全文获取类型
收费全文 | 40591篇 |
免费 | 978篇 |
国内免费 | 72篇 |
专业分类
电工技术 | 445篇 |
综合类 | 38篇 |
化学工业 | 7837篇 |
金属工艺 | 973篇 |
机械仪表 | 826篇 |
建筑科学 | 2081篇 |
矿业工程 | 279篇 |
能源动力 | 1210篇 |
轻工业 | 3273篇 |
水利工程 | 379篇 |
石油天然气 | 215篇 |
武器工业 | 4篇 |
无线电 | 2807篇 |
一般工业技术 | 6376篇 |
冶金工业 | 9207篇 |
原子能技术 | 440篇 |
自动化技术 | 5251篇 |
出版年
2022年 | 232篇 |
2021年 | 453篇 |
2020年 | 386篇 |
2019年 | 452篇 |
2018年 | 551篇 |
2017年 | 575篇 |
2016年 | 588篇 |
2015年 | 526篇 |
2014年 | 834篇 |
2013年 | 2391篇 |
2012年 | 1396篇 |
2011年 | 1828篇 |
2010年 | 1344篇 |
2009年 | 1441篇 |
2008年 | 1651篇 |
2007年 | 1668篇 |
2006年 | 1469篇 |
2005年 | 1328篇 |
2004年 | 1219篇 |
2003年 | 1174篇 |
2002年 | 1165篇 |
2001年 | 781篇 |
2000年 | 752篇 |
1999年 | 755篇 |
1998年 | 1348篇 |
1997年 | 910篇 |
1996年 | 958篇 |
1995年 | 750篇 |
1994年 | 721篇 |
1993年 | 749篇 |
1992年 | 599篇 |
1991年 | 434篇 |
1990年 | 543篇 |
1989年 | 533篇 |
1988年 | 468篇 |
1987年 | 519篇 |
1986年 | 480篇 |
1985年 | 619篇 |
1984年 | 590篇 |
1983年 | 531篇 |
1982年 | 541篇 |
1981年 | 558篇 |
1980年 | 454篇 |
1979年 | 454篇 |
1978年 | 410篇 |
1977年 | 415篇 |
1976年 | 458篇 |
1975年 | 390篇 |
1974年 | 289篇 |
1973年 | 346篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
This paper represents a portion of the evaluation of the use of Statistical Process Control within the realm of Conventional Computer Process Control. Various control charts commonly utilized in continuous processes are evaluated when subjected to process disturbances typical of continuous processes. The control charts considered are the Moving Average and Moving Range Chart combination, the Individual and Moving Range Chart combination, and the Exponentially Weighted moving Average Chart. The types of process disturbances considered are unit step and linear trend disturbances to the process average. The evaluation is based on the determination of the Average Run Lengths (ARLs) resulting from computer simulations. 相似文献
62.
63.
John Hoyes 《Sealing Technology》2003,2003(8):10-13
There are a large number of standards concerned with gasketed joints in the UK that are derived from the applications and practice of different industries. Many other countries also have equivalent standards. John Hoyes, technical director of Flexitallic and chairman of the British Standards Committee concerned with gaskets describes the European initiatives to rationalize the standards and improve the technical basis by which they will lead a user to select the joint design and material. 相似文献
64.
Many organisations suspect that their internal security threat is more pressing than their external security threat. The internal threat is predominantly the result of poor user security behaviour. Yet, despite that, security awareness programmes often seem more likely to put users to sleep than to improve their behaviour. This article discusses the influences that affect a user's security behaviour and outlines how a well structured approach focused on improving behaviour could be an excellent way to take security slack out of an organisation and to achieve a high return for a modest, low-risk investment. 相似文献
65.
Peer-assisted learning interventions with elementary school students: A meta-analytic review. 总被引:1,自引:0,他引:1
Rohrbeck Cynthia A.; Ginsburg-Block Marika D.; Fantuzzo John W.; Miller Traci R. 《Canadian Metallurgical Quarterly》2003,95(2):240
A meta-analytic review of group comparison design studies evaluating peer-assisted learning (PAL) interventions with elementary school students produced positive effect sizes (ESs) indicating increases in achievement (unweighted mean ES = 0.59, SD = 0.90; weighted ES, d = 0.33, p 相似文献
66.
67.
68.
Argues that children's failure on one of Piaget's best known tasks, conservation of solid quantity, reflects ignorance of physical properties rather than inadequate reasoning ability. The evidence for conservation itself, seen from the child's position, is analyzed. It is emphasized that children can learn and enjoy the concepts and methods of physics at much earlier ages than current orthodoxies would indicate. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
69.
This paper highlights the role of the faculty member in recruiting students currently enrolled in B.S. programs in engineering and the sciences into full-time pursuit of a graduate-level engineering degree. The faculty member is demonstrated to be in a unique position to influence such students, providing strong counterforces to a confluence of attitudes and pressures experienced during the B.S. experience which effectively create a barrier to full-time engineering graduate study. We analyze this barrier via the method of force field analysis, and demonstrate that effective recruitment into full-time graduate study must be based on a four-fold strategy of education, expectations, improved B.S. experience and better control of the B.S. environment. Approaches to implement these strategies are discussed. 相似文献
70.
John Hemp 《Flow Measurement and Instrumentation》1994,5(4):247-253
In this paper a fuller and clear derivation of the weight vector theory of Coriolis mass flowmeters is given indicating its potential for the prediction of velocity profile effects in both the traditional kind of meter (vibrating tube) and the compact kind (vibrating element inside a duct). 相似文献