全文获取类型
收费全文 | 5501篇 |
免费 | 955篇 |
国内免费 | 144篇 |
专业分类
电工技术 | 163篇 |
综合类 | 199篇 |
化学工业 | 2280篇 |
金属工艺 | 153篇 |
机械仪表 | 158篇 |
建筑科学 | 122篇 |
矿业工程 | 78篇 |
能源动力 | 136篇 |
轻工业 | 200篇 |
水利工程 | 21篇 |
石油天然气 | 34篇 |
武器工业 | 79篇 |
无线电 | 768篇 |
一般工业技术 | 673篇 |
冶金工业 | 181篇 |
原子能技术 | 32篇 |
自动化技术 | 1323篇 |
出版年
2024年 | 13篇 |
2023年 | 142篇 |
2022年 | 111篇 |
2021年 | 400篇 |
2020年 | 296篇 |
2019年 | 210篇 |
2018年 | 306篇 |
2017年 | 262篇 |
2016年 | 293篇 |
2015年 | 307篇 |
2014年 | 492篇 |
2013年 | 381篇 |
2012年 | 283篇 |
2011年 | 412篇 |
2010年 | 303篇 |
2009年 | 289篇 |
2008年 | 253篇 |
2007年 | 266篇 |
2006年 | 238篇 |
2005年 | 168篇 |
2004年 | 154篇 |
2003年 | 150篇 |
2002年 | 119篇 |
2001年 | 98篇 |
2000年 | 89篇 |
1999年 | 72篇 |
1998年 | 69篇 |
1997年 | 61篇 |
1996年 | 37篇 |
1995年 | 25篇 |
1994年 | 48篇 |
1993年 | 35篇 |
1992年 | 32篇 |
1991年 | 21篇 |
1990年 | 14篇 |
1989年 | 16篇 |
1988年 | 18篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 25篇 |
1983年 | 13篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1976年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有6600条查询结果,搜索用时 390 毫秒
41.
42.
43.
Equal Strain Consolidation by Vertical Drains 总被引:1,自引:0,他引:1
Chin Jian Leo 《Canadian Metallurgical Quarterly》2004,130(3):316-327
This paper shows the development of a series of closed-form solutions of equal strain consolidation in the presence of a vertical drain with smear and well resistance. Using an approach that considers the effects of both the radial and vertical drainage in a fully coupled fashion, solutions are obtained for the excess pore pressure and the degree of consolidation in the compressible soil subjected to a step- or ramp-loading situation. The closed-form solutions in the present paper may be evaluated in an electronic spreadsheet on a standard personal computer. 相似文献
44.
45.
46.
Transformations in machining. Part 1. enhancement of wavelet transformation neural network (WT-NN) combination with a preprocessor 总被引:2,自引:0,他引:2
X. Wang P. Chen I.N. Tansel Yenilmez A 《International Journal of Machine Tools and Manufacture》2006,46(1):36-42
Properly selected transformation methods obtain the most significant characteristics of metal cutting data efficiently and simplify the classification. Wavelet Transformation (WT) and Neural Networks (NN) combination was used to classify the experimental cutting force data of milling operations previously. Preprocessing (PreP) of the approximation coefficients of the WT is proposed just before the classification by using the Adaptive Resonance Theory (ART2) type NNs. Genetic Algorithm (GA) was used to estimate the weights of each coefficient of the PreP. The WT-PreP-NN (ART2) combination worked at lower vigilances by creating only a few meaningful categories without any errors. The WT-NN (ART2) combination could obtain the same error rate only if very high vigilances are used and many categories are allowed. 相似文献
47.
High accuracy path tracking for vehicles in presence of sliding: Application to farm vehicle automatic guidance for agricultural tasks 总被引:1,自引:0,他引:1
Roland Lenain Benoit Thuilot Christophe Cariou Philippe Martinet 《Autonomous Robots》2006,21(1):79-97
When designing an accurate automated guidance system for vehicles, a major problem is sliding and pseudo-sliding effects. This is especially the case in agricultural applications, where five-centimetre accuracy with respect to the desired trajectory is required, although the vehicles are moving on slippery ground. It has been established that RTK GPS was a very suitable sensor to achieve automated guidance with such high precision: several control laws have been designed for vehicles equipped with this sensor, and provide the expected guidance accuracy as long as the vehicles do not slide. In previous work, further control developments have been proposed to take sliding into account: guidance accuracy in slippery environments has been shown to be preserved, except transiently at the beginning/end of curves. In this paper, the design of this control law is first recalled and discussed. A Model Predictive Control method is then applied in order to preserve accuracy of guidance even during these curvature transitions. Finally, the overall control scheme is implemented, and improvements with respect to previous guidance laws are demonstrated through full-scale experiments. 相似文献
48.
49.
50.
The extracellular environment controls many cellular activities thereby linking external material cues to internal cell function. By better understanding these processes, synthetic extracellular material niches can be tailored to present cells with highly regulated physical and/or chemical cues that promote or suppress selected cell functions. Here, poly(ethylene glycol) (PEG) hydrogels were functionalized with fluvastatin-releasing grafts and growth factor binding heparin domains to enable the dynamic exchange of information between the material and cells from the outside-in and inside-out (i.e., bidirectional signaling). By incorporating a fluvastatin-releasing graft and carefully controlling the dose and temporal release, materials were designed to promote bone morphogenic protein (BMP2) and alkaline phosphatase (ALP) production by human mesenchymal stem cells (hMSCs). When the release of fluvastatin was controlled to occur over 2 weeks, BMP2 and ALP production was increased 2.2-fold and 1.7-fold, respectively, at day 28 compared to hMSCs cultured in the absence of fluvastatin. By introducing a heparin functionality into the gel to sequester and localize the hMSC-produced BMP2, the osteogenic differentiation of hMSCs was further augmented over fluvastatin delivery alone. Osteopontin and core binding factor α1 gene expression was 6-fold and 4-fold greater for hMSCs exposed to fluvastatin in the presence of the heparin functionalities, respectively. These results demonstrate how multifunctional gels that interact with cells in a bidirectional manner can efficiently promote selected cell functions, such as the osteogenic differentiation of hMSCs. 相似文献