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41.
The effect of the buffer capacity of test solution on the corrosion rate of cast pure (>99.95 mass%) and high-purity (>99.9999 mass%) magnesium, and AZ31 and AZ91E has been studied. Their corrosion rates were measured gravimetrically in a pH 6.5 and a pH 9 borate buffer including chloride ions, and in a conventional chloride solution. Except for the AZ91E in the pH 6.5, the corrosion rates of all the examined materials depended solely on the pH of the test solution, although the materials had a variety of purity and alloying elements. Higher buffer capacity probably masked the detrimental effect of the “cathodic impurities”. The corrosion rates measured in the buffers were considered as giving the resistivity of the passive film to anodic reactions. The high-purity magnesium had a fair corrosion resistance even in conventional chloride solution. 相似文献
42.
Synthesis of Thermally Stable χ-Alumina by Thermal Decomposition of Aluminum Isopropoxide in Toluene
Okorn Mekasuwandumrong Hiroshi Kominami Piyasan Praserthdam Masashi Inoue 《Journal of the American Ceramic Society》2004,87(8):1543-1549
Thermal decomposition of aluminum isopropoxide in toluene at 315°C resulted in χ-alumina that had high thermal stability, whereas the reaction at lower temperatures resulted in formation of an amorphous product. The χ-alumina thus obtained directly transformed to α-alumina at ∼1150°C, bypassing the other transition alumina phases, whereas the amorphous product transformed to γ-alumina and then to θ-alumina before final transformation to α-alumina. When the χ-alumina, solvothermally synthesized at 315°C, was recovered by the removal of the solvent at the reaction temperature, thermal stability of the product was improved further. This procedure is convenient because it avoids bothersome work-up processes that yield large-surface-area and large-pore-volume alumina. 相似文献
43.
Hydrothermal reactions of fumed silica with lime at 80°C were studied at starting Ca/Si of 0.8–2.0 and water/solid ratio of 20 by weight under periods of reaction time from 10 to 100 days.In the early ages of reaction, CSH having weak and diffuse basal reflections between 10–15Å was formed. On prolonging the reaction, CSH from the starting Ca/Si of 1.2–1.5 crystallised to jennite, and that from the starting Ca/Si of 0.9 to 14Å tobermorite.Lattice parameters were determined on the well crystalline jennite obtained by the reaction for 100 days at the starting Ca/Si of 1.4; i.e. ao 10.59, bo 7.21, co 10.82Å, α 99.60°, β 97.78°, γ 109.85°. Its crystals were lath-like elongated parallel to b with (001) cleavage.It was confirmed that the synthetic jennite was converted to meta-jennite by losing a part of its water on heating in air at 90°C. At higher temperatures it became poorly crystalline, and then crystallised to β-CaSiO3 and β-Ca2SiO4 at 800°C. 相似文献
44.
A poled ferroelectric LiNbO3 single crystal with high spontaneous polarization was employed as a catalyst support, and the static and dynamic effects of the polar substrate surfaces on the adsorptive and catalytic properties of thin film catalysts deposited were shown. For the static effect, it was demonstrated that the surface conductivity of copper and metal-free phthalocyanine films increased by the adsorption of NO gas, to a larger extent, when the substrate was the negative polar surface, compared to the positive one. The role of the polar substrates is explained In terms of a band bending model. For the dynamic effect, the Rayleigh surface acoustic wave generated on the LiNbO3 substrate was shown to enhance the catalytic activity for ethanol oxidation on Cu and Ag thin film catalysts deposited on the propagation path. It is proposed that the catalyst activation is mainly due to an electric Held produced. The use of poled LiNbO3 is suggested to be effective for the development of a device-type catalyst with activity controllable functions. 相似文献
45.
Curing catalyst for epoxy resins was newly found. The catalyst consists of aluminum complex and silanol. Lack of one component of the pair does not cure epoxy resins. The epoxy resins cured with the catalyst are characterized by excellent electrical properties, especially at high temperature, due to the absence of strong acid species in the cured epoxy resin matrix. Heat-resistant property of the resin was also excellent. These properties were compared with those of epoxy resin cured with commonly used BF3 complex. 相似文献
46.
Blended polymer electrolytes based on poly(ethylene oxide) (PEO) and boroxine ring polymer (BP) solvated with lithium triflate were formulated and evaluated. Compared to PEO–salt polymer electrolyte, ionic conductivities of blended polymer electrolytes were two orders of magnitude higher in a low‐temperature range; as well, lithium transference numbers were increased to ~ 0.4. These were due to the increased mobility and anion trapping of boroxine rings. BP also exhibited the stabilizing effect on lithium–polymer electrolyte interface, and a reduced interfacial resistance between lithium metal and the polymer electrolyte was found with increasing of BP content. Polymer electrolytes based on PEO and BP are suitable for use in lithium secondary battery. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 17–21, 2002; DOI 10.1002/app.10090 相似文献
47.
Masayuki Shirai Chandrashekhar V. Rode Eiichi Mine Akiyoshi Sasaki Osamu Sato Norihito Hiyoshi 《Catalysis Today》2006,115(1-4):248-253
Catalytic ring hydrogenations of naphthalene and 1-naphthol were studied over several supported metal catalysts in supercritical carbon dioxide solvent at low temperature. Higher concentration of hydrogen in supercritical carbon dioxide and lower reaction temperature were responsible for higher catalyst activity and selectivities to the desired partial ring hydrogenated products as compared with those observed in organic solvent for the same catalyst. 相似文献
48.
Annadanam V. Sesha Sainath Takashi Inoue Yoshiharu Hatakeyama Masahiro Shishido Kenzo Okamoto Seigou Kawaguchi Takashi Kuriyama Kiyohito Koyama 《大分子材料与工程》2004,289(3):264-268
Summary: Polyacrylonitrile (PAN) particles with micro‐size ranges (0.15–2 μm) were prepared by emulsion and dispersion polymerizationa and in supercritical carbon dioxide media. The PAN particles were blended with Nylon 6 (PA6) at 220 °C by using a miniature mixer; it was found that melt‐mixing was possible for PAN‐rich compositions as high as 70 wt.‐%. Blends were characterized by scanning electron microscopy, IR, viscosity measurements, differential scanning calorimetry, and dynamic mechanical thermal analysis (DMTA). The size and shape of original PAN particles were retained in PAN/PA6 blends. The useful range to blend PAN particles size was less than 1 μm in terms of shape retention of the PAN particles in blends. Blends with 40 wt.‐% PAN content were found to be melt‐processable. The elastic modulus was higher for PAN/PA6 blends than pure PA6.
49.
Eiichi Hoshino Kazunari Maruta Yasunao Wada Kazuo Mori 《Journal of the American Oil Chemists' Society》1995,72(7):785-791
The interaction of highly purified alkaline protease fromBacillus sp. KSM-K16 with the horny cells of human skin contained in skin grime was directly visualized by electron microscopy. It
became clear that the protease first penetrates the horny cells and then adsorbs, mainly onto the internal structure of the
cells at the initial stage of hydrolysis, and directly hydrolyzes the keratin filaments, though the marginal band surrounding
them retains its original shape. Then, hydrolysate produced from the keratin filaments flows out of the cell, and early in
the hydrolysis process keratin filaments decrease and then disappear, leaving a marginal band, i.e., the cell turns to a hollow
state. As a result, the remaining marginal band loses support from inside the cell, thus promoting cleavage and dispersion.
Until this stage in the protease reaction, the remarkable liberation of hydrolysis products as water-soluble protein does
not occur. 相似文献
50.
Ken Shimomai Noboru Higashida Toshiaki Ougizawa Takashi Inoue Bernd Rudolf Jörg Kressler 《Polymer》1996,37(26):5877-5882
The miscibility of poly(methyl methacrylate) (PMMA) and styrene-acrylonitrile random copolymers (SAN) blends was investigated on the basis of the Flory—Orwoll—Vrij equation of state theory. To obtain the equation of state parameters (P*, V*sp, T*: characteristic parameters), the pressure—volume—temperature (PVT) behaviour was measured for PMMA and a series of SANs with various acrylonitrile contents. The exchange energy parameter Xij was also calculated by fitting the theory to some phase diagrams of PMMA/SAN blends. The Flory—Huggins interaction parameter χ was separated into two contributions based on the equation of state theory for mixtures: the exchange energy term χinter and the free volume term χfree. Both the temperature and copolymer composition dependences of χinter and χfree were estimated by calculations using the equation of state parameters. There exists a region in which χinter is negative, leading to a miscibility window in PMMA/SAN blends. However, the immiscibility at high temperatures in the blends cannot be explained only by χinter; it is caused by the free volume contribution, χfree. The miscibility window behaviour in PMMA/SAN blends may be explained within the framework of the equation of state theory. 相似文献