全文获取类型
收费全文 | 39133篇 |
免费 | 4504篇 |
国内免费 | 3560篇 |
专业分类
电工技术 | 3269篇 |
技术理论 | 10篇 |
综合类 | 5550篇 |
化学工业 | 633篇 |
金属工艺 | 349篇 |
机械仪表 | 1860篇 |
建筑科学 | 2443篇 |
矿业工程 | 1100篇 |
能源动力 | 344篇 |
轻工业 | 538篇 |
水利工程 | 1093篇 |
石油天然气 | 501篇 |
武器工业 | 908篇 |
无线电 | 6280篇 |
一般工业技术 | 1909篇 |
冶金工业 | 1479篇 |
原子能技术 | 87篇 |
自动化技术 | 18844篇 |
出版年
2024年 | 167篇 |
2023年 | 444篇 |
2022年 | 884篇 |
2021年 | 1070篇 |
2020年 | 1182篇 |
2019年 | 860篇 |
2018年 | 799篇 |
2017年 | 1088篇 |
2016年 | 1300篇 |
2015年 | 1480篇 |
2014年 | 2794篇 |
2013年 | 2563篇 |
2012年 | 3099篇 |
2011年 | 3145篇 |
2010年 | 2437篇 |
2009年 | 2678篇 |
2008年 | 2888篇 |
2007年 | 3094篇 |
2006年 | 2812篇 |
2005年 | 2472篇 |
2004年 | 2136篇 |
2003年 | 1887篇 |
2002年 | 1341篇 |
2001年 | 1107篇 |
2000年 | 852篇 |
1999年 | 562篇 |
1998年 | 382篇 |
1997年 | 308篇 |
1996年 | 253篇 |
1995年 | 199篇 |
1994年 | 186篇 |
1993年 | 134篇 |
1992年 | 90篇 |
1991年 | 74篇 |
1990年 | 44篇 |
1989年 | 51篇 |
1988年 | 41篇 |
1987年 | 25篇 |
1986年 | 23篇 |
1985年 | 27篇 |
1984年 | 37篇 |
1983年 | 29篇 |
1982年 | 17篇 |
1981年 | 13篇 |
1980年 | 17篇 |
1979年 | 15篇 |
1977年 | 8篇 |
1965年 | 10篇 |
1964年 | 11篇 |
1961年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
12.
P. Powell 《Information Systems Journal》1992,2(4):269-280
Abstract. Expert systems proliferate. They are now a usable and used tool in a variety of organizations. However, little research has been undertaken on the quantification of success or failure of expert system projects. By and large the only test carried out for expert system validation is one of comparison of the conclusions of the system with those of an expert or team of experts. While questioning the validity, this paper accepts that this method is being used and analyses whether or not the results obtained from this type of test should be a surprise. That is, what sort of results should be expected and to what extent do the reported ones live up to these expectations? Earlier research from the field of human information processing casts doubts on the success claims made for current expert systems. The implications of this research are then analysed in order to explore the possible redeeming features of expert systems which are not taken into account in such comparisons. The use of linear models as comparators for expert systems may prove beneficial. 相似文献
13.
CASE与MIS的开发 总被引:1,自引:0,他引:1
本文介绍CASE技术的基本思想与构成,CASE工具在MIS开发中的作用,概要介绍国内流行的CASE产品并对其作出评述。 相似文献
14.
介绍了用自顶向下的结构化方法进行科研项目管理信息系统设计的过程。该系统的应用节省了大量人力、物力和财力,提高了企业科研项目管理水平。 相似文献
15.
In long-term memory, negative information is better remembered than neutral information. Differences in processes important to working memory may contribute to this emotional memory enhancement. To examine the effect that the emotional content of stimuli has on working memory performance, the authors asked participants to perform working memory tasks with negative and neutral stimuli. Task accuracy was unaffected by the emotional content of the stimuli. Reaction times also did not differ for negative relative to neutral words, but on an n-back task using faces, participants were slower to respond to fearful faces than to neutral faces. These results suggest that although emotional content does not have a robust effect on working memory, in some instances emotional salience can impede working memory performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
16.
带类型的λ-演算是一个逻辑系统,它可以作为程序语言的基础.Plotkin所引进的PCF就是这样一类程序语言.Plotkin构造了PCF的一个模型,然后讨论与这个模型相关的指称语义和操作语义之间的配合问题──简单配合和完全配合.本文利用Scott引进的信息系统概念构造PCF的另一种模型,并证明与这个模型对应的指称语义与操作语义是完全配合的. 相似文献
17.
Hironori Oda 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,63(3):223-228
Fluorans are given considerable attention as functional dyes for heat-and/or pressure-sensitive recording media. Numerous potential metal complexes were synthesised to prolong the life of coloured species. The protecting effect of these compounds against the photofading was examined on cellulose. It was found that the zinc or nickel salts of 3,5-dihydroxy-2-naphthoic acid and its derivatives can be applied as effective stabilisers against the fading of fluoran dyes. 相似文献
18.
房地产开发企业会计核算问题探讨 总被引:1,自引:0,他引:1
本文就房地产开发企业会计核算的现状及特点进行了分析,并提出了完善房地产开发企业会计核算规范的对策。 相似文献
19.
Abstract. Knowledge systems development and use have been significantly encumbered by the difficulties of eliciting and formalizing the expertise upon which knowledge workers rely. This paper approaches the problem from an examination of the knowledge competencies of knowledge workers in order to define a universe of discourse for knowledge elicitation. It outlines two categories and several types of knowledge that could serve as the foundations for the development of a theory of expertise. 相似文献
20.
Herbert J. Bernstein 《Quantum Information Processing》2006,5(6):451-461
Recent advances in experimental technique make SuperDense Teleportation (SDT) possible only now, ten years after my first proposal at an ISI Torino summer conference on Quantum Computing. The effect uses remote state preparation to send more state-specifying parameters per bit than ordinary quantum teleportation (QT) can transmit. The SDT uses a maximally entangled state to teleport the relative phases of an n-dimensional state with equal amplitudes on every standard basis vector. For n greater than or equal to 3, the SDT sends more of these state-specifying parameters than QT. In the limit of large n the ratio is 2 to 1, hence the nomenclature by analogy with Super Dense Coding. Alice’s measurements and Bob’s transformations are far simpler than their corresponding operations in QT. The roles of Charles who chooses the state and Diana who deploys it are different than in QT. My discussion includes a brief review of the progress and possibilities of realization for several different experimental approaches around the world. This paper is the write-up of my remarks at the Festschrift conference for Anton Zeilinger, for many years a close collaborator in the Hampshire College NSF grant continuing our work with Mike Horne and Danny Greenberger started under Cliff Shull at MIT in the late 20th century. 相似文献