全文获取类型
收费全文 | 128336篇 |
免费 | 10898篇 |
国内免费 | 6100篇 |
专业分类
电工技术 | 4563篇 |
技术理论 | 8篇 |
综合类 | 10994篇 |
化学工业 | 27074篇 |
金属工艺 | 7217篇 |
机械仪表 | 3414篇 |
建筑科学 | 16024篇 |
矿业工程 | 6020篇 |
能源动力 | 5740篇 |
轻工业 | 10504篇 |
水利工程 | 19189篇 |
石油天然气 | 10225篇 |
武器工业 | 718篇 |
无线电 | 2896篇 |
一般工业技术 | 9829篇 |
冶金工业 | 6271篇 |
原子能技术 | 1300篇 |
自动化技术 | 3348篇 |
出版年
2024年 | 431篇 |
2023年 | 1490篇 |
2022年 | 3028篇 |
2021年 | 3602篇 |
2020年 | 3844篇 |
2019年 | 3252篇 |
2018年 | 3262篇 |
2017年 | 4104篇 |
2016年 | 4439篇 |
2015年 | 4560篇 |
2014年 | 7434篇 |
2013年 | 7526篇 |
2012年 | 9345篇 |
2011年 | 9581篇 |
2010年 | 7156篇 |
2009年 | 7465篇 |
2008年 | 6348篇 |
2007年 | 8715篇 |
2006年 | 8085篇 |
2005年 | 7334篇 |
2004年 | 5818篇 |
2003年 | 5255篇 |
2002年 | 4564篇 |
2001年 | 3701篇 |
2000年 | 3118篇 |
1999年 | 2516篇 |
1998年 | 1921篇 |
1997年 | 1523篇 |
1996年 | 1256篇 |
1995年 | 1065篇 |
1994年 | 849篇 |
1993年 | 595篇 |
1992年 | 514篇 |
1991年 | 362篇 |
1990年 | 237篇 |
1989年 | 237篇 |
1988年 | 153篇 |
1987年 | 147篇 |
1986年 | 108篇 |
1985年 | 104篇 |
1984年 | 96篇 |
1983年 | 58篇 |
1982年 | 31篇 |
1981年 | 17篇 |
1980年 | 23篇 |
1979年 | 21篇 |
1977年 | 9篇 |
1976年 | 6篇 |
1959年 | 6篇 |
1951年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
《Calphad》2014
Thermodynamic properties and phase diagrams of the MCl–YCl3 (M=Na, K, Rb, Cs) systems were reassessed by using the CALPHAD method with the latest phase diagram data. A two-sublattice ionic solution model (M+)P(Cl−, , YCl3)Q reflecting the ionic behavior of the components was adopted to describe the liquid phase in the systems. A new set of optimized model parameters was found, and the calculated phase diagrams and enthalpies of mixing have good agreement with experimental data. The calculated liquidus near to YCl3 side agrees much better with experimental data compared with previous work. In consideration of high and low temperature modifications as well as stability of intermediate compounds, Gibbs energies of formation of these compounds evaluated in the present work are more reasonable. 相似文献
62.
63.
64.
Permeability of a polymer plays an important role in conferring the protective ability of organic coating to the steel surface against atmospheric corrosion. Although the relationship between structure of polymers and their permeability has been extensively studied in various applications like membranes, packaging, etc., such detailed study is lacking in the area of coatings. The systematic study of structure–permeability relationship of polymers in clear coatings can give guidelines in selecting the binder for the required application. This article deals with the effect of introduction of structural defects into a straight chain aliphatic polyesters on the protective ability of their clear coatings against corrosion. The mild steel panels coated with clear coatings based on the polyesters were exposed to humidity in humidity chamber. A novel technique of detecting the onset of corrosion was used instead of conventional methods that detect the failure of the coating due to corrosion. It was observed that even at 1–10% mole defect introduced by replacement of straight chain diols with branched diols, the protective ability of clear coatings was affected drastically. 相似文献
67.
68.
煤的荧光特性与其工艺性能的关系研究 总被引:1,自引:0,他引:1
简述了煤中镜质组荧光产生的机理及荧光参数的测量方法,通过测定一系列煤的粘结性和10kg小焦炉结焦性试验,探讨了煤的荧光特性与其工艺性能的关系。煤的荧光参数与其反射率呈正的线性相关关系,与其挥发分含量呈负的线性相关关系;煤的粘结性、结焦性均与其荧光参数有关;当煤化程度相同、煤岩组成基本相同时,煤的荧光强度愈强,其结焦性能愈好。 相似文献
69.
Although leather has a number of desirable properties such as thermal stability and fire retardancey, in addition to high toughness, it has a few drawbacks such as weight, high water absorption, poor soil and rot resistance, and nonuniformity. If these defects are overcome, leather's usefulness would be further enhanced and its competitive position with respect to synthetics would increase. This study reports the physical and mechanical properties of buffalo leather after chemical graft copolymerization with ethyl acrylate, butyl acrylate, and 2‐ethyl hexyl acrylate using benzoyl peroxide as an initiator. The optimum conditions for grafting (e.g., monomer and initiator concentrations, temperature and time of grafting, and solvent leather ratio) were extensively investigated. The study achieved outstanding properties for buffalo leather in reduction of water uptake after grafting, especially on using 2‐ethyl hexyl acrylate and butyl acrylate monomers. FT‐IR and solid 13C‐NMR for leather before and after grafting confirmed the grafting process.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1478–1483, 2003 相似文献
70.
论述了金属的电化学腐蚀和外加电流阴极保护原理。说明对以海水为介质的冷却、冷凝设备,采用外加电流阴极保护是防止设备腐蚀的有效方法。举例说明了应用效果。 相似文献