全文获取类型
收费全文 | 46963篇 |
免费 | 3845篇 |
国内免费 | 2671篇 |
学科分类
工业技术 | 53479篇 |
出版年
2024年 | 253篇 |
2023年 | 829篇 |
2022年 | 1452篇 |
2021年 | 1567篇 |
2020年 | 1617篇 |
2019年 | 1177篇 |
2018年 | 1033篇 |
2017年 | 1372篇 |
2016年 | 1548篇 |
2015年 | 1756篇 |
2014年 | 2886篇 |
2013年 | 2414篇 |
2012年 | 3545篇 |
2011年 | 3558篇 |
2010年 | 2582篇 |
2009年 | 2574篇 |
2008年 | 2357篇 |
2007年 | 3191篇 |
2006年 | 3028篇 |
2005年 | 2609篇 |
2004年 | 2116篇 |
2003年 | 1865篇 |
2002年 | 1535篇 |
2001年 | 1358篇 |
2000年 | 1086篇 |
1999年 | 868篇 |
1998年 | 641篇 |
1997年 | 563篇 |
1996年 | 449篇 |
1995年 | 397篇 |
1994年 | 312篇 |
1993年 | 214篇 |
1992年 | 153篇 |
1991年 | 117篇 |
1990年 | 99篇 |
1989年 | 95篇 |
1988年 | 76篇 |
1987年 | 31篇 |
1986年 | 30篇 |
1985年 | 19篇 |
1984年 | 11篇 |
1983年 | 18篇 |
1982年 | 14篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 5篇 |
1959年 | 4篇 |
1958年 | 4篇 |
1955年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Comparison of different absorption heat cycles is not always made on the correct manner. This also includes comparison of an ideal absorption cycle with a mechanical analogy. A new Carnot model operating with two heat engines and two mechanical heat pumps is defined to be the correct and logical way to describe the mechanical analogy for an absorption heat pump and an absorption heat transformer. General equations for the Carnot coefficient of performance, COPr, are exemplified and simulated for an absorption heat pump and an absorption heat transformer, and an entropy flow fraction diagram is introduced. The important fact that the absorption heat cycles must operate under the same conditions when they are compared is discussed. 相似文献
72.
73.
盘带机是纺织织带成品分卷设备,需要使用到收放卷控制。本文基于台达变频器在盘带机上的应用案例,论述盘带机自动化系统设计调试过程以及遇到的问题分析。 相似文献
74.
Evgenia Adamopoulou Konstantinos Demestichas Panagiotis Demestichas Michael Theologou 《International Journal of Communication Systems》2008,21(3):311-330
Cognitive radio systems dynamically reconfigure the algorithms and parameters they use, in order to adapt to the changing environment conditions. However, reaching proper reconfiguration decisions presupposes a way of knowing, with high enough assurance, the capabilities of the alternate configurations, especially in terms of achievable transmission capacity and coverage. The present paper addresses this problem, firstly, by specifying a complete process for extracting estimations of the capabilities of candidate configurations, in terms of transmission capacity and coverage, and, secondly, by enhancing these estimations with the employment of a machine learning technique. The technique is based on the use of Bayesian Networks, in conjunction with an effective learning and adaptation strategy, and aims at extracting and exploiting knowledge and experience, in order to reach robust (i.e. stable and reliable) estimations of the configurations' capabilities. Comprehensive results of the proposed method are presented, in order to validate its functionality. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
75.
山特维克可乐满公司切削刀具涂层技术的发展 总被引:3,自引:0,他引:3
佘建芳 《稀有金属与硬质合金》2003,31(3):51-55
介绍了山特维克可乐满公司切削刀具涂层技术的发展,并对该公司自1979年以来硬质合金涂层产品的发展情况进行了总结。 相似文献
76.
Statistical machine translation systems are usually trained on large amounts of bilingual text (used to learn a translation
model), and also large amounts of monolingual text in the target language (used to train a language model). In this article
we explore the use of semi-supervised model adaptation methods for the effective use of monolingual data from the source language
in order to improve translation quality. We propose several algorithms with this aim, and present the strengths and weaknesses
of each one. We present detailed experimental evaluations on the French–English EuroParl data set and on data from the NIST
Chinese–English large-data track. We show a significant improvement in translation quality on both tasks. 相似文献
77.
78.
给出了感应电机内部物理过程的框图描述。这种描述准确地反映了电机学中主、漏磁路分别处理的一般方法,感应电机内部各物理量之间的数量关系和电机学所基于的若干基本电磁定律,感应电机内部物理量之间的关系。 相似文献
79.
Sun-Yuan Hsieh 《The Journal of supercomputing》2007,39(1):39-57
A graph is distance-hereditary if the distance stays the same between any of two vertices in every connected induced subgraph containing both. Two well-known
classes of graphs, trees and cographs, both belong to distance-hereditary graphs. In this paper, we first show that the perfect
domination problem can be solved in sequential linear-time on distance-hereditary graphs. By sketching some regular property
of the problem, we also show that it can be easily parallelized on distance-hereditary graphs. 相似文献
80.
数控母排冲孔机液压系统 总被引:1,自引:0,他引:1
范玉成 《机械制造与自动化》2005,34(4):72-73
介绍了数控母排冲孔机液压系统工作原理及其组成,设计了双泵供油回路、压力控制的差动快进转慢进回路及过载、过热、污染堵塞报警系统。 相似文献