全文获取类型
收费全文 | 79814篇 |
免费 | 10046篇 |
国内免费 | 6256篇 |
专业分类
电工技术 | 7687篇 |
技术理论 | 2篇 |
综合类 | 7461篇 |
化学工业 | 10551篇 |
金属工艺 | 4868篇 |
机械仪表 | 5735篇 |
建筑科学 | 6344篇 |
矿业工程 | 2796篇 |
能源动力 | 2434篇 |
轻工业 | 7058篇 |
水利工程 | 2471篇 |
石油天然气 | 3352篇 |
武器工业 | 1084篇 |
无线电 | 10073篇 |
一般工业技术 | 7401篇 |
冶金工业 | 2701篇 |
原子能技术 | 1273篇 |
自动化技术 | 12825篇 |
出版年
2024年 | 232篇 |
2023年 | 1269篇 |
2022年 | 2974篇 |
2021年 | 4066篇 |
2020年 | 2884篇 |
2019年 | 2218篇 |
2018年 | 2380篇 |
2017年 | 2729篇 |
2016年 | 2457篇 |
2015年 | 3757篇 |
2014年 | 4791篇 |
2013年 | 5655篇 |
2012年 | 6845篇 |
2011年 | 6930篇 |
2010年 | 6536篇 |
2009年 | 6199篇 |
2008年 | 6145篇 |
2007年 | 5957篇 |
2006年 | 5247篇 |
2005年 | 4154篇 |
2004年 | 3001篇 |
2003年 | 2040篇 |
2002年 | 2016篇 |
2001年 | 1677篇 |
2000年 | 1316篇 |
1999年 | 686篇 |
1998年 | 371篇 |
1997年 | 281篇 |
1996年 | 263篇 |
1995年 | 227篇 |
1994年 | 158篇 |
1993年 | 102篇 |
1992年 | 99篇 |
1991年 | 68篇 |
1990年 | 59篇 |
1989年 | 46篇 |
1988年 | 29篇 |
1987年 | 18篇 |
1986年 | 19篇 |
1985年 | 15篇 |
1984年 | 16篇 |
1982年 | 14篇 |
1981年 | 20篇 |
1980年 | 28篇 |
1979年 | 19篇 |
1978年 | 7篇 |
1977年 | 9篇 |
1976年 | 18篇 |
1959年 | 12篇 |
1951年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
在国内,火花放电原子发射光谱分析广泛使用类型标准化进行方法校正。在国外,标准和文献中鲜见使用此方法的相关论述。类型标准化主要采用平移校正和转动校正两种方式,哪种方式更加合理也鲜见报道。国外设备类型标准化的默认设置优先采用转动校正方式,相关国内标准对最优校正方式的规定尚不明确,此默认设置的合理性有待探讨。实验选用低合金钢20CrNi2Mo、R407标准样品和不锈钢317L、0Cr18Ni9标准样品,引用国内相关标准,以正确度临界差为评判依据,模拟类型标准化样品和待测样品“十分接近”和“接近”两种情况下平移校正和转动校正的数据正确度。经数据统计分析,平移校正分析结果均满足要求,转动校正结果在“接近”情况下部分元素不满足要求。结合相关国家标准中元素含量范围和精密度数据进行分析,通过计算允许最大偏倚量并制作曲线图方式展开分析,得出如下结论:在满足文中类型标准化控制要点前提下,分析设置更适合于采用平移校正方式。 相似文献
13.
针对纺织工程中外合作办学模式下的《纺纱综合实验》课程现状和存在的问题,原有的课程体系已经不能适应其教学模式的要求,根据中外合作办学的特点和要求,从《纺纱综合实验》课程教学的内容、教学方法、教学手段和考核方法等方面进行了教学改革实践和探索,以提高学生学习的积极性和主动性,形成师生间良好的教学循环,全面提高教学质量和效果. 相似文献
14.
16.
17.
介绍了已运用于实践中的一种全IP电视直播节目即时回看技术,用户通过遥控器一键实现直播节目的即时回看,极大地提升了用户的观看体验。通过在临汾市智慧广电全IP融合业务网建设实践项目中的使用,技术的先进性和有效性得到实践验证。 相似文献
18.
Qian Wu Xiangmei Liu Bo Li Lei Tan Yong Han Zhaoyang Li Yanqin Liang Zhenduo Cui Shengli Zhu Shuilin Wu Yufeng Zheng 《材料科学技术学报》2021,67(8):70-79
Pathogens pose a serious challenge to environmental sanitation and a threat to public health.The frequent use of chemicals for sterilization in recent years has not only caused secondary damage to the environment but also increased pathogen resistance to drugs,which further threatens public health.To address this issue,the use of non-chemical antibacterial means has become a new trend for environmental disinfection.In this study,we developed red phosphorus nanoparticles(RPNPs),a safe and degradable photosensitive material with good photocatalytic and photothermal properties.The red phosphorus nanoparticles were prepared using a template method and ultrasonication.Under the irradiation of simulated sunlight for 20 min,the RPNPs exhibited an efficiency of 99.98%in killing Staphylococcus aureus due to their excellent photocatalytic and photothermal abilities.Transmission electron microscopy and ultraviolet–visible spectroscopy revealed that the RPNPs exhibited degradability within eight weeks.Both the RPNPs and their degradation products were nontoxic to fibroblast cells.Therefore,such RPNPs are expected to be used as a new type of low-cost,efficient,degradable,biocompatible,and eco-friendly photosensitive material for environmental disinfection. 相似文献
19.
Yi Chen Weijian Sun Haonan Zheng Changhao Li Bo Zhang Baoxiang Wang Chuncheng Hao 《Ceramics International》2021,47(17):24080-24091
In this paper, a novel H2Ti2O5@MoS2@SiO2 ternary composite material was prepared by a combination of dual hydrothermal method and controlled hydrolysis method, in which H2Ti2O5 nanotubes are tightly combined with hierarchical molybdenum disulfide, and the unique structure of titanate nano whiskers, including the loosely bound alkali metal ions between the titanate layers with high dielectric constant and the large aspect ratio, which induce active response to the electric field. Flower-like molybdenum disulfide provides electrical conductivity, and silicon dioxide as a insulative coating layer can suppress excessive the electrical conductivity of the two-dimensional material. The morphological evolution was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results of showed that the sheet-shaped molybdenum disulfide coated with curved H2Ti2O5 nanotubes showed a honeycomb structure with uniform size. Silicon oxide acts as a cladding layer to increase the thickness of the flakes. The existence of H2Ti2O5, molybdenum disulfide and silicon dioxide is confirmed by X-ray powder diffractometer (XRD) and Fourier transform infrared spectroscopy (FT-IR). The prepared product was confirmed by XPS, BET test and electrorheological rheometer. Core/shell nanoparticles not only exert the active response characteristics of titanate nanoparticles and molybdenum disulfide to electric field, but also inherit the excellent characteristics of a core-shell structure produced by the interface polarization and the synergistic effect of the polar groups on the surface of the two-dimensional material further enhance the electrorheological effect. 相似文献
20.
Haiyang Chen Bin Li Xue Yang Guangqi Li Hongqiang Chen Junhong Chen Bo Ren 《Ceramics International》2021,47(16):22911-22917
Understanding the spheroidization process of micron-scaled α-Al2O3 powder in hydrothermal method is of great importance but still not completely revealed. The results demonstrated that SO42? played a significant role in the formation of spherical powder, while the bubble generated from the reaction of urea didn't work in the spheroidization process. The spheroidization process was summed up as two steps. The first was that SO42? limited the hydrolysis of Al3+ and reacted with Al3+ and OH- to form Al4(OH)10SO4, which nucleated and agglomerated into granular precipitates. The second was Ostwald ripening, which gave the spherical precursors a double-layered structure. When the spherical precursors obtained 120 °C were sintered at 1200 °C, α-Al2O3 were got and the spherical morphology still maintained with a large number of nano-sized pores. We anticipate the spherical α-Al2O3 with nano-sized pores can be applied in adsorption and filtration industries. 相似文献