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971.
The polymer‐molding‐releasing properties of metal molds were found to be related to the following factors: (1) interfacial chemical bonding between the surfaces of polymers and metal molds and (2) a friction force or friction coefficient between polar substances and/or low‐molecular‐weight components in the polymers and physical factors on mold surfaces. We theoretically and experimentally confirmed that metal molds with good polymer‐molding‐releasing properties had very small surface free energies. We also proved that the surface free energies in the resulting polymer moldings were lower than before shaping. The molding releasing properties improved with decreasing friction force and friction coefficient between the surface of polymers and metal molds and with decreasing surface free energy. To obtain metal molds with lower surface free energies, we developed a polymer plating method with perfluorinated‐group‐containing triazine dithiol. The Metal mold treated by polymer plating had lower critical surface tension (7.5 mJ/m2) than Teflon (18 mJ/m2), indicating that the surface consisted of CF3 ? groups. The treated mold showed excellent durability in its releasing properties, which was better than that of the untreated mold. This technique was developed for the production of molds for the Fθ lens and the naturally bright focusing screen. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2549–2556, 2003 相似文献
972.
Yoshiyuki Yasutomi Akio Chiba Masahisa Sobue 《Journal of the American Ceramic Society》1991,74(5):950-957
Reaction-bonded Si3 N4 · TiN and Si3 N4 · Al2 O3 composites were successfully fabricated by heating mixed powder compacts of Si and TiN or Si and Al2 O3 in a nitrogen atmosphere. The former showed electrical conductivity, owing to the presence of TiN. An electrical resistivity of 2.6 × 10−5 Ω· m was obtained for the Si3 N4 · TiN composite with 70 vol% TiN. The composite with 20 vol% TiN showed an electrical resistivity of 0.22 Ω· m and a bending strength of 460 MPa. On the other hand, the Si3 N4 · Al2 O3 composite had insulating properties. The use of an appropriate amount of resin binder resulted in a higher green density and, consequently, a higher bending strength. Moreover, electroconductive Si3 N4 · TiN/resistive Si3 N4 · Al2 O3 complex ceramics could be fabricated by heating green compacts composed of two different portions, one composed of mixed powders of Si and TiN and the other of Si and Al2 O3 . Attainment of such complex ceramics was attributed to the small dimensional change at the nitriding stage, under 0.3% and the similarity of the thermal expansion coefficients of the two composites. 相似文献
973.
Ji-Guang Li Takayasu Ikegami Toshiyuki Mori Yoshiyuki Yajima 《Journal of the American Ceramic Society》2004,87(6):1008-1013
Hydroxyl-type Sc2 O3 precursors have been synthesized via precipitation at 80°C with hexamethylenetetramine as the precipitant. The effects of starting salts (scandium nitrate and sulfate) on powder properties are investigated. Characterizations of the powders are achieved by elemental analysis, X-ray diffractometry (XRD), differential thermal analysis/thermogravimetry (DTA/TG), high-resolution scanning electron microscopy (HRSEM), and Brunauer-Emmett-Teller (BET) analysis. Hard-aggregated precursors (γ-ScOOH·0.6H2 O) are formed with scandium nitrate, which convert to Sc2 O3 at temperatures ≥400°C, yielding nanocrystalline oxides of low surface area. The use of sulfate leads to a loosely agglomerated basic sulfate powder having an approximate composition of Sc(OH)2.6 (SO4 )0.2 ·H2 O. The powder transforms to Sc2 O3 via dehydroxylization and desulfurization at temperatures up to 1000°C. Well-dispersed Sc2 O3 nanopowders (∼64.3 nm) of high purity have been obtained by calcining the basic sulfate at 1000°C for 4 h. The effects of SO4 2− on powder properties are discussed. 相似文献
974.
Summary Two copolymers of 2-isopropenyl-2-oxazolinium tetrafluoroborate with methyl methacrylate and with methyl acrylate were prepared, from which the polymerization of 2-oxazolines (2-methyl and 2-t-butyl) was initiated to prepare graft copolymers. 相似文献
975.
Zhongmin Chen Masahiro Suzuki Mutsumi Kimura Yoshiyuki Kondo Kenji Hanabusa Hirofusa Shirai 《应用聚合物科学杂志》2004,92(3):1540-1547
A novel spinning acrylic polymer containing silk protein was synthesized by copolymerization of acrylonitrile (AN) and silk fibroin peptide (SFP) modified by acryloyl chloride (AC) with vinyl groups. From results of the examination to the chemical compositions, we established that the modified SFP is more reactive than AN in the copolymerization. The intrinsic viscosity values of these copolymers showed that the copolymers have good spinnability, which were synthesized under the condition of adding a trace of metal ions into the synthesizing solvent. These copolymers exhibited good thermal property. The fiber based on the poly(acrylonitrile‐co‐silk fibroin peptide) was prepared and characterized by SEM, FTIR measurement of its shell and core flakes, and moisture absorption. The fiber exhibited a smooth surface and could be assumed to have excellent adhesive property between SFP and PAN. Furthermore, these fibers showed a core–shell structure and excellent moisture absorption. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1540–1547, 2004 相似文献
976.
Shogo Uesaka Ryohei Yamaoka Toshiki Sasaki Akihiro Chida Susumu Kawashima Toshiyuki Isa Satoshi Seo Yoshiharu Hirakata Shota Yatsuzuka Takayuki Ohide Masataka Nakada Shunpei Yamazaki Manabu Niboshi Yoshiyuki Isomura Yuto Tsukamoto Shinichi Kawato Katsuhiro Kikuchi Seiichi Mitsui 《Journal of the Society for Information Display》2014,22(12):603-612
In this study, the device structure of a white tandem organic light‐emitting diode (OLED) was changed to control the emission area and thereby achieve less luminance decay. A long‐life 13.5‐inch 4 K flexible c‐axis‐aligned crystal oxide semiconductor (CAAC‐OS) active‐matrix OLED with less color shift and high resolution was fabricated using this long‐life white OLED, transfer technology, and a CAAC‐OS field‐effect transistor. 相似文献
977.
This paper presents a numerical shape optimization method for the optimum free-form design of shell structures. It is assumed that the shell is varied in the out-of-plane direction to the surface to determine the optimal free-form. A compliance minimization problem subject to a volume constraint is treated here as an example of free-form design problem of shell structures. This problem is formulated as a distributed-parameter, or non-parametric, shape optimization problem. The shape gradient function and the optimality conditions are theoretically derived using the material derivative formulae, the Lagrange multiplier method and the adjoint variable method. The negative shape gradient function is applied to the shell surface as a fictitious distributed traction force to vary the shell. Mathematically, this method is a gradient method with a Laplacian smoother in the Hilbert space. Therefore, this shape variation makes it possible both to reduce the objective functional and to maintain the mesh regularity simultaneously. With this method, the optimal smooth curvature distribution of a shell structure can be determined without shape parameterization. The calculated results show the effectiveness of the proposed method for the optimum free-form design of shell structures. 相似文献
978.
Hiromi Yoshida Yuki Hirakawa Yuka Tomiyamaa Yoshiyuki Mizushina 《European Journal of Lipid Science and Technology》2003,105(7):351-358
Peanut seeds (Arachis hypogaea) were roasted for 6, 12, 20, or 30 min at a frequency of 2450 MHz using a microwave oven. The quality characteristics and the compositions of the oils, i.e. their tocopherol distributions and the molecular species of the triacylglycerols (TAGs) were investigated. These results were compared with those of an unroasted oil sample. Only minor increases (p <0.05) in chemical and physical properties of the oils, such as the carbonyl value, the p‐anisidine value and the color development occurred after a prolonged roasting period. Compared to the original level, more than 92 wt‐% tocopherols remained after 30 min of roasting. A modified thin‐layer chromatography argentation procedure provided 12 different groups of TAGs, based on both the degrees of unsaturation and the total fatty acid chain‐length. Although significant increases (p <0.05) generated in these chemical and physical changes of the oils after 20 min of roasting, no significant loss (p >0.05) was observed in the molecular species of the TAGs during microwave roasting. These results indicate that phospholipids may be attributed to the quality characteristics of peanut oils during microwave roasting. 相似文献
979.
Hirofumi Ohashi Yoshitomo Inaba Tetsuo Nishihara Tetsuaki Takeda Koji Hayashi Shoji Takada Yoshiyuki Inagaki 《Nuclear Engineering and Design》2006,236(13):1396-1410
The Japan Atomic Energy Agency has been planning the demonstration test of hydrogen production with the High Temperature Engineering Test Reactor (HTTR). In a HTTR hydrogen production system (HTTR-H2), it is required to control a primary helium temperature within an allowable value at a reactor inlet to prevent a reactor scram. A cooling system for a secondary helium with a steam generator (SG) and a radiator is installed at the downstream of a chemical rector in a secondary helium loop in order to mitigate the thermal disturbance caused by the hydrogen production system. Prior to HTTR-H2, the simulation test with a mock-up test facility has been carried out to establish the controllability on the helium temperature using the cooling system against the loss of chemical reaction. It was confirmed that the fluctuations of the helium temperature at chemical reactor outlet, more than 200 K, at the loss of chemical reaction could be successfully mitigated within the target of ±10 K at SG outlet. A dynamic simulation code of the cooling system for HTTR-H2 was verified with the obtained test data. 相似文献
980.