全文获取类型
收费全文 | 118463篇 |
免费 | 9863篇 |
国内免费 | 4972篇 |
专业分类
电工技术 | 7108篇 |
技术理论 | 7篇 |
综合类 | 7600篇 |
化学工业 | 20451篇 |
金属工艺 | 6484篇 |
机械仪表 | 7318篇 |
建筑科学 | 9664篇 |
矿业工程 | 3461篇 |
能源动力 | 3517篇 |
轻工业 | 7720篇 |
水利工程 | 2106篇 |
石油天然气 | 7299篇 |
武器工业 | 884篇 |
无线电 | 13432篇 |
一般工业技术 | 14291篇 |
冶金工业 | 5513篇 |
原子能技术 | 1292篇 |
自动化技术 | 15151篇 |
出版年
2024年 | 560篇 |
2023年 | 2043篇 |
2022年 | 3554篇 |
2021年 | 4900篇 |
2020年 | 3754篇 |
2019年 | 3151篇 |
2018年 | 3404篇 |
2017年 | 3922篇 |
2016年 | 3302篇 |
2015年 | 4692篇 |
2014年 | 5717篇 |
2013年 | 6786篇 |
2012年 | 7433篇 |
2011年 | 7989篇 |
2010年 | 6967篇 |
2009年 | 6640篇 |
2008年 | 6437篇 |
2007年 | 6088篇 |
2006年 | 6348篇 |
2005年 | 5520篇 |
2004年 | 3774篇 |
2003年 | 3287篇 |
2002年 | 3081篇 |
2001年 | 2804篇 |
2000年 | 2953篇 |
1999年 | 3169篇 |
1998年 | 2676篇 |
1997年 | 2281篇 |
1996年 | 2099篇 |
1995年 | 1828篇 |
1994年 | 1473篇 |
1993年 | 1059篇 |
1992年 | 864篇 |
1991年 | 678篇 |
1990年 | 491篇 |
1989年 | 436篇 |
1988年 | 354篇 |
1987年 | 246篇 |
1986年 | 169篇 |
1985年 | 97篇 |
1984年 | 65篇 |
1983年 | 49篇 |
1982年 | 63篇 |
1981年 | 39篇 |
1980年 | 35篇 |
1979年 | 10篇 |
1978年 | 3篇 |
1965年 | 3篇 |
1959年 | 4篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
881.
882.
Lin Wang Xianju Xie Michael D. Weir Ashraf F. Fouad Liang Zhao Hockin H. K. Xu 《Journal of materials science. Materials in medicine》2016,27(11):168
The objectives of this study were to: (1) develop a new bioactive dental bonding agent with nanoparticles of amorphous calcium phosphate and dimethylaminohexadecyl methacrylate for tooth root caries restorations and endodontic applications, and (2) investigate biofilm inhibition by the bioactive bonding agent against eight species of periodontal and endodontic pathogens for the first time. Bonding agent was formulated with 5?% of dimethylaminohexadecyl methacrylate. Nanoparticles of amorphous calcium phosphate at 30?wt% was mixed into adhesive. Eight species of biofilms were grown on resins: Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Parvimonas micra, Enterococcus faecalis, Enterococcus faecium. Colony-forming units, live/dead assay, biomass, metabolic activity and polysaccharide of biofilms were determined. The results showed that adding dimethylaminohexadecyl methacrylate and nanoparticles of amorphous calcium phosphate into bonding agent did not decrease dentin bond strength (P?>?0.1). Adding dimethylaminohexadecyl methacrylate reduced the colony-forming units of all eight species of biofilms by nearly three orders of magnitude. The killing efficacy of dimethylaminohexadecyl methacrylate resin was: P. gingivalis?>?A. actinomycetemcomitans?>?P. intermedia?>?P. nigrescens?>?F. nucleatum?>?P. micra?>?E. faecalis?>?E. faecium. Dimethylaminohexadecyl methacrylate resin had much less biomass, metabolic activity and polysaccharide of biofilms than those without dimethylaminohexadecyl methacrylate (P?<?0.05). In conclusion, a novel dental adhesive was developed for root caries and endodontic applications, showing potent inhibition of biofilms of eight species of periodontal and endodontic pathogens, and reducing colony-forming units by three orders of magnitude. The bioactive adhesive is promising for tooth root restorations to provide subgingival margins with anti-periodontal pathogen capabilities, and for endodontic sealer applications to combat endodontic biofilms. 相似文献
883.
Yuxia Kong Jigong Hao Dan Xu 《Journal of Materials Science: Materials in Electronics》2016,27(11):11256-11261
High aspect ratio patelike NaNbO3 particles with pure perovskite structure have been successfully synthesized by topochemical microcrystal conversion (TMC) from plate-like precursor particles of the layer-structured Bi2.5Na3.5Nb5O18. By changing the Bi2.5Na3.5Nb5O18/Na2CO3 ratio, large and thin NaNbO3 particles with a thickness of approximately 0.5 μm and a width of approximately 20 μm were obtained. The obtained NaNbO3 particles is quite suitable for fabricating textured (K0.5Na0.5)NbO3-based ceramics. Using the fine platelike NaNbO3 particles as templates, dense <001> -oriented (K0.5Na0.5)NbO3-0.5 mol %MnO2 ceramics with high texture quality (Lotgering factor F 001 = 87 %) and excellent piezoelectric properties were produced by templated grain growth. Compared with randomly oriented ceramics, textured samples show greatly enhanced properties. The room-temperature strain S, the piezoelectric coefficient d 33 * and d 33 reach up to 0.093 %, 233 pm/V and 195pC/N, respectively, which are all about 1.5 times larger than those of non-textured ceramics. 相似文献
884.
885.
886.
887.
888.
Memory Devices: Eliminating Negative‐SET Behavior by Suppressing Nanofilament Overgrowth in Cation‐Based Memory (Adv. Mater. 48/2016) 下载免费PDF全文
889.
890.
目的探讨冰箱形态演变的影响因素并研究形态演变对家电产品风格的影响。方法搜集了海尔冰箱的相关产品资料,提取了冰箱主面板形态特征并进行数据统计分析,对不同型号冰箱的线条特征、分割比例等造型元素进行了归纳总结。结论冰箱的形态演变主要受消费者需求变化和设计风格的影响。 相似文献