全文获取类型
收费全文 | 2746篇 |
免费 | 172篇 |
国内免费 | 128篇 |
专业分类
电工技术 | 30篇 |
综合类 | 128篇 |
化学工业 | 775篇 |
金属工艺 | 500篇 |
机械仪表 | 135篇 |
建筑科学 | 174篇 |
矿业工程 | 25篇 |
能源动力 | 114篇 |
轻工业 | 129篇 |
水利工程 | 9篇 |
石油天然气 | 158篇 |
武器工业 | 7篇 |
无线电 | 89篇 |
一般工业技术 | 245篇 |
冶金工业 | 237篇 |
原子能技术 | 51篇 |
自动化技术 | 240篇 |
出版年
2024年 | 1篇 |
2023年 | 32篇 |
2022年 | 70篇 |
2021年 | 85篇 |
2020年 | 81篇 |
2019年 | 65篇 |
2018年 | 55篇 |
2017年 | 73篇 |
2016年 | 84篇 |
2015年 | 101篇 |
2014年 | 137篇 |
2013年 | 141篇 |
2012年 | 200篇 |
2011年 | 225篇 |
2010年 | 161篇 |
2009年 | 206篇 |
2008年 | 224篇 |
2007年 | 188篇 |
2006年 | 177篇 |
2005年 | 98篇 |
2004年 | 84篇 |
2003年 | 71篇 |
2002年 | 77篇 |
2001年 | 51篇 |
2000年 | 40篇 |
1999年 | 42篇 |
1998年 | 40篇 |
1997年 | 20篇 |
1996年 | 27篇 |
1995年 | 37篇 |
1994年 | 21篇 |
1993年 | 14篇 |
1992年 | 22篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 12篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有3046条查询结果,搜索用时 270 毫秒
1.
以《让·沃奎林向菲利普三世献书》为例,分析15世纪勃艮第公爵菲利普三世统治时期,绘画中的服装对图中人物形象的塑造,以及由此形成的勃艮第宫廷独特的服饰文化特征和宫廷文化特点。《让·沃奎林向菲利普三世献书》不但较为全面地反映出15世纪上半叶勃艮第宫廷的服饰时尚,而且兼具复杂的叙事性。采用历史学和比较学的研究方法,将图像中的服装与社会生活、染织技术、宫廷文化等关联起来,剖析服装与历史生活密切相连的复杂结构。以菲利普三世为代表的勃艮第贵族强烈的个人服饰特征,结合骑士精神和壮丽恢宏的宫廷氛围,形成了勃艮第宫廷独特的宫廷文化,塑造了欧洲顶级宫廷的贵族形象。 相似文献
2.
采用Cr、V微合金化技术开发了抗拉强度≥1180 MPa的SWRH82B钢Φ14~15 mm盘条(/%:0.79~0.82C,0.15~0.35Si,0.60~0.90Mn,≤0.025P,≤0.006S,≤0.015As,0.26~0.32Cr,0.04~0.07V)。水钢用100 t转炉-LF精炼-160 mm×160 mm连铸(结晶器带电磁搅拌)-铸坯缓冷-高速线材轧制-Stellmor风冷的工艺流程生产的SWRH82B钢Φ14~15 mm盘条组织的索氏体化率达到了95%。盘条的抗拉强度为1 180~1 270 MPa,断面收缩率为27.0%~37.5%。盘条满足大规格高强度矿用钢绞线的要求。 相似文献
3.
Xiaofang Wu Yong Li Peng Jiang Jialin Sun 《Journal of the American Ceramic Society》2022,105(3):2268-2276
In this study, alumina-based composite with 12 wt% Al and 16 wt% Si3N4 was designed to achieve the synthesis of 15R-Sialon reinforced alumina composite. To investigate the reaction mechanism, two-step sintered Al-Si3N4-Al2O3 samples at different temperatures ranging from 600°C to 1500°C were prepared and characterized via X-ray diffraction and scanning electron microscope (SEM). The results revealed that 15R-Sialon was synthesized at 1500°C through a novel liquid Si phase sintering and Si3N4 played as a precursor and a reactant. First, Si3N4 precursor reacted with Al to form intermediate phases AlN and Si, which were not further transformed below 1400°C. When the sintering temperature was 1500°C, the formed Si presented as a liquid phase, under the influence of which plate-like15R-Sialon was generated from Al2O3, residual Si3N4, and derived AlN. The obtained Si was also involved in the synthesis of 15R-Sialon and completely transformed. In addition to the AlN from Si3N4, the AlN deriving from the nitridation of Al may not react with liquid Si. Compared to 15R-Sialon from liquid Si, plate-like 15R-Sialon with smaller size was generated from AlN, SiO, and O2. 相似文献
4.
《International Journal of Hydrogen Energy》2019,44(37):20839-20850
A highly active and stable boron-promoted catalyst was successfully prepared by using the sequential incipient wetness impregnation technique and examined for methane bi-reforming reaction. The initial investigation found that the NiO and B2O3 particles were dispersed on the outer surface of the high surface area SBA-15 support. In addition, the catalytic activity was increased linearly with the tested reaction temperature due to the endothermic nature of the reaction. In fact, the catalyst achieved the CH4 conversion and H2/CO molar ratio of approximately 67.3% and 2.7, respectively at 1073 K. The resulting product ratio is highly suitable for downstream Fischer-Tropsch (FT) synthesis. The B-promoted catalyst showed the lowest degree of catalyst deactivation (4%) at 1023 K. Additionally, the XPS measurements unveiled that the boron facilitates the adsorption of CO2 by donating electrons to the neighbouring Ni cluster and thus improved its catalytic performance. Furthermore, Raman and XRD analysis revealed that the boron promotion on 10%Ni/SBA-15 could prevent the reoxidation and deposition of carbonaceous species. 相似文献
5.
利用光学显微镜、扫描电镜和冲击试验机等仪器研究了15CrMoR钢中带状组织在热处理过程中的演变及其对冲击性能的影响。结果表明:奥氏体化后缓冷会出现铁素体-珠光体带状组织, 快冷则可以抑制带状组织的出现,但快冷会导致粒状贝氏体等非平衡组织形成。粒状贝氏体组织中的贝氏体铁素体基体和马氏体-奥氏体岛在回火过程中逐渐沿Cr、Mo等碳化物形成元素偏聚的区域分解出碳化物,形成富碳化物带,降低钢的横向冲击性能。15CrMoR钢加热到1100 ℃并保温7 h后可消除带状组织,改善钢的横向冲击性能。 相似文献
6.
7.
8.
D. Sanz-Villanueva D. Alique A.J. Vizcaíno R. Sanz J.A. Calles 《International Journal of Hydrogen Energy》2021,46(38):20198-20212
Thermal and mechanical resistances of palladium composite membranes prepared by Electroless Pore-Plating (ELP-PP) and containing SBA-15 as intermediate layer were improved by doping the silica material with Pd nuclei before its incorporation on the composite membrane. Textural properties of synthesized SBA-15 materials (both raw and doped ones) were analyzed by XRD, N2 adsorption-desorption at 77 K and TEM, while the main properties of the composite membrane were determined by SEM and gravimetric analyses. Moreover, membrane permeation tests were also carried out with pure gases, hydrogen and nitrogen, and binary mixtures of them at temperature of 400 °C and pressure driving forces in the range of 0.5–2.5 bar. The use of bare SBA-15 intermediate layer leads to the appearance of cracks on the Pd layer during permeation experiments at high temperature. In contrast, the use of Pd-doped SBA-15 particles avoids this problem, thus improving both thermal and mechanical resistances of the composite ELP-PP Pd-membrane. Following this preparation method, an estimated Pd thickness of 7.1 μm was obtained, reaching a hydrogen permeance of 3.81·10?4 mol s?1 m?2 Pa?0.5 and ensuring an ideal H2/N2 separation factor higher than 2550 at 400 °C. 相似文献
9.
10.
《International Journal of Hydrogen Energy》2020,45(36):18411-18425
The successful synthesis of SBA-15 using silica source extracted from palm oil fuel ash (POFA) was proven with the presence of mesostructure characteristics as evidenced by low angle XRD, N2 adsorption-desorption isotherms and TEM. Different amounts of Ni were loaded on the synthesized SBA-15(POFA) using the impregnation method at 80 °C. The influence of Ni loading over the Ni/SBA-15(POFA) physiochemical properties and CO2 reforming of CH4 (CRM) were investigated in a stainless steel fixed-bed reactor at 800 °C and atmospheric pressure with 1:1 CO2:CH4 volumetric feed composition. An increment in Ni loading on SBA-15(POFA) from 1 to 5 wt% decreased the BET surface area and crystallinity of catalyst as proven by N2 adsorption–desorption and XRD analysis. The catalytic performance of CRM followed the sequence of 3 wt% > 5 wt% > 2 wt% > 1 wt% -Ni/SBA-15(POFA). This result was owing to the even distribution of Ni and good Ni–O–Si interaction of 3 wt% Ni/SBA-15(POFA) as proved by TEM, FTIR and XPS. Lowest H2/CO ratio and catalyst activity and stability of 1 wt% Ni/SBA-15(POFA) were due to the weaker Ni–O–Si interaction and small amount of basic sites that favor the reverse water gas shift (RWGS) reaction and carbon formation. The recent finding indicates that a quantity as small as 3 wt% Ni loaded onto SBA-15(POFA) could elicit outstanding catalytic performance in CRM, which was comparable with 10 wt% Ni loading catalysts reported in literature. 相似文献