全文获取类型
收费全文 | 171篇 |
免费 | 3篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 52篇 |
金属工艺 | 9篇 |
机械仪表 | 3篇 |
建筑科学 | 5篇 |
能源动力 | 6篇 |
轻工业 | 9篇 |
石油天然气 | 3篇 |
无线电 | 42篇 |
一般工业技术 | 24篇 |
冶金工业 | 11篇 |
原子能技术 | 2篇 |
自动化技术 | 3篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 9篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 7篇 |
2013年 | 8篇 |
2012年 | 2篇 |
2011年 | 6篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 2篇 |
2007年 | 7篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1987年 | 2篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1971年 | 3篇 |
排序方式: 共有176条查询结果,搜索用时 31 毫秒
1.
The dielectric constant, ε′, and dielectric loss, ε″, were determined for three solid carboxymethyl cellulose samples having different levels of substitution and different degrees of polymerization over a frequency range of 0.1 – 10 000 kHz at temperatures from 10–60°C. In contrast to the two relaxation processes, γ and β, previously observed in native cotton cellulose, only one relaxation process within a frequency range of 0.1 – 1 kHz was identified. It was found that the dielectric properties do not only depend on the degree of substitution, but also on the weight-average degree of polymerization and uniformity of distribution. 相似文献
2.
S. E. Shalaby N. G. Al-Balakocy M. K. Beliakova O. M. Abdel-Fatah A. M. Elshafei 《应用聚合物科学杂志》2008,109(2):942-950
An effective two-stage method has been developed for imparting antimicrobial properties to regular polyethylene terephthalate (R-PET), polyethylene glycol modified polyethylene terephthalate (PEG-M-PET), R-PET/Cotton blend (R-PET/C) and PEG-M-PET/Cotton blend (PEG-M-PET/C) fabrics. The method consists of partial hydrolysis of the fabrics to create carboxylic groups in PET macromolecules followed by subsequent reaction with dimethylalkylbenzyl ammonium chloride (DMABAC) under alkaline conditions. The reaction conditions such as pH, reaction temperature and time, carboxylic content, and DMABAC concentration were studied. Characterization of the finished fabrics was carried out through scanning electron microscopy (SEM) and Fourier transform infrared spectra (FTIR). All the modified PET fabrics showed excellent antibacterial activity towards Gram-positive (Bacillus mycoides), Gram-negative (Escherichia coli), and nonfilamentous fungus (Candida albicans). The achieved antimicrobial functions on the PET fabrics are durable in repeated laundering processes. Even after laundering 10 times the fabrics could still provide more than 85% of its antimicrobial activity against B. mycoides, E. coli, and C. albicans. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
3.
A. Hebeish N. Y. Abou-Zeid E. El-Kharadly S. E. Shalaby E. A. El-Alfy S. H. Abdel-Fattah A. M. Bayazeed H. Nasr 《应用聚合物科学杂志》1983,28(3):1179-1193
Fabric samples of polyester/cotton blend were graft copolymerized to different levels (add-ons) with poly(acrylic acid) and poly(methacrylic acid) using the mutual γ-irradiation technique and the Fe2+–H2O2 redox system, respectively. The copolymers so obtained were given durable press treatments with and without conventional nonionic softener using DMDEU as the crosslinking agent. The susceptibility of the copolymers before and after crosslinking to aqueous and nonaqueous oily soiling and their ability to release the soils were examined. It was found that hydrophilization of the surface of polyester/cotton blend through grafting with the said carboxyl-containing polymers brings about a significant improvement in the resistance of the blend to aqueous and nonaqueous oily soil particularly after crosslinking in presence of nonionic softener. A certain improvement in the ease of oily soil removal could be achieved by grafting. The opposite holds true for aqueous soil release. Soiling and soil release depends on the magnitude and method of grafting, medium of soiling, as well as the formulation of crosslinking treatments. The effect of grafting on some properties of the blend fabric before and after crosslinking was also examined. 相似文献
4.
5.
R. M. Shalaby 《Journal of Materials Science: Materials in Electronics》2005,16(4):187-191
Internal friction Q–1, thermal diffusivity Dth, and thermal properties of the melts of Sn65–xAg25Sb10 Cux (0–2.5 wt.%) solder alloys are investigated and studied by means of vibration resonance technique and calibrated differential thermal analysis respectively. The thermal analysis technique is used to measure the temperature dependence of the specific heat, Cp, the solidus temperature, Ts, the liquidus temperature T1, and the activation energy of ordering U. It is found that Ts and T1 show strong dependence on copper content. The activation energy of ordering U show critical dependence on the amount of the copper added. A typical dependence of Dth and U for all studied alloys is obtained. The formation of intermetallic compound of AgSb and Sb phases in the range of composition investigated causes a pronounced increase in the electrical resistivity. 相似文献
6.
The effect of potassium dichromate and sodium silicate on the corrosion of zinc and three zinc-silver alloys containing about 8, 30 and 92% silver respectively in N NaOH was studied. It was found that both potassium dichromate and sodium silicate (higher concentrations) are efficient inhibitors for zinc and alloy I. The efficiency of the dichromate decreased with the increase in silver content of the alloy while sodium silicate was found to be a poor inhibitor for alloys II and III. The lower concentrations of the silicate stimulated the corrosion of zinc and the three alloys in this medium. 相似文献
7.
8.
N. A. Shams A. M. Kaddah E. I. Enayat Alyaa A. Shalaby A. M. Youssef 《Advanced Synthesis \u0026amp; Catalysis》1989,331(5):757-762
Reaction of acrylonitrile with 4-cyano-5,6-diphenyl pyridazin-3(2H)-one and 3(2H)-thione derivative ( 1a, b ) at elevated temperature gave 7H-5-amino-6-cyano-3,4-diphenylpyrano and thiino [2,3-c] pyridazines ( 2a, b ), respectively. However, the reaction of 4-carbethoxy pyridazine derivatives ( 1c, d ) with the same reagent, under the same conditions afforded 6H, 7H-6-cyano-3,4-diphenyl-5-oxopyrano ( 3a ) and thiino [2,3-c] pyridazine ( 3b ), respectively. In addition, treatment of ( 1a, c ) and ( 1b, d ) with acrylonitrile ar reflux in alkaline medium give the respective 3-(2′-cyanoethyloxo) ( 7a, c ) and 3-2′-cyanoethylthio ( 7b, d ) pyridazine derivatives. Prolonged alkaline hydrolysis of either ( 1a, c ) or ( 7a, c ) yielded the same product ( 8a ). Also hydrolysis of ( 1b, d ) and ( 7b, d ) afforded one and the same product ( 8b ). The structures of the products were assigned on the basis of satisfactory analytical and spectroscopic data. 相似文献
9.
Polymerization of 2-methyl-5-vinylpyridine (MVP) in the presence of poly(ethylene terephthalate) fibers (PET) using benzoyl peroxide (BP) as initiator caused a substantial increase in the weight of fibers. The mechanism of this polymerization is believed to be grafting by vinyl addition to PET radical formed under the influence of BP. Increasing the BP concentration up to 4.26 × 10?3 mole/l. causes a significant enhancement in grafting, while further increase brings about a marked fall in the graft yield. Increasing the MVP concentration up to 10% also improves significantly the graft yield, but the latter, particularly in the later stages of the reaction, shows lower values at higher MVP concentrations. Raising the reaction temperature from 65° to 95°C causes a significant enhancement in the rate of grafting, though the maximum graft yield obtained at 95°C is much lower than at 85°C. Incorporation of Cu2+ ion in the polymerization system enhances the graft yield outstandingly. The same holds true for Fe3+ and Li ions, but the enhancement is much less than for Cu2+ ion. Addition of acetic or oxalic acid to the reaction decreases the magnitude of grafting. The same situation is encountered when a water/solvent mixture is used as reaction medium. Solvents employed were methanol, ethanol, propanol, and butanol. Also studied was the polymerization reaction with respect to homopolymer, total conversion, and graft efficiency. 相似文献
10.
Alireza Hadayeghi Amer S. Shalaby Bhagwant N. Persaud 《Accident; analysis and prevention》2010,42(2):676-688
A common technique used for the calibration of collision prediction models is the Generalized Linear Modeling (GLM) procedure with the assumption of Negative Binomial or Poisson error distribution. In this technique, fixed coefficients that represent the average relationship between the dependent variable and each explanatory variable are estimated. However, the stationary relationship assumed may hide some important spatial factors of the number of collisions at a particular traffic analysis zone. Consequently, the accuracy of such models for explaining the relationship between the dependent variable and the explanatory variables may be suspected since collision frequency is likely influenced by many spatially defined factors such as land use, demographic characteristics, and traffic volume patterns. The primary objective of this study is to investigate the spatial variations in the relationship between the number of zonal collisions and potential transportation planning predictors, using the Geographically Weighted Poisson Regression modeling technique. The secondary objective is to build on knowledge comparing the accuracy of Geographically Weighted Poisson Regression models to that of Generalized Linear Models. The results show that the Geographically Weighted Poisson Regression models are useful for capturing spatially dependent relationships and generally perform better than the conventional Generalized Linear Models. 相似文献