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641.
Inderjeet Kaur Raj Kumar Baljit Singh B. N. Misra Ghanshyam S. Chauhan 《应用聚合物科学杂志》2000,78(6):1171-1178
To introduce functional moieties to Tefzel film, a copolymer of tetrafluoroethylene and ethylene, graft copolymerization of vinyl monomers such as acrylonitrile (AN) and methacrylonitrile (MAN) was attempted by a preirradiation method in aqueous medium. Optimum conditions for obtaining the maximum percentage of grafting have been evaluated for both monomers. Maximum grafting of AN (52.2%) and MAN (77.7%) is obtained at a total dose of 3.14 and 2.69 × 104 Gy, respectively, using [AN] = 3.018 mol/L and [MAN] = 1.177 mol/L in 10 mL of water. The effect of aliphatic alcohols of varying chain length, such as methanol, ethanol, isopropanol, n‐butanol, and cyclohexanol, on percentage add‐on of AN and MAN has also been studied. It has been found that all the alcohols decreased the percentage of grafting. Characterization of Tefzel and grafted Tefzel films has been carried out by IR spectroscopy and thermogravimetric analysis. Grafted Tefzel film has been found to have improved thermal resistance. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1171–1178, 2000 相似文献
642.
Sadaf Jamal Gilani Syed Sarim Imam Adil Ahmed Sanjay Chauhan Mohd. Aamir Mirza 《Drug development and industrial pharmacy》2013,39(11):1799-1806
AbstractA rapid, accurate, and sensitive reverse phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated for the estimation of Thymoquinone (TMQ) in API as well as in noisome. The chromatograms were developed with the mobile phase – water: 2-propanol: methanol (50:45:5 v/v/v) as a solvent system at 254?nm. The method was validated as per ICH guidelines for different parameters and the recovery of TMQ was calculated in developed niosomes. Further, TMQ loaded niosomes (TMQNIOS) were prepared and evaluated for different parameters. The optimized TMQNIOS (F3) was further evaluated for surface morphology, in vitro drug release, permeation study, and confocal laser scanning microscopic (CLSM) study. The method showed linearity range between 6.25 and 100?µg/ml with low detection limit and quantitation limit with a value of 2.08 and 6.25?µg/ml. The developed formulations showed the vesicle size and encapsulation efficiency in the range of 157.32?±?3.15 to 211.44?±?5.23?nm and 59.32?±?4.87 to 83.21?±?3.55%, respectively. The drug release result showed the significant higher release from TMQNIOS in compared to TMQDIS, and the release kinetics data showed Higuchi's equation with highest regression coefficient values. The permeation study and the confocal laser microscopy study further confirmed the enhancement in permeation of TMQ in the intestinal mucosa. 相似文献
643.
Inderjeet Kaur Sunil Kumar B. N. Misra Ghanshyam S. Chauhan 《Materials Science and Engineering: A》1999,270(2):2313
Preirradiated isotactic polypropylene (IPP) powder has been modified by grafting 2-vinyl pyridine (2-VP) and styrene (Sty) in an aqueous medium. The graft copolymerization reaction was studied under different experimental conditions such as total dose, monomer concentration, amount of the solvent, time of reaction and temperature to determine the optimum conditions for affording maximum percentage of grafting (Pg). Maximum grafting percent of 2-VP (180%) and styrene (117%) was obtained under optimum conditions. The rate of grafting (Rg) of 2-VP and styrene has also been determined as a function of total dose, initial monomer concentration and the reaction temperature. From maximum Pg and different Rg values of 2-VP and Sty, 2-VP is more reactive towards grafting as compared to styrene under optimum conditions. Characterization of the graft copolymers is based on differential scanning calorimetric (DSC) analysis. Isolation of the grafted poly(2-VP) and poly(styrene) chains from the grafted samples provides an additional evidence of formation of the graft copolymer. 相似文献
644.
Removal of hexavalent chromium by xanthated chitosan was investigated in a packed bed up-flow column. The experiments were conducted to study the effect of important design parameters such as bed height and flow rate. At a bed height of 20 cm and flow rate of 5 mL min(-1), the metal-uptake capacity of xanthated chitosan and plain chitosan flakes for hexavalent chromium was found to be 202.5 and 130.12 mg g(-1) respectively. The bed depth service time (BDST) model was used to analyze the experimental data. The computed sorption capacity per unit bed volume (N(0)) was 4.6 ± 0.3 and 78.3 ± 2.9 g L(-1) for plain and xanthated flakes respectively at 10% breakthrough concentration. The rate constant (K(a)) was recorded as 0.0507 and 0.0194 L mg(-1)h(-1) for plain and xanthated chitosan respectively. In flow rate experiments, the results confirmed that the metal uptake capacity and the metal removal efficiency of plain and xanthated chitosan decreased with increasing flow rate. The Thomas model was used to fit the column sorption data at different flow rates and model constants were evaluated. The column was successfully applied for the removal of hexavalent chromium from electroplating wastewater. Five hundred bed volumes of electroplating wastewater were treated in column experiments using this adsorbent, reducing the concentrations of hexavalent chromium from 10 mg L(-1) to 0.1 mg L(-1). 相似文献
645.
Bundy Vanessa Chauhan Mehul Fitch Cyrus Modi Prathmesh Morsi K. 《Metallurgical and Materials Transactions A》2018,49(12):6351-6358
Metallurgical and Materials Transactions A - The present paper investigates the effect of carbon nanotube (CNT) length (including the use of short multi-wall CNTs) and milling parameters on the... 相似文献
646.
S. S. Kanwar S. Pathak H. K. Verma S. Kumar R. Gupta S. S. Chimni G. S. Chauhan 《应用聚合物科学杂志》2006,100(6):4636-4644
Four series of noble networks were synthesized with acrylic acid (AAc) copolymerized with varying amount of 2‐hydroxy propyl methacrylate or dodecyl methacrylate (AAc/HPMA or AAc/DMA; 5:1 to 5:5, w/w) in the presence of ethylene glycol dimethacrylate (EGDMA; 1, 5, 10, 15, and 20%, w/w) as a crosslinker and ammonium per sulfate (APS) as an initiator. Each of the networks was used to immobilize a purified lipase from Pseudomonas aeruginosa MTCC‐4713. The lipase was purified by successive salting out with (NH4)2SO4, dialysis, and DEAE anion exchange chromatography. Two of the matrices, E15a, i.e. [poly (AAc5‐co‐DMA1‐cl‐EGDMA15)] and I15c, i.e. [poly (AAc5‐co‐HPMA3‐cl‐EGDMA15)], that showed relatively higher binding efficiency for lipase were selected for further studies. I15c‐hydrogel retained 58.3% of its initial activity after 10th cycle of repetitive hydrolysis of p‐NPP, and I15c was thus catalytically more stable and efficient than the other matrix. The I15c‐hydrogel‐immobilized enzyme showed maximum activity at 65°C and pH 9.5. The hydrolytic activity of free and I15c‐hydrogel‐immobilized enzyme increased profoundly in the presence of 5 mM chloride salts of Hg2+, NH4+, Al3+, K+, and Fe3+. The immobilized lipase was preferentially active on medium chain length p‐nitrophenyl acyl ester (C:8, p‐nitrophenyl caprylate). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4636–4644, 2006 相似文献
647.
Shamsher S. Kanwar Hemant K. Verma Rajeev K. Kaushal R. Gupta Yogesh Kumar Swapandeep S. Chimni Ghansham S. Chauhan 《应用聚合物科学杂志》2006,100(5):4252-4259
A purified alkaline thermo‐tolerant lipase from Pseudomonas aeruginosa MTCC‐4713 was immobilized on a series of five noble weakly hydrophilic poly(AAc‐co‐HPMA‐cl MBAm) hydrogels. The hydrogel synthesized by copolymerizing acrylic acid and 2‐hydroxy propyl methacrylate in a ratio of 5 : 1 (HG5:1 matrix) showed maximum binding efficiency for lipase (95.3%, specific activity 1.96 IU mg?1 of protein). The HG5:1 immobilized lipase was evaluated for its hydrolytic potential towards p‐NPP by studying the effect of various physical parameters and salt‐ions. The immobilized lipase was highly stable and retained ~92% of its original hydrolytic activity after fifth cycle of reuse for hydrolysis of p‐nitrophenyl palmitate at pH 7.5 and temperature 55°C. However, when the effect of pH and temperature was studied on free and bound lipase, the HG5:1 immobilized lipase exhibited a shift in optima for pH and temperature from pH 7.5 and 55°C to 8.5 and 65°C in free and immobilized lipase, respectively. At 1 mM concentration, Fe3+, Hg2+, NH4+, and Al3+ ions promoted and Co2+ ions inhibited the hydrolytic activities of free as well as immobilized lipase. However, exposure of either free or immobilized lipase to any of these ions at 5 mM concentration strongly increased the hydrolysis of p‐NPP (by ~3–4 times) in comparison to the biocatalysts not exposed to any of the salt ions. The study concluded that HG5:1 matrix efficiently immobilized lipase of P. aeruginosa MTCC‐4713, improved the stability of the immobilized biocatalyst towards a higher pH and temperature than the free enzyme and interacted with Fe3+, Hg2+, NH4+, and Al3+ ions to promote rapid hydrolysis of the substrate (p‐NPP). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4252–4259, 2006 相似文献
648.
The article describes the synthesis and characterization of N‐(4‐methoxy‐3‐chlorophenyl) itaconimide (MCPI) and N‐(2‐methoxy‐5‐chlorophenyl) itaconimide (OMCPI) obtained by reacting itaconic anhydride with 4‐methoxy‐3‐chloroanisidine and 2‐methoxy‐5‐chloroanisidine, respectively. Structural and thermal characterization of MCPI and OMCPI monomers was done by using 1H NMR, FTIR, and differential scanning calorimetry (DSC). Copolymerization of MCPI or OMCPI with methyl methacrylate (MMA) in solution was carried out at 60°C using AIBN as an initiator and THF as solvent. Feed compositions having varying mole fractions of MCPI and OMCPI ranging from 0.1 to 0.5 were taken to prepare copolymers. Copolymerizations were terminated at low percentage conversion. Structural characterization of copolymers was done by FTIR, 1H NMR, and elemental analysis and percent nitrogen content was used to calculate the copolymer composition. The monomer reactivity ratios for MMA–MCPI copolymers were found to be r1 (MMA) = 0.32 ± 0.03 and r2 (MCPI) = 1.54 ± 0.05 and that for MMA–OMCPI copolymers were r1 (MMA) = 0.15 ± 0.02 and r2 (OMCPI) = 1.23 ± 0.18. The intrinsic viscosity [η] of the copolymers decreased with increasing mole fraction of MCPI/or OMCPI. The glass transition temperature as determined from DSC scans was found to increase with increasing amounts of OMPCI in copolymers. A significant improvement in the char yield as determined by thermogravimetry was observed upon copolymerization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2391–2398, 2006 相似文献
649.
Jae-Kwang Kim Jou-Hyeon Ahn Gouri Cheruvally Ghanshyam S. Chauhan Jae-Won Choi Dul-Sun Kim Hyo-Jun Ahn Seo Hwan Lee Choong Eui Song 《Metals and Materials International》2009,15(1):77-82
The electrochemical properties of the organic radical battery (ORB) having a lithium metal anode and a cathode consisting
of a nitroxide radical polymer poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA) with 1M LiPF6 as an electrolyte in ethylene carbonate (EC)/dimethyl carbonate (DMC) have been evaluated at room temperature. The cell,
with a thin cathode of 17 μm thickness incorporating 40 wt.% of PTMA, exhibited the full theoretical specific capacity at
current densities up to 10 C (∼1 mA/cm2). However, a decrease in the specific capacity and an increase in the ohmic resistance were observed at higher current densities.
The cell performance was good even on repeated charge-discharge cycles as an excess of 85 % retention of the initial discharge
capacity was observed. This was true even after 400 cycles. However, a gradual decrease in capacity, an increase in charge-discharge
voltage separation, and an electrode/electrolyte interfacial resistance have been observed after a large number of cycles.
The examination of the scanning electron micrographs of the cathode material revealed that prolonged cycling resulted in the
agglomeration of PTMA particles. These in turn increased the resistance and decreased the capacity of the cell. 相似文献
650.
The influence of tetraalkylammonium salts, viz., tetraethylammonium, tetrapropylammonium, and tetrabutylammonium bromides (0.005, 0.010, 0.015 mol kg−1) on the micellar behavior of aqueous solutions of the cationic surfactant cetyltrimethylammonium bromide (CTAB, 0.2–2 mmol kg−1) over the 298.15–313.15 K temperature range has been studied by conductometric method. From conductivity versus surfactant concentration plots, the critical micelle concentration (CMC) of CTAB has been determined, which shows that the tetraalkylammonium bromides promote the formation of CTAB aggregates. Further, from the temperature dependence of CMC values, the degree of ionization, the counterion binding constant along with some thermodynamic parameters of micellization, such as standard free energy change (), standard enthalpy change (), standard entropy change () have been calculated. From the values of , and , it has been concluded that our ternary system is both enthalpy as well as entropy controlled. Similar CMC values were obtained from UV–Visible spectrometry measurements, using pyrene as a probe at ambient temperature. Also 1H-NMR and FTIR methods give a greater understanding of the molecular scale interactions between the tetraalkylammonium bromides and the cationic surfactant. 相似文献