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1.
2.
Micro-coiled fibres of SiC and TiC were prepared by the vapour phase metallizing of micro-coiled carbon fibres with full preservation of the coiling morphology of the source coiled carbon fibres, and their preparation conditions and bulk electrical resistivity were examined. The SiC1,0 coils were obtained at 1400 °C for 2 h, and TiC1.0 coils were obtained at 1100–1200 °C for 1.5 h. The bulk resistivity of the coiled TiC fibres sharply decreased with the bulk density and was 10–2 S–1 cm at 1.4 g cm–3. 相似文献
3.
Seiji Motojima Chiharu Uchida Noriyuki Iwamori Tatsuhiko Hattori 《Journal of Materials Science》1987,22(3):877-881
Molybdenum plate was siliconized using Si2Cl6 as a silicon source, and the siliconizing conditions and some of its properties were examined. The siliconizing of the molybdenum plate began by the deposition here and there of island-like MoSi2 deposits 4 to 6m thick in the initial stage (after 10 min induction time), and then coalescence of the deposits proceeded to form a uniform MoSi2 layer all over the molybdenum plate after 30 min siliconizing time. The weight decrease of the siliconized plate by anodic dissolution in 0.2 M sulphuric acid reduced exponentially with increasing thickness of the MOSi2 layer, and no weight decrease was observed at all above 16m thickness. The sea water corrosion and sea sand abrasion resistivities of the siliconized molybdenum plate increased with increasing siliconizing temperature and Si2Cl6 flow rate. 相似文献
4.
Mishra JS Sakamoto R Motojima G Matsuyama A Yamada H 《The Review of scientific instruments》2011,82(2):023505
A low speed single barrel pellet injector, using a mechanical punch device has been developed for alternative injection in the large helical device. A pellet is injected by the combined operation of a mechanical punch and a pneumatic propellant system. The pellet shape is cylindrical, 3 mm in diameter and 3 mm in length. Using this technique the speed of the pellet can be controlled flexibly in the range of 100-450 m/s, and a higher speed can be feasible for a higher gas pressure. The injector is equipped with a guide tube selector to direct the pellet to different injection locations. Pellets are exposed to several curved parts with the curvature radii R(c) = 0.8 and 0.3 m when they are transferred in guided tubes to the respective injection locations. Pellet speed variation with pressure at different pellet formation temperatures has been observed. Pellet intactness tests through these guide tubes show a variation in the intact speed limit over a range of pellet formation temperatures from 6.5 to 9.8 K. Pellet speed reduction of less than 6% has been observed after the pellet moves through the curved guide tubes. 相似文献
5.
Yasutaka Takahashi Kenji Mutoh Seiji Motojima Kohzo Sugiyama 《Journal of Materials Science》1981,16(5):1217-1222
Both dimethylamino- (I) and diethylamino-alane dimers (II), [(R2N)2AlH]2 (I, R=Me; II, R=Et) decompose above 800° C under a few hundred Pa of hydrogen to dark greyish, hard (Vickers hardness larger than 2000), oxidation-resistive and oxidation-protective deposits which are tentatively identified as Al5C3N. The deposits are stable to moisture and diluted hydrochloric acid in contrast to those obtained below 800° C, but they easily dissolve in sodium hydroxide solution at room temperature evolving a gas. The deposits on a stainless steel substrate adhere strongly to the substrate and remain so on rapid heating and cooling. The electrical resistivity of the deposits is in the range 102 to 104 cm. 相似文献
6.
Transparent hexagonal BN films were deposited onto copper substrates from the reactant gas BCl3-NH3-H2 at temperatures in the range 250–700°C. The lowest deposition temperature of the films was about 250°C. The films deposited at temperatures below 450°C were unstable in moist atmosphere and devitrified; a 20%–30% decrease in weight was observed when these films were heated above 600°C in an argon atmosphere. In contrast, the films deposited at temperatures above 600°C were very stable, decreased in weight by 1%–2% on heating and were stable in air at temperatures below 750°C. 相似文献
7.
Two fusion reactor problems, removal of helium ash and fuel (tritium) injection, can be solved using the concept of “drift
island motion.” The motion of a drift island is an indicator of the broadening of the resonant trajectory of a charged particle
guiding center. This trajectory broadening occurs if two conditions are satisfied. First, the drift pitch angle of the particle
is equal to the resonance values i*=n/m, where n and m are the “wave numbers” of the perturbing magnetic field. Second, the drift pitch angle i*=n/m “moves” over the plasma cross section as the particle moves. This displacement is caused by a slow change in the helical
magnetic field with time as the particle moves. It is shown that this effect may occur in a fusion reactor with an l=3 helical winding and may be used for tritium ion injection.
Pis’ma Zh. Tekh. Fiz. 25, 5–13 (January 26, 1999) 相似文献
8.
Seiji Motojima Noriyuki Iwamori Tatsuhiko Hattori 《Journal of Materials Science》1986,21(11):3836-3842
Si3N4 layers were obtained on a quartz substrate from a gas mixture of Si2Cl6, NH3 and H2 under a reduced pressure in a temperature range of 800 to 1300‡ C. Amorphous Si3N4 layers that were dense and adherent to the substrate were obtained in a temperature range of 800 to 1100‡ C. On the other
hand,α-Si3N4 layers were obtained at 1200‡ C and a source-gas ratio (N/Si) of 1.33 to 1.77. The lowest deposition temperature of amorphous
Si3N4 was considered to be about 700‡ C. The microhardness of amorphous Si3N4 obtained in a temperature range of 800 to 1100‡ C was 2400 to 2600 kg mm−2 (load: 50 g), and that ofα-Si3N4 obtained at 1200‡ C was 3400 kg mm−2. Chlorine contents in the Si3N4 layer decreased with increasing deposition temperature and source-gas ratio (N/Si), and with decreasing total pressure. 相似文献
9.
Takeyuki Suzuki Tsutomu Yamazaki Hiroshi Yoshioka Kuniyuki Hikichi 《Journal of Materials Science》1988,23(1):145-149
Amorphous SnOx films were deposited by ion-beam sputtering on sintered alumina substrates. Amorphous film sensors were prepared by annealing the films at 300° C for 2 h in air. The thickness dependence of resistivity and hydrogen gas sensitivity were measured at 150° C over the thickness range 1 to 700 nm. A resistivity maximum was observed in ultrathin films. Resistivity increased by three orders of magnitude with increasing film thickness from 0.9 to 7.4 nm and then decreased by five orders of magnitude from 7.4 to 35 nm. Ultrathin film sensors showed sensitivity maxima around a thickness of 10 nm. Sensitivity and resistivity of ultrathin films were significantly influenced by the thermal expansion coefficient and the surface state of the substrate. 相似文献
10.
The carbon micro-coils were obtained by the Ni-catalyzed pyrolysis of acetylene. The carbon micro-coils with various coiling morphology: regular double coils, coils built up by circular or flat fibers, super helix coils, single coils, etc. can be observed. The carbon coils with various coil diameters and coil pitches were obtained by controlling reaction conditions, such as reaction temperature, source gas flow rate of sulfur-impurity, acetylene or hydrogen. 相似文献