全文获取类型
收费全文 | 6011篇 |
免费 | 629篇 |
国内免费 | 361篇 |
专业分类
电工技术 | 176篇 |
综合类 | 673篇 |
化学工业 | 1146篇 |
金属工艺 | 116篇 |
机械仪表 | 137篇 |
建筑科学 | 1137篇 |
矿业工程 | 152篇 |
能源动力 | 371篇 |
轻工业 | 377篇 |
水利工程 | 123篇 |
石油天然气 | 337篇 |
武器工业 | 41篇 |
无线电 | 323篇 |
一般工业技术 | 599篇 |
冶金工业 | 250篇 |
原子能技术 | 87篇 |
自动化技术 | 956篇 |
出版年
2024年 | 25篇 |
2023年 | 60篇 |
2022年 | 151篇 |
2021年 | 183篇 |
2020年 | 195篇 |
2019年 | 186篇 |
2018年 | 166篇 |
2017年 | 207篇 |
2016年 | 246篇 |
2015年 | 224篇 |
2014年 | 378篇 |
2013年 | 386篇 |
2012年 | 400篇 |
2011年 | 475篇 |
2010年 | 349篇 |
2009年 | 346篇 |
2008年 | 371篇 |
2007年 | 512篇 |
2006年 | 342篇 |
2005年 | 311篇 |
2004年 | 227篇 |
2003年 | 223篇 |
2002年 | 172篇 |
2001年 | 139篇 |
2000年 | 128篇 |
1999年 | 109篇 |
1998年 | 85篇 |
1997年 | 89篇 |
1996年 | 71篇 |
1995年 | 62篇 |
1994年 | 38篇 |
1993年 | 21篇 |
1992年 | 26篇 |
1991年 | 13篇 |
1990年 | 20篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 3篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 4篇 |
1951年 | 4篇 |
排序方式: 共有7001条查询结果,搜索用时 0 毫秒
51.
52.
L. N. Bortnikov 《Combustion, Explosion, and Shock Waves》2007,43(4):378-383
This paper reports results of an analysis of experimental data on the combustion of a gasoline-hydrogen-air mixture in a reciprocating
internal combustion engine cylinder. The completeness of combustion of the mixture is shown to depend on the amount of hydrogen
in the fuel mixture and the composition and physicochemical properties of the mixture. In particular, the conditions of addition
of hydrogen to the gasoline-air mixture with active chemical action on the combustion process and the action of hydrogen as
an additional fuel component are determined. A dimensionless universal relation is proposed that allows one to uniquely determine
the initial composition of the fuel mixture (hydrogen to gasoline ratio) to accomplish combustion of the fuel mixture at the
lean combustion limit.
__________
Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 4, pp. 8–14, July–August, 2007. 相似文献
53.
54.
55.
Interfacial agents as compatibilizers have recently been introduced into polymer blends to improve microstructure and mechanical properties of thermoplastics. In this way, it is possible to prepare a mixture of polymeric materials that can have superior mechanical properties over a wide temperature range. In this study, an incompatible blend of Polycarbonate (PC) and Acrylonitrile Butadiene Styrene (ABS) Copolymer were made compatible by addition of 5, 10, and 20% Styrene–Isopren–Styrene Copolymer (SIS). The mixing operation was conducted using a twin‐screw extruder. The morphology and the compatibility of the mixtures were examined by SEM and DSC techniques. Furthermore, the elastic modulus, tensile and yield strengths, percentage elongation, hardness, melt flow index, Izod impact resistance, heat deflection temperature (HDT), Vicat softening point values of polymer alloys of various ratios were determined. It was found that addition of SIS to the structures decreased the tensile strength, yield strength, elastic modulus, and hardness, whereas it increased Izod impact strength and percentage elongation values. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 559–566, 2006 相似文献
56.
57.
This article concerns the in situ compatibilization of immiscible isotactic polypropylene/butadiene‐styrene‐butadiene triblock copolymer blends (i‐PP/SBS) by means of a reactive mixture. For this purpose, maleated PP (PP‐MAH) and SBS (SBS‐MAH) were used as functionalized polymers and 4,4′‐diaminediphenylmethane was used as a coupling agent between maleated polymers, resulting in a graft copolymer. Binary blends i‐PP/SBS, nonreactive ternary blends i‐PP/PP‐MAH/SBS, and reactive ternary blends i‐PP/PP‐MAH/SBS‐MAH with varying diamine and anhydride molar ratios were prepared. Torque measurements suggest a graft copolymerization during the melt blending for ternary reactive blends, but the extension of the grafting does not vary with the diamine and anhydride molar ratio, but with the elastomer concentration. The morphology of the blends was investigated by scanning electron microscopy. The morphology of binary and ternary nonreactive blends is similar, exhibiting elastomer domains disperse in the i‐PP matrix, whose sizes increase with elastomer concentration. On the other hand, the elastomer domain size in the ternary reactive blends is practically independent of the blends composition and of the diamine and anhydride molar ratio. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 847–855, 2002 相似文献
58.
59.
目前,大多数多目标进化算法采用为单目标优化所设计的重组算子.通过证明或实验分析了几个典型的单目标优化重组算子并不适合某些多目标优化问题.提出了基于分解技术和混合高斯模型的多目标优化算法(multiobjective evolutionary algorithm based on decomposition and mixture Gaussian models,简称MOEA/D-MG).该算法首先采用一个改进的混合高斯模型对群体建模并采样产生新个体,然后利用一个贪婪策略来更新群体.针对具有复杂Pareto前沿的多目标优化问题的测试结果表明,对给定的大多数测试题,该算法具有良好的效果. 相似文献
60.
提出了一种基于改进的混合粒子群优化(particle swarm optimization,PSO)算法的高斯混合模型地形分类方法。高斯混合模型的求解通常是使用期望最大化算法(expectation maximization,EM),然而EM算法易陷入局部最优,收敛速度不稳定且对初值敏感。因此引入混合PSO算法,并对其进行了一系列改进。实验结果表明:改进后的算法较其它优化算法提高了全局搜索能力和收敛速度,利用该算法求解高斯混合模型可以提高参数估计的精度,并且在户外场景图像的地形分类实验中所提出的地形分类方法也表现优良。 相似文献