全文获取类型
收费全文 | 1064398篇 |
免费 | 154430篇 |
国内免费 | 108279篇 |
专业分类
电工技术 | 100495篇 |
技术理论 | 1篇 |
综合类 | 119090篇 |
化学工业 | 130066篇 |
金属工艺 | 82844篇 |
机械仪表 | 72469篇 |
建筑科学 | 82227篇 |
矿业工程 | 50963篇 |
能源动力 | 29422篇 |
轻工业 | 110742篇 |
水利工程 | 36596篇 |
石油天然气 | 42831篇 |
武器工业 | 16539篇 |
无线电 | 119966篇 |
一般工业技术 | 97441篇 |
冶金工业 | 42819篇 |
原子能技术 | 15523篇 |
自动化技术 | 177073篇 |
出版年
2024年 | 7335篇 |
2023年 | 17320篇 |
2022年 | 37799篇 |
2021年 | 48430篇 |
2020年 | 37986篇 |
2019年 | 33103篇 |
2018年 | 35637篇 |
2017年 | 41659篇 |
2016年 | 38071篇 |
2015年 | 53368篇 |
2014年 | 63700篇 |
2013年 | 72646篇 |
2012年 | 88943篇 |
2011年 | 89911篇 |
2010年 | 86590篇 |
2009年 | 81971篇 |
2008年 | 82303篇 |
2007年 | 80432篇 |
2006年 | 69003篇 |
2005年 | 56985篇 |
2004年 | 44151篇 |
2003年 | 30273篇 |
2002年 | 28154篇 |
2001年 | 25594篇 |
2000年 | 21035篇 |
1999年 | 10843篇 |
1998年 | 5981篇 |
1997年 | 5165篇 |
1996年 | 4736篇 |
1995年 | 4582篇 |
1994年 | 3740篇 |
1993年 | 3451篇 |
1992年 | 3226篇 |
1991年 | 2364篇 |
1990年 | 1921篇 |
1989年 | 1850篇 |
1988年 | 1364篇 |
1987年 | 559篇 |
1986年 | 496篇 |
1985年 | 322篇 |
1984年 | 277篇 |
1983年 | 213篇 |
1982年 | 245篇 |
1981年 | 300篇 |
1980年 | 374篇 |
1979年 | 225篇 |
1976年 | 235篇 |
1975年 | 215篇 |
1972年 | 239篇 |
1960年 | 206篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
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
43.
44.
新型建筑工业化具有高质量、低消耗、可循环发展等特征,其推广已上升到国家战略层面。利用演化博弈方法,建立“政府-开发商-银行” 的三方动态演化博弈模型,进行各博弈主体策略的演化稳定性分析,并针对初始状态、奖惩力度、借贷风险和开发成本等对演化结果的影响进行动态仿真。在此基础上, 考虑开发商群体的网络拓扑特征对演化真实性的影响,引入复杂网络理论, 以无标度网络为载体描述开发商个体的连接偏好和决策机制,构建政府监管下的建筑工业化扩散模型,并通过仿真深入研究相关因素对扩散深度的影响作用,最后结合仿真结果给出相应对策建议。 相似文献
45.
利用双轴搅拌机的工作原理设计的石粉和脱硫石膏混合装置,将石粉和脱硫石膏混合成干湿均匀料加入水泥磨,既利用了石粉、节约了石子,又解决了水泥生产过程中脱硫石膏水分大、不便输送和难稳定入磨的问题,效果显著。 相似文献
46.
食品安全示范城市创建是食品安全治理体系的重要载体。本文系统性回顾食品安全治理体系相关研究,从“党政同责”、政府监管、市场主体、社会共治等四个治理主体,构建生产规范、产业转型升级等27个评价指标的治理标准,利用层次分析法实证分析了浙江省食品安全示范城市创建情况。结果表明:采用暗查暗访、现场检查、体系评估、示范引领答辩等形式,按照一定的评价流程、评价标准的食品安全示范城市创建,是实现食品安全现代化目标的重要载体。食品安全治理体系包括“治理载体—治理主体—治理标准—治理目标”。食品安全治理成效与跟踪评价、群众满意度以及体系评估高度关联。 相似文献
47.
48.
Shuhai Liu Ming Han Xiaolong Feng Qiuhong Yu Long Gu Longfei Wang Yong Qin Zhong Lin Wang 《Advanced functional materials》2021,31(17):2010339
Utilizing inner-crystal piezoelectric polarization charges to control carrier transport across a metal-semiconductor or semiconductor–semiconductor interface, piezotronic effect has great potential applications in smart micro/nano-electromechanical system (MEMS/NEMS), human-machine interfacing, and nanorobotics. However, current research on piezotronics has mainly focused on systems with only one or rather limited interfaces. Here, the statistical piezotronic effect is reported in ZnO bulk composited of nanoplatelets, of which the strain/stress-induced piezo-potential at the crystals’ interfaces can effectively gate the electrical transport of ZnO bulk. It is a statistical phenomenon of piezotronic modification of large numbers of interfaces, and the crystal orientation of inner ZnO nanoplatelets strongly influence the transport property of ZnO bulk. With optimum preferred orientation of ZnO nanoplatelets, the bulk exhibits an increased conductivity with decreasing stress at a high pressure range of 200–400 MPa, which has not been observed previously in bulk. A maximum sensitivity of 1.149 µS m−1 MPa−1 and a corresponding gauge factor of 467–589 have been achieved. As a statistical phenomenon of many piezotronic interfaces modulation, the proposed statistical piezotronic effect extends the connotation of piezotronics and promotes its practical applications in intelligent sensing. 相似文献
49.
Recently, the successful synthesis of wafer-scale single-crystal graphene, hexagonal boron nitride (hBN), and MoS2 on transition metal surfaces with step edges boosted the research interests in synthesizing wafer-scale 2D single crystals on high-index substrate surfaces. Here, using hBN growth on high-index Cu surfaces as an example, a systematic theoretical study to understand the epitaxial growth of 2D materials on various high-index surfaces is performed. It is revealed that hBN orientation on a high-index surface is highly dependent on the alignment of the step edges of the surface as well as the surface roughness. On an ideal high-index surface, well-aligned hBN islands can be easily achieved, whereas curved step edges on a rough surface can lead to the alignment of hBN along with different directions. This study shows that high-index surfaces with a large step density are robust for templating the epitaxial growth of 2D single crystals due to their large tolerance for surface roughness and provides a general guideline for the epitaxial growth of various 2D single crystals. 相似文献
50.
Qianying Hoo Xiaohu Wang Feng Yuan Xuewei Cao Tiewa Cao Maolin Zhang 《Journal of the European Ceramic Society》2021,41(6):3816-3822
Jingdezhen is famous for its bluish white (Qingbai) porcelains of the Song Dynasty, and those decorated with iron spots are distinctive among them. Herein, iron spots on a bluish white porcelain were investigated using a series of microscopic and spectroscopic characterizations. We found the decreasing iron content from more than 8 wt% to about 2 wt% during the glaze color transition from rusty to brown and finally into green, which built a connection on the coloring mechanism of iron-rich crystallized glaze and celadon glaze. We identified the rare ε-Fe2O3, a promising magnetic material, in both the dark brown crystals and the triangular crystals in the rusty area, which is its first discovery among bluish white porcelains. Based on these findings, we discussed the coloring mechanism of iron-spot decoration along with the physical form of the iron oxide crystals, indicating the partially reducing atmosphere during firing process. 相似文献