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71.
Takatoshi Asada Yosuke Hirata Rie Aizawa Yasushi Fujishima Tetsu Suzuki Eiji Hoashi 《Journal of Nuclear Science and Technology》2013,50(5):633-640
Annular linear induction pumps (ALIPs) are one of the electromagnetic (EM) pumps, which drive liquid metal using EM force, for fast reactors and have been developed in many countries. An ALIP mainly consists of multiple coils, iron cores and an annular flow channel. We have calculated the developed pressure of ALIPs using a two-dimensional magnetohydrodynamics (MHD) code. There are some reports in which pressure drop and fluctuation were observed in EM pump operations near the top of the pressure and flow rate relation (P–Q) curve. For fear of this phenomenon, the EM pump design is sometimes too conservative. To simulate the pressure drop and fluctuation occurrence conditions, we have developed a new three-dimensional (3D) MHD code. Clarification of this condition and its phenomena in the sodium flow will enable design of a new structure or determination of operation conditions that preclude this pressure drop and fluctuation and, thereby, achieve high efficiency. In this paper, the model of our new 3D MHD code, the accuracy of the code, simulation results focusing on pressure drop and fluctuation by radial and circumferential vortices are reported. 相似文献
72.
Formation of intermolecular excimers in polyethersulfone (PES) dichloromethane solutions were observed at a PES concentration about 2.7 × 10?2 mol/l by the fluorescence analysis. External light energy irradiation enabled the formation of intramolecular excimers in the PES dichloromethane solution. These chains can gain an access to each other in parallel though the molecular chains are considerably rigid. The electron micrograph of the PES film, heat treated at 200°C for 72 hours, presented a diffraction micrograph, which suggests that the PES molecular aggregation is changed from a randomly coiled amorphous phase to an ordered one. 相似文献
73.
74.
BaZrSi3O9:Eu2+, Sm3+ (Em:525 nm) is prepared. The role played by the trivalent co-doping ion Sm3+ in the afterglow and the type of trap are clarified. BaZrSi3O9:Eu2+, Sm3+ is found to produce Sm2+ during the excitation by X-ray absorption near-edge structure (XANES), etc., and it is thus proved that Sm3+ exists as an electron trap in the afterglow process. In the field of persistent phosphors activated by Eu2+ and Re3+ such as Sm3+ or Dy3+ having been widely utilized as emergency guide lights, clock faces, etc. for > 25 years, for the first time it is successfully observed that after excitation Re2+ is formed, transferring its electron to 5d band of Eu2+, returning to Re3+ by itself, where the decrease in Sm2+ coincides with the increase in Sm3+, and the two decay time τ1 and τ2 of PL (5D0→7F0) of Sm2+ coincides with the two evolution time of PL (5d→4f) of Eu2+. The behavior of electron transfer from Sm2+ to Eu2+ as a key of afterglow is detected. The detailed afterglow mechanism is proposed by analysis of thermoluminescence and defect reaction, which is very important for the in-depth investigation of the long afterglow material and the further improvement of the mechanism. 相似文献
75.
Summary Reaction of silanol groups on the surface of glass fiber with diisocyanates were investigated. It was found that the effect of organometallic catalysts upon the reaction varied with their metal ions or their ester substituents. Then the addition reaction of isocyanate group on glass fiber surface, with amino acid was carried out successfully to prepare a glass fiber-amino acid adduct. 相似文献
76.
Ohkuri Takatoshi; Yamagishi Akihiko 《Protein engineering, design & selection : PEDS》2003,16(8):615-621
We have investigated factors affecting stability at the subunitsubunitinterface of the dimeric enzyme 3-isopropylmalate dehydrogenase(IPMDH) from Bacillus subtilis. Site-directed mutagenesis wasused to replace methionine 256, a key residue in the subunitinteraction, with other amino acids. Thermal stability againstirreversible inactivation of the mutated enzymes was examinedby analyzing the residual activity after heat treatment. Themutations M256V and M256A increased thermostability by 2.0 and6.0°C, respectively, whereas the mutations M256L and M256Ihad no effect. Thermostability of the M256F mutated enzyme was4.0°C lower than that of the wild-type enzyme. To our surprise,increasing the hydrophobicity of residue 256 within the hydrophobiccore of the enzyme resulted in a lower thermal stability. Themutated enzymes showed an inverse correlation between thermostabilityand the volume of the side chain at position 256. Based on theX-ray crystallographic structure of Escherichia coli IPMDH,the environment around M256 in the B.subtilis homolog is predictedto be sterically crowded. These results suggest that Met256prevents favorable packing. Introduction of a smaller aminoacid at position 256 improves the packing and stabilizes thedimeric structure of IPMDH. The van der Waals volume of theamino acid residue at the hydrophobic subunit interface is animportant factor for maintaining the stability of the subunitsubunitinterface and is not always optimized in the mesophilic IPMDHenzyme. Received September 3, 2002; revised June 13, 2003; accepted June 20, 2003. 相似文献
77.
Novel Synthesis of Silica-Coated Ferrite Nanoparticles Prepared Using Water-in-Oil Microemulsion 总被引:2,自引:0,他引:2
Teruoki Tago Takatoshi Hatsuta Kanta Miyajima Masahiro Kishida Shizuka Tashiro Katsuhiko Wakabayashi 《Journal of the American Ceramic Society》2002,85(9):2188-2194
Ferrite nanoparticles (magnetite (Fe3 O4 ) and cobalt-ferrite (Co x Fe3− x O4 )) coated with silica (SiO2 ) were prepared using water-in-oil microemulsion of a polyoxyethylen(15)cetylether/cyclohexene system. Observation via transmission electron microscopy revealed that the ferrite nanoparticles were located nearly at the center of spherical SiO2 particles. The sizes of Fe3 O4 and Co x Fe3− x O4 nanoparticles were in the range of 8–12 nm and 10–14 nm, respectively, and the thickness of the SiO2 layer was ∼14.0 nm. The solid solution of cobalt ions into Fe3 O4 to form Co x Fe3− x O4 nanoparticles led to an increase in the coercivity of the SiO2 -coated ferrite nanoparticles. The coercivity increased with increasing amounts of added cobalt, obtaining a maximum value of 780 Oe around a Co/Fe ratio of 0.3–0.4. 相似文献
78.
Magnetic properties of metal layer deposited by reduction of polymer containing metal ions were investigated. Varying the ratio of the cobalt ion to the nickel ion in the polymer, the coercivity, the maximum flux density and the remanent flux density of the deposited metal layer were changed from 100 to 600 Oe, from 1 000 to 12 600 G and from 500 to 7 600 G, respectively. The X-ray diffraction pattern of the metal layer with excellent magnetic properties gives distinct peaks corresponding to the (101) and (100) planes of the crystal of α-Co. This suggests that such a deposited metal layer has the structure of highly crystalline metal layer. 相似文献
79.
Nanako Kato Tomoaki Masuzawa Yuki Kudo Yuka Kuwajima Hisato Yamaguchi Ken Okano Takatoshi Yamada Ichitaro Saito Tim Butler Nalin L. Rupesinghe Gehan A.J. Amaratunga 《Diamond and Related Materials》2008,17(2):95-99
An imaging device that could detect weak light of approximately 0.001 lx with high SN ratio is capable of opening up the possibility of creating artificial visions as a substitute for a human eye. In terms of sensitivity and SN ratio, amorphous selenium (a-Se) is known to be one of the best candidates among other photoconductive target. Combined with a-Se, a diamond cold cathode would be one of the best options in order to steadily emit electrons under low vacuum. The a-Se film is modified with Arsenic (As) and Tellurium (Te) to prevent crystallization and narrow the optical gap for red light detection. An RGB filtered light from a halogen light source was illuminated onto this modified a-Se film and the photo-response was measured for each color. The device could detect extremely weak illumination of under 0.39 lx, which is approximately the darkness under moonlight. Results of the photo-response compared between films with and without Te clarified that Te dopants enhances red light detection significantly. The illuminated light was then pulsed at 10 mHz and the current to time stability was observed. It showed clear correspondence between the intensity of the luminance and current, which the Te modified samples showed good response to other colored light as well. 相似文献
80.
Repassivation behavior of type-312L stainless steel containing 6% of molybdenum was examined in NaCl solution using in situ micro-indentation technique, together with type-304 and 316L stainless steels. High stability of the passive film formed on the type-312L stainless steel was also examined by depth profiling analysis of passive films using glow discharge optical emission spectroscopy (GDOES). In 0.9 mol dm−3 NaCl solution at 296 K the type-304 and 316L stainless steels are passive only up to 0.3 V (SHE), above which pitting corrosion occurs. In contrast, no pitting corrosion occurs on type-312L stainless steel. Despite the significant difference of the pitting corrosion resistance, the repassivation kinetics of the three stainless steels, examined by micro-indentation at 0.3 V (SHE), is similar. The presence of molybdenum in the stainless steel does not influence the repassivation kinetics. The charge required to repassivate the ruptured type-312L stainless steel surface increases approximately linearly with the potential, even though the passivity-maintaining current increased markedly at potentials close to the transpassive region. Repassivation occurs without accompanying significant dissolution of steel, regardless of the stability of passive state. Depth profiling analyses of the passive films on the type-312L stainless steels formed at several potentials revealed that molybdenum species enrich in the outer layer of the passive film, below which chromium-enriched layer is present. The permeation of chloride ions may be impeded by the outer layer containing molybdate, enhancing the resistance against the localized corrosion of the type-312L stainless steel. 相似文献