全文获取类型
收费全文 | 33013篇 |
免费 | 923篇 |
国内免费 | 66篇 |
专业分类
电工技术 | 366篇 |
综合类 | 35篇 |
化学工业 | 6788篇 |
金属工艺 | 858篇 |
机械仪表 | 621篇 |
建筑科学 | 1839篇 |
矿业工程 | 247篇 |
能源动力 | 1016篇 |
轻工业 | 2762篇 |
水利工程 | 335篇 |
石油天然气 | 207篇 |
武器工业 | 2篇 |
无线电 | 2150篇 |
一般工业技术 | 5195篇 |
冶金工业 | 6641篇 |
原子能技术 | 322篇 |
自动化技术 | 4618篇 |
出版年
2022年 | 196篇 |
2021年 | 386篇 |
2020年 | 332篇 |
2019年 | 399篇 |
2018年 | 488篇 |
2017年 | 507篇 |
2016年 | 520篇 |
2015年 | 463篇 |
2014年 | 736篇 |
2013年 | 2132篇 |
2012年 | 1240篇 |
2011年 | 1590篇 |
2010年 | 1169篇 |
2009年 | 1258篇 |
2008年 | 1436篇 |
2007年 | 1467篇 |
2006年 | 1256篇 |
2005年 | 1172篇 |
2004年 | 1052篇 |
2003年 | 1023篇 |
2002年 | 1031篇 |
2001年 | 634篇 |
2000年 | 615篇 |
1999年 | 576篇 |
1998年 | 599篇 |
1997年 | 499篇 |
1996年 | 604篇 |
1995年 | 546篇 |
1994年 | 532篇 |
1993年 | 534篇 |
1992年 | 486篇 |
1991年 | 321篇 |
1990年 | 438篇 |
1989年 | 424篇 |
1988年 | 379篇 |
1987年 | 425篇 |
1986年 | 382篇 |
1985年 | 515篇 |
1984年 | 491篇 |
1983年 | 443篇 |
1982年 | 464篇 |
1981年 | 445篇 |
1980年 | 353篇 |
1979年 | 365篇 |
1978年 | 329篇 |
1977年 | 307篇 |
1976年 | 268篇 |
1975年 | 318篇 |
1974年 | 243篇 |
1973年 | 279篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
171.
172.
Tim Baines Stephen Mason Peer-Olaf Siebers John Ladbrook 《Simulation Modelling Practice and Theory》2004,12(7-8):515
Computer based discrete event simulation (DES) is one of the most commonly used aids for the design of automotive manufacturing systems. However, DES tools represent machines in extensive detail, while only representing workers as simple resources. This presents a problem when modelling systems with a highly manual work content, such as an assembly line. This paper describes research at Cranfield University, in collaboration with the Ford Motor Company, founded on the assumption that human variation is the cause of a large percentage of the disparity between simulation predictions and real world performance. The research aims to improve the accuracy and reliability of simulation prediction by including models of human factors. 相似文献
173.
Ioannis Arvanitoyannis John M. V. Blanshard Ioannis Kolokuris 《Polymer International》1992,27(1):7-15
Mastication of gutta percha (trans-polyisoprene) resulted in the selective scission of molecules, producing a narrower distribution of lower molecular weights. The mechanical properties of the samples also underwent a significant change due to mastication. The greater the content of incompatible substances (salts and oxides) in commercial gutta percha. the more substantial were these effects. The atmosphere (air, N2, O2) in which the experiments were conducted yielded significantly different results. The decrease in molecular weight was far greater in an O2 atmosphere than under a current of nitrogen or air, owing to the combination of double bonds with O2. 相似文献
174.
Joseph D. Rigney M.S. Preet M. Singh Ph.D. John J. Lewandowski Ph.D. 《JOM Journal of the Minerals, Metals and Materials Society》1992,44(8):36-41
A variety of materials have been toughened via the addition of a ductile phase. Brittle silicide intermetallics such as Nb5Si3 have been significantly toughened by niobium particles incorporated during in-situ processing techniques. In the work described here, toughness tests conducted on Nb5Si3 were monitored in a scanning electron microscope to view the process of toughening provided by the niobium particles. In particular, the behavior of the ductile phase was monitored and related to the toughness obtained. In an attempt to vary the behavior of the ductile phase, the composite materials were exposed to a variety of gaseous environments and subsequently tested in air. The resulting toughness, resistance-curve behavior, and in-situ results highlight the importance of the behavior of the ductile phase on subsequent properties. 相似文献
175.
176.
177.
Conditioned eyeblink responses are presumably learned in the cerebellum and relayed to motoneurons by way of the red nucleus. Projections from the red nucleus to cerebellar cortex (Larsell's lobule HVI) could be important for shaping temporally adaptive features of the conditioned response. Rabbits that had pipettes containing wheat germ agglutinated horseradish peroxidase (WGA-HRP) implanted unilaterally into HVI showed retrograde labeling of neurons within subregions of the contralateral red nucleus implicated in eyeblink conditioning by lesioning and recording studies. Retrogradely labeled neurons were also observed in the pontine nuclei, inferior olive, and spinal trigeminal nucleus pars oralis. Projections to HVI provide a possible neural substrate for implementing time-derivative computational models of learning in the cerebellum. Time-derivative models are capable of describing the timing and topography of conditioned responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
178.
179.
Krieshok Thomas S.; Arnold John J.; Kuperman Bernard D.; Schmitz Nancy K. 《Canadian Metallurgical Quarterly》1988,35(2):211
We respond to Cochran's critique of our 1986 study, which was in part a replication of Cochran's original grid methodology for the study of career values. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
180.
Illustrates how discrete-time survival analysis can address questions about onset, cessation, relapse, and recovery. Using data on the onset of suicide ideation and depression and relapse into cocaine use, the authors introduce key concepts underpinning the method, describe the action of the discrete-time hazard model, and discuss several types of main effects and interactions that can be included as predictors. Practical issues of data analysis and strategies for interpretation and presentation are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献