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51.
Bacteriocins produced by lactic acid bacteria are safer alternatives to the more popularly used chemical preservatives which exhibit several adverse effects. The bacteriocins have an advantage of being efficient in controlling food pathogens without possessing any side‐effects. However, the bacteriocins have a limitation of exhibiting a narrow antimicrobial spectrum and having a high‐dosage requirement. With an aim to combat these limitations, the present study involved the biosynthesis of bacteriocin‐capped nanoparticles, using two bacteriocins (Bac4463 and Bac22) extracted and purified from Lactobacillus strains. Nanoconjugates synthesised at optimum conditions were characterized using various physico‐chemical techniques. The interaction of bacteriocin‐capped silver nanoparticles with the pathogenic bacteria was observed using scanning electron microscopy, wherein the deformed and elongated cells were clearly visible. In vitro antimicrobial efficacy of both Bac4463‐capped silver nanoparticles and Bac22‐capped silver nanoparticles against different food pathogens was observed to be enhanced in comparison to the antimicrobial activity of bacteriocins alone. Minimum inhibitory concentration was observed to be as low as 8 μg/ml for Bac4463‐capped silver nanoparticles against Staphylococcus aureus, and 2 μg/ml for Bac22‐capped silver nanoparticles against Shigella flexneri. This study, therefore, recommends the use of bacteriocin‐capped nanoparticles as food preservatives to control the growth of food spoiling bacteria.Inspec keywords: preservatives, elongation, food safety, silver, biotechnology, antibacterial activity, food preservation, nanoparticles, nanofabrication, food products, scanning electron microscopy, microorganismsOther keywords: bacteriocins, chemical preservatives, food pathogens, bacteriocin‐capped nanoparticles, bacteriocin‐capped silver nanoparticles, Bac4463‐capped silver nanoparticles, Bac22‐capped silver nanoparticles, enhanced antimicrobial efficacy 相似文献
52.
H. K. Seo Farheen S. A. Ansari Nazish Parveen Shabeena Qadir H. Fouad H. S. Shin Moo Hwan Cho S. G. Ansari Z. A. Ansari 《Journal of Materials Science: Materials in Electronics》2017,28(4):3210-3216
Extensive research have been made in improving the dye sensitized solar cells (DSSC) performance by designing, tailoring and enhancing the photoconversion properties of the matrix. The approaches used are material synthesis, dye permutation combinations, use of natural extracts or using several sensitizers. The polymers are also being explored in this regards in their pristine or composite forms. Therefore, in this study an attempt is made to synthesize a mesoporous polyaniline–titanium dioxide (PANI–TiO2) nanocomposites with one pot synthesis approach at different concentrations of PANI (0.3–0.7 ml). Titanium isopropoxide was used as precursor for TiO2 with aniline and the material was synthesized at ice bath temperature. Morphological observations showed that the composite is a mesoporous material with tubular structure where TiO2 particles are seen entrapped in the polymer matrix and found that intercalation can be tailored with PANI concentration. Structural, functional and optical characterization indicate anatase phase of TiO2, with several functional bands that can help in dye interaction and broad absorption bands within visible region. The photocurrent-voltage response was measured with simulated light and source-meter. It is interesting to note that increasing PANI concentration enhances the mesoporous structure and hence increases the dye loading capacity and photoconductivity of the material. The efficiency increased by about 22 % with addition of 0.5 ml of PANI from 0.3 ml. The proposed study has indicated that such material have the potential to be used for DSSC fabrication with which the device performance can further be increased to a better levels. 相似文献
53.
Periyasamy Thirukumaran Raji Atchudan Rukmanikrishnan Balasubramanian Asrafali Shakila Parveen Seong-Cheol Kim 《International Journal of Hydrogen Energy》2018,43(29):13266-13275
In this work, we propose a novel nitrogen-rich carbon sheets (N-CSs), with conceivable use as efficient catalysts for hydrogen evolution reaction (HER). N-CSs are directly synthesized from polybenzoxazine (PBz) by carbonization followed by KOH activation. PBz was prepared from eugenol, melamine, and paraformaldehyde through ring-opening polymerization. FT-IR and NMR spectroscopy confirmed the corresponding chemical structures of the new benzoxazine monomer. The morphology, structure and surface properties of the N-CSs are investigated by Raman spectroscopy, wide-angle X-ray diffraction, and X-ray photoelectron spectroscopy. The catalytic activity of N-CSs towards HER is thoroughly investigated by electrochemical techniques. In N-CSs, it is established that nitrogen gratified electrocatalytic activity, and hence nitrogen atoms should enhance the electrocatalytic properties by increasing the active sites. As the kinetic current is stabilized by the outer nitrogen atom as such, HER is proposed to proceed on these active sites by the Volmer-Heyrovsky mechanism. The N-CSs show outstanding catalytic activity towards HER with lowest onset-potential (?10 mVRHE) and Tafel slope (45 mV dec?1) in 0.5 M H2SO4 aqueous electrolyte. 相似文献
54.
Nahid Nishat Shamim Ahmad Khan Raza Rasool Shadma Parveen 《Journal of Inorganic and Organometallic Polymers and Materials》2011,21(3):673-681
The polymer metal complexes of transition metal ions Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with a new polymeric Schiff
base containing formaldehyde and piperazine moieties have been synthesized by the condensation and characterized by elemental
analyses, infrared spectra, electronic spectra, magnetic susceptibility measurements and thermogravimetric analyses (TGA).
The results of the electronic spectra and magnetic moments indicate that the polymer–metal complexes of Mn(II), Co(II) and
Ni(II) have octahedral geometry, while the complexes of Cu(II) and Zn(II) show square planar and tetrahedral geometry, respectively.
The analyses of the thermal curves of all the polymer metal complexes show better thermal stability than the polymeric Schiff
base. All compounds show excellent antibacterial as well as antifungal activity against three types of bacteria and two types
of fungi. The antimicrobial activities were determined by using the agar well diffusion method with 100 μg/mL concentrations
of polymer metal complex. 相似文献
55.
56.
Parveen Sultana Sukhen Das Biswajoy Bagchi Alakananda Bhattacharya Ruma Basu Papiya Nandy 《Bulletin of Materials Science》2011,34(7):1663-1670
Quartz is widely replaced by fly ash in traditional porcelain composite. Increased strength and stability of the fly ash-mixed composite depends on the quantity and crystallinity of the mullite phase in the fly ash. Our aim in this investigation is to increase the formation of mullite in nanocrystalline form and study the effect of temperature. Quantitative estimation of mullite and residual quartz content were done by X-ray diffraction (XRD) and nanostructure and crystallization were studied using differential thermal analysis (DTA), field effect scanning electron microscopy (FESEM), XRD and Fourier transform infrared (FTIR) spectroscopy. The results show that fly ash sieved through 250 holes/cm2 mesh contain more mullite initially and growth of mullite as well as glass formation was faster in this sample compared to coarse fly ash. The maximum mullite in these samples was formed at 1600°C. Transformation of quartz and cristobalite phases into glassy phase was also faster for smaller particle sizes of fly ash. 相似文献
57.
In 3 experiments, participants saw lists of 16 words for free recall with or without a 6-digit immediate serial recall (ISR) task after each word. Free recall was performed under standard visual silent and spoken-aloud conditions (Experiment 1), overt rehearsal conditions (Experiment 2), and fixed rehearsal conditions (Experiment 3). The authors found that in each experiment, there was no effect of ISR on the magnitude of the recency effect, but interleaved ISR disrupted free recall of those words that would otherwise be rehearsed. The authors conclude that ISR and recency cannot both be outputs from a unitary limited-capacity short-term memory store and discuss the possibility that the process of rehearsal may be common to both tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
58.
To determine the significance of antibodies to single-stranded (anti-ssDNA) and double-stranded DNA (anti-dsDNA) in antinuclear antibody (ANA)-positive type 1 autoimmune hepatitis, sera from 53 patients were tested by enzyme immunosorbent assay (ELISA) and indirect immunofluorescence using the Crithidia luciliae substrate. Anti-dsDNA were detected in 18 patients (34%) by ELISA and 12 patients (23%) by the Crithidia-based assay. Twenty patients with anti-dsDNA by either assay (38%) had higher serum levels of immunoglobulin G (3971 +/- 270 mg/dL vs. 3201 +/- 247 mg/dL, P = .05) than seronegative patients. They also had human leukocyte antigen (HLA) DR4 more commonly than other patients (83% vs. 41%, P = .006) and normal subjects (83% vs. 30%, P = .00007). In contrast to patients seropositive by the Crithidia-based assay, those seropositive by ELISA failed corticosteroid therapy more commonly (24% vs. 3%, P = .04). Anti-ssDNA were found in 45 patients (85%) and they did not distinguish patients with different clinical features or outcomes. We conclude that anti-dsDNA are common in ANA-positive type 1 autoimmune hepatitis. HLA DR4 is associated with their production, and seropositivity by ELISA characterizes patients who have a poorer immediate response to corticosteroid treatment. Anti-ssDNA are common but they do not have important clinical implications. 相似文献
59.
Kamaljit Singh Sarbjit Singh Parveen Kumar Garg Maninder Singh Hundal 《Coloration Technology》2004,120(2):72-76
Crystals of the title novel red disperse dye were grown by slow evaporation from a chloroform solution and the crystal structure was determined by single crystal X-ray diffraction analysis. The dye molecule crystallises in the triclinic space group P 1 with the unit cell dimensions a = 7.561(2), b = 11.628(10) and c = 15.607(3) Å. The diffraction analysis showed that the hetarylazo skeleton of the dye is nearly planar, with the ester groups oriented up and down the plane of the molecule thus imparting it a 'Y' shape structure. The intramolecular hydrogen bonds, together with van der Waals interactions, stabilise the molecular conformation and crystal packing. 相似文献
60.
Divya Shukla Shashi Singh Shahla Parveen Manisha Gupta J.P. Shukla 《International Journal of Thermophysics》2008,29(4):1376-1384
Densities and viscosities have been measured for the binary mixtures of methanol with chlorobenzene and with bromobenzene
from 293 K to 313 K over the complete composition range. Densities were used to compute the excess molar volume ( , for these binary systems. The results have been discussed in terms of molecular interactions. Furthermore, viscosity results
were compared with a corresponding-states model. The average absolute deviation was found to be 1.9 %. 相似文献