全文获取类型
收费全文 | 53189篇 |
免费 | 4941篇 |
国内免费 | 2853篇 |
专业分类
电工技术 | 3138篇 |
综合类 | 3450篇 |
化学工业 | 14440篇 |
金属工艺 | 8402篇 |
机械仪表 | 1751篇 |
建筑科学 | 4305篇 |
矿业工程 | 1297篇 |
能源动力 | 3194篇 |
轻工业 | 3035篇 |
水利工程 | 1060篇 |
石油天然气 | 2505篇 |
武器工业 | 336篇 |
无线电 | 3054篇 |
一般工业技术 | 6119篇 |
冶金工业 | 2233篇 |
原子能技术 | 655篇 |
自动化技术 | 2009篇 |
出版年
2024年 | 269篇 |
2023年 | 1019篇 |
2022年 | 1865篇 |
2021年 | 2118篇 |
2020年 | 1904篇 |
2019年 | 1615篇 |
2018年 | 1527篇 |
2017年 | 2041篇 |
2016年 | 1905篇 |
2015年 | 1916篇 |
2014年 | 2760篇 |
2013年 | 3356篇 |
2012年 | 3497篇 |
2011年 | 3865篇 |
2010年 | 2805篇 |
2009年 | 3176篇 |
2008年 | 2658篇 |
2007年 | 3122篇 |
2006年 | 2992篇 |
2005年 | 2523篇 |
2004年 | 2140篇 |
2003年 | 1829篇 |
2002年 | 1561篇 |
2001年 | 1353篇 |
2000年 | 1164篇 |
1999年 | 1011篇 |
1998年 | 856篇 |
1997年 | 712篇 |
1996年 | 579篇 |
1995年 | 591篇 |
1994年 | 470篇 |
1993年 | 338篇 |
1992年 | 272篇 |
1991年 | 244篇 |
1990年 | 197篇 |
1989年 | 180篇 |
1988年 | 117篇 |
1987年 | 85篇 |
1986年 | 53篇 |
1985年 | 58篇 |
1984年 | 51篇 |
1983年 | 28篇 |
1982年 | 41篇 |
1981年 | 20篇 |
1980年 | 26篇 |
1979年 | 11篇 |
1978年 | 8篇 |
1975年 | 6篇 |
1959年 | 8篇 |
1951年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Adrian Thomas Christopher D. Gilson Tanveer Ahmed 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,64(1):73-79
Equipment was developed to measure the time for complete gelling of sodium alginate fibres in calcium chloride solution, taken as the time to achieve maximum tensile strength. The effects of fibre diameter, alginate concentration, alginate composition and calcium chloride concentration on gelling time were investigated. A diffusional model, developed to predict the gelling time, agreed with experimental results except for the effect of calcium ion concentration which was modelled empirically. 相似文献
62.
63.
Two thermoplastic and two thermosetting fibrereinforced plastic composites were subjected to dynamic tests over a wide range of temperature, covering both cryogenic and hot environments. The thermal behaviour of each composite, as indicated by its dynamic mechanical properties, was assessed individually, and was compared collectively with that of the other composites. 相似文献
64.
本文介绍了采金船渡汛时的停泊方向及采金船在洪水中可能产生拖曳力的估算方法,为了防止采金船汛期发生溜船事故,建议采用缆绳牵拉固船的措施,以保障采金船的汛期安全。 相似文献
65.
66.
人工接地装置设计方法分析 总被引:1,自引:0,他引:1
本文系统地论述了人工接地装置的设计方法,修正了现有文献中有关论述的缺点和错误,提出了通过迭代求解方程组来设计人工接地装置的新方法。 相似文献
67.
68.
A generalized diffusion coefficient correlation for a binary system of liquids has been developed to represent the data for a wide range of temperatures. Detailed analysis shows that the proposed correlation fits the experimental measurements of diffusivity with the corresponding calculated values with an acceptable percentage error. 相似文献
69.
《Drying Technology》2007,25(7):1275-1280
When using the convective drying method, the mass transfer between drying air and moisture diffusion of the material is very important. The moisture moves inside the material because of the volume change caused by the increased temperature. This movement is additionally affected by the texture of the material. According to the research dealing with colloid capillary porous texture of vegetables and fruit, the humidity migration inside the material occurs in both fluid and steam condition at the same time. This migration is stimulated by the heating and decreasing humidity along with the flow. In this research, winter varieties of apples (Jonathan, Golden Delicious, and Idared) were studied by heating of a 20 × 20 × 20 piece of apple with a thermocouple in it. On the basis of the measurements it can be stated that for the fruits with a high percentage of moisture (75-90%), when making the drying condition, the moisture gradient is influenced by the fractured cells of the cut area. It was found that the variety of apple is very important in relation to the heating and water loss gradient. According to the results, the wet volume change due to the heating highly influences the water loss. The models that describe the temperature of the material have a connection with the water loss. 相似文献
70.