全文获取类型
收费全文 | 8642篇 |
免费 | 718篇 |
国内免费 | 370篇 |
专业分类
电工技术 | 153篇 |
技术理论 | 2篇 |
综合类 | 686篇 |
化学工业 | 2277篇 |
金属工艺 | 550篇 |
机械仪表 | 661篇 |
建筑科学 | 853篇 |
矿业工程 | 307篇 |
能源动力 | 399篇 |
轻工业 | 209篇 |
水利工程 | 159篇 |
石油天然气 | 289篇 |
武器工业 | 63篇 |
无线电 | 294篇 |
一般工业技术 | 937篇 |
冶金工业 | 709篇 |
原子能技术 | 100篇 |
自动化技术 | 1082篇 |
出版年
2024年 | 18篇 |
2023年 | 95篇 |
2022年 | 181篇 |
2021年 | 232篇 |
2020年 | 240篇 |
2019年 | 306篇 |
2018年 | 201篇 |
2017年 | 208篇 |
2016年 | 221篇 |
2015年 | 279篇 |
2014年 | 438篇 |
2013年 | 529篇 |
2012年 | 576篇 |
2011年 | 667篇 |
2010年 | 514篇 |
2009年 | 453篇 |
2008年 | 390篇 |
2007年 | 459篇 |
2006年 | 484篇 |
2005年 | 404篇 |
2004年 | 373篇 |
2003年 | 386篇 |
2002年 | 283篇 |
2001年 | 258篇 |
2000年 | 221篇 |
1999年 | 198篇 |
1998年 | 180篇 |
1997年 | 171篇 |
1996年 | 129篇 |
1995年 | 100篇 |
1994年 | 86篇 |
1993年 | 71篇 |
1992年 | 64篇 |
1991年 | 62篇 |
1990年 | 39篇 |
1989年 | 39篇 |
1988年 | 21篇 |
1987年 | 11篇 |
1986年 | 12篇 |
1985年 | 19篇 |
1984年 | 17篇 |
1983年 | 22篇 |
1982年 | 13篇 |
1981年 | 20篇 |
1980年 | 13篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1955年 | 1篇 |
1951年 | 6篇 |
排序方式: 共有9730条查询结果,搜索用时 15 毫秒
81.
NEW METHODS FOR CALCULATING ACTIVITIES OF COMPONENTS FROM PHASE DIAGRAMS IN BINARY PERITECTIC SYSTEMS 总被引:3,自引:0,他引:3
Zhang Yongjun Hunan Superior Tech Materials Company Ltd. Changsha Zhang Xunying The Fourth Smelter Shuikoushan Mineral Bureau Henyang Fu Chongyue Department of Nonferrous Metallurgy Central South University of Technology Chang 《中国有色金属学会会刊》1997,(2)
NEWMETHODSFORCALCULATINGACTIVITIESOFCOMPONENTSFROMPHASEDIAGRAMSINBINARYPERITECTICSYSTEMS①ZhangYongjunHunanSuperiorTechMateri... 相似文献
82.
Modification mechanism of cerium on the Al-18Si alloy 总被引:14,自引:1,他引:14
The effect of the rare earth cerium (Ce) on the hypereutectic Al-Si alloy under different casting states have been studied by optical microscope and quantitative image analysis. It is found that the size and the quantity of primary silicon in castings decrease with the increase of added Ce in the melt. Meanwhile primary silicon changes from branched shape to fine facetted shape. Although the modification on eutectic silicon in castings also improves with the increase of added Ce in the melt, the effect of modification on eutectic silicon away from primary silicon is more obvious than that on eutectic silicon close to primary silicon. The modification mechanism was analyzed in detail by means of scanning electron microscope equipped with energy dispersive analysis of X-ray and thermodynamics analysis, which included the analysis on the change in standard Gibbs energy of reaction and reaction equilibrium. 相似文献
83.
To solve current industrial problems, manufacturers need to supply service rather than materialized products to consumers. We propose a novel engineering paradigm to deal with services, service engineering. We define services as a state change. A service model consists of three sub-models: scope model, view model and flow model. A computer-aided design tool, called Service Explorer, is developed to represent a network of the parameters and determines the influence weight one another. As the result, we verify the usefulness of the design tool. 相似文献
84.
介绍国内外不锈钢生产的发展应用状况,认为建立不锈钢生产基地是迈向“钢铁强国”的坚实步代,重点介绍了宝钢集团一钢公司不锈钢工程。 相似文献
85.
86.
ATHERMODYNAMICINVESTIGATIONONSPINODALDECOMPOSITIONBOUNDARYINCu-TiALLOYS¥WeiYinghui;WangXiaotian(InstituteofMaterialsSciencean... 相似文献
87.
ANALYSIS ON THE BEHAVIOR OF PRECIPITATES IN ULTRA-THIN HOT STRIP OF PLAIN LOW CARBON STEEL PRODUCED BY COMPACT STRIP PRODUCTION 总被引:7,自引:0,他引:7
H.Yu Y.L.Kang H.B.Dong D.L.Liu J.FuUniversity of Science Technology Beijing Beijing China Manuscript received October in revised form January 《金属学报(英文版)》2002,15(4):375-379
This paper investigated the mechanism of precipitation and its influence upon prop-erties of ultra-thin hot strips of low carbon steel produced by CSP techniques using experiment and thermodynamics theory. The experimental results show that there are lots of fine and dispersive precipitates in microstructures. By analysis, most of aluminum nitrides are in grains, while coexisted precipitates of MnS are along grain boundaries. Coexisted precipitates compose cation-vacancy type oxides such as Al2O3 in the core, while MnS is at the fringe of surface. The precipitation behavior of AlN and MnS in the hot strip is studied by thermodynamic calculation. At last, implica-tions between strengthening effect and techniques are analyzed using obtained solubility products. 相似文献
88.
89.
网络协议是网络通信中一系列标准的集合,未知协议的识别和分析对网络监管、保障网络安全具有重大意义。协议识别技术多种多样,但大都不适用于二进制的协议识别。在此针对现有的协议识别技术的局限性,提出了一种在双方单协议通信环境下的多种类型二进制数据帧的协议识别方法。该方法首先利用n-gram技术对数据帧进行分割,然后利用无监督的特征选择算法提取特征串集合,从而利用聚类算法实现协议消息的识别。最后在ICMP上对该方法进行评估,消息识别的准确率和召回率均可达到90%以上。 相似文献
90.
Hypermedia technologies have been available for about a decade. Beginning with Douglas Engelbart, researchers have become interested in applying hypermedia concepts and technologies to software development. This paper assesses this symbiosis between hypermedia and software development as described by research contributions; by our count, more than one hundred articles. To date, no collection of, or guide to, this literature has been published. A number of significant contributions are classified, described, and appraised — providing a guide into what has been a rich but perhaps under-reported research area. Hypermedia has made significant contributions to software development in three primary areas: coping with massive amounts of information associated with software development projects; establishing and maintaining linkages between various types of software engineering documents; and enabling development engineers to record, document, and preserve knowledge about development thoughts, processes and rationale. These contributions may help direct the focus of future research towards building on, combining and assessing the resulting contributions. A research agenda is proposed along these lines. 相似文献