color depths of warp and weft yarns. The color tolerance ellipses indicated that, even though the warp and weft yarns had an apparent color difference, they could be woven in fabrics with relatively uniform color appearance and meet the requirements for yarn-dyed fabric. This work provided valuable insight into the production of qualified yarn-dyed fabrics from unqualified dyed yarns. 相似文献
2.
为了适应煤矿产能的提升和开采规模的不断加大,南岭矿对现有机电运输设备进行了重新的选型和升级.实际应用表明,优化后的井下运输设备的运输能力能够很好地满足矿井的安全高效生产. 相似文献
3.
介绍装配式建筑电气设计中的管线分离SI体系、模块化机电设计、集成机电部品、装配式建筑防雷接地系统等关键技术,并进行简要分析. 相似文献
4.
Shilin Du Yichen Dong Feiqiang Guo Beile Tian Songbo Mao Lin Qian Chengyun Xin 《International Journal of Hydrogen Energy》2021,46(27):14138-14147
The potential of using high metals containing coal gangue and lignite to prepare high-activity coal char-based catalysts is investigated for effective biomass tar decomposition. Loose structure and rough surface are formed for these char-based catalysts with heterogeneous distribution of a large number of inorganic particles. In the biomass tar decomposition, the performance of the coal char-based catalysts is significantly influenced by the content of the metals in the raw materials and coal gangue char (GC) with the ash content as high as 50.80% exhibits the highest activity in this work. A high biomass tar conversion efficiency of 93.5% is achieved at 800 °C along with a significant increase in the fuel gas product. During the five-time consecutive tests, the catalytic performance of GC increases a little at the second or third times reuse and remains relatively stable, showing the remarkable stability of the catalyst in biomass tar decomposition applications. 相似文献
5.
Chunyan Xu Ying Wang Daodong Pan Changyu Zhou Jun He Jinxuan Cao 《International Journal of Food Science & Technology》2021,56(4):1690-1702
To investigate the effect of cooking temperature (55, 65, 75, 85 and 95 °C) on texture and flavour binding of braised sauce porcine skin (BSPS), sensory acceptance, microstructure and flavour-binding capacity were investigated during the processing of BSPS. Samples cooked at 85 and 95 °C showed better texture and aroma scores. Hardness and chewiness of BSPS were obviously improved at 85 and 95 °C than control group. Collagen structure was significantly destroyed over 85 °C. The porcine skin collagen heated at 85 and 95 °C showed relatively higher flavour-binding capacity than other samples. The improvement of texture of BSPS was mainly attributed to the degradation of collagen. Higher aroma scores of BSPS were related to intense binding abilities with aroma compounds at 85 and 95 °C. Cooking at 85 or 95 °C could be an optimal cooking temperature for BSPS. 相似文献
6.
Yuzhu Su Junpu Wang Xin Li Qiqi Tang Jing Yang Li Lei Yi Tian Zhiwei Wang Duanwei He 《Ceramics International》2021,47(15):21077-21082
The in situ axial X-ray diffraction patterns of four ceramic powder samples (MgO, Al2O3, AlN, and cBN) that were compressed in a diamond anvil cell under uniaxial non-hydrostatic conditions were recorded. The microscopic deviatoric stress as a function of the pressure was determined from the X-ray diffraction peak broadening analysis: the curves increased approximately linearly with the pressure at the initial compression stage and then levelled off under further compression. Pressure-induced transparency was observed in all of the samples under compression, and the pressure at the turning point on the curves of the microscopic deviatoric stress versus pressure corresponded to the pressure at which the samples became transparent. Analysis of the microstructural features of the pressure-induced transparent samples indicated that the compression caused the grains to fracture, and the broken grains bonded with each other. We demonstrated that the ceramics’ pressure-induced transparency was a process during which the grains were squeezed and broken, the pores were close between the grains, and the broken grains were re-bonded under compression. 相似文献
7.
Fenqi Du Dongmei Yang Yue Sun Yang Jiao Feng Teng Haibo Fan 《Ceramics International》2021,47(4):4963-4971
Ultrawide band gap semiconductor materials have attracted considerable attention in recent years owing to their great potential in the photocatalytic field. In this study, Zn-doped Ga2O3 nanofibers with various concentrations were synthesized via electrospinning; they exhibited a superior photocatalytic degradation performance of rhodamine B dye compared to that of undoped Ga2O3 nanofibers. The Zn dopant replaced Ga sites via replacement doping, which could increase the concentration of oxygen vacancies and lead to enhanced photocatalytic properties. When the Zn concentration increased, a Ga2O3/ZnGa2O4 hybrid structure formed, which could further enhance the photocatalytic performance. The separation of photogenerated carriers due to Zn doping and heterojunctions were the primary causes of the enhanced photocatalytic performance. This study provides experimental data for the fabrication of high-performance photocatalysts based on Ga2O3 nanomaterials. 相似文献
9.
10.
Fangjun Zhu You Shi Guorong Hu Zhongdong Peng Yanbing Cao Qian Sun Zhichen Xue Yinjia Zhang Ke Du 《Ceramics International》2021,47(3):3070-3078
Titanium and boron are simultaneously introduced into LiNi0.8Co0.1Mn0.1O2 to improve the structural stability and electrochemical performance of the material. X-ray diffraction studies reveal that Ti4+ ion replaces Li+ ion and reduces the cation mixing; B3+ ion enters the tetrahedron of the transition metal layers and enlarges the distance of the [LiO6] layers. The co-doped sample has spherical secondary particles with elongated and enlarged primary particles, in which Ti and B elements distribute uniformly. Electrochemical studies reveal the co-doped sample has improved rate performance (183.1 mAh·g-1 at 1 C and 155.5 mAh·g-1 at 10 C) and cycle stability (capacity retention of 94.7% after 100 cycles at 1 C). EIS and CV disclose that Ti and B co-doping reduces charge transfer impedance and suppresses phase change of LiNi0.8Co0.1Mn0.1O2. 相似文献