全文获取类型
收费全文 | 292085篇 |
免费 | 35485篇 |
国内免费 | 12344篇 |
专业分类
电工技术 | 17072篇 |
技术理论 | 21篇 |
综合类 | 17511篇 |
化学工业 | 57316篇 |
金属工艺 | 14883篇 |
机械仪表 | 17107篇 |
建筑科学 | 21761篇 |
矿业工程 | 8371篇 |
能源动力 | 8666篇 |
轻工业 | 24003篇 |
水利工程 | 5178篇 |
石油天然气 | 15741篇 |
武器工业 | 2071篇 |
无线电 | 35948篇 |
一般工业技术 | 40040篇 |
冶金工业 | 13113篇 |
原子能技术 | 2798篇 |
自动化技术 | 38314篇 |
出版年
2024年 | 1214篇 |
2023年 | 4636篇 |
2022年 | 8696篇 |
2021年 | 11845篇 |
2020年 | 10003篇 |
2019年 | 9803篇 |
2018年 | 10687篇 |
2017年 | 12019篇 |
2016年 | 11389篇 |
2015年 | 14277篇 |
2014年 | 16893篇 |
2013年 | 20483篇 |
2012年 | 19779篇 |
2011年 | 20364篇 |
2010年 | 18294篇 |
2009年 | 17093篇 |
2008年 | 16201篇 |
2007年 | 15162篇 |
2006年 | 14943篇 |
2005年 | 12826篇 |
2004年 | 9250篇 |
2003年 | 8539篇 |
2002年 | 8536篇 |
2001年 | 7536篇 |
2000年 | 6588篇 |
1999年 | 6518篇 |
1998年 | 4814篇 |
1997年 | 4107篇 |
1996年 | 3924篇 |
1995年 | 3100篇 |
1994年 | 2474篇 |
1993年 | 1822篇 |
1992年 | 1452篇 |
1991年 | 1098篇 |
1990年 | 799篇 |
1989年 | 643篇 |
1988年 | 537篇 |
1987年 | 350篇 |
1986年 | 293篇 |
1985年 | 173篇 |
1984年 | 158篇 |
1983年 | 121篇 |
1982年 | 111篇 |
1981年 | 90篇 |
1980年 | 88篇 |
1979年 | 39篇 |
1978年 | 28篇 |
1977年 | 27篇 |
1976年 | 26篇 |
1975年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
43.
A new aqueous slurry-based laminated object manufacturing process for porous ceramics is proposed: firstly, an organic mesh sheet is pre-paved as a pore-forming template before slurry layer scraping; secondly, the 2D pattern is built with laser outline cutting of the dried mesh–ceramic composite layer; finally, the pore structure is formed after degreasing and sintering. Alumina parts with porosities of 51.5 %, round hole diameters of 80 ± 5 μm were fabricated using 70 wt. % solid content slurry and 100 mesh nylon net. Using an organic mesh as the framework and template not only reduces the risk of damage of the green body but also ensures the regularity, uniformity and connectivity of the micron scaled pore network. The layer-by-layer drying method avoids the delamination phenomenon and improves the paving density. The new method can realize the flexible design of the pore structure by using various organic mesh templates. 相似文献
44.
In this study, a kind of Ni-based superalloy specially designed for additive manufacturing (AM) was investigated. Thermo-Calc simulation and differential scanning calorimetry (DSC) analysis were used to determine phases and their transformation temperature. Experimental specimens were prepared by laser metal deposition (LMD) and traditional casting method. Microstructure, phase constitution and mechanical properties of the alloy were characterized by scanning electron microscopy (SEM), transmission scanning electron microscopy (TEM), X-ray diffraction (XRD) and tensile tests. The results show that this alloy contains two basic phases, γ/γ', in addition to these phases, at least two secondary phases may be present, such as MC carbides and Laves phases. Furthermore, the as-deposited alloy has finer dendrite, its mean primary dendrite arm space (PDAS) is about 30-45 μm, and the average size of γ' particles is 100-150 nm. However, the dendrite size of the as-cast alloy is much larger and its PDAS is 300-500 μm with secondary and even third dendrite arms. Correspondingly, the alloy displays different tensile behavior with different processing methods, and the as-deposited specimen shows better ultimate tensile stress (1,085.7±51.7 MPa), yield stress (697±19.5 MPa) and elongation (25.8%±2.2%) than that of the as-cast specimen. The differences in mechanical properties of the alloy are due to the different morphology and size of dendrites, γ', and Laves phase, and the segregation of elements, etc. Such important information would be helpful for alloy application as well as new alloy development. 相似文献
45.
Sheng Mingming Yang Rongkun Gong Hongyu Zhang Yujun Lin Xiao Jing Jie 《Journal of Materials Science》2022,57(10):5805-5824
Journal of Materials Science - With the extensive use of high-power electronic appliances, polymer-based thermal insulation composites with excellent thermal properties are utilized in the field of... 相似文献
46.
At present, the development and implementation of digital transformation are the keys to promoting high-quality industry development. The new digital fabrication method of robotic 3D printing is a research area being studied by many to tackle the issue of the declining productivity of traditional construction methods. Although many studies have been done, most of the current 3D printing projects are facing limitations in terms of scale. In order to bridge the gap, this article proposed a mass customization 3D printing framework system for large-scale projects. This article discusses how mass customization is made possible through the joint operation of the FUROBOT software and 3D printing hardware. By taking the east gate of Nanjing Happy Valley Plaza as a case study, the article demonstrates and studies the feasibility of the large-scale mass customization 3D printing framework system. 相似文献
47.
48.
Water Resources Management - Urban river not only has the important function in urban hydrological environment, but also is an area for entertainment. Water quality assessment is the core technique... 相似文献
49.
50.