全文获取类型
收费全文 | 62481篇 |
免费 | 5830篇 |
国内免费 | 3629篇 |
学科分类
工业技术 | 71940篇 |
出版年
2024年 | 247篇 |
2023年 | 902篇 |
2022年 | 1687篇 |
2021年 | 2425篇 |
2020年 | 1872篇 |
2019年 | 1481篇 |
2018年 | 1721篇 |
2017年 | 1925篇 |
2016年 | 1685篇 |
2015年 | 2517篇 |
2014年 | 3439篇 |
2013年 | 3887篇 |
2012年 | 4685篇 |
2011年 | 4902篇 |
2010年 | 4526篇 |
2009年 | 4190篇 |
2008年 | 4301篇 |
2007年 | 4194篇 |
2006年 | 3962篇 |
2005年 | 3518篇 |
2004年 | 2437篇 |
2003年 | 1868篇 |
2002年 | 1689篇 |
2001年 | 1471篇 |
2000年 | 1274篇 |
1999年 | 1153篇 |
1998年 | 802篇 |
1997年 | 659篇 |
1996年 | 603篇 |
1995年 | 459篇 |
1994年 | 378篇 |
1993年 | 221篇 |
1992年 | 214篇 |
1991年 | 163篇 |
1990年 | 129篇 |
1989年 | 112篇 |
1988年 | 73篇 |
1987年 | 42篇 |
1986年 | 39篇 |
1985年 | 14篇 |
1984年 | 17篇 |
1983年 | 11篇 |
1982年 | 14篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1978年 | 2篇 |
1959年 | 2篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Gang Chen Zhonghua Yang Chor Ping Low 《Industrial Informatics, IEEE Transactions on》2006,2(4):269-280
In this paper, we address agent coordination from a dynamic systems perspective and propose a dynamic coordination model, which is inspired by biological metabolic systems. A new coordination mechanism through dynamic local adjustment (CDLA) is presented, and coordination is achieved when every agent utilizes explicitly the global system dynamics and performs iteratively a dynamic local adjustment procedure. The CDLA mechanism is investigated in an example multiagent shop floor system. The results show that the example manufacturing process is well-coordinated and the coordination approach is practically applicable and effective 相似文献
32.
Wenhui MA Gang XIE Hua WANGFaculty of Materials Metallurgical Engineering Kunming University of Science Technology Kunming China Manuscript received January in revised form May 《材料科学技术学报》2002,18(3):286-287
The thermal expansion behavior of La1-xSrxMn1-yCoyO3-δ (x=0.2-0.4, y=0.1-0.3) perovskites in air has been investigated. The average linear thermal expansion coefficients increased with increasing Sr content up to 40 mole fraction or Co content up to 30 mole fraction. The expansion is generally attributed to an increase in the average cation radius as some of the cations in the perovskite are reduced in valence when oxygen ions are removed from the structure. 相似文献
33.
The Gd substituting effects for La in La0.67Ca0.33MnO3 has been studied .With increasing the substituting amount of Gd,the phase transition temperature of metal-isolator for the samples decreases,the corresponding peak resistivity increases,the Curie temperature decreases monotonically.The substitution of La-Ca-Mn-O with 11% Gd for La improved the magnetoresistance ratio by an order of magnitude.The effects of substituting Gd can be explained in terms of the lattice effects.An irreversible MR behaviour was observed in Gd-substituting compounds.This effect became marked when the substituting amount of Gd was greater than 7%.A maximum irreversible increment of MR ratio as large as 91% was obtained when Gd substituting amount was 11%. 相似文献
34.
35.
36.
37.
邓风 《青岛理工大学学报》2003,24(1):29-32
对取水泵站水泵部分调速运行和全部调速运行在水源枯水位、常水位及洪水位时的节能效果进行了分析比较 ,并给出了结论 相似文献
38.
人本理念,是在对当代社会发展过程中人的主体地位和作用日益突出的反思中,提出的一种发展理念,是一种对人在社会发展中的主体作用与地位的肯定.教育科学中的人本理念,关键是要以学生为本,坚持"一切为了学生、为了一切学生、为了学生一切". 相似文献
39.
Gang Guo Guangli Liu Karsten E. Thompson 《Chemical Engineering Communications》2003,190(12):1641-1660
Many engineering problems require the estimation of mass transfer coefficients in porous materials. In heterogeneous materials or in cases where mass transfer sites are not spatially uniform, empirical equations for mass transfer coefficients vary widely, and the origin of these differences is not well understood. In this article, we use a stochastic algorithm to model mass transfer from single particles in a two-dimensional heterogeneous packed bed. The computed mass transfer coefficients are used to generate a distribution of local Peclet numbers in the bed. Detailed hydrodynamics are then used to interpret variations in the local Peclet number. The results show clear relationships between pore structure, streamline patterns, and mass transfer rates. 相似文献
40.