全文获取类型
收费全文 | 224篇 |
免费 | 9篇 |
专业分类
电工技术 | 1篇 |
综合类 | 1篇 |
化学工业 | 74篇 |
金属工艺 | 1篇 |
机械仪表 | 3篇 |
建筑科学 | 3篇 |
矿业工程 | 2篇 |
能源动力 | 12篇 |
轻工业 | 31篇 |
水利工程 | 4篇 |
石油天然气 | 1篇 |
无线电 | 18篇 |
一般工业技术 | 36篇 |
冶金工业 | 14篇 |
原子能技术 | 1篇 |
自动化技术 | 31篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 8篇 |
2018年 | 13篇 |
2017年 | 8篇 |
2016年 | 5篇 |
2015年 | 8篇 |
2014年 | 13篇 |
2013年 | 20篇 |
2012年 | 7篇 |
2011年 | 24篇 |
2010年 | 15篇 |
2009年 | 15篇 |
2008年 | 17篇 |
2007年 | 9篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 4篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1995年 | 1篇 |
排序方式: 共有233条查询结果,搜索用时 11 毫秒
91.
Vildan Bilgin 《Journal of Electronic Materials》2009,38(9):1969-1978
Zinc oxide thin films doped with Li were deposited by ultrasonic spray pyrolysis (USP) at 350 ± 5°C on glass substrates from
solutions of zinc acetate [Zn(CH3COO)2 · 2H2O] and lithium acetate [C2H3LiO2 · 2H2O], in which the Li/Li + Zn ratios were 1 at.%, 3 at.%, and 5 at.%. The effects of the doping on the structural, optical,
electrical, and morphological properties of the films were examined. X-ray diffraction patterns indicated that the undoped
and Li-doped ZnO films had a polycrystalline hexagonal wurtzite structure with a (002) preferred orientation. The films showed
optical transmission around 60–80% in the visible region of the spectrum. The films were found to be transparent in the wavelength
range of 450–900 nm, with sharp ultraviolet absorption edges in the wavelength range of 350–450 nm. The absorption edge analysis
revealed that the optical band gap energies for the films were between 3.24 eV and 3.29 eV, and the electronic transition
was of the direct transition type. The width of the band tail states, which is connected to the localized states in the band
gap, was estimated to be 82–113 meV by Urbach tail analysis. For study of the electrical properties of the films, Hall effect
measurements, electrical conductivities, conductivity activation, and trap energies were investigated. The electrical measurements
of the films were obtained in the dark, in vacuum, and in the temperature range of 10–300 K. Morphological studies for the
films were carried out by scanning electron microscopy. 相似文献
92.
The dyadic wavelet transform is an effective tool for processing piecewise smooth signals; however, its poor frequency resolution (its low Q-factor) limits its effectiveness for processing oscillatory signals like speech, EEG, and vibration measurements, etc. This paper develops a more flexible family of wavelet transforms for which the frequency resolution can be varied. The new wavelet transform can attain higher Q-factors (desirable for processing oscillatory signals) or the same low Q-factor of the dyadic wavelet transform. The new wavelet transform is modestly overcomplete and based on rational dilations. Like the dyadic wavelet transform, it is an easily invertible 'constant-Q' discrete transform implemented using iterated filter banks and can likewise be associated with a wavelet frame for L2(R). The wavelet can be made to resemble a Gabor function and can hence have good concentration in the time-frequency plane. The construction of the new wavelet transform depends on the judicious use of both the transform's redundancy and the flexibility allowed by frequency-domain filter design. 相似文献
93.
Sinan Korpe Bariş Erdoğan Goknur Bayram Serkan Ozgen Yusuf Uludag Niyazi Bicak 《Reactive and Functional Polymers》2009,69(9):660-665
Loosely crosslinked cationic polyelectrolytes (polyquats) with super-water-sorption abilities are presented, for the first time. Hydrogels obtained by radically initiated copolymerization of N,N-diallyl, N,N-dimethyl ammonium chloride (DADMAC) with N-vinyl 2-pyrrolidone (NVP) in presence of N,N,N′,N′-tetraallyl piperazinium dichloride (TAP) as crosslinker showed reasonably high equilibrium swelling ratios, as high as those for poly(acrylic acid)-based super absorbents.The highest swelling ratios (up to 360) were attained by fully cationic hydrogels derived from DADMAC and 0.5% TAP. The hydrogels with 0.5–5% crosslinkers exhibited rapid expansion in neutral water, so that the equilibrium swelling values were attained within 2–3 min. The crosslinking densities of the gels were estimated by Flory-type swelling model using “phantom network elasticity” for the elastic contribution. This estimation revealed low crosslinking efficiencies of TAP (0.24–0.35) due to its double cationic charge.In the study “the salt effect” and effects of the comonomer ratios and crosslinker contents on the swellings were also investigated. 相似文献
94.
T Ulutin H S?nmez N U?i?ik S Süer C Bayram E K?koglu G Sultuybek 《Canadian Metallurgical Quarterly》1997,88(3):329-332
The male Otsuka Long-Evans Tokushima Fatty (OLETF) rat shows insulin resistance in skeletal muscle and visceral obesity. To obtain information on the mechanism of the insulin resistance in the diabetic rats, we examined the content of insulin-regulated glucose transporter (GLUT4) in skeletal muscles. The results indicate that the total content of the transporter is significantly decreased (P < 0.05) in muscles of the diabetic rats. Plasma membrane content of the GLUT4 protein in muscles of the diabetic rats was increased in the basal state as compared to control rats. Hyperinsulinemic clamps increased GLUT4 levels in the plasma membrane of control rats but failed to do so in the diabetic rats. The distribution of GLUT4 in OLETF rat is reminiscent of the characteristics of human non-insulin-dependent diabetes mellitus. 相似文献
95.
96.
Resettlement takes place when major construction projects, which are a most important element of development force people who have lived in a region for a long time to leave their homes and any other immovable properties, their place in society, economic and agricultural activities, relationships and opportunities, to live in other places. It is necessary to create satisfactory policies and procedures in order to eliminate or minimize the adverse effects of relocation and resettlement both on people and on the national economy. These effects are not only economic, but social, cultural, psychological and environmental as well. For this reason, the approach to resettlement and rehabilitation concepts should deal with these issues in an integrated manner. To ensure that resettlement takes place in a well-planned way, and to minimize its adverse effects, it is necessary for people, NGOs and institutions who run the country and make decisions to define their goals, policies and strategies for resettlement and rehabilitation. In particular, one of the problems observed by experts who have worldwide experience has been the inadequacy and inconsistency of laws arranging resettlement procedures in different countries. 相似文献
97.
Vildan Aykan Emel Sezgin Zeynep B. Guzel‐Seydim 《European Journal of Lipid Science and Technology》2008,110(6):516-520
The purpose of this research was to determine the effects of different fat replacers on the sensory and texture attributes of vanillin‐flavored ice cream. Inulin is a fairly new fat replacer which has been proven to be a health promoter. Two vanilla ice cream formulations were produced using different ratios of inulin and Simplesse® as fat replacers to provide better flavor and textural properties. Aspartame and acesulfam‐K were used as sweeteners in the low‐calorie ice creams. Sensory and instrumental analyses were used to evaluate the texture quality of light (4.55%) (control group), low‐fat (2%) and fat‐free vanilla ice creams. The experimental mixes were significantly more viscous than the control mix due to the water binding capacity of carbohydrate‐ and protein‐based substances. The texture scores of the ice creams (sensory evaluation) paralleled the viscosity values. Ice creams manufactured with fat replacers were free of cooked‐milk flavor. The energy value of ice cream was reduced compared to full‐fat ice cream (207 kcal/100 g): by 75% for non‐fat ice cream, 71% for low‐fat ice cream and 41% for light ice cream. An increase in total solids in the mix resulted in better texture, a lower melting rate and better shape retention. 相似文献
98.
Aysegul Bayram Irfan Siap 《Applicable Algebra in Engineering, Communication and Computing》2013,24(5):369-386
In this paper, we study the structure of linear codes over the non chain ring $Z_{3}[v]/\langle v^{3}-v\rangle $ . In order to study the codes, we first study the structure of this ring via a distance preserving Gray map which also induces a relation between codes over this ring and ternary codes. Further, the algebraic structure of cyclic and dual codes is also studied. A MacWilliams type Identity between the Gray weight enumerators of the original code and its dual is established. In all cases examples that illustrate the theorems and lemmas are provided. Also, a BCH-type bound and an example that attains this bound is presented. 相似文献
99.
ABSTRACTIn this study, two new calixarene derivatives bearing thiourea and carbamate moieties were synthesized and characterized. Moreover, thiourea- and carbamate-bridged calixarene derivatives with Fe3O4 magnetic nanoparticle were employed for the first time as the convenient additives in the encapsulation process of lipase. The results of catalytic activity and enantioselectivity of the encapsulated lipases in the hydrolysis reaction of racemic flurbiprofen methyl ester indicate that both of the encapsulated lipases (Enc-TuC[4]@Fe3O4 and Enc-CbC[4]@Fe3O4) exhibit higher conversion and enantioselectivity compared to the free-encapsulated lipase (Enc-Lipase). However, the highest affinities result was obtained when the encapsulated lipase (Enc-CbC[4]@Fe3O4) was used in the kinetic resolution reaction of racemic flurbiprofen methyl ester. 相似文献
100.
ABSTRACT After preextraction with ethanol-benzene (1:2) in a Soxhlet apparatus Tunçbilek lignite was extracted with dioxane at 330°C in an autoclave at different pressures and for different exposure times. The extracts were fractionated and many of the compounds they contain were identified by gas chromatography/mass spectrometry. The formation and yields of these compounds are discussed in terms of the structure of the parent fuel and the mechanism of extraction. 相似文献