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排序方式: 共有2254条查询结果,搜索用时 31 毫秒
31.
Kimiyasu Sato Miyuki Kawai Yuji Hotta Takaaki Nagaoka Koji Watari 《Journal of the American Ceramic Society》2007,90(4):1319-1322
Because the pyrolysis of organic substances can result in the emission of harmful pollutant gases, a reduction in the use of organic binders is one aim of today's ceramics industry. A novel ceramic-forming process was developed that requires considerably less organic binder than conventional techniques. The process involves immobilizing reactive molecules on the surfaces of the particles, which on subsequent irradiation with microwaves, form bridges that bind the entire particle assembly together. The chemical forces involved produce strong bonds, resulting in a significant reduction in the amount of organic binder that is required to maintain the shape of the ceramic green body. This method will help to decrease emissions of harmful gases produced from pyrolysis of the binder. 相似文献
32.
Polystyrene (PS)/poly(ethylene oxide) (PEO) prototype brushes were prepared by alternating free‐radical copolymerization of methacryloyl‐terminated PS and α‐vinylbenzyl‐ω‐hydroxy or α‐vinylbenzyl‐ω‐perfluoroalkyl (Rf) PEO macromonomers with the addition of Lewis acid (SnCl4). It was found from their dilute‐solution properties that PS/PEO end‐capped with Rf (PBRf), and PS/PEO having OH groups at terminal ends (PBOH) prototype brushes formed a single molecule in benzene and aggregates in chloroform, respectively. However, the brush PBOH formed a single molecule in N,N‐dimethylformamide. Such aggregation behaviors seemed to be caused by the interaction between hydroxy groups of PEO chain ends. The brush PBOH was also converted into PBRf‐type brush by chemical modification, using corresponding acid chloride. The substitution of Rf groups was ~70% due to slipping of terminal hydroxy groups into PEO internal domains. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 772–778, 2006 相似文献
33.
Koji Tsukuma Kuniyoshi Ueda Masahiko Shimada 《Journal of the American Ceramic Society》1985,68(1):4-C-5
Composites of Al2 O3 and Y2 O3 partially-stabilized ZrO2 were isostatically hot-pressed using submicrometer powders as the starting material. The addition of Al2 O3 resulted in a large increase in bending strength. The average bending strength for a composite containing 20 wt% Al2 O3 was 2400 MPa, and its fracture toughness was 17 MN·w−3/2 相似文献
34.
Extraction and implementation of muscle synergies in neuro-mechanical control of upper limb movement
Hang Pham Yohei Ariga Kenta Tominaga Takanori Oku Kanna Nakayama Mitsunori Uemura 《Advanced Robotics》2014,28(11):745-757
This work faces the redundancy problem, a central concern in robotics, in a particular force-producing task by using muscle synergies to simplify the control. We extracted muscle synergies from human electromyograph signals and interpreted the physical meaning of the identified muscle synergies. Based on the human analysis results, we hypothesized a novel control framework that can explain the mechanism of the human motor control. The framework was tested in controlling a pneumatic-driven robotic arm to perform a reaching task. This control method, which uses only two synergies as manipulated variables for driving antagonistic pneumatic artificial muscles to generate desired movements, would be useful to deal with the redundancy problem; thus, suggesting a simple but efficient control for human-like robots to work safely and compliantly with humans. 相似文献
35.
Model compound studies were carried out to elucidate the reaction mechanisms taking place during the liquefaction of coal with the hydrogen produced from the reaction of zinc and water. In compounds of the type Ph-(CH2)n-Ph the splitting of the aliphatic bridge was easier with higher n values. Ether type compounds such as diphenylether were unreactive although the C-O bond in dibenzylether was easily cleaved. Condensed ring aromatic compounds gave low conversion with hydrogenation being facilitated by an increase in ring number. Phenolic compounds such as phenol did not react well, but the reactivity increased with increase in aromatic ring size. The cleavage of the aliphatic bridge was accelerated by the OH group, for example, in the case of 4-hydroxydiphenylmethane bond scission was about 15 times higher than that of diphenylmethane. Heterocyclic compounds were unreactive. 相似文献
36.
Effects of Annealing on Dielectric Loss and Microstructure of Aluminum Nitride Ceramics 总被引:1,自引:0,他引:1
Shoichi Kume Masaki Yasuoka Naoki Omura Koji Watari 《Journal of the American Ceramic Society》2005,88(11):3229-3231
The effect of annealing on tan δ and microstructures of aluminum nitride (AlN) ceramics were explored. Yttria was added as a sintering additive to AlN powders, and the powders were pressureless-sintered at 1900°C for 2 h in a nitrogen flow atmosphere. In succession to sintering, AlN samples were annealed at 720, 970 and 1210°C for 2 and 4 h. Very low tan δ values between 2.6 and 6.0 × 10−4 at 28 GHz were obtained when the AlN samples were annealed for 4 h at all the annealing temperatures. 相似文献
37.
Koji Watari Hiromi Nakano Kimiyasu Sato Kazuyoshi Urabe Kozo Ishizaki Shixun Cao Katsunori Mori 《Journal of the American Ceramic Society》2003,86(10):1812-1814
The thermal conductivity of a SiC ceramic was measured as 270 W·m−1 ·K−1 at room temperature. At low temperatures ( T < 25 K), the decrease in the conductivity was proportional to T 3 on a logarithmic scale, which indicated that the conductivity was controlled by boundaries. The calculated phonon mean free path in the ceramic increased with decreased temperature, but was limited to ∼4 μm, a length almost equal to the grain size, at temperatures below 30 K. We concluded that the thermal conductivity of the ceramic below 30 K was influenced significantly by grain boundaries and grain junctions. 相似文献
38.
Dimethylsiloxane-tetramethyl-p-silphenylenesiloxane-dimethylsiloxane (DMS-TMPS-DMS) triblock copolymer was synthesized by employing living anionic polymerization of hexamethylcyclotrisiloxane (D3). Two synthetic methods were carried out for the polymerization. One of those methods was the anionic polymerization of D3 initiated at the silanolate anion which was prepared from the terminal hydroxyl group of silanol-terminated TMPS prepolymer by reaction with n-butyllithium (method 1). The other was the coupling reaction of vinyl-terminated TMPS prepolymer with hydrosilyl-terminated DMS prepolymer obtained from the anionic polymerization of D3 by using diphenylmethylsilanolate anion as initiator (method 2). In method 1, DMS contents of the copolymers ranged from 25.8 to 72.5 wt% and the values agreed with the ratio of D3 to TMPS prepolymer. The weight-average molecular weights ranged from 1.36×104 to 19.4×104 and were close to the predicted values calculated from the of the TMPS prepolymer and the amount of D3 added. In the case of method 2, weight-average molecular weights ranged from 19.5×104 to 24.2×104. The high molecular weight copolymer could thus be obtained by method 2. Intrinsic viscosity values of the triblock copolymers agreed with calculated values obtained by considering the copolymer as a binary mixture of these homopolymers. Differential scanning calorimetry and thermogravimetry were carried out on the triblock copolymers. The equilibrium melting temperatures of each of the copolymers were very close to that of poly-TMPS (160°C). The glass transition temperature and heat of fusion were decreased as the DMS content was increased. The thermogravimetric curves for the copolymers indicated that the thermal stability of the triblock copolymer was intermediate between the DMS and TMPS homopolymers. 相似文献
39.
Tetsuya Tanigami Kanna Kai Koji Tanaka Shuji Matsuzawa 《Journal of Inorganic and Organometallic Polymers》2003,13(4):237-253
Poly[bis(-phenoxyethoxy)phosphazene] [PBPEP] had been shown in our previous paper to be a very useful polymer for investigating the crystallization mechanism of polymers, as the crystallization rate of PBPEP is extraordinarily small when isothermally crystallized from the melt. The crystallization of the low molecular weight oligomers of PBPEP was first studied in comparison to the high molecular weight polymers. The oligomer-rich fraction was obtained by fractionation of the as-polymerized sample, which had a broad molecular weight distribution. The fractions thus obtained were characterized by solution viscometry and size exclusion chromatography. The melting temperature and the growth rate of the spherulite from the melt were investigated by differential scanning calorimetry and optical microscopy. The growth rate was one or two orders of magnitude smaller in the oligomer-rich fraction than in the other high molecular weight fractions. A collapsed spherulite appeared in the oligomer-rich fraction at high crystallization temperatures. It is speculated that in the oligomer-rich fraction there is an excess free energy due to defects in the crystal phase. This defect is considerably larger in the oligomer-rich fraction than in the other fractions because a large quantity of short length chains is present. 相似文献
40.
The effect of the N-linked glycans on structural features and physicochemical functions of soybean β-conglycinin homotrimers 总被引:2,自引:0,他引:2
Nobuyuki Maruyama Mohamad Ramlan Mohamed Salleh Koji Takahashi Kazuhiro Yagasaki Hideyuki Goto Naho Hontani Shuko Nakagawa Shigeru Utsumi 《Journal of the American Oil Chemists' Society》2002,79(2):139-144
β-Conglycinin is a trimeric protein consisting of three subunits, α,α′,and β, which are N-glycosylated. The α and α′ subunits
contain extension regions in addition to core regions common to all subunits. We purified homogeneous trimers consisting of
only α, α′, or β from mutant soybean cultivars containing β-conglycinin lacking one or two subunits: α homotrimers from an
α′-lacking mutant, α′ homotrimers from an α-lacking mutant, and β homotrimers from an α-and α′-lacking mutant. Structural
features and physicochemical functions of the three homotrimers were examined and compared with those of recombinant homotrimers
having no N-linked glycans. The native homotrimers have secondary structures very similar to those of the recombinant ones.
In analogy with the recombinant homotrimers, the native ones exhibit different thermal stabilities from one another (β>α′>α),
and the native α and α′ homotrimers exhibit better solubility, emulsifying ability, and heat-induced association than the
native β homotrimer. Further, the N-linked glycans contribute to solubilities of the three subunits at low ionic strength
(μ=0.08) and to the emulsifying ability of the native β homotrimer. N-Linked glycans also prevent heat-induced associations
of the native α and α′ homotrimers but do not contribute to the secondary structure and the thermal stability of β-conglycinin. 相似文献