全文获取类型
收费全文 | 57722篇 |
免费 | 7426篇 |
国内免费 | 5801篇 |
专业分类
电工技术 | 5078篇 |
技术理论 | 9篇 |
综合类 | 6323篇 |
化学工业 | 1352篇 |
金属工艺 | 690篇 |
机械仪表 | 3581篇 |
建筑科学 | 2245篇 |
矿业工程 | 1513篇 |
能源动力 | 767篇 |
轻工业 | 717篇 |
水利工程 | 1362篇 |
石油天然气 | 2883篇 |
武器工业 | 792篇 |
无线电 | 8878篇 |
一般工业技术 | 2822篇 |
冶金工业 | 1017篇 |
原子能技术 | 736篇 |
自动化技术 | 30184篇 |
出版年
2024年 | 272篇 |
2023年 | 796篇 |
2022年 | 1676篇 |
2021年 | 2110篇 |
2020年 | 2186篇 |
2019年 | 1709篇 |
2018年 | 1530篇 |
2017年 | 1892篇 |
2016年 | 2142篇 |
2015年 | 2478篇 |
2014年 | 3965篇 |
2013年 | 3571篇 |
2012年 | 4270篇 |
2011年 | 4592篇 |
2010年 | 3554篇 |
2009年 | 3512篇 |
2008年 | 3976篇 |
2007年 | 4497篇 |
2006年 | 3799篇 |
2005年 | 3431篇 |
2004年 | 2956篇 |
2003年 | 2486篇 |
2002年 | 1903篇 |
2001年 | 1450篇 |
2000年 | 1245篇 |
1999年 | 900篇 |
1998年 | 691篇 |
1997年 | 583篇 |
1996年 | 482篇 |
1995年 | 432篇 |
1994年 | 341篇 |
1993年 | 247篇 |
1992年 | 172篇 |
1991年 | 178篇 |
1990年 | 132篇 |
1989年 | 106篇 |
1988年 | 85篇 |
1987年 | 67篇 |
1986年 | 58篇 |
1985年 | 85篇 |
1984年 | 58篇 |
1983年 | 71篇 |
1982年 | 60篇 |
1981年 | 37篇 |
1980年 | 20篇 |
1979年 | 34篇 |
1978年 | 12篇 |
1977年 | 20篇 |
1976年 | 13篇 |
1959年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
271.
Reviews the book, ILe choc de l'informatique: Les répercussions psychosociales et le r?le des attitudes by Serge Guimond and Guy Bégin (1987). This monograph is concise and easy to read. The reader knows immediately that technological questions will be explored, as well as the psychological and human questions being attached to the new use of information technology. Three fields are covered, each one the subject of a chapter: 1) computers in the educational circle; 2) computers and work; and 3) computers in the house. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
272.
William Kent 《Computer Standards & Interfaces》1991,13(1-3):201-206
OSQL is the object-oriented database language developed for the Iris object-oriented database management system at Hewlett-Packard Laboratories. Its three fundamental constructs are objects, types, and functions. This paper provides an overview of the underlying concepts and some important features of OSQL. 相似文献
273.
The way data is presented can seriously affect the ease with which it can be understood. The objectives and results of a survey of different types of presentation are given. Some psychological aspects of the problem are analysed. 相似文献
274.
Ed Lowry 《Computer Standards & Interfaces》1991,13(1-3):105-108
Maximizing the satisfaction of a value in an engineering design is usually limited by tradeoffs in which other values become unacceptably sacrificed. In a few cases, however, the maximization is limited by a boundary between what is mathematically possible and what is not. Round wheels, vertical pillars, and binary memory elements are examples of optimum engineering structures which result from such mathematical limits. It is proposed that optimum characteristics of a language data model result similarly by minimizing the variety of primitive data objects, the complexity of those objects, and the number of objects needed to represent data states. Reducing these measures is needed to combine both rich data structure and powerful operations in one language. The minimizations lead to a narrow range of designs for language semantics in which the potential advantages of specialization is small compared with the advantages of commonality. Universal language for support of technical literacy appears to be an appropriate scope of generality in language design. 相似文献
275.
An integrated automatic test data generation system 总被引:3,自引:0,他引:3
A. Jefferson Offutt 《Journal of Systems Integration》1991,1(3-4):391-409
The Godzilla automatic test data generator is an integrated collection of tools that implements a relatively new test data generation method—constraint-based testing—that is based on mutation analysis. Constraint-based testing integrates mutation analysis with several other testing techniques, including statement coverage, branch coverage, domain perturbation, and symbolic evaluation. Because Godzilla uses a rule-based approach to generate test data, it is easily extendible to allow new testing techniques to be integrated into the current system. This article describes the system that has been built to implement constraint-based testing. Godzilla's design emphasizes orthogonality and modularity, allowing relatively easy extensions. Godzilla's internal structure and algorithms are described with emphasis on internal structures of the system and the engineering problems that were solved during the implementation.Parts of this research were supported by Contract F30602-85-C-0255 through Rome Air Development Center while the author was a graduate student at the Georgia Institute of Technology. 相似文献
276.
277.
Klaus Witt 《Color research and application》1994,19(4):273-276
The proposed new color-difference formula of CIE TC 129, which is a modified version of CIELAB, was tested with a recently published data set of textile pass/fail judgments. Goodness of fit is improved, if the parameter of lightness is set near 2, and if, additionally, a weight function for lightness is defined that reduces the weight of a lightness difference with lightness level in relation to chroma or hue scaling. © 1994 John Wiley & Sons, Inc. 相似文献
278.
显式BEZIER三角曲面的构造及其在离散数据插值中的应用 总被引:1,自引:0,他引:1
本文较系统地讨论了显式Bezier三角曲面的Clough-Tocher分割构造方法,并从工程应用角度提出了一种准C‘连续的Bezier三角曲面。由这种准C‘连续的Bezier三角曲面,通过进一步求解整体C‘连续的Bezier三角曲面在解决3D离散数据的曲面插值中取得了较好的应用效果。 相似文献
279.
非平稳ARMA信号自校正滤波器及其应用 总被引:2,自引:1,他引:1
本文处理带白色观测噪声的非平稳ARMA信号估计问题.应用状态空间方法和现代时
间序列分析方法[1],基于ARMA新息模型,提出了非平稳ARMA信号自校正滤波器,推广了
Hagander和Wittenmafk的结果[2],并给出了在雷达跟踪系统和检测数据数字滤波方面的应
用.仿真结果说明了本文结果的实用性和有效性. 相似文献
280.