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991.
992.
Jujjavarapu Ashok Marek Kostrzewa Maddireddy Srinivasa Reddy Vandana Ravi Kumar Nutalapati Venkatramiah Michal Piasecki Nalluri Veeraiah 《Journal of the American Ceramic Society》2019,102(4):1628-1641
Na2O-Sb2O3 glasses doped with different concentrations of Au2O3 were prepared by melt quenching technique and later were heat treated at 800°C for 6 hours. Structural analysis by XRD, XPS, SEM, EDS, and DSC techniques indicated that the samples are embedded with multiple crystallites composed of Sb3+, Sb5+, Au3+ ions, and Au0 metallic particles. These studies have further demonstrated a gradual increasing fraction of Au0 metallic particles with increasing Au2O3 concentration. IR spectral studies suggested increasing the degree of polymerization of the glass network (due to increasing concentration of Sb5+ ions that participate in the glass network with SbVO4 structural units) with rise in the concentration of Au2O3. Optical absorption spectra of the titled samples have exhibited a broad absorption band at about 530 nm predicted due to the surface plasmon resonance (SPR) and exhibited a spectral red shift with increasing intensity with increase in Au2O3 content. Photoluminescence (PL) spectra of the samples recorded (at λexc = corresponding SPR band position) exhibited an emission peak at about 580 nm (identified as being due to interband transition between sp and d bands of gold particles). Overall, the analysis of these results has confirmed increasing concentration of Au metallic particles with increase in Au2O3 content in the titled material. Finally, it is predicted that the presence of higher concentration of gold particles in the polymerized antimonate glass network makes the materials useful for designing different nano dimensional optoelectronic devices. 相似文献
993.
Friction welding of dissimilar metal combination of aluminum alloy and austenitic stainless steel was examined to investigate
the effect of welding conditions on mechanical properties of the dissimilar metal combination. The welded joints were produced
by varying forge pressure (F
g), friction pressure (F
r), and burn-off length (B). The joints were subjected to mechanical testing methods such as the tension, notch Charpy impact tests. The tensile strength
and toughness decrease with an increase in friction pressure. The tensile strength decreases with an increase in burn-off
length at a low forge pressure while tensile strength increases with an increase in burn-off length at a high forge pressure.
The tensile failure of the welded joint occurred in aluminum alloy just away from interface in the thermo-mechanically affected
zone indicates good joint strength at the condition of low friction pressure, high forge pressure, and high burn-off length.
The maximum tensile strength was observed with low friction pressure and high forge pressure. The tensile strength of dissimilar
joint is approximately equal to tensile strength of 6063 aluminum alloys at the condition of low friction pressure, high forge
pressure, and high burn-off length. The tensile and impact failure of joints was examined under scanning electron microscope
and failure modes were discussed. 相似文献
994.
Ring opened structures of C60 and C70 are shown to be stabilized by complexation with transition metal fragments of the form CnHnM, where n = 3 to 6 and M = Cr, Mn, Fe, Co, and Rh. The ring opening of C60 and C70 is compared with the reverse process of the well-known catalytic conversion of acetylene into benzene. Calculations at the semi-empirical PM3(tm) level show that the 6-membered ring in C60 and C70 can be opened up in different ways through complexation with transition metal fragment. The mode of ring opening depends on the number of external 5- and 6-membered rings around the 6-membered ring being cleaved. The structures and energetics of the various ring-opened structures are discussed. 相似文献
995.
996.
Identification of the Sex Pheromone of Holotrichia reynaudi 总被引:1,自引:0,他引:1
The male attractant pheromone of the scarab beetle Holotrichia reynaudi, an agricultural pest native to southern India, was extracted from abdominal glands of females with hexane and analyzed by gas chromatography–mass spectrometry. Field testing of the candidate chemicals, indole, phenol, and anisole, both alone and as binary mixtures, led us to conclude that anisole was the major component of the sex pheromone. Neither male nor female beetles were attracted to indole or phenol on their own. Similarly, when indole and anisole were combined, the attractiveness of the solution did not increase over that obtained with anisole alone. However, combination of phenol and anisole did alter the attractiveness of anisole, with fewer male beetles attracted to the binary mixture than to anisole on its own. The behavior of female beetles was not altered by any of the chemicals tested. Anisole is also the sex pheromone of H. consanguinea, making this the first known example of two melolonthine scarabs sharing the same pheromone. 相似文献
997.
《Materials Chemistry and Physics》2005,89(2-3):260-267
Corrosion inhibition of aluminum in hydrochloric acid solution by hexamine–halide blends (HA–KI and HA–CaCl2) was investigated using gravimetric method, open circuit potential and polarization measurements. Results showed that single additives HA and KI are moderate inhibitors, while CaCl2 is poor inhibitor for corrosion inhibition of Al in 2 M HCl solution. In the presence of blends HA–KI and HA–CaCl2, the corrosion resistance of aluminum is improved and the corrosion rate (CR) and corrosion current (Ic) are reduced significantly, so the inhibition efficiency (IE) and polarization resistance (Rp) are increased. With the mixed inhibitors, there is a compact adsorbed film formation on the surface of Al, due to a synergistic action between the halides ions and HA. 相似文献
998.
《Cement and Concrete Composites》2007,29(6):505-514
This paper presents a laboratory investigation on optimum level of ground granulated blast-furnace slag (GGBS) on the compressive strength of concrete. GGBS was added according to the partial replacement method in all mixtures. A total of 32 mixtures were prepared in four groups according to their binder content. Eight mixes were prepared as control mixtures with 175, 210, 245 and 280 kg/m3 cement content in order to calculate the Bolomey and Féret coefficients (KB, KF). For each group 175, 210, 245 and 280 kg/m3 dosages were determined as initial dosages, which were obtained by removing 30 percent of the cement content of control concretes with 250, 300, 350, and 400 kg/m3 dosages. Test concretes were obtained by adding GGBS to concretes in an amount equivalent to approximately 0%, 15%, 30%, 50%, 70%, 90% and 110% of cement contents of control concretes with 250, 300, 350 and 400 kg/m3 dosages. All specimens were moist cured for 7, 14, 28, 63, 119, 180 and 365 days before compressive strength testing.The test results proved that the compressive strength of concrete mixtures containing GGBS increases as the amount of GGBS increase. After an optimum point, at around 55% of the total binder content, the addition of GGBS does not improve the compressive strength. This can be explained by the presence of unreacted GGBS, acting as a filler material in the paste. 相似文献
999.
《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2007,574(1):127-132
The paper describes the development and testing of an Inconel600 (2 mm diameter×21 cm long) self-powered neutron detector for in-core neutron monitoring. The detector has 3.5 mm overall diameter and 22 cm length and is integrally coupled to a 12 m long mineral insulated cable. The performance of the detector was compared with cobalt and platinum detectors of similar dimensions. Gamma sensitivity measurements performed at the 60Co irradiation facility in 14 MR/h gamma field showed values of −4.4×10−18 A/R/h/cm (−9.3×10−24 A/γ/cm2-s/cm), −5.2×10−18 A/R/h/cm (−1.133×10−23 A/γ/cm2-s/cm) and 34×10−18 A/R/h/cm (7.14×10−23 A/γ/cm2-s/cm) for the Inconel, Co and Pt detectors, respectively. The detectors together with a miniature gamma ion chamber and fission chamber were tested in the in-core Apsara Swimming Pool type reactor. The ion chambers were used to estimate the neutron and gamma fields. With an effective neutron cross-section of 4b, the Inconel detector has a total sensitivity of 6×10−23 A/nv/cm while the corresponding sensitivities for the platinum and cobalt detectors were 1.69×10−22 and 2.64×10−22 A/nv/cm. The linearity of the detector responses at power levels ranging from 100 to 200 kW was within ±5%. The response of the detectors to reactor scram showed that the prompt response of the Inconel detector was 0.95 while it was 0.7 and 0.95 for the platinum and cobalt self-powered detectors, respectively. The detector was also installed in the horizontal flux unit of 540 MW Pressurised Heavy Water Reactor (PHWR). The neutron flux at the detector location was calculated by Triveni code. The detector response was measured from 0.02% to 0.07% of full power and showed good correlation between power level and detector signals. Long-term tests and the dynamic response of the detector to shut down in PHWR are in progress. 相似文献
1000.
《Journal of Catalysis》2007,245(1):144-155
Hysteresis of catalytic performance with respect to temperature increasing and decreasing in oxidative steam reforming of methane (CH4/H2O/O2/Ar = 40/30/20/10) over the monometallic Ni catalysts disappeared by the modification with Pt, and the additive effect of Pt by the sequential impregnation method (Pt/Ni) was much more significant than that by the co-impregnation method (Pt + Ni) in terms of catalytic performance and catalyst bed temperature profile. Characterization results by means of TEM, TPR, EXAFS, and FTIR suggest that the Pt atoms on the Pt/Ni catalysts were located more preferably on the surface to form a PtNi alloy than those on the Pt + Ni catalysts. The modification of Ni with Pt suppressed the oxidation of Ni species near the bed inlet in the oxidative steam reforming of methane at 1123 K, although the species on the monometallic Ni catalysts were oxidized under similar conditions. This can be due to the decreased oxidation rate of the species and the increased reduction rate caused by the surface modification of Ni with Pt. Consequently, the PtNi species can be maintained in the metallic state near the bed inlet, and the species can be the active site for the reforming reaction as well as the combustion reaction, which this leads to a lower bed temperature and smaller temperature gradient than those seen for the monometallic Ni catalysts. 相似文献