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PURPOSE OF STUDY: To assess whether selected periapical radiographs, taken according to High Yield Criteria, can reveal as much intra-osseous pathology as universal panoramic screening. POPULATION STUDIED: The records of 1101 RAF recruits enlisted in 1988-89, average age 19 years (range 16-26). METHODS: The clinical records and bitewing radiographs of the recruits were examined and the requirement for periapical radiographs determined according to high yield criteria. A template, cut out to simulate the area covered by a periapical bitewing radiograph, was placed over the suspect region on the panoramic film and any findings found within the template recorded. The entire dental panoramic tomograph was then examined on a masked screen under 2X magnification and any further findings recorded. FINDINGS: There was a considerable number of findings reported, including three large isolated radiolucent areas, 75 periradicular radiolucent areas, four probable cysts and 1187 unerupted mandibular third molars. However, when the clinical significance of these 'lesions' was assessed only those related to dental causes appeared to have significant clinical implications and the results indicated that these could have been detected by selective radiology. CONCLUSION: This study showed that the only pathology which occurs frequently enough to justify radiographic screening of the jaws in young adults is related to teeth. It seems probable that this type of pathology can be at least as well detected by selective periapical screening, using high yield criteria, as is possible by universal panoramic screening.  相似文献   
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In this article, a novel mathematical approach is proposed to determine the minimal proton exchange membrane fuel cell efficiency below which it is not recommended to operate the fuel cell. The objective of this proposal is to minimize the annual fuel cost and the electricity cost of a proton exchange membrane (PEM) fuel cell since both terms are efficiency dependent. A new concept developed in this article might be used as a valuable mathematical tool to determine the minimal efficiency required to operate a fuel cell in a reasonable fashion in order to make the fuel cell system technically and economically feasible. Two dimensionless mathematical criteria J1 and J2 were proposed for the annual fuel cost and electricity cost, respectively. A minimum fuel cell efficiency of was obtained with J1 and J2 values of 2.7 and 0.026, respectively.  相似文献   
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Flexible electronics utilizing single crystalline semiconductors typically require post-growth processes to assemble and incorporate the crystalline materials onto flexible substrates. Here we present a high-precision transfer-printing method for vertical arrays of single crystalline semiconductor materials with widely varying aspect ratios and densities enabling the assembly of arrays on flexible substrates in a vertical fashion. Complementary fabrication processes for integrating transferred arrays into flexible devices are also presented and characterized. Robust contacts to transferred silicon wire arrays are demonstrated and shown to be stable under flexing stress down to bending radii of 20 mm. The fabricated devices exhibit a reversible tactile response enabling silicon based, nonpiezoelectric, and flexible tactile sensors. The presented system leads the way towards high-throughput, manufacturable, and scalable fabrication of flexible devices.  相似文献   
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This work performs dimensionality reduction-based classification on fleece fabric-based images taken by a thermal camera. In order to convert images into the gray level, a principal component analysis-based dimension reduction stage was proposed. In addition, symmetric central local binary patterns were performed with the help of the proposed method by using the images after dimension reduction process. The local binary pattern features preserve local texture features from different kinds of defective image types. The experimental results showed that combined work has a great classification accuracy. The classification accuracy was reported using two different algorithms: Naive Bayes and K-nearest neighbor classifier.  相似文献   
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The objective of the current study was to introduce the coumarin structure into a conventional reactive dye system. A fluorescent reactive dye was synthesised based upon 7‐amino‐4‐methylcoumarin. The dye was obtained by a multi‐step sequence initiated by displacement of a chlorine group from 2,4,6‐trichloro‐1,3,5‐triazine using H‐acid. Diazo coupling of 3‐aminobenzenesulphato‐ethylsulphone to this adduct, followed by a second chlorine displacement using aminomethylcoumarin completed the sequence. The fluorescent dye and the non‐fluorescent precursor were characterised by mass spectrometry, infrared spectroscopy and capillary electrophoresis. The newly synthesised dye was applied to wool fibres using an exhaust dyeing method. The exhaustion, fixation and total efficiency values were calculated by ultraviolet–visible spectrophotometric analysis of the dyebath. The synthesised red dye presented high values for exhaustion, fixation and total efficiency on the wool fibres. The novel dye, after its application to the wool fibres, exhibited fluorescence under an ultraviolet light. This feature confirmed that the novel dye retained the inherent characteristic feature of fluorescence on the wool fibres. The dyed wool fibres exhibited level 4–5 of light fastness when compared with international wool light fastness standards.  相似文献   
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The present work involves the synthesis of polythiophene–potassium octacyanotungstate(IV) dihydrate composite via in-situ oxidative chemical polymerization method using \(\hbox {FeCl}_{3}\) as an oxidant. The resulting composite has been subjected to Fourier transform infrared, X-ray diffraction (XRD) and scanning electron microscopy characterization techniques, which confirm the successful synthesis of the composite. XRD shows that the crystalline structure of \(\hbox {K}_{4}[\hbox {W(CN)}_{8}]\cdot \hbox {2H}_{2}\hbox {O}\) has been retained in the composite. Thermogravimetric analysis data confirm the higher thermal stability of the composite in comparison with pure polythiophene, thus allowing it to be used as a promising material for high-temperature application purposes. Dielectric studies reveal that the dielectric constant and ac-conductivity of the composite increased by several orders of magnitude as compared with pure polythiophene at all frequencies, thus showing that the material can be used for various applications in the fields of charge storage devices and high-frequency device applications, and can also serve as a potential candidate for solar cell applications.  相似文献   
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