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11.
Nguyen-Dung Tien Sono Sasaki Hiroyasu Masunaga Nobutaka Shimizu Noriyuki Igarashi Shinichi Sakurai 《Polymer》2014
Direct determination of the discrete distribution for crystalline lamellar thickness has been performed for poly(d,l-lactic acid)/poly(oxyethylene) (PDLLA/PEG) blends by conducting small-angle X-ray scattering (SAXS) measurements using synchrotron radiation. The PDLLA used was an random (racemic) copolymer of bio-based poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) with the lactide monomer ratio of l:d = 50:50. It is known that PLA is miscible with PEG in the amorphous state. In the current paper, we report comprehensive results on structural analyses of PDLLA/PEG blends in the course of heating and cooling process using SAXS to elucidate the change in the thickness distribution of the lamellae. As a consequence, it was found that the distribution of the lamellar thickness moves toward the larger value (in other words, lamellar thickening) as temperature approaches the melting point. Typically, the thickness distribution was dispersed in the range of 10–20 nm at room temperature and it changed toward 40 nm in the vicinity of the melting temperature. To the best of our knowledge, this is the first report of direct determination of the discrete distribution for the crystalline lamellar thickness and their in-situ changes in the course of the lamellar thickening process. As a result, the lamellar thickening was found to occur at much lower temperature for the blend samples with 10% and 20% of PDLLA contents as compared to the PEG 100% sample. This phenomenon can be ascribed to the melting point depression owing to the miscibility between PEG and PDLLA. Thereby, thinner lamellae were melted and thicker ones appeared at much lower temperature for the blends than for the PEG 100% sample. As for the average repeating distance (long period) of the lamellar stacks, an abrupt increase similar to the critical divergence was observed (from 25 nm to 50 nm) in the heating process. Not only for the melting behavior but also in the course of recrystallization, change in the lamellar-thickness distribution was uncovered, which shows strong hysteresis depending on what temperature the sample was cooled down from. 相似文献
12.
13.
Hiroyasu Kido Sridhar Komarneni Rustum Roy 《Journal of the American Ceramic Society》1991,74(2):422-424
The La2 Zr2 O7 phase was prepared from metal acetylacetonates by a sol—gel route without any intermediate phase formation. X-ray peaks appeared at a temperature as low as 500°C at the positions expected for La2 Zr2 O7 , although they were broad. The crystal structure of La2 Zr2 O7 was found to be of the fluorite type below 900°C and of thepyrochlore type above 1000°C. The substitution of a small amount of Eu for La was carried out to investigate the crystal structure from the viewpoint of fluorescence, and these results confirmed the formation of fluorite type La2 Zr2 O7 below 900°C. 相似文献
14.
21世纪柴油机降低油耗和排放的关键技术 总被引:7,自引:0,他引:7
本文论述了下世纪柴油机降低油耗和排放所需关键技术的现状。这些技术可分为三门:燃油、燃油系统和后处理。它们所体现的新发展在于采用共轨式电控燃油喷射装置、中置式喷油器和四气门气缸盖。要使柴油机能在很长一段时期内保持其竞争力,需要合理地综合应用这些技术。 相似文献
15.
Yusaku Takita Jun-ichi Moriyama Hiroyasu Nishiguchi Tatsumi Ishihara Fusakazu Hayano Tetsuo Nakajo 《Catalysis Today》2004,88(3-4):103-109
Activity for hydrolysis of CCl2F2 (CFC12) on various metal sulfate was investigated. Zr(SO4)2 was found to be the most active while FeSO4, Cr2(SO4)3, Al2(SO4)3, La2(SO4)3 and Ce2(SO4)3 had intermediate activity. MnSO4, CoSO4, and MgSO4 showed low activity and SrSO4, CaSO4, and BaSO4 had even less activity. The major carbon containing product was CO2 and small amount of CClF3 and CO were formed over several sulfates. The crystal structure of the sulfates was stable during decomposition of CCl2F2, and the conversion reached a steady state after initial decrease at 275 °C over Zr(SO4)2 catalyst. The concentration of surface hydroxyl was larger than that over AlPO4-based catalysts and a reaction mechanism similar to that over AlPO4-based catalysts was proposed. 相似文献
16.
Tatsumi Ishihara Kuninobu Shimose Takanari Kudo Hiroyasu Nishiguchi Taner Akbay Yusaku Takita 《Journal of the American Ceramic Society》2000,83(8):1921-1927
A yttria-stabilized zirconia (YSZ) thin film on an La0.8 Sr0.2 MnO3 porous cathode substrate was prepared, using electrophoretic deposition (EPD) to fabricate a solid oxide fuel cell (SOFC). The electrical conductivity of an La0.8 Sr0.2 MnO3 substrate is satisfactorily high at room temperature; therefore, YSZ powder could be deposited electrophoretically onto an La0.8 Sr0.2 MnO3 substrate without any extra surface treatment, such as a metal coating. Successive repetition of EPD and sintering was required to obtain a film without gas leakage, because of the thermal expansion coefficient mismatch between the YSZ and the La0.8 Sr0.2 MnO3 substrate. On the other hand, the electromotive force of the oxygen concentration in the cell that used YSZ film prepared via EPD increased and attained the theoretical value when the number of deposition and calcination cycles was increased. Six or more successive repetitions were required to obtain a YSZ film without gas leakage. A planar-type SOFC was fabricated, using nickel as the anode and YSZ film (∼10 μm thick) that had been deposited onto the La0.8 Sr0.2 MnO3 substrate as the electrolyte and cathode. The cell exhibited an open circuit voltage of 1.0 V and a maximum power density of 1.5 W/cm2 . Thus, the EPD method could be used as a colloidal process to prepare YSZ thin-film electrolytes for SOFCs. 相似文献
17.
Hiroyasu Koizumi 《Journal of Superconductivity and Novel Magnetism》2011,24(6):1997-2011
We present a theory of superconductivity based on the theoretical prediction that a macroscopic persistent current is generated
by spin-vortices. It explains the origin of the phase variable θ that is canonical conjugate to the superfluid density as a Berry phase arising from the spin-vortex formation. This superconductivity
does not require Cooper-pairs as charge carriers, thus, is not directly related to the standard theory based on the BCS one;
however, it exhibits the flux quantization in the unit Φ
0=hc/2|e|, where h is Planck’s constant, c the speed of light, and e the electron charge; and the AC Josephson frequency, f
J=2|e|V/h, where V is the voltage of the battery connected to the superconductor–insulator–superconductor junction. In due course, it is found
that the standard derivation of the AC Josephson frequency misses a term arising from the flow of particles through the leads
connected to the junction. If this contribution is included, the observed f
J indicates that the phase θ is a variable conjugate to the number density of charge e carriers instead of the currently accepted charge 2e carriers. We propose an experiment that discriminates whether it is e or 2e. If the above claim is verified, it means that the BCS theory cannot predict whether a particular compound is a superconductor
or not since it does not explain the origin of θ. A connection between the present mechanism and the BCS mechanism is discussed; the fact that the BCS theory gives an excellent
estimate of T
c is attributed to the fact that it predicts the temperature at which spin-vortices become long-lived due to the energy gap
formation; since the stabilization by the electron-pair formation is compatible with the present mechanism, asymmetries observed
in the even and odd number of electron systems are preserved. The most notable difference is that the persistent current generation
is formulated in a strictly particle-number-conserving manner. Thus, it does not violate the superselection rule for the total
charge. 相似文献
18.
In this study, bacteriophages were isolated from activated sludge and their host range was studied. Bacterial isolates were obtained from an activated sludge process treating urban sewage, and bacteriophages were obtained by plaque assay using the bacterial isolates obtained in this study as the host. Out of 15 bacteria isolated, 9 supported plaque formation. The host range test was conducted with a combination of 8 bacteriophage isolates and 9 bacterial isolates. All of the 8 bacteriophages tested were found to form plaques on more than 1 host, and 4 of them formed plaques on both gram-positive and gram-negative bacterial isolates. Three of the 8 bacteriophages failed to form plaques on their original bacterial host. The experimental result indicates that bacteriophages are an active part of the activated sludge microbial ecosystem, having a very close ecological relationship with their host bacteria. 相似文献
19.
Hiroyasu Hotokezaka Noboru Aoyagi Yasuhiro Kawahara Noriko U. Yamaguchi Shinya Nagasaki Ken Sasaki Satoru Tanaka 《Microsystem Technologies》2005,11(8-10):974-979
Laser-induced breakdown spectroscopy (LIBS) has been applied for quantitative analysis of Al2O3, CaCO3 and MgO particles suspended in water. In the single elemental system, the plasma emission intensities of Al, Ca and Mg were linearly increased with concentration of elements in the range of 1.0×10?5–1.0×10?3 M, 1.0×10?4–2.0×10?3 M and 8.0×10?5 –4.0×10?3 M, respectively. We also investigated the concentration dependence of breakdown spectra for suspended mixtures of Al2O3, CaCO3 and MgO particles. The emission lines, such as Al I, Ca I, Ca II and Mg I, were appeared in the LIBS spectrum simultaneously, and each emission peak could be deconvoluted. The plasma emission intensities of Al, Ca and Mg in the multielemental system were also linearly increased with their concentrations in the range of 1.0×10?5–1.0×10?3 M, 1.0×10?4–2.0×10?3 M and 4.0×10?4–2.0×10?3 M, respectively. LIBS was found to be available for quantitative and qualitative measurement of the concentrations of Al2O3, CaCO3 and MgO particles suspended in water. The present results suggest that LIBS is a potentially useful tool for in-situ analysis on particles composition and concentrations for environmental monitoring by the wearable information equipments. 相似文献
20.
Hiroyasu Fujiwara Eiji Ichise Masahiro Kitou Takayuki Matsui 《Metallurgical and Materials Transactions B》1999,30(3):419-427
In order to determine the ferrous and ferric ion capacities: 3
for an MgO-saturated MgO + CaO + Al2O3 slag, two experiments were carried out at 1873 K: (1) the distribution of iron between Fe
x
O dilute slags of the system and Pt + Fe alloys under controlled atmosphere, and (2) the equilibrium among molten iron or
iron alloys, magnesiowustite, and molten slags. Although the activity of iron and the partial pressure of oxygen in each experiment
are remarkably different, the values of the ferrous and ferric ion capacities agree well with each other. The influence of
the MgO:CaO:Al2O3 ratio on the values of
and
was found to be limited within the experimental composition range. Using
and
, the relationship between total iron content, (pct Fe
T
), and partial pressure of oxygen,
, under iron saturation was calculated. The change in log
with respect to the bulk slag composition is less than 0.2 within the range of (pct Fe
T
) < 5. 相似文献