全文获取类型
收费全文 | 28148篇 |
免费 | 2497篇 |
国内免费 | 775篇 |
专业分类
电工技术 | 1303篇 |
综合类 | 2526篇 |
化学工业 | 7650篇 |
金属工艺 | 1141篇 |
机械仪表 | 4965篇 |
建筑科学 | 5952篇 |
矿业工程 | 1027篇 |
能源动力 | 490篇 |
轻工业 | 342篇 |
水利工程 | 790篇 |
石油天然气 | 956篇 |
武器工业 | 177篇 |
无线电 | 290篇 |
一般工业技术 | 2089篇 |
冶金工业 | 1098篇 |
原子能技术 | 84篇 |
自动化技术 | 540篇 |
出版年
2024年 | 155篇 |
2023年 | 326篇 |
2022年 | 702篇 |
2021年 | 876篇 |
2020年 | 854篇 |
2019年 | 571篇 |
2018年 | 665篇 |
2017年 | 783篇 |
2016年 | 915篇 |
2015年 | 957篇 |
2014年 | 1760篇 |
2013年 | 1439篇 |
2012年 | 2043篇 |
2011年 | 1984篇 |
2010年 | 1464篇 |
2009年 | 1603篇 |
2008年 | 1287篇 |
2007年 | 1857篇 |
2006年 | 1723篇 |
2005年 | 1528篇 |
2004年 | 1153篇 |
2003年 | 1120篇 |
2002年 | 1037篇 |
2001年 | 842篇 |
2000年 | 727篇 |
1999年 | 609篇 |
1998年 | 537篇 |
1997年 | 393篇 |
1996年 | 387篇 |
1995年 | 262篇 |
1994年 | 222篇 |
1993年 | 143篇 |
1992年 | 115篇 |
1991年 | 92篇 |
1990年 | 73篇 |
1989年 | 62篇 |
1988年 | 28篇 |
1987年 | 24篇 |
1986年 | 14篇 |
1985年 | 25篇 |
1984年 | 18篇 |
1983年 | 11篇 |
1982年 | 17篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
G.R Mitchell 《Polymer》1984,25(11):1562-1572
Molecular orientation parameters have been measured for the non-crystalline component of crosslinked natural rubber samples deformed in uniaxial tension as a function of the extension ratio and of temperature. The orientation parapeters 〈P2(cosα)〉 and 〈P4(cosα)〉 were obtained by an analysis of the anisotropy of the wide-angle X-ray scattering functions. For the measurements made at high temperatures the level of crystallinity detected was negligible and the orientation-strain behaviour could be compared directly with the predictions of molecular models of rubber elasticity. The molecular orientation behaviour with strain was found to be at variance with the estimates of the affine model particularly at low and moderate strains. Extension of the crosslinked rubber at room temperature led to strain-crystallization and measurements of both the molecular orientation of the non-crystalline chains and the degree of crystallinity during extension and relaxation enabled the role of the crystallites in the deformation process to be considered in detail. The intrinsic birefringence of the non-crystalline component was estimated, through the use of the 〈P2(cosα)〉 values obtained from X-ray scattering measurements, to be 0.20±0.02. 相似文献
994.
995.
《Polymer-Plastics Technology and Engineering》2013,52(4):505-517
The effects of a diamine salt of fatty acid of general structure [RNH2 +[CH2)3NH+] [R′COO?]2 referred to as a multifunctional additive (MFA) on curing characteristics and mechanical properties and swelling behavior of natural rubber (SMR L) and polychloroprene (CR) rubber blends were studied. Compared to SMR L/CR blends without MFA, the incorporation of 2 phr (parts per hundred parts of rubber) of MFA in the blends increased mechanical properties, i.e., tensile strength, tensile modulus and hardness, and improved swelling resistance toward toluene and ASTM oil No. 1. However the scorch time, t 5 and cure index, Δt L decrease with incorporation of MFA into the blends. 相似文献
996.
Blends of syndiotactic polystyrene (s-PS), thermotropic liquid crystalline polymer (Vectra A-950), and silicone rubber with two different loading levels, have been prepared through melt processing in internal mixer at 285°C. Silicone rubber was used as a compatibilizer for this blend system. The effect of silicon rubber on crystalline, dynamic mechanical, rhelogical, thermal properties, and phase morphology of the (s-PS/TLCP) blend has been investigated in details. With the addition of compatibilizer the viscosity of the blend system increased to an order of magnitude. Dynamic mechanical analysis (DMTA) and differential scanning calorimetry (DSC) results showed that the glass transition temperature (Tg) of the blend, in presence of silicone rubber, shifted towards lower temperature region. From FTIR analysis it is evident that the ‘C=O’ stretching frequency has shifted towards lower side. SEM analysis suggested that, the TLCP domain size is reduced in ternary blend in comparison to binary blend system. 相似文献
997.
介绍了用甲基丙烯酸树脂改性的氟树脂涂料包覆于天然胶塞表面的包覆材料,选用适当碳数甲基丙烯酸树脂改性聚四氟乙烯,在保持聚四氟乙烯良好气密性、阻隔性、耐热性的基础上使聚四氟乙烯硬度降低,与柔性物质橡胶的粘结力增强。所制成的薄膜具有优异的性能,又与天然橡胶具有良好的粘结性能,防止橡胶胶塞中的重金属水溶性物质迁移到药品中。 相似文献
998.
999.
1000.
乙烯-辛烯共聚物/再生丁基橡胶热塑性弹性体的制备及其性能 总被引:2,自引:0,他引:2
采用动态硫化法制备了乙烯-辛烯共聚物(POE)/再生丁基橡胶(RIIR)热塑性弹性体(TPE),考察了共混比、硫黄、软化剂白油和炭黑N330对TPE力学性能的影响,研究了TPE的动态力学性能和流变性能。结果表明,当POE/RIIR(质量比)为2/1、硫黄为0.5份、软化剂白油为20份、炭黑为30份时,TPE的综合力学性能较佳;POE和RIIR具有较好的相容性;当体系中加入白油时,TPE的动态复数黏度(η*)降低,炭黑的加入使TPE的η*迅速增大。 相似文献