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1.
I. Kashif H. Farouk S. A. Aly A. M. Sanad M. H. El-Kottamy E. E. Assem 《Journal of Materials Science: Materials in Electronics》1992,3(3):144-146
The effect of the addition of Fe2O3 and heat treatment duration on the magnetic susceptibility of vanadium borophosphate glass were studied. The magnetic susceptibility of glass samples was found to increase with increasing Fe2O3 content, which may be explained by the formation of the FeO6 group and the change of Fe2+ to Fe3+ which has higher paramagnetic properties. No detectable changes in the magnetic susceptibility with heat treatment for the samples containing 0.0, 0.5 and 1.0 mol% Fe2O3 was observed. The magnetic susceptibility for the heat treated samples containing 2.5, 5.0 and 7.5 mol% Fe2O3 decreases sharply with increasing duration of heat treatment up to 6 h and then remains almost constant. The sharp decrease in magnetic susceptibility of 2.5 mol% Fe2O3 is attributed to the increase in the number of ferrous ions. The sharp decrease for samples containing 5.0 and 7.5 mol% Fe2O3 is attributed to the increase in the number of Fe3+ in tetrahedral co-ordination. The rate of crystallization owing to the heat treatment was calculated and was found to increase with increasing iron oxide content. The geometry of crystallization was found to be in three-, two-and one-dimension(s) for samples containing 2.5, 5.0 and 7.5 mol% Fe2O3, respectively. 相似文献
2.
Farouk M. Slibi Dhia-Aldin Abd El-Fattah Z. M. Atallah M. El-Sherbiny M. A. Hassan Moukhtar A. 《SILICON》2021,13(9):3003-3010
Silicon - Melt-quenching technique was used to prepare borosilicate glasses of composition xSiO2- (75-x) B2O3–24.7Li2O-0.3Cr2O3 (x = 0, 10, 20, 30, 40 and 50 mol%). With... 相似文献
3.
Raouf Sh. Mikhail Suzy A. Selim Farouk I. Zeidan 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1976,26(4):191-198
The surface properties of a stannic oxide gel and its thermal dehydration products obtained both in vacuo and in the presence of air in the temperature range 100–600°C have been examined by N2 adsorption. Phase and structural changes have been followed by differential thermal analysis and X-ray diffractometry. Complete pore structure analysis showed that samples dehydrated at or below 250°C were microporous. Above 250°C the pores were found to widen with increase of temperature, the widening occurring concurrently with the crystallisation process. Doping with cations of lower valency (Li+ and Al3+) than the host cation (Sn4+) had little effect on the pore structure and specific surface area for the low temperature samples (≤250°), whereas at higher temperatures, e.g. 600°C, it increased the specific area remarkably. The dope ions produce oxygen vacancies and hinder or retard sintering in SnO2. 相似文献
4.
Zheng Liu Heng Dai Farouk Alkadhi Jufeng Dai 《Frontiers of Computer Science in China》2010,4(1):135-142
With the utilization of concurrent transmission strategy, a throughput-enhanced scheduling scheme is devised for multicast
service in wireless multi-hop mesh networks. Since the performance of a multicast mechanism is constrained in a wireless setting
due to the interference among local wireless transmissions, the interference relationships are first characterized by introducing
a graph transformation method. Based on the graph transformation, the multicast scheduling problem is converted to the graph
coloring problem, and then a capacity greedy algorithm is designed to provide concurrent transmission scheduling so that the
demanded multicast transmission rate can be achieved. Moreover, the necessary and sufficient conditions of multicast schedulable
feasibility are derived. Through corresponding simulations, it is shown that the proposed strategy can enhance the throughput
of wireless multi-hop multicast systems significantly. 相似文献
5.
M. Hesham Farouk 《International Journal of Speech Technology》2017,20(4):891-896
In this work, Quantum clustering (QC) algorithm is applied to a labeled dataset of Arabic vowels. The accuracy and processing time are, then, compared with nonhierarchical kernel approaches for unsupervised clustering; namely, k-means, self-organizing map and fuzzy c-means. The choice of speech data is according to large database statistics which reveal that vowels class represents about 60–70% of Arabic speech whereas the remaining percentage is distributed among other sounds. The analysis features, in this work, are the mel-frequency cepstarl coefficients. The results show that all algorithms are competitive from accuracy point of view while QC still guarantees the solution stability. 相似文献
6.
Metaheuristics and exact methods to solve a multiobjective parallel machines scheduling problem 总被引:1,自引:1,他引:0
Xiaohui Li Farouk Yalaoui Lionel Amodeo Hicham Chehade 《Journal of Intelligent Manufacturing》2012,23(4):1179-1194
This paper deals with a multiobjective parallel machines scheduling problem. It consists in scheduling n independent jobs on m identical parallel machines. The job data such as processing times, release dates, due dates and sequence dependent setup times are considered. The goal is to optimize two different objectives: the makespan and the total tardiness. A mixed integer linear program is proposed to model the studied problem. As this problem is NP-hard in the strong sense, a metaheuristic method which is the second version of the non dominated sorting genetic algorithm (NSGA-II) is proposed to solve this problem. Since the parameters setting of a genetic algorithm is difficult, a fuzzy logic controller coupled with the NSGA-II (FLC-NSGA-II) is therefore proposed. The role of the fuzzy logic is to better set the crossover and the mutation probabilities in order to update the search ability. After that, an exact method based on the two phase method is also developed. We have used four measuring criteria to compare these methods. The experimental results show the advantages and the efficiency of FLC-NSGA-II. 相似文献
7.
The annealing effects on the structural and electrical properties of fluorinated amorphous carbon (a-C:F) thin films prepared from C6F6 and Ar plasma are investigated in a N2 environment at 200 mTorr. The a-C:F films deposited at room temperature are thermally stable up to 250 °C, but as the annealing temperature is increased beyond 300 °C, the fluorine incorporation in the film is reduced, and the degree of crosslinking and graphitization in the film appears to be enhanced. At the annealing temperature of 250 °C, the chemical bond structures of the film are unchanged noticeably, but the interface trapped charges between the film and the silicon substrate are reduced significantly. The increased annealing temperature contributes the decrease of both the interface charges and the effective charge density in the a-C:F film. Higher self-bias voltage is shown to reduce the charge density in the film. 相似文献
8.
A simple method was developed for labeling N-{4-[(3-chloro-4-fluorophenyl)amino]quinazolin-6-yl}-3-bromopropionamide, an EGFR inhibitor, with radioactive iodine via nucleophilic iododebromination. The factors affecting the radiochemical yield of 125I-EGFR such as reaction medium, substrate concentration, CuCl concentration, and temperature were examined. Reducing agents such as ascorbic acid, SnCl2, and Na2S2O5 were used to prevent disproportionation. The radiochemical yield and purity of the labeled product were determined by TLC and HPLC. 相似文献
9.
The consolidation and curing history during the processing of composite materials affects the final properties of a part in various inter-related ways. In order to improve the quality of composites, these process-property relations must be understood in detail. Using a computer-controlled compression molding and data acquisition system, the processing of PMR-15/C3k composites has been investigated. The process parameters considered were the pressure, the time at which it was applied and the crosslinking temperature. Parts were tested for inter-laminar shear strength and flexural modulus, and measurements were made for void content and thickness. Full compaction strength, optimum compaction strength and void sensitivity factor have been defined. 相似文献
10.
The functional properties of thawed pre-rigor beef that had been minced and salted or not salted when its pH value reached 6.8, 6.6, 6.4, 6.2 and 6.0, then immediately frozen, were determined. The mince samples were used to manufacture a finely comminuted sausage batter. Presalting before frozen storage resulted in higher (p < 0.05) thawed mince pH, and batter cook yield and shear strain, and lower (p < 0.05) mince salt soluble proteins, thaw drip and Hunter L* and b* values and batter shear stress than unsalted controls. The pre-rigor pH at time of salting/mincing affected (p < 0.05) thaw drip (unsalted mince only), Hunter L* and b* values and shear stress. Shear stress tended to increase (p < 0.01) and Hunter L* (p < 0.05) and b* (p < 0.01) values tended to decrease with fall in pre-rigor salting pH. No interaction (p > 0.05) between salting and pre-rigor pH at time of salting was observed. 相似文献