全文获取类型
收费全文 | 170735篇 |
免费 | 7897篇 |
国内免费 | 3852篇 |
专业分类
电工技术 | 5689篇 |
技术理论 | 5篇 |
综合类 | 7843篇 |
化学工业 | 26798篇 |
金属工艺 | 10059篇 |
机械仪表 | 8408篇 |
建筑科学 | 9979篇 |
矿业工程 | 3122篇 |
能源动力 | 3445篇 |
轻工业 | 8858篇 |
水利工程 | 2810篇 |
石油天然气 | 5575篇 |
武器工业 | 683篇 |
无线电 | 18359篇 |
一般工业技术 | 26484篇 |
冶金工业 | 7063篇 |
原子能技术 | 1313篇 |
自动化技术 | 35991篇 |
出版年
2024年 | 359篇 |
2023年 | 1492篇 |
2022年 | 2419篇 |
2021年 | 3354篇 |
2020年 | 2622篇 |
2019年 | 2185篇 |
2018年 | 16528篇 |
2017年 | 15850篇 |
2016年 | 12159篇 |
2015年 | 3839篇 |
2014年 | 4337篇 |
2013年 | 5237篇 |
2012年 | 8616篇 |
2011年 | 15112篇 |
2010年 | 13133篇 |
2009年 | 10375篇 |
2008年 | 11392篇 |
2007年 | 12226篇 |
2006年 | 4984篇 |
2005年 | 5527篇 |
2004年 | 3991篇 |
2003年 | 3640篇 |
2002年 | 2819篇 |
2001年 | 2113篇 |
2000年 | 2474篇 |
1999年 | 2734篇 |
1998年 | 2231篇 |
1997年 | 1801篇 |
1996年 | 1867篇 |
1995年 | 1491篇 |
1994年 | 1221篇 |
1993年 | 866篇 |
1992年 | 711篇 |
1991年 | 576篇 |
1990年 | 402篇 |
1989年 | 332篇 |
1988年 | 279篇 |
1987年 | 184篇 |
1986年 | 123篇 |
1985年 | 88篇 |
1984年 | 57篇 |
1983年 | 36篇 |
1982年 | 40篇 |
1968年 | 43篇 |
1966年 | 42篇 |
1965年 | 46篇 |
1958年 | 37篇 |
1957年 | 36篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
液压系统广义可靠性设计 总被引:3,自引:0,他引:3
介绍了广义可靠性和有效度的基本概念,简要论述了对液压系统进行广义可靠性设计的重要性,并从可靠性设计和维修性设计两方面提出了提高液压系统有效度的具体措施。/ 相似文献
72.
氧化铝生产过程结疤溶解的研究 总被引:1,自引:0,他引:1
针对氧化铝生产过程结疤现象。研制出一种新型清洗溶剂,溶垢率可达95%,清洗效果达到《工业设备化学清洗质量标准》要求。 相似文献
73.
Three interesterified vegetable oils (IVOs) prepared from palm, cottonseed, and olive oil, respectively, have been studied for application to Frankfurters. Beef fat (10%) was replaced by one of the IVOs at 20, 60 or 100%. Fatty acid composition of the lipid fraction in the Frankfurters and saturated/unsaturated ratios were established for all batches. We found that total or partial replacement of beef fat by IVOs did not lead to significant changes in appearance, colour, texture, flavour or sensory score. We conclude that IVOs may be successfully applied as beef fat substitutes in Frankfurters. 相似文献
74.
J-M Choe 《欧洲信息系统杂志》2002,11(2):142-158
This study empirically examined the organisational learning effects of the nonfinancial performance information provided by management accounting information systems (MAISs) under advanced manufacturing technology (AMT). In this study, a target costing system and the frequent and quick reporting of information were considered the facilitators of learning. First, we examined the relationships between AMT level and the amount of nonfinancial performance information produced by MAISs. The empirical results showed that there are significant positive relationships between the level of AMT and nonfinancial performance information. With a systems approach, we also proved the impact of the relationships among AMT levels, nonfinancial performance information and learning facilitators on the organisational performance of a firm. The results of our research suggest that under a high level of AMT, for the provision of information to result in an increase of performance through organisational learning, a target costing system must be introduced and a large amount of information should be provided frequently and quickly. The results of this study also showed that although AMT level may be low, fairly well-arranged facilitators and a moderately large amount of information may be necessary for the improvement of performance. In conclusion, effective organisational learning depends on the provision of relevant information as well as efficient learning support mechanisms. 相似文献
75.
76.
77.
78.
Less may not be more,but it still counts: The state of social capital in Yeoville,Johannesburg 总被引:2,自引:2,他引:0
Kirsten Harrison 《Urban Forum》2002,13(1):67-84
79.
Asymptotic stability of finite-dimensional linear continuous-time periodic (FDLCP) systems is studied by harmonic analysis. It is first shown that stability can be examined with what we call the harmonic Lyapunov equation. Another necessary and sufficient stability criterion is developed via this generalized Lyapunov equation, which reduces the stability test into that of an approximate FDLCP model whose transition matrix can be determined explicitly. By extending the Gerschgorin theorem to linear operators on the linear space l2, yet another disc-group criterion is derived, which is only sufficient. Stability of the lossy Mathieu equation is analyzed as a numerical example to illustrate the results 相似文献
80.
Yanqiu Shao Jiqing Han Ting Liu Yongzhen Zhao 《International Journal of Speech Technology》2007,10(1):45-55
In real speech, not like lexical words (LWs), prosodic words (PWs) are basic rhythmic units. The naturalness of a Text-to-Speech
(TTS) system is directly influenced by the segmentation of the PWs. Most of the PWs are the combination of several LWs. In
this paper, three Lexical Combination Models are proposed to combine LWs into PWs, including a Directed Acyclic Graph Model,
a Segmentation Model and a Markov Model (MM). To cope with the situation where some long LWs should be segmented into two
or more PWs, a Lexical Split Model (LSM) is applied to the long LWs. Experimental results prove that relatively constant results
with various training data can be obtained from a MM. The Transformation-Based Error Driven Learning (TBED) algorithm, for
its high performance of individual property, is applied in combination with the MM to improve the precision of PW segmentation.
Experiments show that among the three proposed models, the MM combined with TBED and LSM, leads to the best performance, in
which a precision of 93.00% and a recall of 93.23% are achieved. The perception test indicates that by using PWs as the lowest
prosodic units a speech sounds more natural and acceptable than by using LWs.
This paper is supported by NSFC Project (60503071); 973 Natural Basic Research Program of China (2004CB318102); Postdoctor
Science Foundation of P. R. China (20070420275). 相似文献