全文获取类型
收费全文 | 9629篇 |
免费 | 533篇 |
国内免费 | 290篇 |
专业分类
电工技术 | 364篇 |
综合类 | 768篇 |
化学工业 | 874篇 |
金属工艺 | 1625篇 |
机械仪表 | 2639篇 |
建筑科学 | 157篇 |
矿业工程 | 559篇 |
能源动力 | 383篇 |
轻工业 | 449篇 |
水利工程 | 31篇 |
石油天然气 | 250篇 |
武器工业 | 121篇 |
无线电 | 305篇 |
一般工业技术 | 900篇 |
冶金工业 | 641篇 |
原子能技术 | 52篇 |
自动化技术 | 334篇 |
出版年
2024年 | 32篇 |
2023年 | 139篇 |
2022年 | 215篇 |
2021年 | 247篇 |
2020年 | 326篇 |
2019年 | 198篇 |
2018年 | 231篇 |
2017年 | 327篇 |
2016年 | 326篇 |
2015年 | 373篇 |
2014年 | 584篇 |
2013年 | 575篇 |
2012年 | 670篇 |
2011年 | 750篇 |
2010年 | 480篇 |
2009年 | 553篇 |
2008年 | 429篇 |
2007年 | 643篇 |
2006年 | 570篇 |
2005年 | 478篇 |
2004年 | 408篇 |
2003年 | 380篇 |
2002年 | 336篇 |
2001年 | 235篇 |
2000年 | 230篇 |
1999年 | 154篇 |
1998年 | 112篇 |
1997年 | 108篇 |
1996年 | 64篇 |
1995年 | 48篇 |
1994年 | 61篇 |
1993年 | 41篇 |
1992年 | 28篇 |
1991年 | 27篇 |
1990年 | 19篇 |
1989年 | 14篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1976年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
In recent years, ultra-precision micromachining technology has been used in a variety of fields such as optical instruments, electronic devices, medical equipments, etc. At present, it is essential to meet the requirement of producing various shapes, one of which is a structure with a high aspect ratio. Such structures are applied, for example, to a shaft of micro robot, a long part of microactuator and micromachine, a microneedle for syringe, etc. However, due to its fragile nature, it is extremely difficult to fabricate the structure with a high aspect ratio since it is easily damaged during cutting. It is intended to produce micro towers with high aspect ratios by applying the ultra-precision milling technology using a single crystal diamond cutting tool. The method enables accurate creation of a variety of microstructures with high aspect ratios. In addition, the study also proposes a new machining method to create microneedle arrays, avoiding the contact of cutting edge with already machined parts again. As a result, it is concluded that the proposed method has the potential of producing a variety of microstructures with high aspect ratios. 相似文献
34.
Transformations in machining. Part 1. enhancement of wavelet transformation neural network (WT-NN) combination with a preprocessor 总被引:2,自引:0,他引:2
X. Wang P. Chen I.N. Tansel Yenilmez A 《International Journal of Machine Tools and Manufacture》2006,46(1):36-42
Properly selected transformation methods obtain the most significant characteristics of metal cutting data efficiently and simplify the classification. Wavelet Transformation (WT) and Neural Networks (NN) combination was used to classify the experimental cutting force data of milling operations previously. Preprocessing (PreP) of the approximation coefficients of the WT is proposed just before the classification by using the Adaptive Resonance Theory (ART2) type NNs. Genetic Algorithm (GA) was used to estimate the weights of each coefficient of the PreP. The WT-PreP-NN (ART2) combination worked at lower vigilances by creating only a few meaningful categories without any errors. The WT-NN (ART2) combination could obtain the same error rate only if very high vigilances are used and many categories are allowed. 相似文献
35.
介绍龙门铣床的直流调速控制系统的改造方案,根据龙门铣床工作台运动过程及原直流电机的容量来选择交流电机和变频器并对变频器的功能进行设定。 相似文献
36.
以Y30H-1的SrM预烧料为原料,通过对二次添加剂、二次球磨及烧结曲线的调整,做出了Br≥380mT,Hcb≥240kA穖-1,Hcj≥250kA穖-1,(BH)max≥27.0kJm-3的干压各向异性锶铁氧体产品。 相似文献
37.
38.
In this paper, a new real-time sensor system has been developed to detect chatter in milling operations. In the developed sensor system, a pattern recognition technique based on an unsupervised neural network using the adaptive resonance theory (ART) is adopted for detection of milling chatter. The features on the cutting force spectrum are fed into the sensor system to classify the milling process with or without chatter. The experimental results indicate that the proposed sensor system can accurately detect milling chatter regardless of the variation in cutting conditions. 相似文献
39.
Mechanical activation before carbothermic reduction can substantially enhance the formation of SiC from SiO2 and carbon mixtures. However, the morphology (e.g., particles or whiskers) of SiC formed from mechanically activated SiO2 and carbon mixtures is dependent of the degree of mechanical activation and the condition of the subsequent carbothermic reduction. These phenomena are investigated and rationalized based on the increased reactivity of the reactants and SiC formation mechanisms. 相似文献
40.
在高速气流粉碎作用下PVC的力化学降解及形态变化的研究 总被引:4,自引:0,他引:4
通过GPT、FT-IR、SEM和力学性能测试,研究了在高速气流作用下聚氯乙烯(PVC)的力化学降解反应、颗粒形态和微晶结构变化及其对PVC物理、力学性能的影响。实验结果表明,经过高速气流处理PVC,分子量将有所降低,晶体结构发生变化,颗粒尺寸和表观密度降低,比表面积增大,加工性能和力学性能得到明显改善。 相似文献