全文获取类型
收费全文 | 12732篇 |
免费 | 1418篇 |
国内免费 | 1037篇 |
专业分类
电工技术 | 1140篇 |
综合类 | 1237篇 |
化学工业 | 1770篇 |
金属工艺 | 705篇 |
机械仪表 | 771篇 |
建筑科学 | 1153篇 |
矿业工程 | 383篇 |
能源动力 | 376篇 |
轻工业 | 1245篇 |
水利工程 | 292篇 |
石油天然气 | 441篇 |
武器工业 | 106篇 |
无线电 | 1502篇 |
一般工业技术 | 1281篇 |
冶金工业 | 497篇 |
原子能技术 | 245篇 |
自动化技术 | 2043篇 |
出版年
2024年 | 31篇 |
2023年 | 165篇 |
2022年 | 372篇 |
2021年 | 544篇 |
2020年 | 379篇 |
2019年 | 333篇 |
2018年 | 325篇 |
2017年 | 370篇 |
2016年 | 329篇 |
2015年 | 532篇 |
2014年 | 631篇 |
2013年 | 769篇 |
2012年 | 900篇 |
2011年 | 914篇 |
2010年 | 938篇 |
2009年 | 811篇 |
2008年 | 922篇 |
2007年 | 895篇 |
2006年 | 710篇 |
2005年 | 635篇 |
2004年 | 560篇 |
2003年 | 568篇 |
2002年 | 701篇 |
2001年 | 668篇 |
2000年 | 330篇 |
1999年 | 187篇 |
1998年 | 127篇 |
1997年 | 88篇 |
1996年 | 65篇 |
1995年 | 63篇 |
1994年 | 42篇 |
1993年 | 45篇 |
1992年 | 32篇 |
1991年 | 16篇 |
1990年 | 33篇 |
1989年 | 34篇 |
1988年 | 12篇 |
1987年 | 20篇 |
1986年 | 14篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 10篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 8篇 |
1975年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
传统网络性能预测技术存在网络状态获取不够全面及网络性能评估准确性欠佳等问题,利用图神经网络学习推理网络关系数据的特点,结合捕获的网络全局信息,提出了一种基于图神经网络的网络性能智能预测方法。通过网络系统抽象及网络性能建模,将复杂的网络信息转化为形式化的图数据进行描述,利用图空域卷积处理图网络节点的消息传递过程,实现网络信息之间的关系推理,研究了实现网络性能预测的图神经网络模型,提出了一种能处理流量矩阵、网络拓扑、路由策略、节点配置的图神经网络体系结构,最后通过实验论证了模型能更好地实现包括时延、抖动和丢包率的网络性能的准确预测。 相似文献
2.
3.
Bianka Rocha Saraiva Lucas Henrique Maldonado da Silva Fernando Antônio Anjo Ana Carolina Pelaes Vital Jéssica Bassi Da Silva Marcos Luciano Bruschi Paula Toshimi Matumoto Pintro 《International Journal of Food Science & Technology》2020,55(5):1962-1970
Debittered trub (brewing waste) is an important source of protein source (70.26%). Trub and whey protein were used for 5% protein enrichment of ice cream frozen by liquid nitrogen. Three formulations were elaborated: ice cream standard (ICS), ice cream with whey protein (ICW) and ice cream with trub (ICT). Chemical composition, rheological properties, texture, overrun, melting rate, scanning electron microscopy and a sensorial test were performed. Results showed that ICT presented a higher viscosity, obtained on the upward curve up to 6.76 Pa s−1, consistency index (22.96 (Pa s−1)n), hysteresis area (140.40 mPa s−1) and hardness (31113.33 g) but a lower melting rate (0.38 g min−1), overrun (13.92%) and sensorial acceptability than the other formulations. The addition of trub debittered for protein enrichment improved ice cream properties and demonstrated that it could be used as a food ingredient. 相似文献
4.
5.
Adaptive backstepping repetitive learning control design for nonlinear discrete‐time systems with periodic uncertainties 下载免费PDF全文
Qiao Zhu Jian‐Xin Xu Shiping Yang Guang‐Da Hu 《International Journal of Adaptive Control and Signal Processing》2015,29(4):524-535
This paper addresses a tracking problem for uncertain nonlinear discrete‐time systems in which the uncertainties, including parametric uncertainty and external disturbance, are periodic with known periodicity. Repetitive learning control (RLC) is an effective tool to deal with periodic unknown components. By using the backstepping procedures, an adaptive RLC law with periodic parameter estimation is designed. The overparameterization problem is overcome by postponing the parameter estimation to the last backstepping step, which could not be easily solved in robust adaptive control. It is shown that the proposed adaptive RLC law without overparameterization can guarantee the perfect tracking and boundedness of the states of the whole closed‐loop systems in presence of periodic uncertainties. In addition, the effectiveness of the developed controller is demonstrated by an implementation example on a single‐link flexible‐joint robot. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
6.
7.
Correlation between instrumental texture and colour quality attributes with sensory analysis of selected cheeses as affected by fat contents 下载免费PDF全文
A. Półtorak J. Wyrwisz M. Moczkowska M. Marcinkowska‐Lesiak A. Stelmasiak U. Ulanicka M. Zalewska A. Wierzbicka Da‐Wen Sun 《International Journal of Food Science & Technology》2015,50(4):999-1008
This study evaluated several physical and sensory parameters of different types of cheese available in the Polish market. The measurements of textural properties were conducted in an Instron universal testing machine, while the colour properties of cheeses were measured using a Minolta chromameter. The chemical composition was determined by means of the near‐infrared spectroscopy (NIRs). Moreover, a trained sensory panel was invited to assess the cheese texture‐related properties. Generally, cheeses with reduced fat content were characterised by higher hardness, adhesiveness, cohesiveness and elasticity. Texture‐related parameters of cheese with canola oil were comparable to that of most of full‐fat cheeses. The correlation analysis between physical and sensory attributes related to cheese textural properties indicated the potential applications of TPA, shear and penetration tests (r = 0.766, r = 0.75 and r = 0.765, respectively) for the evaluation of sensory properties related to the hardness. Meanwhile, the elasticity of cheese obtained from sensory evaluation was strongly correlated with the elasticity determined from the shear test (r = 0.722) and moderately correlated with the elasticity from penetration test (r = 0.588), indicating a need to refine the method of penetration test. In addition, cheeses exhibited higher meltability during convection heating at 230 °C than microwave heating. The values of meltability for cheese with reduced fat content were lower than those of full‐fat cheese. 相似文献
8.
9.
Properties and applications of β‐glycosidase from Bacteroides thetaiotaomicron that specifically hydrolyses isoflavone glycosides 下载免费PDF全文
Da‐Hye Byun Hye‐Jeong Choi Hye‐Won Lee Hye‐Yeon Jeon Woo‐Jae Choung Jae‐Hoon Shim 《International Journal of Food Science & Technology》2015,50(6):1405-1412
To modify the glycan part of glycosides, the gene encoding β‐glycosidase was cloned from Bacteroides thetaiotaomicron VPI‐5482. The cloned gene, bt_1780, was expressed in Escherichia coli MC1061 and the expressed enzyme was purified using Ni‐NTA affinity chromatography. The purified enzyme, BTBG, showed optimal activity at 50 °C and pH 5.5. Interestingly, this enzyme did not have any hydrolysing activity on ordinary β‐linkage–containing substrates such as xylobiose, lactose and cello‐oligosaccharide, but specifically hydrolysed isoflavone glycosides such as daidzin, genistin and glycitin. Compared to a commercial beta glucosidase, BTBG selectively hydrolysed isoflavone glycosides in soybean extract mixture solution. These results suggest that BTBG may be a specialized enzyme for the hydrolysis of glycosides and that the substrate specificity of BTBG is applicable for the bioconversion of isoflavone glycosides in the food industry. 相似文献
10.
Catalytic Hydrocracking of a Bitumen‐Derived Asphaltene over NiMo/γ‐Al2O3 at Various Temperatures 下载免费PDF全文
Hydrocracking of a bitumen‐derived asphaltene over NiMo/γ‐Al2O3 was investigated in a microbatch reactor at varying temperatures. The molar kinetics of asphaltene cracking reaction was examined by fitting the experimental data. Below a defined temperature, the molar reaction showed the first‐order kinetic feature while at higher temperatures secondary reactions such as coke formation became significant, causing deviation of the reaction behavior from the proposed first‐order kinetic model. Selectivity analysis proved that dominant products varied from gases to liquids to gases with increasing temperature, shifting the dominant reaction from C–S bonds cleavage to C–C bonds cleavage. 相似文献