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1.
In this present study, we have reported the preparation of yttrium doped polycrystalline Ca2−xYxCo2O5 (x=0.0–1.0) material by a molten flux method and its various properties like electrical, optical, dielectric and magnetic behaviors. Characterization techniques have been adopted to confirm its physical nature and properties. X-ray diffraction results confirmed the crystal structure of prepared Ca2−xYxCo2O5 as orthorhombic and the scanning electron microscope pictured the presence of platelet-shaped particles with the dimensions of 150–300 nm. It also reveals the state of higher concentration of yttrium (Y3+) controls the grain size of Ca2−xYxCo2O5 ceramics. Further, we find out that the higher concentration of yttrium (Y3+) increases the optical band gap due to the occurrence of metal–insulator transition and also the same in electrical resistivity from 0.2  cm to 0.5  cm, which is due to the replacement of holes by Y3+ ions. The result of dielectric studies proves that the conduction mechanism of yttrium doped calcium cobalt oxide is due to space charge polarization. The magnetic saturation behavior shows the decreasing area in the hysteresis curve while the Y3+ concentration is increased, which is due to the phase transition of ferromagnetic to paramagnetic.  相似文献   
2.
Thin film transistors (TFT) with an indium based mixed oxide semiconductor are investigated for titanium–gold top-contacts. It is noticed that upon post annealing, in order to remove chemical residuals from top-contact lift-off steps, oxidation of titanium occurs depending on the annealing conditions. Mobility of the TFT is strongly affected by contact oxidation arising from this post lift-off annealing process. Oxidation of the top-contact is facilitated by adsorbed surface oxygen or out-diffusing oxygen from the semiconductor depending on the post lift-off annealing conditions. A passivation layer that binds effectively to surface vacancies and removes adsorbed oxygen species from the semiconductor surface is demonstrated. The combinations of this passivation layer with relatively low temperature and short post lift-off annealing in an oxygen deficient environment result in significantly reduced contact oxidation and subsequently better transistor performance. Contact resistance as low as 90 Ω cm and mobility as high as 5.3 cm2/V s are obtained for solution processed mixed metal oxide semiconductor in top-contact geometry.  相似文献   
3.
铜渣是极有价值的冶金二次资源,铜渣的主要矿物成分是铁橄榄石、磁铁矿、铜锍及一些脉石组成的无定形玻璃体.本实验基于热力学分析,用CO2和CO混合气体来控制体系内的氧势来焙烧铜渣样品.在600℃~9000℃时,焙烧产物为单质铁,此时是混合气体起还原作用.在1000℃,焙烧渣中重新出现了FeO,说明CO2-CO混合气体体系中产生的氧起了作用.在1100℃时,焙烧4h,焙烧渣中产生了Fe3O4,此时焙烧铜渣磁选后全铁含量94.35%,铁的回收率达到了90.8%.在600℃~1100℃,适当条件下焙烧时,铁橄榄石的物相变化为:2FeO·SiO2→FeO+SiO2→Fe→FeO→Fe3O4, 铁的回收率是随着温度的升高而升高的.在适当范围内, 延长焙烧时间、增大分压比都有利于Fe3O4的生成.   相似文献   
4.
This investigation discusses a structural phase transition of organic crystalline phenanthrene and the resulting changes of its electronic and optical properties investigated by ab initio calculations based on density functional theory (DFT). The structure of phase I has been optimized then its electronic and optical properties have been calculated. Our computational results on phase I (at ambient pressure) get along well with the available experimental data.Calculating the electronic and optical properties of phase II are proceeded in the same way and the results, particulary Raman spectra, reveal a crystallographic phase transition indicated by abrupt changes in lattice constants which are accompanied by rearrangement of the molecules. This results in modifications of the electronic structure and optical response. For both phases the band dispersion of the valence and conduction bands are anisotropic, whereas the band splitting is strongly noticeable in phase II. By calculating the imaginary part of the dielectric function of phase II, we have found the appearance of new peaks at the lowest z-polarized absorption and about 30 eV in all absorption components. Excitonic effects in the optical properties of phases I and II have been investigated by solving the Bethe–Salpeter equation (BSE) on the basis of the FPLAPW method. Phase II shows four main excitonic structures in the energy range below band gap, whereas phase I shows two. The excitonic structures in the optical spectra of phase II show a red shift in comparison to phase I. The calculated binding energies of spin-singlet excitons in phase II are larger than the ones in phase I.  相似文献   
5.
李立清  李敏  杨丽钦 《广州化工》2012,40(9):237-238
世界金融危机爆发后,将高校大学生就业难的问题大大显示出来。大学生就业困难固然有经济危机的影响,但最根本的还是要从培养大学生的教育方式中寻找答案。本论文以就业率为导向,探索高校化工类人才的培养模式,提出了"加强应用创新型人才培养"的基本内容及高校需要解决的主要问题,为21世纪高校人才的培养提供了较好的方案。  相似文献   
6.
Experimental analysis concerning supercritical flow over a dentated sill in nonsubmerged conditions and the local scour downstream of this sill is presented. In this case, the energy dissipation is incomplete so that a scour control downstream of the hydraulic structure could be required. The use of this type of dissipation device could be needed in cases where the maximum flow depth upstream of the sill must be limited to satisfy physical or structural conditions. This could happen, for instance, in the restoration of stilling basin in gravity dams and at the outlet of diversion systems. Experimental and theoretical results, useful in the design of this type of stilling basin and scour control, are presented in the paper, with an application to the case of the Molato Dam in Italy.  相似文献   
7.
染料敏化TiO2纳米薄膜太阳能电池是一种新型太阳能电池,其结合了有机染料光敏剂和无机半导体的优势,具有较宽的光谱响应范围,制造工艺简单,成本较低,绿色环保,是国内外研究的热点。本文介绍了染料敏化纳米薄膜太阳能电池的结构和工作原理,并对其组成要素如染料敏化、TiO2纳米膜、电解质等最新研究进展进行了简述。  相似文献   
8.
This paper characterizes the temporal behavior of uplift force generated by turbulent pressure fluctuations in spillway stilling basins. Theoretical and experimental analyses are presented that define the magnitude and temporal evolution of the maximum uplift acting on the lining of such basins. Analyses for the dynamic behavior of anchored floor slabs are also investigated. It is concluded that the applicability of the equivalent thickness criterion based on the balance of the forces acting on the slabs in static condition is unsafe for anchored slabs, because this criterion yields an inadequate area for the anchor steel. The results lead to a recommendation to double the area of anchor steel as computed by the equivalent thickness criterion for the design of slabs in stilling basins.  相似文献   
9.
A theory is developed, based on theoretical-group analysis, to describe the linear, reversible, time-dependent response of an icosahedral quasicrystal, containing point defects, to a stress field and known as anelastic relaxation. We obtain also anelastic relaxation relationships for the practical Young’s, shear and Poisson’s moduli.  相似文献   
10.
Summary Principal component analysis has been applied to analyze the correlation matrix obtained from a 8 × 43 data matrix. The 8 trace metals are Mn, Co, Ni, Cu, Zn, Cd, Hg, Ph, which are contained in the soft part of mussels (Mytilus galloprovincialis Lamarck). Mussels were sampled from two sites in the Gulf of Trieste. In both samples, 76–78% of the total variance is explained by the four principal components. The orthogonally rotated factor matrix indicates that Co and Ni are bonded to the first principal component and Cd and Pb to the first (site 2) or second principal component (site 1). The origin of trace metals in the soft part of mussels from the Gulf of Trieste is discussed.
Analyse der Hauptkomponenten zur Identifizierung der Verunreinigungsursachen von Muscheln über die Spurenmetalle
Zusammenfassung Die Analyse der Hauptkomponenten wurde auf die Korrelationsmatrix, die aus der 8 × 43-Datenmatrix hervorgeht, angewandt. Diese 8 Spurenmetalle sind Mn, Co, Ni, Cu, Zn, Cd, Hg, Pb, die im Fleisch der Miesmuscheln (Mytilus galloprovincialis Lamarck) gefunden worden sind. Die Miesmuscheln stammen aus zwei Gegenden des Golfes von Triest. Vier Hauptkomponenten erklären 76–78 % der totalen Varianz der beiden Stichproben. Die orthogonale-rotierte Faktorenmatrix zeigt, daß Co und Ni an die erste Hauptkomponente und Cd und Pb an die erste (Lage 2) oder an die zweite Hauptkomponente (Lage 1) gebunden sind. Die Herkunft der Spurenmetalle im Muschelfleisch aus dem Golf von Triest wird diskutiert.


L. Felician is the author of the statistical analysis for site 1 as a part of his thesis in Commodity Science, Faculty of Economics, University of Trieste- L. Gabrielli Favretto is the author of the statistical analysis of the data for site 2. All authors contributed to the rest of the paper  相似文献   
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