全文获取类型
收费全文 | 5427篇 |
免费 | 661篇 |
国内免费 | 197篇 |
专业分类
电工技术 | 233篇 |
综合类 | 312篇 |
化学工业 | 1958篇 |
金属工艺 | 137篇 |
机械仪表 | 81篇 |
建筑科学 | 143篇 |
矿业工程 | 70篇 |
能源动力 | 182篇 |
轻工业 | 1612篇 |
水利工程 | 82篇 |
石油天然气 | 133篇 |
武器工业 | 30篇 |
无线电 | 258篇 |
一般工业技术 | 590篇 |
冶金工业 | 168篇 |
原子能技术 | 24篇 |
自动化技术 | 272篇 |
出版年
2024年 | 31篇 |
2023年 | 104篇 |
2022年 | 163篇 |
2021年 | 216篇 |
2020年 | 226篇 |
2019年 | 171篇 |
2018年 | 184篇 |
2017年 | 192篇 |
2016年 | 202篇 |
2015年 | 157篇 |
2014年 | 263篇 |
2013年 | 323篇 |
2012年 | 413篇 |
2011年 | 388篇 |
2010年 | 273篇 |
2009年 | 273篇 |
2008年 | 246篇 |
2007年 | 337篇 |
2006年 | 326篇 |
2005年 | 282篇 |
2004年 | 226篇 |
2003年 | 205篇 |
2002年 | 212篇 |
2001年 | 149篇 |
2000年 | 146篇 |
1999年 | 113篇 |
1998年 | 92篇 |
1997年 | 74篇 |
1996年 | 62篇 |
1995年 | 59篇 |
1994年 | 50篇 |
1993年 | 25篇 |
1992年 | 25篇 |
1991年 | 18篇 |
1990年 | 12篇 |
1989年 | 9篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1959年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有6285条查询结果,搜索用时 15 毫秒
71.
Chemical modification of Carbon Vulcan XC-72R for fuel cell applications has been undertaken. Treated carbons were used as carriers for the deposition of Pt nanoparticles and used as electrocatalysts. The influence of the carbon treatment, as well as that of the Pt nanoparticles generation and their deposition route has been studied. The behaviour of the electrocatalysts in the CO and hydrogen oxidation reaction (HOR) has been studied. It was observed that carbon pre-treatment lead to difference behaviour in the CO oxidation reaction compared with the performance over non treated supports. In this way, CO oxidation was controlled by the nature of the support rather than by the nature of the Pt particles alone. 相似文献
72.
73.
Dynamic properties of polymethylvinylsiloxane (PMVS) filled with filler‐blends composed of carbon black (CB) and silica (SiO2) were investigated using an advanced rheometric expansion system. A variety of weight fraction of CB to SiO2 were 0/100, 10/90, 30/70, 50/50, 70/30, 90/10, and 100/0, and a bifunctional organsilane, bis(3‐triethoxysilylpropyl)tetrasurfane, was used to facilitate the filler dispersion. The results reveal that the incorporation of CB/SiO2 filler‐blends into PMVS result in a reduced Payne effect. This effect reaches a minimum when the ratio of CB/SiO2 approaches 1, and then it began to rebound with the ratio increase. Meanwhile, a characteristic Newtonian viscosity plateau appearing in low frequencies also significantly decreases, depending on the amount of CB or SiO2 added. On the basis of a simplified Fowke model, we ascribe this phenomenon to the deteriorated filler network, which is predominantly induced by the totally different surface activity between CB and SiO2. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3477–3482, 2006 相似文献
74.
75.
76.
77.
An optimization strategy has been applied to describe the chemical composition at the furnace bottom in the Kraft recovery boiler of a pulp production process. The concentrations of each involved chemical species were calculated through an optimization approach, minimizing the Gibbs free energy of the system. Various systems were proposed and tested, assuming different chemical species and phases number. Because serious initialization problems were found at this stage for some of the proposed systems, an optimization heuristic method (PSO) was used for the first approach to the problem. Once the appropriate phases number and chemical species in the system were determined, the initialization problems disappeared and the use of a deterministic optimization method (SQP) became viable. The proposed approach has shown to be satisfactory to reproduce industrial data and also data reported in the open scientific literature. 相似文献
78.
79.
根据碱回收蒸发工段的工艺特点和控制要求,设计了S7-300PLC控制系统.详细说明了控制系统的硬件组成、软件程序设计,工程实际运行表明,该系统控制效果良好,具有较好的经济价值. 相似文献
80.
新型细胞固定化载体强化白腐菌降解活性染料 总被引:1,自引:0,他引:1
为提高白腐真菌的产酶能力和后续对染料的降解效果,采用摇瓶试验研究新型细胞固定化载体——聚氨酯泡沫固定化白腐真菌后的锰过氧化物酶(MnP)产生情况以及后续对活性染料——活性艳红K-2BP的降解效果.结果显示,新型载体固定化培养白腐真菌的5d脱色率为95%,比悬浮培养7d的脱色率高15%.固定化培养产生的MnP酶活为936.61U/L,而悬浮培养的MnP仅为269.52U/L,并且酶活高峰期提前4d.另外,固定化培养体系中碳、氮源的消耗比悬浮培养快很多,而且固定化培养使得白腐真菌具有较高的H2O2产量.因此,新型细胞固定化载体强化白腐真菌降解活性染料的原因应归于这种培养体系碳、氮源的快速消耗而带来的MnP酶活的提高和高H2O2产量. 相似文献