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排序方式: 共有633条查询结果,搜索用时 15 毫秒
51.
S Miyata BF Liu H Shoda T Ohara H Yamada K Suzuki M Kasuga 《Canadian Metallurgical Quarterly》1997,272(7):4037-4042
Previous studies suggested that the interaction between proteins modified by advanced glycation end products (AGEs) and cells, such as macrophages, may be involved in diabetic angiopathy. Pyrraline is one of the AGEs and known to be elevated in plasma of diabetic rats and humans, and is present in vascular lesions of diabetic and elderly subjects. We examined whether modification of albumin by pyrraline influences its degradation by macrophage-like cell line, P388D1 cells. Degradation of pyrraline-modified albumin by these cells was diminished, causing accumulation of the albumin in these cells. The susceptibility of pyrraline-modified albumin to lysosomal proteolytic enzymes was reduced by approximately 40% in vitro, while lysosomal activity in the cells per se was not affected. This phenomenon was also observed when human monocytes were used instead of P388D1 cells. Our results suggest that accumulation of pyrraline-modified albumin in P388D1 cells is due to the reduced susceptibility of the protein to lysosomal enzymatic degradation. Such alterations in the interaction between AGEs-modified protein and phagocytes may contribute to angiopathy in elderly subjects and patients with diabetes. 相似文献
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Ludwik Blaz Makoto Sugamata Junichi Kaneko Jakub Sobota Grzegorz Wloch Wlodzimierz Bochniak Anna Kula 《Journal of Materials Processing Technology》2009,209(9):4329-4336
Experiments on mechanical consolidation of rapidly solidified (RS) powder of 6061 + 26 mass% Si alloy were performed using the oscillating-die extrusion method. The RS powder was wrapped in thin-wall 6061-alloy cup 35 mm in diameter and vacuum-compressed by means of 100 ton press. Bars 8 mm in diameter were extruded with cross-section reduction of λ = 19 without any preheating of the charge. Tubes with a diameter/wall thickness of 14 mm/1 mm and cross-section reduction of λ = 33 were also manufactured with success. TEM/STEM observations revealed a very fine structure of as-extruded material and bimodal distribution of quasi-spherical silicon particles. Statistical analysis revealed a silicon fine fraction of 0.1–0.7 μm and a coarse fraction 2.1–2.5 μm in diameter. Examination by means of TEM did not reveal any significant changes in the morphology of the silicon particles, even when a high extrusion ratio and the material annealing after deformation were used. Hot compression tests on as-extruded rods (λ = 19) and preliminary annealed samples were performed at a constant true strain rate of 5 × 10?3 s?1 within the temperature range of 293–823 K. High strength of the material and relatively high ductility of samples deformed by compression up to ?t ? 0.4 were observed. The maximum flow stress value for as-extruded material was reduced with deformation temperature from ~390 to ~3.5 MPa for 293 and 823 K, respectively. Annealing of the samples at 773 K/30 min was found to reduce the maximum flow stress by 30–40%. Tensile strengths of similar as-cast alloys and materials manufactured by means of other powder metallurgy methods were shown for the purpose of comparison. 相似文献
54.
Jianxin Sheng Tatsuo Fukami Junichi Karasawa 《Journal of the American Ceramic Society》1998,81(1):260-262
An anomalous increase of current with time has been found in iron-doped titania ceramics that have been subjected to a constant field. The result of thermally stimulated current analysis shows a peak at a temperature of 170°–180°C, which increases because of the depolarization of oxygen vacancies. X-ray photoemission spectroscopy indicates that an electrical stress results in an electrochemical reduction inside the specimen, particularly on the cathodic side. These results reinforce the viewpoint that the space charge that is responsible for the anomalous current results from a blockage of the O2 ( g )/O2− ( s ) ion transfer at the cathode. 相似文献
55.
Sarah Katharina Gaßmeyer Hiroyuki Yoshikawa Junichi Enoki Nadine Hülsemann Prof. Raphael Stoll Prof. Dr. Kenji Miyamoto Prof. Dr. Robert Kourist 《Chembiochem : a European journal of chemical biology》2015,16(13):1943-1949
Structure‐guided protein engineering achieved a variant of the unique racemase AMDase G74C, with 40‐fold increased activity in the racemisation of several arylaliphatic carboxylic acids. Substrate binding during catalysis was investigated by saturation‐transfer‐difference NMR (STD‐NMR) spectroscopy. All atoms of the substrate showed interactions with the enzyme. STD‐NMR measurements revealed distinct nuclear Overhauser effects in experiments with and without molecular conversion. The spectroscopic analysis led to the identification of several amino acid residues whose substitutions increased the activity of G74C. Single amino acid exchanges increased the activity moderately; structure‐guided saturation mutagenesis yielded a quadruple mutant with a 40 times higher reaction rate. This study presents STD‐NMR as versatile tool for the analysis of enzyme–substrate interactions in catalytically competent systems and for the guidance of protein engineering. 相似文献
56.
Junichi Koseki Hong Kimhor Susumu Nakajima Sarju Mulmi Kenji Watanabe Masaru Tateyama 《Soils and Foundations》2010,50(5):747-755
In order to investigate the seismic behavior of conventional type and geosynthetic-reinforced soil retaining walls, 1-g model shaking tests were conducted. Model walls having a height of about 50 cm were placed on a subsoil layer and backfilled with a layer of dense dry Toyoura sand. They were subjected to several steps of horizontal irregular excitations. As a result, generation of negative pore air pressure in the backfill was observed. The maximum amplitude of the negative pore air pressure during each shaking step increased with the base acceleration. Based on analyses of the measured data, it was inferred that such negative pore air pressure was caused by outward wall displacement relative to the backfill and not by dilative behavior of the backfill. It would cause a reduction in the seismic earth pressures exerted from the backfill. This feature suggests an advantage of a rigid full-height facing for reinforced soil walls over the segmental types of facing. A simplified numerical procedure to evaluate earth pressure was applied while considering the effects of the negative pore air pressure, and it could qualitatively simulate the measured behavior in terms of the seismic earth pressure and the angle of failure plane in the backfill. 相似文献
57.
Mikinori Hotta Junichi Tatami Cheng Zhang Katsutoshi Komeya Takeshi Meguro Mark R. Terner Yi-Bing Cheng 《Ceramics International》2010
The formation process of hollow spheres composed of nanosized Ca-α SiAlON particles was investigated using SiO2 starting powders with different characteristics in particle size, shape and crystalline state. TEM observations showed Ca-α SiAlON hollow spheres composed of a large number of nanosized particles in the products prepared at 1450 °C for 120 min in nitrogen. In all systems, the Ca-α SiAlON hollow spheres were always produced through an intermediate Si–Al–Ca–O liquid phase in the same mechanism, regardless of the characteristics of SiO2 starting powders used. Spherical solid particles consisted of amorphous phase containing Si, Al, Ca, O and a small amount of N were generated at the initial stage of carbothermal reduction–nitridation. These spherical solid particles changed into hollow particles with the progression of the reaction from the liquid phase to the crystalline Ca-α SiAlON with increasing temperature. 相似文献
58.
59.
A newly isolated marine bacterium, Vibrio alginolyticus was used to remove a high load of ammonia gas. By a stepwise increase in ammonia supply over the concentration range of 120-2000 ppm (v/v), complete removal of ammonia was observed from the start of the experiment in a suspended culture of the bacterium in basal medium containing 3% NaCl. When cells were inoculated onto an inorganic packing material in a biofilter, and a high load of ammonia was introduced continuously under nonsterile conditions, the average percentage of gas removed exceeded 85% for a 61-d operation. The maximum removal capacity and the complete removal capacity were 22.8 g-N/kg-dry packing material/d and 18.6 g-N/kg-dry packing material/d, respectively, which were about four times larger than those obtained in nitrifying sludge inoculated onto the same packing material. During this operation, the nonsterile air supply had no adverse effect on the removability of ammonia by V. alginolyticus. 相似文献
60.
Takeda K Ishiguro Y Tanaka R Maruyama J Kasamatsu T Okawa S Hori S 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2002,43(5):280-288
Ion-trap GC/MS/MS was evaluated for the multi-residue determination of pesticides in agricultural products. Matrices were extracted from samples (spinach, carrot, onion and brown rice) with acetone and submitted to gel permeation chromatography, followed by a clean-up step through a graphite carbon cartridge. Thirty-five pesticides were added to either matrix, and analyzed by GC/MS/MS. Detection limits of pesticides by GC/MS/MS was almost the same as those by GC/MS (SIM). Coefficients of variation of peak area in 5 measurements of each pesticide at 0.1 microgram/mL or 0.05 microgram/mL with or without matrices were mostly acceptable, though those of 20 pesticides out of 35 were higher than 10% at a concentration of 0.02 microgram/mL. It was indicated that matrix artifacts, which interfere with GC/MS-Scan analysis, could be eliminated in some cases by using GC/MS/MS. 相似文献