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1.
Summary Well-defined living polymers of isobutyl vinyl ether were obtained in the polymerization initiated with ethylaluminum dichloride (EtAlCl2) in conjunction with a stoichiometric excess of dioxane (5–10 vol%) in n-hexane at 0°C. Under these conditions, the number-average molecular weight of the polymers increased in direct proportion to monomer conversion, while the molecular weight distribution stayed narrow (Mw/Mn = 1.1–1.25). In sharp contrast, the EtAlCl2-initiated polymerization in the absence of dioxane led to non-living polymers with a broad molecular weight distribution. It was concluded that the propagating carbocation is stabilized not by the counteranion but by an externally added basic compound (dioxane) that strongly interacts with the active end. 相似文献
2.
Kenichi Asakawa Kensuke Watari Hidetoshi Ohuchi Masahiko Nakamura Tadahiro Hyakudome Yasuhisa Ishihara 《Advanced Robotics》2016,30(1):41-49
A buoyancy engine with a swashplate-type axial piston pump was developed. Its oil extrusion and drawing properties under high hydraulic pressure were evaluated. This buoyancy engine is now installed in an underwater glider that will achieve long-term monitoring of ocean environments up to 2100 m depth in a designated area with lower operational costs. This bidirectionally functioning pump can control the amount of oil in extrusion and draw operations. When drawing oil under high pressure, the hydraulic pump and the electric motor, respectively, act as a hydraulic motor and an electric generator. The generated electric power is absorbed by a damping resistor. The oil-drawing and extrusion properties were measured using a large hyperbaric chamber that is able to produce an almost identical environment to that of actual operations. Results confirmed stable oil extrusion operations up to 21 MPa. Regarding oil-drawing properties, although it was measured only up to 10 MPa in the hyperbaric chamber, it can be inferred that the system can draw the oil and can control the buoyancy precisely up to 21 MPa by replacing the two-way ball valve with an electromagnetic latching solenoid valve. 相似文献
3.
Nobuyoshi Koshino Masayuki Harada Yasuji Morita Toshiaki Kiikuchi Yasuhisa Ikeda 《Progress in Nuclear Energy》2005,47(1-4):406-413
We have developed a simple reprocessing process for spent FBR fuels using N-cyclohexyl-2-pyrrolidone (NCP) which has selective precipitation ability for UO22+ ions. It was confirmed that NCP has sufficient precipitation ability for UO22+ ions, decontamination capability (separation of UO22+ from simulated fission products), and resistance to γ-ray radiation in nitric acid solutions. These findings indicate that NCP is applicable to our reprocessing process. We have also evaluated performances of other precipitants such as N-n-propyl-2-pyrrolidone (NProP), N-n-butyl-2-pyrrolidone (NBP), and N-n-butyl-2-pyridone (NBPyr). It was found that higher decontamination factors (DFs) are obtained by using NProP and NBP. This can be interpreted that the hydrophobicity of NProP and NBP is lower than that of NCP. Furthermore, we have obtained an experimental result that the resistance of NBPyr to γ-ray radiation is superior to that of NCP. 相似文献
4.
Naoyuki Kanetake Yasuhisa Tozawa Toshio Otani 《International Journal of Mechanical Sciences》1983,25(5):337-345
The present study aims to calculate the height at each peripheral position of a cup drawn from polycrystalline sheet using texture data. In the analytical treatment the polycrystalline sheet is simplified to an aggregation of many single crystals with various orientations, and the texture is represented by a three-dimensional crystallite orientation distribution function. The ear is calculated crystallographically using the orientation distribution function as a volume fraction of a certain oriented crystal. In the experiment aluminium, Al-Mg alloy and copper sheets which are treated under various conditions of cold rolling and heat treatment are used. The average textures over the thicknesses of the sheets are measured by the Schulz reflection method. The calculated ears based on the measured textures are compared with the experimental ears for each material. The results show that all the principal features of the ears of drawn cups are predicted satisfactorily by the calculation. 相似文献
5.
Makoto Kobayashi Masashi Shimada Yuji Hatano Takuji Oda Brad Merrill Yasuhisa Oya Kenji Okuno 《Fusion Engineering and Design》2013,88(9-10):1749-1752
The deuterium trapping behaviors in tungsten damaged by light ions with lower energy (10 keV C+ and 3 keV He+) or a heavy ion with higher energy (2.8 MeV Fe2+) were compared by means of TDS to understand the effects of cascade collisions on deuterium retention in tungsten. By light ion irradiation, most of deuterium was trapped by vacancies, whose retention was almost saturated at the damage level of 0.2 dpa. For the heavy ion irradiation, the deuterium trapping by voids was found, indicating that cascade collisions by the heavy ion irradiation would create the voids in tungsten. Most of deuterium trapped by the voids was desorbed in higher temperature region compared to that trapped by vacancies. It was also found that deuterium could accumulate in the voids, resulting in the formation of blisters in tungsten. 相似文献
6.
Aem Nuylert Dr. Fumihiro Motojima Prof. Dr. Chartchai Khanongnuch Prof. Dr. Tipparat Hongpattarakere Prof. Dr. Yasuhisa Asano 《Chembiochem : a European journal of chemical biology》2020,21(1-2):181-189
Because the synthesis of chiral compounds generally requires a broad range of substrate specificity and stable enzymes, screening for better enzymes and/or improvement of enzyme properties through molecular approaches is necessary for sustainable industrial development. Herein, the discovery of unique hydroxynitrile lyases (HNLs) from two species of passion fruits, Passiflora edulis forma flavicarpa (yellow passion fruit, PeHNL-Ny) and Passiflora edulis Sims (purple passion fruit, PeHNL-Np), isolated and purified from passion fruit leaves is reported. These are the smallest HNLs (comprising 121 amino acids). Amino acid sequences of both enzymes are 99 % identical; there is a difference of one amino acid in a consensus sequence. PeHNL-Np has an Ala residue at position 107 and is nonglycosylated at Asn105. Because it was confirmed that natural and glycosylated PeHNL-Ny showed superior thermostability, pH stability, and organic tolerance to that of PeHNL-Np, it has been speculated that protein engineering around the only glycosylation site, Asn105, located at the C-terminal region of PeHNL-Ny, might contribute to the stabilization of PeHNL. Therefore, the focus is on improved stability of the nonglycosylated PeHNL by truncating its C-terminal region. The C-terminal-truncated PeHNLΔ107 was obtained by truncating 15 amino acids from the C terminus followed by expression in Escherichia coli. PeHNLΔ107 expressed in E. coli was not glycosylated, and showed improved thermostability, solvent stability, and reusability similar to that of the wild-type glycosylated form of PeHNL expressed in Pichia pastoris. These data reveal that the lack of the high-flexibility region at the C terminus of PeHNL might be a possible reason for improving the stability of PeHNL. 相似文献
7.
We report an analysis for the morphology and breaking behavior of deposits of spherical latex particles (1 and 3.6 μm in diameter) at a cylindrical collector in a microfluidic channel fabricated by soft-lithography. In-situ observation of particle deposition over a large range of flow rate conditions evidence the relationship between deposit morphology and mode of particle transport toward the collector. For low Pe?clet number (Pe), particle deposits are nearly uniform all over the collector surface except at the rear where particles do not attach. Upon increase of Pe, deposits gradually adopt a columnar morphology at the collector stagnation point. These results are qualitatively consistent with previously reported Monte Carlo simulations of deposits formation in stagnation point flow systems. However, these simulations fail to quantitatively predict the observed deposition at the rear of the collector for sufficiently high flow rate. Additional deposit breaking experiments together with numerical evaluations of particle flux around the collector suggest that such "anomalous" deposition at large Pe is significantly governed by concomitant detachment of deposited particles at the stagnation point and the presence of recirculation flow at the collector rear. Finally, kinetics of deposition are discussed in connection with particle size-dependence of deposit breaking features. 相似文献
8.
9.
Matsumura K Obata H Hata Y Kawato A Abe Y Akita O 《Journal of Bioscience and Bioengineering》2004,98(2):77-84
We cloned and characterized a novel gene (abfA) encoding alpha-L-arabinofuranosidase (alpha-L-AFase) from Aspergillus oryzae. One clone homologous to the alpha-L-AFase gene of Thermotoga maritima was found in an expressed sequence tag (EST) library of A. oryzae and a corresponding gene was isolated. Molecular analysis showed that the abfA gene carried six exons interrupted by five introns and had an open reading frame encoding 481 amino acid residues. The amino acid sequence similarity at active sites to the alpha-L-AFases from other organisms indicated that the alpha-L-AFase encoded by abfA was classified as a family 51 glycoside hydrolase. When the abfA was overexpressed in the homologous hyperexpression system of A. oryzae, a large amount of alpha-L-AFase was produced as intracellular protein. The apparent molecular mass of the purified enzyme was estimated to be 228,000 by gel filtration and that of its subunit as 55,000 by SDS-PAGE, suggesting that the enzyme is a tetramer. The enzyme hydrolyzed p-nitrophenyl-alpha-L-arabinofuranoside but not other p-nitrophenyl glycosides. These results demonstrated that the abfA gene encodes a functional alpha-L-AFase. 相似文献
10.
Patients with muscle weakness such as muscular dystrophy usually need someone’s assistance in their daily activities. In order to reduce the caregiver burden and to improve quality of life (QOL) of the patients, various robotic technologies have been developed. This paper presents an exoskeletal assistance system EMAS II for the patients, which assists the upper extremity for the purpose of daily activities such as eating, writing, or other desk works. The EMAS II assists four DOF; shoulder flexion-extension, shoulder abduction-adduction, shoulder medial-lateral rotation, and elbow flexion-extension. The EMAS II has three kinds of user interfaces which are operated by residual functions of the patients, because it is important for patients’ health and initiative to use the residual functions. In order to control the four DOFs exoskeleton system using the interfaces with less DOF, the EMAS II simulates upper limb motion patterns of healthy people. The patterns are modeled by extracting correlations between the height of the wrist joint and that of the elbow joint. Therefore, users have only to control the position of their wrist joint to do tasks at a table. Through an experiment with a healthy subject, the feasibility of meal assistance by the EMAS II was confirmed. Furthermore, the system was applied to a spinal muscular atrophy patient in a clinical trial to check the usability. The experimental results indicated that the EMAS II could support the patient’s upper extremity to do tasks at a table. 相似文献