全文获取类型
收费全文 | 12338篇 |
免费 | 221篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 119篇 |
综合类 | 8篇 |
化学工业 | 1901篇 |
金属工艺 | 195篇 |
机械仪表 | 247篇 |
建筑科学 | 558篇 |
矿业工程 | 71篇 |
能源动力 | 294篇 |
轻工业 | 941篇 |
水利工程 | 127篇 |
石油天然气 | 58篇 |
武器工业 | 1篇 |
无线电 | 1013篇 |
一般工业技术 | 1831篇 |
冶金工业 | 3770篇 |
原子能技术 | 120篇 |
自动化技术 | 1315篇 |
出版年
2022年 | 56篇 |
2021年 | 131篇 |
2020年 | 87篇 |
2019年 | 114篇 |
2018年 | 126篇 |
2017年 | 112篇 |
2016年 | 135篇 |
2015年 | 92篇 |
2014年 | 182篇 |
2013年 | 590篇 |
2012年 | 285篇 |
2011年 | 467篇 |
2010年 | 378篇 |
2009年 | 330篇 |
2008年 | 480篇 |
2007年 | 411篇 |
2006年 | 428篇 |
2005年 | 396篇 |
2004年 | 338篇 |
2003年 | 312篇 |
2002年 | 314篇 |
2001年 | 236篇 |
2000年 | 235篇 |
1999年 | 329篇 |
1998年 | 850篇 |
1997年 | 576篇 |
1996年 | 434篇 |
1995年 | 287篇 |
1994年 | 298篇 |
1993年 | 277篇 |
1992年 | 163篇 |
1991年 | 154篇 |
1990年 | 156篇 |
1989年 | 170篇 |
1988年 | 164篇 |
1987年 | 137篇 |
1986年 | 136篇 |
1985年 | 156篇 |
1984年 | 189篇 |
1983年 | 126篇 |
1982年 | 142篇 |
1981年 | 155篇 |
1980年 | 141篇 |
1979年 | 124篇 |
1978年 | 110篇 |
1977年 | 164篇 |
1976年 | 229篇 |
1975年 | 82篇 |
1974年 | 98篇 |
1973年 | 86篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Moustapha Moussa Amudhan Ponrajan Osvaldo H. Campanella Martin R. Okos Mario M. Martinez Bruce R. Hamaker 《International Journal of Food Science & Technology》2022,57(7):4594-4601
Traditional West African pearl millet couscous products are popular; however, their preparation is laborious, time-consuming and energy-demanding, involving agglomeration, steaming, drying and sieving steps. In this study, a process was developed to produce millet couscous using a high pressure, high temperature and low-cost single-screw extruder. The innovation was to directly process the cooked low-moisture extrudate to a couscous product by drying and milling to the appropriate particle size (ranging between 1 and 2 mm). Throughput for the traditional process as prepared for commercial sale is 50 kg per day, but with the same amount of labour, the extrusion process yields ~350 kg per day. A consumer sensory study held in Niamey (Niger) showed that the extruded millet couscous was comparable to traditional couscous, though this was dependent on selection of the proper millet variety. This novel extrusion process could stimulate small- to medium-scale manufacturing of couscous and couscous-type products in West Africa. 相似文献
2.
3.
4.
F. Schröder R. M. Ward A. R. Walpole R. P. Turner M. M. Attallah J.-C. Gebelin 《Materials Science & Technology》2015,31(3):372-384
Linear friction welding of the Ti6Al4V alloy is studied. A new definition of the energy input rate is proposed, based on an integration over time of the in-plane force and velocity; a strong correlation with the upset rate is then found. The effective friction coefficient is estimated to be 0·5±0·1 for varying frequencies and amplitudes, with only a weak dependence on the processing conditions displayed. A model is proposed that accounts for both the conditioning and equilibrium stages of the process, which is shown to be in good agreement with the experimental data. The model is used to study the mechanism by which the flash is formed. A criterion is proposed by which the rippled nature of its morphology can be predicted. 相似文献
5.
6.
Ron Wilson 《电子设计技术》2006,13(11):126-126
无线USB的前途似乎无与伦比——它能消除那些把大家桌面弄得像鼠窝一样小小的不怎么灵便的电缆。但事实上,只有需要大量的外设时无线USB设备才有优势,而且它必须非常微型而廉价,否则带来的麻烦远多于缠绕的电缆。因此,插在PC USB端口作为无线基站的硬件锁就必须有尽可能高的集成度。但一片芯片中要包含USB有线接口、控制器、无线基带和RF电路,技术上还无法实现。下面我们将看到一家供应商Wisalr的一种可量产参考设计,它是如何接近于解决这个问题的。 相似文献
7.
The aim of this work was to establish the important parameters that control the hot compaction behaviour of woven oriented polypropylene. Five commercial woven cloths, based on four different polypropylene polymers, were selected so that the perceived important variables could be studied. These include the mechanical properties of the original oriented tapes or fibres, the geometry of the oriented reinforcement (fibres or tapes), the mechanical properties of the base polymer (which are crucially dependant on the molecular weight and morphology), and the weave style. The five cloths were chosen so as to explore the boundaries of these various parameters, i.e. low and high molecular weight: circular or rectangular reinforcement (fibres or tapes): low or high tape initial orientation: coarse or fine weave.A vital aspect of this study was the realisation that hot compacted polypropylene could be envisaged as a composite, comprising an oriented ‘reinforcement’ bound together by a matrix phase, formed by melting and recrystallisation of the original oriented material. We have established the crucial importance of the properties of the melted and recrystallised matrix phase, especially the level of ductility, in controlling the properties of the hot compacted composite. 相似文献
8.
K. P. Lee S. J. Pearton M. E. Overberg C. R. Abernathy R. G. Wilson S. N. G. Chu N. Theodoropolou A. F. Hebard J. M. Zavada 《Journal of Electronic Materials》2002,31(5):411-415
In p-GaN implanted with Mn (3×1016 cm−2 at 250 keV), the material after annealing shows ferromagnetic properties below 250 K. Cross-sectional transmission electron
microscopy (TEM) revealed the presence of platelet structures with hexagonal symmetry. These regions are most likely GaxMn1−xN, which produce the ferromagnetic contribution to the magnetization. In p-GaN implanted with Fe, the material after annealing
showed ferromagnetic properties at temperatures that were dependent on the Fe dose, but were below 200 K in all cases. In
these samples, TEM and diffraction analysis did not reveal any secondary phase formation. The results for the Fe implantation
are similar to those reported for Fe doping during epitaxial growth of GaN. 相似文献
9.
IC Wilson TJ Gardner JM DiNatale AM Gillinov WE Curtis DE Cameron 《Canadian Metallurgical Quarterly》1993,106(5):805-810
Leukocyte depletion improves early postischemic ventricular performance in neonatal models of global myocardial ischemia. However, the rate of leukocyte reaccumulation after cardiopulmonary bypass and its subsequent impact on myocardial function is not known. This laboratory study examined the effect of leukocyte depletion on myocardial performance during the initial 6-hour period after bypass in an in situ, in vivo porcine model of neonatal cardiac surgery. Fifteen 3- to 5-day-old piglets (eight control and seven leukocyte depleted animals) were instrumented by placement of left ventricular short-axis sonomicrometry crystals and an intraventricular micromanometer catheter. Mechanical leukocyte depletion was achieved with Pall RC100 filters (Pall Biomedical, Inc., Fajardo, Puerto Rico) in the cardiopulmonary bypass circuit. Neonatal hearts were subjected to 90 minutes of hypothermic ischemia after a single dose of cold crystalloid cardioplegia. Two control animals died after the operation and were excluded from data analysis. Leukocyte filtration reduced the granulocyte count during initial myocardial reperfusion to 0.8% of control values. However, circulating granulocyte counts increased in leukocyte depleted animals throughout the postoperative period, reaching 68% of control values by 6 hours. Despite this rapid return of circulating granulocytes, animals subjected to leukocyte depletion had significantly better preservation of left ventricular performance (measured by preload recruitable stroke work, p < or = 0.02), left ventricular systolic function (measured by end-systolic pressure-volume relationship, p < or = 0.05), and ventricular compliance (p < or = 0.04) during the experiment. These changes in ventricular function were associated with a significant increase in left ventricular water content (p < or = 0.02) and tissue myeloperoxidase activity (p < or = 0.005) in control animals compared with leukocyte depleted animals. This study demonstrates that leukocyte depletion during initial reperfusion results in sustained improvement in postischemic left ventricular function despite the rapid return of granulocytes to the circulation. 相似文献
10.
Vivien Walsh Robin Roy Margaret Bruce Stephen Potter 《Creativity & Innovation Management》1993,2(2):78-86
A series of studies of top European and other firms has revealed patterns of design management associated with commercial success. Firms that invest resources and professional expertise in product and industrial design in traditional and new industries have been commercially more successful than firms that pay less attention to these aspects of design. As an industry matures there is a shift in emphasis from design associated with technological innovation, to designs supporting technical improvements, and then to supporting user needs, fashion and product variants. These issues are illustrated through the history of the evolution of the bicycle. 相似文献