全文获取类型
收费全文 | 10428篇 |
免费 | 794篇 |
国内免费 | 343篇 |
专业分类
电工技术 | 361篇 |
综合类 | 790篇 |
化学工业 | 2118篇 |
金属工艺 | 644篇 |
机械仪表 | 545篇 |
建筑科学 | 1957篇 |
矿业工程 | 459篇 |
能源动力 | 350篇 |
轻工业 | 1633篇 |
水利工程 | 438篇 |
石油天然气 | 348篇 |
武器工业 | 18篇 |
无线电 | 278篇 |
一般工业技术 | 697篇 |
冶金工业 | 661篇 |
原子能技术 | 54篇 |
自动化技术 | 214篇 |
出版年
2024年 | 36篇 |
2023年 | 137篇 |
2022年 | 288篇 |
2021年 | 324篇 |
2020年 | 323篇 |
2019年 | 259篇 |
2018年 | 272篇 |
2017年 | 319篇 |
2016年 | 384篇 |
2015年 | 345篇 |
2014年 | 604篇 |
2013年 | 661篇 |
2012年 | 733篇 |
2011年 | 743篇 |
2010年 | 555篇 |
2009年 | 571篇 |
2008年 | 473篇 |
2007年 | 714篇 |
2006年 | 687篇 |
2005年 | 618篇 |
2004年 | 443篇 |
2003年 | 433篇 |
2002年 | 341篇 |
2001年 | 275篇 |
2000年 | 215篇 |
1999年 | 176篇 |
1998年 | 97篇 |
1997年 | 96篇 |
1996年 | 75篇 |
1995年 | 75篇 |
1994年 | 69篇 |
1993年 | 49篇 |
1992年 | 33篇 |
1991年 | 29篇 |
1990年 | 20篇 |
1989年 | 26篇 |
1988年 | 23篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 3篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
介绍了煤炭振动流化床气力分级新技术的工作原理和特点;通过该机组在郑煤集团米村矿的应用实例,说明了该技术可实现煤炭选前0~10mm内任一粒度干法分级,从而降低动力煤洗选粒度下限,优化产品结构,减少煤泥量,提高企业经济效益。 相似文献
32.
聚酯酰胺热熔胶的合成及其性能研究 总被引:2,自引:1,他引:2
研究了以聚酯胶和聚酰胺胶为原料在催化剂作用下加热共熔,通过大分子链交换反应制备织物用聚酯酰胺热熔胶的方法。用聚酯胶的溶剂对所得产品进行溶取试验并且通过红外光谱分析都证明了链交换反应的存在。用该法所得产品粘接强度大,既耐水洗又耐干洗,适用于粘合衬生产。 相似文献
33.
Strength, durability and micro-structural aspects of high performance volcanic ash concrete 总被引:2,自引:0,他引:2
This paper presents the results of investigations to assess the suitability of using volcanic ash (VA) as a cement replacement material to produce high performance concrete. Tests were conducted on concrete mixtures replacing 0 to 20% by mass of ordinary Portland cement (OPC) by VA. The performance of high performance volcanic ash concrete (HPVAC) mixtures was evaluated by conducting comprehensive series of tests on fresh and hardened properties as well as durability. The mechanical properties were assessed by compressive strength, while durability characteristics were investigated by rapid chloride permeability (RCP), drying shrinkage (DS), mercury intrusion porosimetry (MIP), differential scanning calorimetry (DSC) and microhardness tests. HPVACs showed better durability properties compared to control concrete with 0% VA. The improved performance of HPVACs was attributed to the refinement of pore structure, and pozzolanic action of VA. HPVAC having a minimum 28-day compressive strength of 60 MPa can be obtained by replacing up to 20% (by mass) of cement by VA. Development of non-expensive and environmentally friendly HPVAC with acceptable strength and durability characteristics (as illustrated in this study) is extremely helpful for the sustainable development and rehabilitation of volcanic disaster areas around the world. 相似文献
34.
K Harmsen 《Nutrient Cycling in Agroecosystems》1984,5(4):371-382
Agronomic efficiency (AE) is defined as the increase in economic yield of a crop per unit fertilizer applied. Components of AE are physiological efficiency and apparent recovery fraction. The latter can be further separated into uptake efficiency and availability index. Ways to increase the nitrogen fertilizer use efficiency in rainfed agriculture through fertilizer management are discussed. 相似文献
35.
36.
The important mechanical mechanism for the electrical conduction of anisotropic conductive films (ACFs) is the joint clamping force after the curing and cooling processes of ACFs. In this study, the mechanism of shrinkage and contraction stress and the relationship between these mechanisms and the thermomechanical properties of ACFs were investigated in detail. Both thickness shrinkages and modulus changes of four kinds of ACFs with different thermomechanical properties were experimentally investigated with thermomechanical and dynamic mechanical analysis. Based on the incremental approach to linear elasticity, contraction stresses of ACFs developed along the thickness direction were estimated. Contraction stresses in ACFs were found to be significantly developed by the cooling process from the glass‐transition temperature to room temperature. Moreover, electrical characteristics of ACF contact during the cooling process indicate that the electrical conduction of ACF joint is robustly maintained by substantial contraction stress below Tg. The increasing rate of contraction stresses below Tg was strongly dependent on both thermal expansion coefficient (CTE) and elastic modulus (E) of ACFs. A linear relationship between the experimental increasing rate and E × CTE reveals that the build‐up behavior of contraction stress is closely correlated with the ACF material properties: thermal expansion coefficient, glassy modulus, and Tg. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2634–2641, 2004 相似文献
37.
38.
介绍氨纶干法纺丝技术中纺丝介质 (SM )循环系统的主要设备 ,对循环风压力、风温度和风量控制进行了探讨。严格控制SM循环工艺参数 ,可减少并丝现象。 相似文献
39.
转炉干法除尘蒸发冷却器出口烟气温度大多数采用常规串级控制方式,但转炉冶炼前期控制效果并不理想.对转炉冶炼过程及蒸发冷却器出口烟气温度的控制难点进行研究,找出常规串级控制方式的缺点,并设计出一种智能混合控制器.采用智能模糊控制器和常规控制器并联的控制方式,对蒸发冷却器出口烟气温度进行控制,控制效果理想.实际应用表明,同常规串级控制器相比,智能混合控制器具有响应快、被控对象稳定等优点. 相似文献
40.
柔软热收缩材料的研制 总被引:2,自引:0,他引:2
总结了经共混和辐射交联制备柔软耐老化的热收缩材料的研制过程。测得了不同乙丙橡胶含量和不同辐照剂量下的共混物的力学性能和凝胶含量,确定了共混物辐射交联的合适剂量。此外,还测试了EPDM和PE共混物经辐照后的耐油性能。在此基础上,制得了手感柔软的热收缩管材。 相似文献