全文获取类型
收费全文 | 11741篇 |
免费 | 654篇 |
国内免费 | 647篇 |
专业分类
电工技术 | 261篇 |
技术理论 | 1篇 |
综合类 | 680篇 |
化学工业 | 236篇 |
金属工艺 | 131篇 |
机械仪表 | 696篇 |
建筑科学 | 850篇 |
矿业工程 | 209篇 |
能源动力 | 89篇 |
轻工业 | 234篇 |
水利工程 | 101篇 |
石油天然气 | 92篇 |
武器工业 | 95篇 |
无线电 | 1292篇 |
一般工业技术 | 380篇 |
冶金工业 | 307篇 |
原子能技术 | 44篇 |
自动化技术 | 7344篇 |
出版年
2024年 | 15篇 |
2023年 | 91篇 |
2022年 | 146篇 |
2021年 | 209篇 |
2020年 | 213篇 |
2019年 | 167篇 |
2018年 | 172篇 |
2017年 | 236篇 |
2016年 | 322篇 |
2015年 | 276篇 |
2014年 | 684篇 |
2013年 | 549篇 |
2012年 | 689篇 |
2011年 | 1004篇 |
2010年 | 671篇 |
2009年 | 620篇 |
2008年 | 765篇 |
2007年 | 838篇 |
2006年 | 886篇 |
2005年 | 729篇 |
2004年 | 630篇 |
2003年 | 639篇 |
2002年 | 511篇 |
2001年 | 398篇 |
2000年 | 297篇 |
1999年 | 266篇 |
1998年 | 212篇 |
1997年 | 143篇 |
1996年 | 115篇 |
1995年 | 124篇 |
1994年 | 60篇 |
1993年 | 54篇 |
1992年 | 40篇 |
1991年 | 38篇 |
1990年 | 22篇 |
1989年 | 30篇 |
1988年 | 15篇 |
1987年 | 17篇 |
1986年 | 21篇 |
1985年 | 32篇 |
1984年 | 17篇 |
1983年 | 14篇 |
1982年 | 9篇 |
1981年 | 18篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1973年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Fellers Gloria; McInnis Charles; Cappelli Mario; Cragg Susan; Vaillancourt Raymond 《Canadian Metallurgical Quarterly》1987,19(1):108
The WAIS-R Information subtest was combined with 21 potential substitute Canadian content items and group-administered to 119 high school students ranging in age from 16 to 19 years. Seven acceptable substitute items were identified. Mean scores on the American items for the 16-17 and 18-19 age groups suggested that Canadians of these ages are not penalized by American content with respect to either Verbal or Full Scale IQ. Nevertheless, the research identified eight Information items, four easier and four more difficult than the standard WAIS-R implies. Similar results were noted in two previous studies of the WAIS-R, and indicate the extreme caution required for the clinical interpretation of intra test scatter. There is also evidence that item difficulty within the Information subtest may vary with the age of the subject. These results were considered indicative of the necessity for Canadian content Information items and the development of Canadian norms for an adapted WAIS-R Information subtest. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
32.
Business, not technology leaders should manage the change of Information Technology (IT) from a self-contained business support unit of the sixties to a distributed strategic business function of the nineties. Top management should recognize that a good business plan can only be developed and executed through the partnership between the business unit managers and the managers of the financial, the personnel, and the IT resource units. The technical problems associated with the management of IT may again be the easier part of the total management challenge. 相似文献
33.
34.
We present some new lower bounds on the optimal information rate and on the optimal average information rate of secret sharing schemes with homogeneous access structure. These bounds are found by using some covering constructions and a new parameter, the k-degree of a participant, that is introduced in this paper. Our bounds improve the previous ones in almost all cases. 相似文献
35.
The State of the Art in Text Filtering 总被引:1,自引:0,他引:1
This paper develops a conceptual framework for text filtering practice and research, and reviews present practice in the field.
Text filtering is an information seeking process in which documents are selected from a dynamic text stream to satisfy a relatively
stable and specific information need. A model of the information seeking process is introduced and specialized to define text
filtering. The historical development of text filtering is then reviewed and case studies of recent work are used to highlight
important design characteristics of modern text filtering systems. User modeling techniques drawn from information retrieval,
recommender systems, machine learning and other fields are described. The paper concludes with observations on the present
state of the art and implications for future research on text filtering.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
36.
本文介绍了全球N-ISDN的商用情况和B-ISDN的发展趋势,展示出N-ISDN走了低谷、B-ISDN迈向市场的美好前景。 相似文献
37.
集成光学干涉仪光纤陀螺 总被引:2,自引:0,他引:2
简述了集成光学干涉仪光纤陀螺(FOG)的技术优势、发展概况和采用的技术途径,介绍了适用于不同技术条件要求的三种多功能集成光学芯片结构和相应的信息处理方法。简要地概括了目前国外FOG的发展水平。 相似文献
38.
Data-logging: effects on practical science 总被引:2,自引:0,他引:2
Abstract This paper describes an investigation into the processes and effects of using electronic data-logging in practical science. A pilot study of classical laboratory work in schools was compared with similar tasks performed with data-logging systems. A more detailed exploration of pupils' performance was then conducted through an extensive series of observations in a range of secondary schools. The results reinforce previous indications of the potential benefits of data-logging, but such benefits must be viewed in the curriculum context of the type of measurement activity and the pedagogical context of teaching and learning objectives. The paper concludes with a discussion of the latter issues. 相似文献
39.
强度型光纤传感器的信号检测系统 总被引:1,自引:0,他引:1
余向东 《中国计量学院学报》1996,(1)
本文阐述了一种可提高强度型光纤传感器测量精度的检测系统。该系统利用同一检测电路交替检测信号、参考通道的输出信号,并将信号、参考两通道的检测结果相除,从而消除了因发光二极管光源波动及检测电路系统不稳定所带来的误差。采用同步相关技术抑制了噪声,提高了输出信噪比。实验证明,当时间常数RC为0.05S时,采用该检测系统可获得优于千分之一的零点稳定性和优于2×103的输出信噪比。 相似文献
40.