全文获取类型
收费全文 | 142901篇 |
免费 | 13456篇 |
国内免费 | 6094篇 |
专业分类
电工技术 | 8425篇 |
技术理论 | 14篇 |
综合类 | 9704篇 |
化学工业 | 23586篇 |
金属工艺 | 8446篇 |
机械仪表 | 9860篇 |
建筑科学 | 11575篇 |
矿业工程 | 4444篇 |
能源动力 | 4172篇 |
轻工业 | 11156篇 |
水利工程 | 2570篇 |
石油天然气 | 9271篇 |
武器工业 | 1199篇 |
无线电 | 15797篇 |
一般工业技术 | 16325篇 |
冶金工业 | 6545篇 |
原子能技术 | 1697篇 |
自动化技术 | 17665篇 |
出版年
2025年 | 9篇 |
2024年 | 1778篇 |
2023年 | 2869篇 |
2022年 | 4478篇 |
2021年 | 6148篇 |
2020年 | 4946篇 |
2019年 | 3750篇 |
2018年 | 4213篇 |
2017年 | 4674篇 |
2016年 | 4380篇 |
2015年 | 5902篇 |
2014年 | 7073篇 |
2013年 | 8450篇 |
2012年 | 9255篇 |
2011年 | 9942篇 |
2010年 | 8626篇 |
2009年 | 8295篇 |
2008年 | 8167篇 |
2007年 | 7656篇 |
2006年 | 7855篇 |
2005年 | 6800篇 |
2004年 | 4442篇 |
2003年 | 3951篇 |
2002年 | 3752篇 |
2001年 | 3325篇 |
2000年 | 3172篇 |
1999年 | 3508篇 |
1998年 | 2781篇 |
1997年 | 2323篇 |
1996年 | 2195篇 |
1995年 | 1852篇 |
1994年 | 1474篇 |
1993年 | 986篇 |
1992年 | 859篇 |
1991年 | 597篇 |
1990年 | 463篇 |
1989年 | 401篇 |
1988年 | 314篇 |
1987年 | 194篇 |
1986年 | 177篇 |
1985年 | 95篇 |
1984年 | 75篇 |
1983年 | 57篇 |
1982年 | 52篇 |
1981年 | 43篇 |
1980年 | 43篇 |
1979年 | 24篇 |
1976年 | 7篇 |
1975年 | 4篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Lijin Xie Junfeng Ma Jun Zhou Zhongqiang Zhao Hua Tian Yonggang Wang Jiantao Tao Xiaoyi Zhu 《Journal of the American Ceramic Society》2006,89(5):1717-1720
Well-crystallized bismuth tungstate (Bi2 WO6 ) powders with different morphologies were successfully synthesized via a low-temperature molten salt method. The powders were characterized by X-ray diffraction, transmission electron microscopy, and UV-Vis, respectively. It was found that the variation of morphology of the obtained Bi2 WO6 powder mainly depends on the different reaction temperatures and the weight ratio of LiNO3 –NaNO3 salt to precursor. In addition, the UV-Visible absorption spectra showed that the synthesized powders had strong light absorption properties not only in the ultraviolet light but also in the visible light region. 相似文献
82.
Poly(ethylene terephthalate) (PET) was blended with two different poly(oxybenzoate‐p‐trimethylene terephthalate) copolymers, designated T28 and T64, with the level of copolymer varying from 1 to 15 wt %. All samples were prepared by solution blending in a 60/40 (by weight) phenol/tetrachloroethane solvent at 50°C. The crystallization behavior of the samples was studied by DSC. The results indicate that both T28 and T64 accelerated the crystallization rate of PET in a manner similar to that of a nucleating agent. The acceleration of PET crystallization rate was most pronounced in the PET/T64 blends with a maximum level at 5 wt % of T64. The melting temperatures for the blends are comparable to that of pure PET. The observed changes in crystallization behavior are explained by the effect of the physical state of the copolyester during PET crystallization as well as the amount of copolymer in the blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1599–1606, 2002 相似文献
83.
CeO2 particles confined within the pores of an SBA-15 mesoporous silica host were prepared by incipient wetness impregnation (IMP)
and deposition precipitation (DP) methods. The materials were characterized by XRD, N2-adsorption and temperature programmed reduction (TPR) to evaluate the structure, texture, and redox properties. The preparation
procedure had significant impact on the assembling mode of CeO2 inside the SBA-15 mesopores. A high dispersion of CeO2 particles was achieved via DP, whereas the dispersion of CeO2 prepared by IMP was found to be inhomogeneous and CeO2 partially blocked the pores. The CO conversion in the water-gas-shift reaction was enhanced over 1 wt% Pt supported on CeO2-modified SBA-15 obtained by DP. 相似文献
84.
赵明 《重庆科技学院学报(社会科学版)》2010,(1):129-130,137
为进一步了解情感隐喻的实质,以人类基本情感的隐喻表达作讨论对象,对英汉语言中的基本情感隐喻进行共性与差异分析。 相似文献
85.
本文针对地铁车厢内控制设备分散的问题,设计了基于TCNRTP的地铁列车控制网络系统。采用NS2网络模拟软件构建的虚拟网络环境,编写消息数据传输层协议,通过测试列控网络的通信效率,得出了影响通信效率的因素;通过配置列控通信设备的基本功能和设定装置运行参数达到配置网络化通信的目的。 相似文献
86.
文章力图以VR(虚拟现实)技术手段应用于城市地下步行商业街规划设计,来解决当前传统规划手段地下步行商业街规划中普遍存在的对其心理环境构筑的忽视和考虑不完善的诟病,以期最大限度消除规划设计中消极空间的产生,并对其关键技术进行了研究和探讨 相似文献
87.
建设鄱阳湖生态经济区是国家从战略全局和长远发展出发作出的一项重大决策。如何主动策应鄱阳湖生态经济区建设,推动吉安进位赶超、跨越发展,是摆在我们各级政府和科技部门面前一项亟待解决的问题。为此,一是要提高认识,统一思想,切实增强策应规划的使命感和责任感;二是要结合实际,突出重点,全面对接鄱阳湖生态经济区规划;三是要加强领导,落实措施,确保吉安进位赶超、绿色崛起取得明显成效。 相似文献
88.
Jianfeng Wu Jian Li Xiaohong Xu Lanfang Yang Jufang Wu Fang Zhao Chuanguo Li 《武汉理工大学学报(材料科学英文版)》2009,24(4):651-653
A new type of high temperature energy storage material was obtained through the melt infiltration method, using compounding
SiC ceramic foam as matrix and Na2SO4 as phase change material. The resulting composite material was measured by XRD, SEM, TG-DSC methods. The experimental results
indicate that the composite is composed of silicon carbide, sodium sulfate and square quartz, and no chemical reactions occurs
between Na2SO4 and SiC matrix. Na2SO4 has a good bonding with the SiC ceramic foam matrix. As the composite material is characterized by high thermal energy storage
density and high thermal conductivity, it is suit for energy storage under high temperature.
Funded by the “863” Hi-Tech Research and Development Program of China (2008AA05Z418) 相似文献
89.
Efficient and selective oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones catalyzed by potassium permanganate supported on Kieselguhr reagent under solvent free conditions are reported. 相似文献
90.