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701.
The shape of arc plasma in gas-shielded arc welding is an important factor for the quality and efficiency of the welding. The arc plasma changes its shape by an external magnetic field because the arc is a flow of electricity and is subjected to the electromagnetic force. In this study, we examined the control of arc plasma by a cusp-type magnetic field. The field produces a high and low magnetic area alternatively, and changes the cross-section of the arc plasma from a circular to an elliptical shape. The previous study using solenoid coils to produce a cusp-type magnetic field reported that magnetized arc plasma provided deeper penetration. However, the solenoid device developed for the cusp magnetic field was too large in comparison with the size of the welding torch used for production welding. Therefore, this study investigated the magnetic control of arc plasma with permanent magnets that have recently become smaller in size and higher in intensity. Theoretical analysis model was constructed to determine the optimum arrangement of the magnets. This analysis requires a three-dimensional numerical model because the temperature-, velocity-, and electromagnetic fields of arc plasma change three-dimensionally by the additional magnetic field. It was analytically and experimentally shown in TIG arc welding that the arc shape could be elliptical cross-section even using the permanent magnets. Furthermore, our analysis showed that the effective magnetization direction of magnets was vertical, and this result was confirmed experimentally. As a result, we obtained the good bead appearance in the high-speed welding with this magnetic control. 相似文献
702.
To launch quantum key distribution (QKD) into the commercial market, it is important to develop a system that is simpler and more reliable using current technology. This report proposes quantum encoders and decoders using a passive planar lightwave circuit (PLC) that is useful for implementing optical-fiber-based QKD systems. Our encoders and decoders are based on an asymmetric Mach–Zehnder interferometer and allow us to prepare and analyze various photonic time-bin qubits reliably. The system can be stable and polarization-insensitive merely by stabilizing and controlling the device temperature. Our PLC-based devices enables us to simplify the QKD system and increase its reliability. 相似文献
703.
Hydrogen fermentation properties of undiluted cow dung 总被引:2,自引:0,他引:2
Yokoyama H Waki M Ogino A Ohmori H Tanaka Y 《Journal of Bioscience and Bioengineering》2007,104(1):82-85
Anaerobic treatment of undiluted cow dung (15% total solids), so-called dry fermentation, produced hydrogen (743 ml-H(2)/kg-cow dung) at an optimum temperature of 60 degrees C, with butyrate and acetate formation. The hydrogen production was inhibited by the addition of NH(4)(+) in a dose-dependent manner. A bacterium with similarity to Clostridium cellulosi was detected in the fermented dung by a 16S rDNA analysis. 相似文献
704.
Kana Hirayama Keisuke Yoshino Ryuji Ueno Yoshiaki Iwamura Haigui Yang Dong Wang Hiroshi Nakashima 《Solid-state electronics》2011,60(1):122-127
Ge-MOS capacitors were fabricated by a novel method of ultra-thin SiO2/GeO2 bi-layer passivation (BLP) for Ge surface combined with the subsequent SiO2-depositions using magnetron sputtering. For the Ge-MOS capacitors fabricated by BLP with O2, to decrease oxygen content in the subsequent SiO2 deposition is helpful for improving interface quality. By optimizing process parameters of the Ge surface thermal cleaning, the BLP, and the subsequent SiO2 deposition, interface states density of 4 × 1011 cm−2 eV−1 at around mid-gap was achieved, which is approximately three times smaller than that of non-passavited Ge-MOS capacitors. On the contrary, for the Ge-MOS capacitors fabricated by BLP without O2, interface quality could be improved by an increase in oxygen contents during the subsequent SiO2 deposition, but the interface quality was worse compared with BLP with O2. 相似文献
705.
The exemption levels for surface contamination in units of Bq cm(-2) were derived by developing a new universal dose assessment model that consists of three generic scenarios assessed by considering manually, closely and remotely handled objects. In this paper, as part of the process of verifying the validity of these generic scenarios, annual doses that arise from transport-specific aspects are calculated. The maximum annual doses are found to be lower than 10 μSv, which is the bottom line of the exemption dose criterion. The result verifies the validity of the generic scenarios used in the previous derivation of exemption levels for surface contamination. 相似文献
706.
Akashi Mochida Hiroshi Yoshino Toshimasa Kakegawa 《Journal of Wind Engineering & Industrial Aerodynamics》2005,93(6):437-449
This paper investigates methods for controlling airflow in and around a building in order to improve indoor thermal comfort by utilizing cross-ventilation. In the first part of the study, field measurements are carried out to evaluate the effects of cross-ventilation on indoor thermal comfort. It was confirmed that a comfortable indoor thermal environment could be attained in a considerable part over summer by controlling the window opening in order to maintain the PMV value within the range −0.5<PMV<+0.5. The latter part reports on CFD predictions of flow in and around a building. The effects of planted tree arrangements around the building, openings locations and size of openings in the building are numerically investigated. 相似文献
707.
Tanino T Ito T Ogino C Ohmura N Ohshima T Kondo A 《Journal of Bioscience and Bioengineering》2012,114(2):209-211
Four kinds of transporters, HXT1 and HXY7 from Saccharomyces cerevisiae, and GXF1 and GXS1 from Candida intermedia, were overexpressed in xylose-metabolizing S. cerevisiae harboring a xyloseisomerase-based pathway. Overexpression of transporter enhanced sugar consumption and ethanol production, and GXF1 was efficient for ethanol fermentation from both glucose and xylose. 相似文献
708.
Inhibitory effects of acidic xylooligosaccharide on stress-induced gastric inflammation in mice 总被引:1,自引:0,他引:1
Yoshino K Higashi N Koga K 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2006,47(6):284-287
The preventive effects of acidic xylooligosaccharide prepared from xylan of corncobs and related sugars on stress-induced gastric inflammation in mice were investigated. Oral administration of acidic xylooligosaccharide and hydrocortisone at doses of 100 and 200 mg/kg body weight significantly reduced the number of bleeding points in the gastric mucosa of mice loaded with cold-restraint stress. Acidic xylooligosaccharide showed concentration-dependent superoxide anion radical-scavenging activity at concentrations of 3.3-4.3 mg/mL and its IC50 was 3.5 mg/mL, although this value is approximately six times that of quercetin. The antioxidant activity of acidic xylooligosaccharide could contribute, in part, to its suppressive activities on stress-induced mouse gastritis. Xylose, xylobiose, xylan, and glucuronic acid showed no significant suppressive activities on mouse gastric inflammation at a dose of 100 mg/kg body weight. These results suggest that an appropriate degree of polymerization of xylan (larger than trimer) is necessary for the activities of acidic xylooligosaccharide. 相似文献
709.
We have improved electrical characteristics of a film bulk acoustic wave (BAW) resonator that features the injection of H2O gas into a process chamber. The preferred crystallinity of piezoelectric ZnO film was obtained by RF sputtering at a high H2O partial pressure 1.5×10−4 Pa. The effective electromechanical coupling coefficient () of the BAW resonator remarkably goes up from 1.8% to 4.7% for which the corresponding H2O partial pressures are 2.7×10−5 and 1.5×10−4 Pa. Injection of H2O during the deposition process contributes to the improvement of crystallinity of ZnO thin film and the electrical characteristics of the BAW resonator. 相似文献
710.