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排序方式: 共有1643条查询结果,搜索用时 20 毫秒
111.
Abdel Monem Mohamed Soltan Hassan Elshimy Fawzia Abd EL-Raoof Florian Fuchs Andreas Köenig Ahmed Mohamed Yahya Mohamed Mostafa AbdelFattah Mohamed Serry Herbert Pöllmann 《Ceramics International》2018,44(6):5855-5866
The aim of this work is to study the effect of phase composition and microstructure of cordierite-based co-clinkers on the electrical properties and coefficient of thermal expansion of cordierite briquettes. To achieve this aim talc and kaolinite samples were collected from quarries in the Egyptian desert. The samples are characterized using XRD, XRF, polarized light, cathodoluminescence and SEM microscopy attached with EDAX, in addition to X-ray micro-computed tomography (3D- µXCT). The electrical properties and coefficient of thermal expansion of the cordierite briquettes are determined using HiTESTER instrument and automatic Netzsch DIL402 PC dilatometer, respectively.Five talc-based batches were shaped and fired in the temperature range 1000–1350 °C for 2 h. The microstructural and physical characteristics of the resulted cordierite-based co-clinkers depend mainly on the viscosity of the liquid phase developed during firing. The microchemistry of the cordierite briquettes confirms their enrichment of both cordierite and ferroan-cordierite crystallized directly from locally developed melts. The dielectric constant and loss factor values for cordierite briquettes allow their possible use as insulator components in electronic applications. 相似文献
112.
Shaharuddin Salleh Stephan Olariu Bahrom Sanugi Mohd Ismail Abd Aziz 《The Journal of supercomputing》2005,31(3):265-279
A complete graph is a fully-connected graph where every node is adjacent to all other nodes in the graph. Very often, many applications in science and engineering are reducible to this type of graph. Hence, a simplified form of a complete graph contributes in providing the solutions to these problems. In this paper, we present a technique for transforming a complete graph into a single-row routing problem. Single-row routing is a classical technique in the VLSI design that is known to be NP-complete. We solved this problem earlier using a method called ESSR, and, the same technique is applied to the present work to transform a complete graph into its single-row routing representation. A parallel computing model is proposed which contributes in making the problem modular and scalable. We also discuss the application of this work on the channel assignment problem in the wireless cellular telephone networks. 相似文献
113.
B. A. El-Sayed M. A. El-Nawawy E. M. Abd Ellah R. S. Farag 《Journal of Materials Science》1999,34(11):2715-2718
Correlation of the molecular structure and utilizing measurements of the electrical conductivity, activation energy of conduction of 4,4 bis(2-thenylideneamino)biphenyl (SB) and 4,4 bis(thenyl-diphenylphosphinylmethyleneamino)biphenyl (OPSB) compounds have been carried out. The results of the activation energies, obtained from the electrical conductivity measurements, as well as the energy gaps calculated from ultraviolet (u.v.) and visible spectra in the solid state indicate that the investigated compounds behave like semiconducting materials. The delocalized -electrons in addition to the lone pairs of electrons on the nitrogen atoms of the two compounds as well as the donor effect of diphenylphosphinyl groups of OPSB compound were considered as the main sources participating in the conduction processes. 相似文献
114.
Saleh A. H. Khalil Sawsan Abd El-Fattah M. A. Shams-Eldeen 《Drug development and industrial pharmacy》1984,10(10):1737-1755
A study has been carried out to investigate the dissolution rate profiles of twelve batches of sugar-coated phenylbutazone tablets belonging to four commercial brands. Using the rotating basket method, significant inter-brand and inter-batch variations in dissolution rates were found. Only two batches of one brand passed the B.P. dissolution limit whilst other batches had percentages dissolution between 0.3 and 58 after 45 min. Batches with poor dissolution characteristics exhibited significant tablet-to-tablet variations in dissolution rates; a finding which was not observed in the relatively fast-dissolving batches. When the paddle method was substituted for the B.P. basket method, the dissolution rates were relatively faster but similar dissolution failure was found. However, the tablet-to-tablet dissolution variability was decreased in some of the batches. The observed differences in dissolution rates of the batches examined were unrelated to their disintegration times. Inspite of the poor dissolution characteristics of most of the batches studied, no apparent chemical degradation was found. It is recommended that when evaluating the dissolution rates of brands of phenylbutazone tablets, a number of batches from each brand should be tested. 相似文献
115.
The technique of polymerizing methyl methacrylate (MMA) in water using sodium bisulphite as initiator in presence of various substances and metal powders was extended to Casuarina sawdust which was used either without or after being washed with water or solvents. The percentage of conversion of monomer to polymer increased with increase of Casuarina sawdust and with increase of temperature. In absence of sawdust, the average molecular weights of the polymers obtained increased with increasing concentration of sodium bisulphite initiator under the studied conditions, while the reverse was true in the presence of sawdust. Some of the Casuarina sawdust-PMMA-composites prepared had high compressive strength depending on the content of polymer and its distribution in the composite. 相似文献
116.
Mahmoud M. Farag Mohamed H. Abd El Latif 《Metallurgical and Materials Transactions A》1975,6(7):1353-1358
Commercial purity Al-Al3Ni eutectic composites have been prepared by directional solidification at growth rates ranging from 9.63 x 10-3 to 1.0 mm/s. The composites were tested in tension and in compression and the results were analyzed using a simple model taking into consideration the difference in Poisson’s ratio of the phases, interfiber spacing, and discontinuity and premature fracture of fibers. The theoretically predicted values of the tangent modulus and strength in tension and compression were shown to closely fit the experimental results up to a growth rate of about 0.3 mm/s. Beyond this value, the excessive misalignment of the fibers caused some deterioration in the mechanical properties and a change in the mode of fracture. It has been concluded that the elastic constrained matrix exerts considerable effect on the mechanical properties thus providing an effective means of improving them by increasing the surface area of the fiber-matrix interface. 相似文献
117.
M. A. El-Taraboulsi M. M. Nassar E. A. Abd El-Rehim 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1983,33(8):387-396
Pulping of bagasse by a rapid and mild nitric acid process was successfully carried out to produce different grades of pulp. Nitric chemimechanical bagasse pulp was produced in a high yield of 91 % on pulping depithed bagasse with 4% HNO3 for a period of 30 min at 80°C, followed by alkali pulping with 2% NaOH at 95°C for 30 min. The pulp had a satisfactory strength and high opacity. On increasing the strengths of nitric acid to 7% and alkali to 7% a nitric semichemical pulp of 65% yield was obtained. The pulp had a superior strength and high opacity. The pulp was easily bleached to 71% general electric brightness (GE) with the chlorination-alkali-extraction-hypochlorite (CEH) sequence. With 15% HNO3 and 8% NaOH, nitric chemical bagasse pulp was produced. The pulp was easily bleached to a high brightness of 82% GE with one stage hypochlorite. The pulp had a higher strength than kraft bagasse pulp. A satisfactory newsprint paper was produced on an experimental paper machine with a furnish composed of 80% bleached nitric semichemical bagasse pulp, 10% bleached softwood pulp and 10% clay. 相似文献
118.
Novel poly (vinyl chloride) matrix membrane electrodes for the determination of phenolic pollutants in waste water 总被引:1,自引:0,他引:1
The construction and electrochemical response characteristics of poly (vinyl chloride) matrix membrane sensors for seven phenolic compounds (phenol, o-cresol, p-cresol, p-chlorophenol, o-nitrophenol, alpha-naphthol and beta-naphthol) are described.The membranes incorporate ion association complexes of these seven phenolic anions with phenanthroline-iron(II) as electroactive materials.These sensors show linear response for phenol, o-cresol, p-cresol, p-chlorophenol, o-nitrophenol, alpha-naphthol, and beta-naphthol over wide concentration ranges, with an average anionic slope 54.3 mV per concentration decade.The suggested sensors exhibit fast response time (1 min), low determination limits (1 x 10(-5)M), good stability (2-3 weeks), reasonable selectivity to phenolic compounds in the presence of other water pollutants. The average percentage recovery was 99.78+/-0.088 for individual phenolates and 99.61+/-0.198 for phenolates in mixtures.The investigated sensors were successfully used for direct potentiometric determination of traces of these phenolic compounds in wastewater samples. Results with mean accuracy of 99.74+/-0.29%, 99.82+/-0.36%, 99.65+/-0.47%, 99.73+/-0.37%, 99.77+/-0.30%, 99.86+/-0.31% and 99.91+/-0.22% was obtained for the seven sensors, respectively.These results were compared with data obtained using the British pharamacopial method (The British Pharmacopoeia, Her Majesty's Stationary Office, London, 1993) and others (Clarke's Isolation and Identification of Drugs in Pharmaceuticals Body Fluids and Post-mortem Materials, 2nd Edition, The Pharmaceutical Press, London, 1998). 相似文献
119.
F. Abd El-Salam L. A. Wahab R. H. Nada H. Y. Zahran 《Journal of Materials Science》2007,42(10):3661-3669
The hardness of Al–5wt%Zn (alloy A) and Al–5wt%Zn–0.25wt%In (alloy B) was measured at room temperature for samples heat treated
in the range 300–453 K and dwell times in the range 30–300 s under 50 gm load. Softening was observed for all the samples
and the hardness decreased with increasing temperature and/or dwell time. Hardness drop was larger for alloy (B), which in
general showed higher hardness than alloy (A). The stress exponent n increased with increasing temperature and showed high values falling in the power law breakdown region. The parameters deduced
from the analysis of X-rays data and micrographs were found to be consistant with the calculated mechanical data. 相似文献
120.
Mostafa Rezazadeh Shirdar Mohammad Mahdi Taheri Izman Sudin Arezou Shafaghat Muhd Zaimi Abd. Majid 《Journal of Experimental Nanoscience》2016,11(10):816-822
ABSTRACTThe present study is an investigation to demonstrate the effectiveness of in situ approach in the synthesis of hydroxyapatite-grafted titanium nanotube composite (HA-TNT). This method involves combining the process of HA sol–gel and rapid breakdown anodisation of titanium in a novel solution consisting of NaCl and N3PO4. This new synthesis approach produced a uniform dispersion of Anatase and Rutile phases of TiO2 nanotubes with minimal agglomeration in the matrix of crystalline HA. The characterisation of homogenised HA-TNT composite was investigated via field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), transmission electron microscope (TEM) and X-ray diffraction (XRD). FESEM and TEM images indicated the nanostructure of composite with TiO2 nanotube diameter of approximately 10 nm. XRD and EDS analyses confirmed the formation of HA crystalline with the Ca/P ratio of 1.58 and formation of Anatase and Rutile phase of TiO2 nanotubes. 相似文献