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41.
42.
The multidimensional multiple-choice knapsack problem (MMKP) is an extension of the 0–1 knapsack problem. The core concept has been used to design efficient algorithms for the knapsack problem but the core has not been developed for the MMKP so far. In this paper, we develop an approximate core for the MMKP and utilize it to solve the problem exactly. 相似文献
43.
Riad Taha Al-Kasasbeh 《Advances in Engineering Software》2011,42(8):547-554
Methods for the selection of candidates for operators of man-machine systems are analyzed. Vector mean estimates of group intelligence and estimates defining the group’s collective decision-making ability to obtain the unified solution to the selection problem and to retain the correct original solution to the problem, and estimates of solution quality and interoperability in correct decision-making are proposed. The properties of the suggested estimates are studied with a test example of five candidates. Amongst these properties are estimates of the group’s psychological traits, such as average estimates of professional competence, static components of the intelligence vector for tested candidates, components of the trainability vector for tested candidates, average intelligence estimates for tested candidates, average estimates for the basis of groups, average different-mindedness estimates of groups, variations in the trainability of operators, and arithmetic estimates of group intelligence variability such as levels of awareness, knowledge level, mean speed of knowledge variation, comprehension and motivation in operators’ reasoning. 相似文献
44.
Two sensitive, spectrophotometric and atomic absorption spectrometric procedures are developed for the determination of ramipril and perindopril. Both methods are based on the formation of a ternary complex, extractable with chloroform, between copper(II), eosin and the two cited drugs. Spectrophotometrically under the optimum condition, the ternary complexes showed an absorption maximum at 535 nm, with apparent molar absorptivities of 6.55 and 4.00 x 10(3) mol(-1) x cm(-1) and Sandell's sensitivities of 5.80 x 10(-2) and 1.04 x 10(-1) microg x cm(-2) for perindopril and ramipril, respectively. The solution of ternary complex obeyed Beer's law in concentration ranges 10-60 and 20-100 microg x ml(-1) for perindopril and ramipril, respectively. The proposed method was applied to the determination of the two cited drugs in pharmaceutical tablets. The atomic absorption spectrometric method, directly through the quantitative determination of copper content of the organic extract of the complex, was also investigated for the purpose of enhancing the sensitivity of the determination. The spectrophotometric and atomic absorption spectrometric procedures hold their accuracy and precision well when applied to the determination of ramipril and perindopril dosage forms. 相似文献
45.
Riad Taha Al-Kasasbeh 《Advances in Engineering Software》2012,45(1):137-143
A new software technique for determining emotional tension on humans is developed by means of psychological tests connected with the psycho-emotional sphere and on indicators characterizing the state of a subject’s visual attention. Each of these two areas determines several factors for psycho-emotional tension. The level of tension is determined as an aggregate of these two components with the rules of fuzzy logic. The membership functions and solving rules for the psychological tests, and for the state of visual attention, are constructed using fuzzy logic theory. It is shown that the resulting method can be used as an informative feature for prediction of many properties, such as the situational awareness (training and experience) of an operator and the operator’s individual capacity to function (mental-physiological limits). The second group of indicators characterize properties such as switchable attention (the ability to switch attention) (SWA), concentration (ability to concentrate) (CNA), stability of visual attention (STA) and parameters determining the state of memory. One of the most important issues for man-machine systems is to evaluate the performance of operators under abnormal conditions such as stress or tension. 相似文献
46.
M. G. Abd El-Wahed H. El-Didamony A. M. Amin A. S. Taha 《Journal of Materials Science》1989,24(1):276-280
The aim of the present work was to study the effect of quartz on the hydration characteristics of hydrothermally hardened granulated slag-alite pastes. The pastes, of water: solid ratio 0.20, were moulded at a pressure of 50 kg cm–2 and autoclaved at 10 atm for 0.5, 2, 6, 12 and 24 h. Compressive strengths of the hardened product were determined, and the kinetics of reaction were studied by the quantitative determination of free lime and combined water contents. The phases formed after autoclaving were determined using XRD techniques. The reaction mechanism of the system under investigation was discussed and correlated to the strength of the hardened product. It can be concluded that the addition of quartz to slag-alite mixture increases the strength of the final product. The strength obtained for samples with high alite content are higher than that of low-alite content. Finally, the addition of quartz assists the formation of tobermorite in the hardened specimens. 相似文献
47.
Ziad Mansour Mohd Raihan Taha Zamri Chik 《Bulletin of Engineering Geology and the Environment》2009,68(1):97-106
Problems have occurred with dykes constructed on the Lisan Marl to retain brine pumped from the Dead Sea, which is chemically
processed to produce potash. In this study the engineering behavior, collapse potential and compressibility of the Lisan Marl
were assessed by undertaking laboratory tests with both natural, distilled water and brine as the media. The results showed
that the liquid limit and fine particles increased when the soil was mixed with fresh/distilled water compared with brine
water. The soil can be classified as highly compressible with a low undrained shear strength. In terms of collapsibility,
the soil could be classified as slightly collapsible upon inundation with distilled water and moderately collapsible when
soaked in Dead Sea brine. The results are important when determining the height and nature of the dykes.
相似文献
48.
A novel methodology for the solvent free auto-oxidation of methylbenzenes under mild conditions is disclosed. The new scheme is based on a combination of metallic salt (cobalt chloride) and a quaternary ammonium phase transfer catalyst (didecyldimethylammonium bromide) which together form a complex soluble catalyst in the organic phase. Major reaction parameters are studied and optimized and the procedure is applied for the conversion of several substituted toluenes to the corresponding benzoic acids in excellent isolated yields. 相似文献
49.
Microalloyed steels are characterised by their mechanical properties. Nowadays, they are used in a wide range of applications. The convenience and simplicity of hardness tests permit to obtain economically and rapidly information on the structure of steels and control their treatments. This study has been carried out to derive equations for prediction of the mechanical properties of microalloyed steels by hardness measurement. With this objective, V‐ and Ti‐microalloyed plain carbon steel bars were melted, hot rolled, heat treated and machined for the measurement of their mechanical properties and to reach a correlation between both ultimate tensile strength, yield strength and uniform elongation and Vickers hardness. The obtained data were treated using different mathematical fittings. They are mathematically treated as groups according to the heat treatment processes and as one group. The derived equations show good agreement with each other and with most of the little relations found in the literature. General equations for deducing mechanical properties values from the easily measured Vickers hardness values were derived. The equations derived from one group without regarding the treatment processes are more reliable. 相似文献
50.
Mohamed A. Taha Nahed A. El-Mahallawy Rawia M. Hammouda Sherif I. Nassef 《Journal of Coatings Technology and Research》2010,7(6):793-800
Although magnesium alloys have the advantage of high specific strength, they have poor atmospheric corrosion resistance. An
important method of improving the corrosion resistance is by applying a coating layer. In this work, the physical vapor deposition
(PVD) technique is used for coating a magnesium (Mg) AZ31 sheet substrate with a thin layer of high purity aluminum (Al) and
Al–12.6% Si. Aluminum is expected to be suitable as a coating layer on Mg sheets, due to its corrosion resistance and its
formability. Before coating, the substrate was subjected to several consecutive surface preparations, including sand-blasting,
mechanical grinding, mirror-like polishing, ultrasonic etching, and finally ion etching by magnetron sputtering (MS). PVD
coating was conducted using a PVD machine with max electron beam power and voltage of 100 kW and 40 kV, respectively. This
was either with or without plasma activation, and with variable substrate speeds ranging between 10 and 70 mm/s. During MS
ion etching and coating, the substrate temperature increased. The substrate temperature increased with the application of
plasma activation and with lower substrate speeds. The coating-layer thickness varied inversely with substrate speed. A thinner
coat with finer morphology was obtained in the case of plasma activation. Other results included coating layer characteristics,
diffusion between the AZ 31 substrate and the Al coating layer, adhesion of the coating layer to the substrate, and corrosion
resistance by a humidity test. 相似文献