全文获取类型
收费全文 | 17552篇 |
免费 | 1595篇 |
国内免费 | 449篇 |
专业分类
电工技术 | 221篇 |
综合类 | 804篇 |
化学工业 | 4482篇 |
金属工艺 | 2300篇 |
机械仪表 | 746篇 |
建筑科学 | 1261篇 |
矿业工程 | 145篇 |
能源动力 | 344篇 |
轻工业 | 4604篇 |
水利工程 | 106篇 |
石油天然气 | 462篇 |
武器工业 | 76篇 |
无线电 | 542篇 |
一般工业技术 | 2126篇 |
冶金工业 | 988篇 |
原子能技术 | 105篇 |
自动化技术 | 284篇 |
出版年
2024年 | 83篇 |
2023年 | 266篇 |
2022年 | 379篇 |
2021年 | 636篇 |
2020年 | 539篇 |
2019年 | 543篇 |
2018年 | 500篇 |
2017年 | 585篇 |
2016年 | 686篇 |
2015年 | 580篇 |
2014年 | 882篇 |
2013年 | 1106篇 |
2012年 | 1011篇 |
2011年 | 1353篇 |
2010年 | 911篇 |
2009年 | 1022篇 |
2008年 | 927篇 |
2007年 | 957篇 |
2006年 | 970篇 |
2005年 | 784篇 |
2004年 | 709篇 |
2003年 | 701篇 |
2002年 | 646篇 |
2001年 | 475篇 |
2000年 | 392篇 |
1999年 | 300篇 |
1998年 | 312篇 |
1997年 | 250篇 |
1996年 | 189篇 |
1995年 | 166篇 |
1994年 | 135篇 |
1993年 | 105篇 |
1992年 | 73篇 |
1991年 | 70篇 |
1990年 | 57篇 |
1989年 | 41篇 |
1988年 | 24篇 |
1987年 | 29篇 |
1986年 | 17篇 |
1985年 | 29篇 |
1984年 | 40篇 |
1983年 | 17篇 |
1982年 | 32篇 |
1981年 | 6篇 |
1980年 | 21篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1975年 | 9篇 |
1974年 | 4篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 49 毫秒
31.
32.
A.V. GomonnaiI.M. Voynarovych A.M. SolomonYu.M. Azhniuk A.A. KikineshiV.P. Pinzenik M. Kis-VargaL. Daroczy V.V. Lopushansky 《Materials Research Bulletin》2003,38(13):1767-1772
Lattice structure and rod-like shaped SbSI nanocrystals obtained by ball milling with rod thickness down to 70 nm, as estimated from X-ray diffraction (XRD) and electron microscopy, is similar to that of the bulk crystals. The dependence of the grain size on the milling duration is discussed in view of the chain-like crystalline structure of SbSI. Possible factors, responsible for the observed Raman line broadening, are discussed, scattering by surface phonons being considered the predominant one. 相似文献
33.
Micro assembly injection moulding 总被引:1,自引:0,他引:1
Injection moulding is established as one of the most common manufacturing processes of thermoplastics due to its high degree of automation and the short cycle times. Micro injection moulding is a rapidly growing technology that allows for the efficient production of very complex micro parts in high series. The “Market Analysis for Microsystems II 2002–2005” of the Nexus Task Force anticipates a yearly growth in the field of micro system technology of about 20% (Wechsung et al. 2002). This study identifies in addition to the continuous miniaturization the growing use of polymers in micro systems (Schneider et al. 2001). No other material group offers this wide range of material properties and permits to choose processing parameters and application properties according to necessities (Gächter 2000). While the production processes of micro technical components are mainly controllable, the assembly of these components to hybrid micro systems is a bottleneck to the industrial large scale production. The assembly itself represents a large fraction of the added product value and gains in importance with growing complexity and miniaturization of the systems. 相似文献
34.
H. W. Brinks V. A. Yartys B. C. Hauback H. Fjellvg B. Ouladdiaf 《Journal of Alloys and Compounds》2002,340(1-2):62-66
TbNiSiD1.78 has been studied by powder neutron diffraction below 100 K. The compound takes the hexagonal room temperature structure at 100 and 50 K (P63/mmc). At 2 K, below the antiferromagnetic ordering temperature of 10 K, there is a small orthorhombic distortion of the lattice. The refined unit-cell dimensions at 2 K (space group Pnma) are a=7.9505(2), b=4.02502(14), c=6.9823(2) Å. The magnetic moments of Tb are 8.71(6) μB, and are ordered antiferromagnetically along a. 相似文献
35.
36.
本文运用一典型的人工神经网络模型─“反向传播”模型,对高氧化态(Ⅱ─Ⅳ)三核金属簇合物的构型分布进行了分析,得到了较好的分类、预报结果为化合物结构分析提供了新的工具。 相似文献
37.
论述了电磁铁铁芯 (硅钢片 )模具的设计要点及其线切割加工的技巧 ,提出了提高模具加工精度和使用寿命的有效措施。 相似文献
38.
ABSTRACT: The traditional small-scale production of boucané, a cured smoked pork-belly product from Réunion, involves several unit operations that are performed in a single step. The aim of this study was to highligh the impact of 4 unit operations (salting, drying, cooking, and smoking) on stability, color, and flavor development in processed pork. These characateristics are the 3 main criteria of boucané's quality. Mass transfer, color, and volatile compounds were measured, analyzed, and compared in 4 products. Results indicated that a major quantity of volatile compounds detected in the processed meat were derived from the smoking process. Color variations were mainly explained by muscle pigment modification due to the cooking process, and by the input of volatile compounds of smoke. 相似文献
39.
Recent developments in rubber-toughened structural acrylic adhesives now offer sheet steel fabricators the opportunity to replace conventional metal fastening techniques such as spot welding with lower cost, durable, more versatile structural adhesive bonding. These developments, in particular much improved ability to bond oily/waxy surfaces common to the motor car industry and improved retention of fracture toughness after exposure to paint stoving temperatures, are discussed in this paper. 相似文献
40.
The mechanical fracture strength and toughness of short-fibre composites, injection moulded from compounds of poly(ethylene terephthalate) (PET) containing 10 and 30% (by weight) (w/o) glass, have been investigated and the dependence upon matrix hydrolytic stability determined. Mouldings have been characterised by several physical techniques to evaluate molecular weight, degradation rates, crystallinity and morphology, whilst time-dependent gravimetric data were derived to quantify sorption kinetics and allow comparisons with theoretical reaction rates to be made. During melt processing, PET is hydrolysed extremely rapidly by traces of moisture (<0.02w/o). yet the inherent strength of moulded composites declines significantly only below an apparently critical molecular weight. However, on long-term humid ageing in hot water, impact behaviour especially is rendered more complex by simultaneous crystallisation, molecular reorder and losses of interfacial bond strength. 相似文献