全文获取类型
收费全文 | 448篇 |
免费 | 3篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 43篇 |
金属工艺 | 34篇 |
机械仪表 | 9篇 |
建筑科学 | 4篇 |
能源动力 | 10篇 |
轻工业 | 84篇 |
水利工程 | 13篇 |
石油天然气 | 1篇 |
无线电 | 20篇 |
一般工业技术 | 56篇 |
冶金工业 | 158篇 |
原子能技术 | 2篇 |
自动化技术 | 14篇 |
出版年
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2014年 | 7篇 |
2013年 | 20篇 |
2012年 | 12篇 |
2011年 | 17篇 |
2010年 | 13篇 |
2009年 | 7篇 |
2008年 | 12篇 |
2007年 | 12篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 10篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 15篇 |
1998年 | 36篇 |
1997年 | 24篇 |
1996年 | 25篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 11篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 10篇 |
1977年 | 9篇 |
1976年 | 14篇 |
1975年 | 7篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1972年 | 9篇 |
1971年 | 4篇 |
1970年 | 2篇 |
1969年 | 4篇 |
1968年 | 2篇 |
排序方式: 共有451条查询结果,搜索用时 15 毫秒
111.
T.H.C. Childs D. RichingsA.B. Wilcox 《International Journal of Mechanical Sciences》1972,14(6):359-368
Orthogonal planing experiments have been carried out on 70/30 brass workpieces in the cutting speed range 0·3–150 ft/min. Measurements of chip radius, shear plane angle and the average coefficient of friction between chip and tool have been made and their inter-relationships are successfully explained in terms of a slip line field theory. For a non-hardening workpiece, chip shape is completely determined by the friction stress distribution between chip and tool, but three parameters are required to define this sufficiently, rather than the one, the coefficient of friction, of earlier theories. 相似文献
112.
A 22-mo experiment was conducted to determine effects of mineral supplementation of cows on mineral elements in milk, colostrum, and blood serum. Purebred Brahman beef cows grazing pastures grown on sandy and well-drained soils were allotted to three treatments of 12 cows each as follows: control, a complete commercial mineral mixture, control plus dietary and injected Se, and control plus fortified mineral mixture. Milk and serum were analyzed for minerals 2 consecutive yr at parturition and 3 mo postpartum. Mean cow serum, Ca, Mg, P, and packed cell volume values were higher at parturition than 3 mo later, whereas serum Cu was highest at 3 mo. Mean serum concentrations were affected by year with higher Ca and hemoglobin and lower Cu concentrations in 1982 than in 1981. Increasing dietary Se resulted in higher serum Se. Colostrum was higher in Mg, P, Cu, Fe, Se, and Zn than milk, whereas milk was higher than colostrum in Mn. Means for treatment X time showed cows fed dietary and dietary plus injected Se and vitamin E had more Se in milk than milk from cows fed no supplemental Se. 相似文献
113.
Tawatchai Charinpanitkul Pat Nartpochananon Thornchaya Satitpitakun Jenifer Wilcox Takafumi Seto Yoshio Otani 《Journal of Industrial and Engineering Chemistry》2012,18(1):469-473
Facile synthesis of tetrapodal ZnO nanoparticles was conducted using a modified French process in which oxygen and nitrogen flow rates were controlled. The synthesized ZnO nanoparticles exhibit photoluminescent characteristics depending on the synthesis conditions. Electron microscopic analysis revealed that the tetrapodal nanostructure of ZnO with high crystallinity which was confirmed by XRD analyses could be controlled by a variation of O2/N2 feed ratio. Typical photoluminescence with UV and blue emission of the tetrapodal ZnO nanoparticles was influenced by the particle size and crystallinity, which is manipulated by the oxidation condition. 相似文献
114.
115.
This paper reports the use of artificial neural network models to simulate the thermal performance of a compact, fin-tube heat exchanger with air and water/ethylene glycol anti-freeze mixtures as the working fluids. The model predictions were compared with experimental data over a range of flow rates and inlet temperatures and with various ethylene glycol concentrations. In addition, the inlet air flow was distorted by obstructing part of the inlet ducting near the front face of the exchanger. The artificial neural networks were able to predict the overall rate of heat transfer in the exchanger with a high degree of accuracy and in this respect were found to be superior over conventional non-linear regression models in capturing the underlying non-linearity in the data. Moreover the detailed spatial variations in outlet air temperature were also adequately predicted. The results indicate that appropriately trained neural networks can simulate both the overall and “local” characteristics of the compact heat exchanger. In addition the paper demonstrates how an alternative type of neural network, the so-called Self-Organising-Map (SOM), can be employed for heat exchanger condition monitoring by identifying and classifying the deterioration in exchanger performance which, in this case, was associated with different levels of inlet obstruction. 相似文献
116.
117.
John W. F. To Jia Wei Desmond Ng Samira Siahrostami Ai Leen Koh Yangjin Lee Zhihua Chen Kara D. Fong Shucheng Chen Jiajun He Won-Gyu Bae Jennifer Wilcox Hu Young Jeong Kwanpyo Kim Felix Studt Jens K. Nørskov Thomas F. Jaramillo Zhenan Bao 《Nano Research》2017,10(4):1163-1177
The development of high-performance and low-cost oxygen reduction and evolution catalysts that can be easily integrated into existing devices is crucial for the wide deployment of energy storage systems that utilize O2-H2O chemistries,such as regenerative fuel cells and metal-air batteries.Herein,we report an NH3-activated N-doped hierarchical carbon (NHC) catalyst synthesized via a scalable route,and demonstrate its device integration.The NHC catalyst exhibited good performance for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER),as demonstrated by means of electrochemical studies and evaluation when integrated into the oxygen electrode of a regenerative fuel cell.The activities observed for both the ORR and the OER were comparable to those achieved by state-of-the-art Pt and Ir catalysts in alkaline environments.We have further identified the critical role of carbon defects as active sites for electrochemical activity through density functional theory calculations and high-resolution TEM visualization.This work highlights the potential of NHC to replace commercial precious metals in regenerative fuel cells and possibly metal-air batteries for cost-effective storage of intermittent renewable energy. 相似文献
118.
119.
120.
Cox BD Wilcox RK Levesley MC Hall RM 《Journal of materials science. Materials in medicine》2006,17(6):553-557
In vitro testing of bone cement has historically resulted in the belief that porosity should be minimised to help reduce the risk
of prosthesis failure through aseptic loosening. Traditional porosity measurement techniques rely on the analysis of a two
dimensional representation of a three dimensional structure. However, with an increasing interest in the number, size and
distribution of pores in bone cement, the reliability of a two dimensional approach is questionable. The purpose of this study
was to investigate the use of micro computed tomography (micro-CT) for the three dimensional measurement of bone cement porosity
by comparison with two traditional techniques. Eighteen bone cement specimens were analysed for porosity using each technique.
Levels of agreement between techniques were evaluated, and technique precision was assessed in terms of repeatability and
sensitivity to changes in threshold. Micro-CT data was used to illustrate the effectiveness of predicting the porosity of
a whole structure from a sample region; an approach often used with traditional techniques. In summary, poor agreement was
found between all techniques. However, micro-CT was found to be significantly more repeatable and less sensitive to changes
in threshold. The results demonstrated that porosity cannot be reliably determined using traditional techniques and that a
large proportion of a specimen is required to provide an accurate porosity measurement. 相似文献