全文获取类型
收费全文 | 15449篇 |
免费 | 536篇 |
国内免费 | 48篇 |
专业分类
电工技术 | 161篇 |
综合类 | 25篇 |
化学工业 | 2854篇 |
金属工艺 | 341篇 |
机械仪表 | 260篇 |
建筑科学 | 949篇 |
矿业工程 | 50篇 |
能源动力 | 378篇 |
轻工业 | 1246篇 |
水利工程 | 167篇 |
石油天然气 | 52篇 |
武器工业 | 1篇 |
无线电 | 1084篇 |
一般工业技术 | 2690篇 |
冶金工业 | 3193篇 |
原子能技术 | 73篇 |
自动化技术 | 2509篇 |
出版年
2023年 | 80篇 |
2022年 | 157篇 |
2021年 | 250篇 |
2020年 | 184篇 |
2019年 | 206篇 |
2018年 | 284篇 |
2017年 | 233篇 |
2016年 | 345篇 |
2015年 | 272篇 |
2014年 | 441篇 |
2013年 | 907篇 |
2012年 | 725篇 |
2011年 | 983篇 |
2010年 | 745篇 |
2009年 | 693篇 |
2008年 | 830篇 |
2007年 | 817篇 |
2006年 | 699篇 |
2005年 | 648篇 |
2004年 | 551篇 |
2003年 | 451篇 |
2002年 | 536篇 |
2001年 | 342篇 |
2000年 | 311篇 |
1999年 | 282篇 |
1998年 | 372篇 |
1997年 | 301篇 |
1996年 | 256篇 |
1995年 | 277篇 |
1994年 | 235篇 |
1993年 | 238篇 |
1992年 | 200篇 |
1991年 | 98篇 |
1990年 | 176篇 |
1989年 | 154篇 |
1988年 | 138篇 |
1987年 | 142篇 |
1986年 | 110篇 |
1985年 | 172篇 |
1984年 | 156篇 |
1983年 | 104篇 |
1982年 | 93篇 |
1981年 | 85篇 |
1980年 | 69篇 |
1979年 | 79篇 |
1978年 | 67篇 |
1977年 | 52篇 |
1976年 | 78篇 |
1975年 | 42篇 |
1974年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
van der Schalk Job; Fischer Agneta; Doosje Bertjan; Wigboldus Dani?l; Hawk Skyler; Rotteveel Mark; Hess Ursula 《Canadian Metallurgical Quarterly》2011,11(2):286
In the present research, we test the assumption that emotional mimicry and contagion are moderated by group membership. We report two studies using facial electromyography (EMG; Study 1), Facial Action Coding System (FACS; Study 2), and self-reported emotions (Study 2) as dependent measures. As predicted, both studies show that ingroup anger and fear displays were mimicked to a greater extent than outgroup displays of these emotions. The self-report data in Study 2 further showed specific divergent reactions to outgroup anger and fear displays. Outgroup anger evoked fear, and outgroup fear evoked aversion. Interestingly, mimicry increased liking for ingroup models but not for outgroup models. The findings are discussed in terms of the social functions of emotions in group contexts. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
102.
103.
Eylem Dizman Tomak Mark Hughes Umit C. Yildiz Hannu Viitanen 《Journal of Materials Science》2011,46(3):598-607
The aim of the study was to screen any possible synergistic effect available with combination of plant oils and boron compounds to decrease boron leaching and improve thermal degradation of wood by means of dual treatment. In order to reduce the leachability of boron compounds, sapwood of beech and Scots pine samples were treated with oils to create a hydrophobic layer on the wood cells that may prevent water uptake. Increase (%) of boron retained in double-treated samples after leaching was approximately 20% compared to boron-treated samples without oil. The most promising results on boron leaching obtained in the case of using waste and sunflower oil. Thermogravimetric residues were increased by the higher loading of boron compounds in double-treated samples. Spectra of FTIR-Photoacoustic spectrometer showed some deformation of lignin and cellulose followed by degradation of hemicelluloses of treated wood samples due to heat effect at 160 °C. 相似文献
104.
Surface modification of Scots pine: the effect of process parameters on the through thickness density profile 总被引:2,自引:0,他引:2
Lauri Rautkari Kristiina Laine Nick Laflin Mark Hughes 《Journal of Materials Science》2011,46(14):4780-4786
This study evaluated the significance of different process parameters (press temperature, closing time, holding time, moisture content and compression ratio) on solid wood surface densification and its effect on the density profile generated in Scots pine sapwood. Changes in the microstructure of the wood were also evaluated microscopically. The results showed that with a shorter closing time, densification occurred closer to the sample surface than with an extended closing time. At a compression temperature of 150 °C, the vertical density profile exhibited a sharp peak in density that was close to the wood surface. A higher temperature of 200 °C resulted in a slightly broader density peak that was less intense and further from the surface. A holding time of 10 min resulted in the wood compressing to a slightly greater extent than when using a holding time of 1 min. Higher moisture content led to more extensive deformation. The results indicate that surface modification by densification is a viable method of enhancing wood properties. 相似文献
105.
It is demonstrated that for an isolated Mode I planar crack embedded in an infinite body, the stress intensity factor along the crack front is a function independent of the elastic constants. 相似文献
106.
Mark J.Schulz 《材料科学技术学报》2012,28(3):261-267
The corrosion behavior of pure Mg,AZ31,and AZ91D were evaluated in various in vitro and in vivo environments to investigate the potential application of these metals as biodegradable implant materials.DC polarization tests and immersion tests were performed in different simulated body solutions,such as distilled(DI) water,simulated body fluid(SBF) and phosphate buffered solution(PBS).Mg/Mg alloys were also implanted in different places in a mouse for in vivo weight loss and biocompatibility investigations.The in vivo subcutis bio-corrosion rate was lower than the corrosion rate for all of the in vitro simulated corrosive environments.The Mg/Mg alloys were biocompatible based on histology results for the liver,heart,kidney,skin and lung of the mouse during the two months implantation.Optical microscopy and scanning electron microscopy were carried out to investigate the morphology and topography of Mg/Mg alloys after immersion testing and implantation to understand the corrosion mechanisms. 相似文献
107.
For fiber-reinforced plastics exists a big number of different criteria for the failure prediction. The intention of this paper is to compare the TSAI-HIL-, the LaRC04- and PUCK’s criterion in terms of their fracture curves for a unidirectional glass-fiber reinforced composite layer. Therefore after the implementation of these three criteria, the two-dimensional fracture curves for all possible stress combinations, which can be derived from a general spatial stress tensor, are computed. In this way, the characteristics of the criteria, similarities and differences and possible weak points become obvious. 相似文献
108.
Yingping Huang Ross McMurran Mark Amor-Segan Gunwant Dhadyalla R. Peter Jones Peter Bennett Alexandros Mouzakitis Jan Kieloch 《The International Journal of Advanced Manufacturing Technology》2010,51(1-4):233-246
A current premium vehicle is implemented with a variety of information, entertainment, and communication functions, which are generally referred as an infotainment system. During vehicle development, testing of the infotainment system at an overall level is conventionally carried out manually by an expert who can observe at a customer level. This approach has significant limitations with regard to test coverage and effectiveness due to the complexity of the system functions and human’s capability. Hence, it is highly demanded by car manufacturers for an automated infotainment testing system, which replicates a human expert encompassing relevant sensory modalities relating to control (i.e., touch) and observation (i.e., sight and sound) of the system under test. This paper describes the design, development, and evaluation of such a system that consists of simulation of vehicle network, vision-based inspection, automated navigation of features, random cranking waveform generation, sound detection, and test automation. The system developed is able to: stimulate a vehicle system across a wide variety of initialisation conditions, exercise each function, check for system responses, and record failure situations for post-testing analysis. 相似文献
109.
110.
Mark O''''Sullivan 《电子产品世界》2005,(10):87-89
目前,大部分为通信和数据处理应用而设计的电路板需要多种集成电路供电电压.长期以来,在上电和断电过程中正确的给这类电源定序一直是个设计问题,这个问题由于最新集成电路的苛刻要求而日益严重.本文考察了各类定序方法,重点阐述了具有内置定序特性的新一代模块式负载点(POL)转换器,它提供了一种特别有成本效益的解决方案. 相似文献