全文获取类型
收费全文 | 381篇 |
免费 | 25篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 17篇 |
化学工业 | 93篇 |
金属工艺 | 9篇 |
机械仪表 | 27篇 |
建筑科学 | 20篇 |
能源动力 | 17篇 |
轻工业 | 21篇 |
水利工程 | 8篇 |
石油天然气 | 4篇 |
无线电 | 27篇 |
一般工业技术 | 68篇 |
冶金工业 | 6篇 |
原子能技术 | 1篇 |
自动化技术 | 92篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 19篇 |
2021年 | 25篇 |
2020年 | 31篇 |
2019年 | 28篇 |
2018年 | 39篇 |
2017年 | 30篇 |
2016年 | 24篇 |
2015年 | 16篇 |
2014年 | 31篇 |
2013年 | 45篇 |
2012年 | 31篇 |
2011年 | 29篇 |
2010年 | 16篇 |
2009年 | 7篇 |
2008年 | 8篇 |
2007年 | 7篇 |
2006年 | 1篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1990年 | 1篇 |
1986年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有410条查询结果,搜索用时 0 毫秒
61.
Differential Cascode Voltage Switch (DCVS) is a well-known logic style, which constructs robust and reliable circuits. Two main strategies are studied in this paper to form static DCVS-based standard ternary fundamental logic components in digital electronics. While one of the strategies leads to fewer transistors, the other one has higher noise margin. New designs are simulated with HSPICE and 32 nm CNTFET technology at various realistic conditions such as different power supplies, load capacitors, frequencies, and temperatures. Simulations results demonstrate their robustness and efficiency even in the presence of PVT variations. In addition, new noise injection circuits for ternary logic are also presented to perform noise immunity analysis. 相似文献
62.
Sadeq Hooshmand Zaferani Mahmood Peikari Davood Zaarei Iman Danaei 《Journal of Adhesion Science and Technology》2013,27(22):2411-2420
In the recent years, silane materials, because of their environmental friendly nature and ease of application have been attended as an alternative for chromate conversion coatings. Different materials were searched for improvement of the efficiency of silane formulation. In this research, pretreatment of carbon steel substrates was carried out using γ-glycidoxypropyl-trimethoxysilane (γ-GPS) as functionalized silane. Cerium nitrate as a corrosion inhibitor material was introduced into the silane material and epoxy resin was applied on the pretreated steel substrates. Effects of the pretreatment on electrochemical properties, cathodic disbondment, dry and wet adhesion strength, and surface morphology of resultant epoxy coating were investigated. Results showed that pretreatment of steel substrate with γ-glycidoxypropyl-trimethoxysilane (γ-GPS) doped with cerium nitrate leads to improvement of cathodic disbondment and also dry and wet adhesion of epoxy coating. Furthermore, this type of pretreatment reduced the disruption of interfacial bonds at the binder/substrate interface. Addition of 2?wt% cerium nitrate into the silane formulation led to the maximum efficiency of resultant coating. 相似文献
63.
Saeed Mirzaee Ghazani Alejandro G. Marangoni 《Journal of the American Oil Chemists' Society》2013,90(7):923-932
Crude canola oil is composed mainly of triacylglycerols but contains considerable amounts of desirable and undesirable minor components. Crude canola oil is refined in order to remove undesirable minor compounds that make this oil unusable in food products. However, refining can also cause the removal of desirable health-promoting minor components from the oil. The first section of this review describes the chemical composition of canola oil, followed by a brief introduction to the effects of minor components on canola oil quality and stability. Following a review of traditional canola oil refining methods, the effects of individual refining stages on the removal of both desirable and undesirable components from canola oil are presented and contrasted with other common vegetable oils. 相似文献
64.
Iman Beheshti Tabar Alireza Keyhani Shaheen Rafiee 《Renewable & Sustainable Energy Reviews》2010,14(2):849-855
In this study data from 17 years (1990–2006) were collected to determine energy intensive areas and evaluate energy parameters of Iran's agronomy sector. All the direct and indirect inputs of energy for the production of 19 agricultural commodities were evaluated. The inputs and outputs were calculated by multiplying the amounts of inputs and outputs by their energy equivalents. The results indicated that total energy input increased from 32.40 GJ ha?1 in 1990 to 37.20 GJ ha?1 in 2006. At the same period, total output energy increased from 30.85 to 43.68 GJ ha?1. The results show that irrigation with 40.0% and fertilizer (28.4%) had the highest share in energy consumption. The average net energy gain was a positive value; however, about 87% of the input energy emanates from non-renewable sources of energy. The mean energy ratio was estimated to be 1.07 and showed an increasing trend during the period rising from 0.95 in 1990 to 1.17 in 2006. This indicates that increased use of inputs ha?1 in production was accompanied by a larger increase in the output levels. It can be inferred from the results that improvements in irrigation and fertilizer application can significantly affect the energy efficiency of Iranian agriculture. 相似文献
65.
The fracture toughness and deformation mechanism of PP/CaCO3 (15 wt.%) composites were studied and related to load-bearing capacity of the particles. To alter the load-bearing capacity of the particles, different particle sizes (0.07–7 μm) with or without stearic acid coating were incorporated. The fracture toughness of the composites was determined using J-Integral method and the deformation mechanism was studied by transmission optical microscopy of the crack tip damage zone. It was observed that the load-bearing capacity of the particles decreased by reduction of particle size and application of coating. A linear relationship between normalized fracture toughness and inverse of load-bearing capacity of particles was found. The crack tip damage zone in composites, which consists in massive crazing, further grows by reduction in load-bearing capacity. 相似文献
66.
Mohammad Norouzi Masoud Soleimani Iman Shabani Fatemeh Atyabi Hana H. Ahvaz Abusaeed Rashidi 《Polymer International》2013,62(8):1250-1256
The main purpose of tissue engineering is the preparation of fibrous scaffolds with similar structural and biochemical cues to the extracellular matrix in order to provide a substrate to support the cells. Controlled release of bioactive agents such as growth factors from the fibrous scaffolds improves cell behavior on the scaffolds and accelerates tissue regeneration. In this study, nanofibrous scaffolds were fabricated from biocompatible and biodegradable poly(lactic‐co‐glycolic acid) through the electrospinning technique. Nanofibers with a core–sheath structure encapsulating bovine serum albumin (BSA) as a model protein for hydrophilic bioactive agents were prepared through emulsion electrospinning. The morphology of the nanofibers was evaluated by field‐emission scanning electron microscopy and the core–sheath structure of the emulsion electrospun nanofibers was observed by transmission electron microscopy. The results of the mechanical properties and X‐ray diffraction are reported. The scaffolds demonstrated a sustained release profile of BSA. Biocompatibility of the scaffolds was evaluated using the MTT (3(4,5‐ dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide) assay for NIH‐3T3 fibroblast cells. The results indicated desirable biocompatibility of the scaffolds with the capability of encapsulation and controlled release of the protein, which can serve as tissue engineering scaffolds. © 2013 Society of Chemical Industry 相似文献
67.
H. Mirzaee Moghaddam M. H. Khoshtaghaza M. Barzegar 《Polymer-Plastics Technology and Engineering》2013,52(17):1759-1767
The role of nanoclays and TiO2 nanoparticle loadings were investigated on low density polyethylene crystalline structure, in addition to studying packaging film properties such as barrier, thermal and mechanical properties. The polymer crystal study indicated for the orthorhombic crystal phase and about 20% lower degree of crystallinity for nanocomposites containing more than 2 wt.% TiO2 nanoparticles. Based on the X-ray diffraction technique, the dispersion of nanoclays was improved to almost good degree of clay exfoliation with the company of 4 wt.% TiO2 nanoparticles. In agreement with XRD results, the TEM morphological studies mainly suggest that TiO2 has a helpful effect on nanoclay exfoliation. The increase in degradation temperature of nanocomposites may be attributed to the formation of inorganic char on polymer melt. The barrier properties of TiO2/clay nanocomposite packaging films depend mainly on nanoclay loading with an unclear trend from TiO2 nanoparticles. The increase in elastic modulus and the yield stress of nanocomposite films showed great effects on film mechanical properties by nanoclays. 相似文献
68.
Alarm flooding is one of the main problems in alarm management. Alarm flood pattern analysis is helpful for root cause analysis of historical floods and for incoming flood prediction. This paper deals with a data driven method for alarm flood pattern matching. An alarm flood is represented by a time-stamped alarm sequence. A modified Smith–Waterman algorithm considering the time stamp information is proposed to calculate a similarity index of alarm floods. The effectiveness of the algorithm is validated by a case study on actual chemical process alarm data. 相似文献
69.
In this work, using electrochemical techniques the authors investigated the protective properties of a polypyrrole/polyaniline bilayer as a conductive polymer. A polypyrrole/polyaniline bilayer was deposited on carbon steel substrate by potentiostatic method. The electric capacitance and resistance of the films were monitored with the immersion time in a corrosive solution to investigate the water permeability of the films. Polypyrrole/polyaniline bilayer has a relatively low permeability and good catalytic behavior in passivation of carbon steel in longer periods. The results show that the bilayer has a better anticorrosive behavior compared to homopolymers (polypyrrole and polyaniline). 相似文献
70.
Preparation and characterization of chitosan films,crosslinked with symmetric aromatic dianhydrides to achieve enhanced thermal properties
下载免费PDF全文
![点击此处可从《Polymer International》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Iman Kavianinia Paul G Plieger Nadia G Kandile David RK Harding 《Polymer International》2015,64(4):556-562
This study has developed a new generation of crosslinked chitosan‐based films using symmetric aromatic dianhydrides as crosslinking agents. The formation of the dianhydride‐crosslinked chitosan hydrogel films was confirmed using Fourier transform infrared and solid‐state 13C NMR spectral analyses. The films obtained from these derivatives were characterized by their thermal, swelling and hydrophilic properties. The results showed that introducing a cyclic imide moiety into the chitosan matrices played a significant role in enhancing the thermal properties of these chitosan films. It was found that even at high levels of substitution, thermal stability of the studied chitosan derivatives was improved, in spite of a reduction in crystallinity. Heterocyclic imide linkages produced networks that were insoluble in both acidic and alkaline media but allowed swelling in aqueous media. An increase in the hydrophobicity of the chitosan film surfaces was observed after introduction of the cyclic imide moiety. These engineered films produced noteworthy results concerning their thermal and swelling properties. There is a need to further investigate these films for drug delivery and biomaterials applications. © 2014 Society of Chemical Industry 相似文献