全文获取类型
收费全文 | 11745篇 |
免费 | 1092篇 |
国内免费 | 615篇 |
专业分类
电工技术 | 719篇 |
综合类 | 902篇 |
化学工业 | 1981篇 |
金属工艺 | 713篇 |
机械仪表 | 772篇 |
建筑科学 | 879篇 |
矿业工程 | 285篇 |
能源动力 | 333篇 |
轻工业 | 912篇 |
水利工程 | 256篇 |
石油天然气 | 665篇 |
武器工业 | 90篇 |
无线电 | 1315篇 |
一般工业技术 | 1283篇 |
冶金工业 | 486篇 |
原子能技术 | 119篇 |
自动化技术 | 1742篇 |
出版年
2024年 | 48篇 |
2023年 | 190篇 |
2022年 | 329篇 |
2021年 | 507篇 |
2020年 | 383篇 |
2019年 | 302篇 |
2018年 | 337篇 |
2017年 | 384篇 |
2016年 | 326篇 |
2015年 | 478篇 |
2014年 | 567篇 |
2013年 | 701篇 |
2012年 | 791篇 |
2011年 | 834篇 |
2010年 | 708篇 |
2009年 | 723篇 |
2008年 | 717篇 |
2007年 | 578篇 |
2006年 | 647篇 |
2005年 | 532篇 |
2004年 | 414篇 |
2003年 | 454篇 |
2002年 | 446篇 |
2001年 | 376篇 |
2000年 | 264篇 |
1999年 | 291篇 |
1998年 | 199篇 |
1997年 | 165篇 |
1996年 | 171篇 |
1995年 | 131篇 |
1994年 | 118篇 |
1993年 | 87篇 |
1992年 | 75篇 |
1991年 | 48篇 |
1990年 | 35篇 |
1989年 | 32篇 |
1988年 | 17篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1959年 | 1篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
2.
3.
Da-Wang Tan Zhen-Yong Lao Zhan Zhang Wei-Ming Guo Shi-Kuan Sun Hua-Tay Lin 《Journal of the American Ceramic Society》2021,104(6):2860-2867
B4C-TiB2 ceramics (TiB2 ranging 5~70 vol%) with Mo-Co-WC as the sintering additive were prepared by spark plasma sintering. In comparison with B4C-TiB2 without additive, the enhanced densification was evident in the sintered specimen with Mo-Co-WC additive. Core-rim structured grain was observed around TiB2 grains. The interface of the rim between TiB2 and B4C phases demonstrated different feature: the inner borderline of the rim exhibited a smooth feature, whereas a sharp curved grain boundary was observed between the rim and the B4C grain. The formation mechanism is discussed: the epitaxial growth of (Ti,Mo,W)B2 rim around the TiB2 core may occur as a result of the solid solution and dissolution-precipitation between TiB2 phase and the sintering additive. It was revealed that the fracture toughness increased as the content of TiB2 content increased, alongside the decreased hardness. B4C-30 vol% TiB2 specimen demonstrated the optimal combination of mechanical properties, reaching Vickers hardness of 24.3 GPa and fracture toughness of 3.33 MPa·m1/2. 相似文献
4.
Chengkai Li Zheyi Zhang Haifei Zhan Zhuoqun Zheng Jingshuai Bai Yuantong Gu 《大分子材料与工程》2021,306(10):2100292
Low-dimensional carbon nanostructures are ideal nanofillers to reinforce the mechanical performance of polymer nanocomposites due to their excellent mechanical properties. Through molecular dynamics simulations, the mechanical performance of poly(vinyl alchohol) (PVA) nanocomposites reinforced with a single-layer diamond – diamane is investigated. It is found the PVA/diamane exhibits similar interfacial strengths and pull-out characteristics with the PVA/bilayer-graphene counterpart. Specifically, when the nanofiller is fully embedded in the nanocomposite, it is unable to deform simultaneously with the PVA matrix due to the weak interfacial load transfer efficiency, thus the enhancement effect is not significant. In comparison, diamane can effectively promote the tensile properties of the nanocomposite when it has a laminated structure as it deforms simultaneously with the matrix. With this configuration, the interlayer sp3 bonds endows diamane with a much higher resistance under compression and shear tests, thus the nanocomposite can reach very high compressive and shear stress. Overall, enhancement on the mechanical interlocking at the interface as triggered by surface functionalization is only effective for the fully embedded nanofiller. This work provides a fundamental understanding of the mechanical properties of PVA nanocomposites reinforced by diamane, which can shed lights on the design and preparation of next generation high-performance nanocomposites. 相似文献
6.
Xiaoyan Qiu Yongqiang Zhang Haitao Wu Rui Yang Jun Yang Rongjuan Liu Yong Liu Zhiping Zhou Tongfan Hao Yijing Nie 《Polymer International》2019,68(2):218-224
The crystallization of capped ultrathin polymer films is closely dependent on film thickness and interfacial interaction. Using dynamic Monte Carlo simulations, the crystallization behaviors of polymer films confined between two substrates were investigated. The crystallization rate of confined polymers is reduced with high interfacial interactions. Above a critical strength of interfacial interaction, polymer crystallization in the thin film is inhibited within the simulation time scales. An increase in film thickness leads to a rise in critical interfacial interaction. In thicker films, the chains have more space to change conformation to form crystal stems. In addition, there are fewer absorbed segments in confined chains for the thicker films, and thus the chains have stronger ability to adjust their conformation. Therefore an increase in film thickness can cause a reduction in the entropic barrier required for the formation of crystals and thus an increase in the critical interfacial interaction. © 2018 Society of Chemical Industry 相似文献
7.
Lü Qing Xu Bin Yu Yang Zhan Wei Zhao Yu Zheng Jun Ji Jian 《Bulletin of Engineering Geology and the Environment》2021,80(8):6513-6525
Bulletin of Engineering Geology and the Environment - Many uncertainties exist in pile-stabilized slopes which make their design substantially complicated. In this paper, a first-order reliability... 相似文献
8.
9.
10.
针对现有混合入侵检测模型仅定性选取特征而导致检测精度较低的问题,同时为了充分结合误用检测模型和异常检测模型的优势,提出一种采用信息增益率的混合入侵检测模型.首先,利用信息增益率定量地选择特征子集,最大程度地保留样本信息;其次,采用余弦时变粒子群算法确定支持向量机参数构建误用检测模型,使其更好地平衡粒子在全局和局部的搜索能力,然后,选取灰狼算法确定单类支持向量机参数构建异常检测模型,以此来提高对最优参数的搜索效率和精细程度,综合提高混合入侵检测模型对攻击的检测效果;最后,通过两种数据集进行仿真实验,验证了所提混合入侵检测模型具有较好的检测性能. 相似文献