全文获取类型
收费全文 | 80245篇 |
免费 | 6529篇 |
国内免费 | 4096篇 |
学科分类
工业技术 | 90870篇 |
出版年
2024年 | 280篇 |
2023年 | 917篇 |
2022年 | 1864篇 |
2021年 | 2541篇 |
2020年 | 1928篇 |
2019年 | 1668篇 |
2018年 | 1877篇 |
2017年 | 2136篇 |
2016年 | 2008篇 |
2015年 | 2874篇 |
2014年 | 3681篇 |
2013年 | 4686篇 |
2012年 | 5394篇 |
2011年 | 5777篇 |
2010年 | 5309篇 |
2009年 | 5276篇 |
2008年 | 5450篇 |
2007年 | 5372篇 |
2006年 | 5183篇 |
2005年 | 4418篇 |
2004年 | 3237篇 |
2003年 | 2553篇 |
2002年 | 2426篇 |
2001年 | 2088篇 |
2000年 | 1943篇 |
1999年 | 1714篇 |
1998年 | 1459篇 |
1997年 | 1217篇 |
1996年 | 1144篇 |
1995年 | 951篇 |
1994年 | 793篇 |
1993年 | 631篇 |
1992年 | 455篇 |
1991年 | 325篇 |
1990年 | 296篇 |
1989年 | 237篇 |
1988年 | 187篇 |
1987年 | 128篇 |
1986年 | 100篇 |
1985年 | 60篇 |
1984年 | 54篇 |
1983年 | 40篇 |
1982年 | 37篇 |
1981年 | 27篇 |
1980年 | 24篇 |
1979年 | 12篇 |
1977年 | 11篇 |
1976年 | 13篇 |
1975年 | 8篇 |
1973年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 18 毫秒
31.
32.
33.
Weiming Shen S.Y.T. Lang Lihui Wang 《IEEE transactions on systems, man and cybernetics. Part C, Applications and reviews》2005,35(3):371-381
Global competition is driving manufacturing companies to change the way they do business. New kinds of shop floor control systems need to be implemented for these companies to respond quickly to changing shop floor environments and customer demands. This paper presents a new concept called iShopFloor-an intelligent shop floor based on the Internet, web, and agent technologies. It focuses on the implementation of distributed intelligence in the manufacturing shop floor. The proposed approach provides the framework for components of a complex control system to work together as a whole rather than as a disjoint set. It encompasses both information architecture and integration methodologies. The paper introduces the basic concept of iShopFloor, a generic system architecture, and system components. It also describes the implementation of eXtensible Markup Language message services in iShopFloor and the application of intelligent agents to distributed manufacturing scheduling. A prototype environment is presented, and some implementation issues are discussed. 相似文献
35.
36.
The acquisition of new skills over a life span is a remarkable human ability. This ability, however, is constrained by age of acquisition (AoA); that is, the age at which learning occurs significantly affects the outcome. This is most clearly reflected in domains such as language, music, and athletics. This article provides a perspective on the neural and computational mechanisms underlying AoA in language acquisition. The authors show how AoA modulates both monolingual lexical processing and bilingual language acquisition. They consider the conditions under which syntactic processing and semantic processing may be differentially sensitive to AoA effects in second-language acquisition. The authors conclude that AoA effects are pervasive and that the neural and computational mechanisms underlying learning and sensorimotor integration provide a general account of these effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
37.
Fernando J. Muzzio Marcos Llusa Christopher L. Goodridge Nhat-Hang Duong Elizabeth Shen 《Powder Technology》2008,186(3):247-254
This paper investigates the effects of processing and equipment parameters of a ribbon blender (i.e. loading method of lubricant, fill level, blade speed and blade design) on magnesium stearate homogeneity. A core sampling technique is used to obtain at least one hundred samples per sampling event, which are extracted throughout the blender and yield a thorough characterization of the entire bed. The results presented here can be used as a guideline to develop appropriate blending processes and characterization protocols for ribbon blenders. 相似文献
38.
39.
We report the growth of highly C-axis orientation of Sr
x
Ba1−x
Nb2O6 (SBN) thin films on p-type (100) Si substrates by using a potassium-substituted SBN template layer with the sol–gel method. The crystallization of SBN thin films was found closely related to the potassium ion doping concentration and the postannealing temperature of the K-SBN template layer. Secondary ion mass spectrometry analysis showed that potassium elements were accumulated at the interface of the template layer and silicon substrate. SBN films postannealed at 750 °C with K-SBN template layer has a smaller full width at half maximum of X-ray rocking curve of 2.45° than that of 5.40° for the pure SBN films. By introducing a template layer, the surface morphologies of SBN films fabricated on silicon substrate were greatly improved. 相似文献
40.
Ring‐opening polymerization of D,L ‐lactide (LA) has been successfully carried out by using rare earth 2,6‐dimethylaryloxide (Ln(ODMP)3) as single component catalyst or initiator for the first time. The effects of different rare earth elements, solvents, monomers and catalyst concentration as well as polymerization temperature and time on the polymerization were investigated. The results show that La(ODMP)3 exhibits higher activity to prepare poly(D,L ‐lactide) (PLA) with a viscosity molecular weight of 4.5 × 104 g mol?1 and the conversion of 97 % at 100 °C in 45 min. The catalytic activity of Ln(ODMP)3 has following sequence: La > Nd > Sm > Gd > Er > Y. A kinetic study has indicated that the polymerization is first order with respect to both monomer and catalyst concentration. The apparent activation energy of the polymerization of LA with La(ODMP)3 is 69.6 kJ mol?1. The analyses of polymer ends indicate that the LA polymerization proceeds according to ‘coordination–insertion’ mechanism with selective cleavage of the acyl–oxygen bond of the monomer. Copyright © 2004 Society of Chemical Industry 相似文献