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排序方式: 共有581条查询结果,搜索用时 31 毫秒
31.
Fabrication of optics by use of plasma chemical vaporization machining with a pipe electrode 总被引:1,自引:0,他引:1
Takino H Shibata N Itoh H Kobayashi T Yamamura K Sano Y Mori Y 《Applied optics》2002,41(19):3971-3977
We figure optical surfaces by plasma chemical vaporization machining (CVM) with a pipe electrode, in which an rf plasma generated at the electrode tip under approximately atmospheric pressure moves over the surfaces. We propose a shaping method in which the movement of plasma on the surfaces can be determined. Flat and aspheric surfaces are successfully figured with the desired peak-to-valley shape accuracy of 0.1 microm. The root-mean-square roughness of the resultant surfaces is at the subnanometer level. These results confirm that the plasma CVM and the shaping method have the capability to fabricate optics with high accuracy. 相似文献
32.
Kazuya Tamura 《Chemical engineering science》2006,61(17):5818-5826
Crystallization of calcium carbonate using a gas (CO2)-liquid (Ca(OH)2) reaction was conducted using a three-stage column crystallizer. In this study, the staging effect of the multistage column crystallizer and the effect of the operating parameters on the particle size distribution were experimentally and theoretically investigated. From an economic viewpoint, the multistage column crystallizer has been developed to replace a cascade of MSMPR crystallizers, which requires a large installation area and high operating cost because some crystallizers are connected in a series. In the multistage column crystallizer, a narrower particle size distribution was obtained compared to that obtained in the standard column crystallizer. The theoretical approach to predict the particle size distribution is based on the population balance equation which takes account of the back flow into the crystallizer. The calculation results of particle size distribution fairly coincide with the experimental results, which indicates the particle size distribution in the multistage column crystallizer can be roughly predicted by this theoretical model. 相似文献
33.
Efficient construction of cDNA microarrays utilizing normalized cDNA libraries of Arabidopsis thaliana 总被引:1,自引:0,他引:1
Ando K Yamakawa S Miyashita K Yoshida K Yokota A Shinmyo A Kohchi T 《Journal of Bioscience and Bioengineering》2004,97(1):85-88
We have demonstrated the utility of normalization for efficient cDNA microarray preparation using Arabidopsis as a model. Nonredundant cDNAs including 5722 species were efficiently collected from random 7914 expressed sequence tags (ESTs) in four normalized cDNA libraries. The prepared microarrays were successfully used to monitor gene expression. These methodologies should be applicable to the study of other species in plant biotechnology. 相似文献
34.
Mitsuhiro Horade Sommawan Khumpuang Kazuya Fujioka Susumu Sugiyama 《Microsystem Technologies》2007,13(3-4):215-219
We have investigated and report in this paper the factors influencing the deformation caused by the dependence between the
absorbed X-ray energy on the resist and the shape of the absorber on the X-ray mask. Based on the measurement of errors that
occurred during the transferring process between the 2-D shape of mask pattern and the resulting wall of the fabricated 3-D
structure, we have developed newly useful graphical data on the absorbed X-ray energy, dosage, and shape of a microstructure.
As a result, it is being reported as a method for compensation for the deformed shape after the fabrication of a quadruplets-microneedle.
We have considered a number of factors affecting the deformation and finally realized that the effect of a dose–depth nonlinear
curve is the most possible cause. Without the compensation of the mask design, we could observe the deformed shapes of the
sloped sidewall on the exposed structures. Polymethylmethacrylate microneedle structures fabricated by X-ray lithography with
an additional plane-pattern to cross-section transfers technique are directly influenced by the absorber on the X-ray mask
pattern. The sidewall of the microneedle was improved by changing the mask pattern from a double right-triangular pattern
to a double semi-circular pattern, modeled by comparing the results from a mask-pattern and the actual structure. 相似文献
35.
Isaku Nagai Genki Yamauchi Keiji Nagatani Keigo Watanabe Kazuya Yoshida 《Advanced Robotics》2013,27(15):1147-1160
We propose a novel method for positioning a mobile robot in an outdoor environment using lasers and optical sensors. Position estimation via a noncontact optical method is useful because the information from the wheel odometer and the global positioning system in a mobile robot is unreliable in some situations. Contact optical sensors such as computer mouse are designed to be in contact with a surface and do not function well in strong ambient light conditions. To mitigate the challenges of an outdoor environment, we developed an optical device with a bandpass filter and a pipe to restrict solar light and to detect translation. The use of two devices enables sensing of the mobile robot’s position, including posture. Furthermore, employing a collimated laser beam allows measurements against a surface to be invariable with the distance to the surface. In this paper, we describe motion estimation, device configurations, and several tests for performance evaluation. We also present the experimental positioning results from a vehicle equipped with our optical device on an outdoor path. Finally, we discuss an improvement in postural accuracy by combining an optical device with precise gyroscopes. 相似文献
36.
37.
Yugo Tadano Shota Urushibata Kazuya Ogura Akira Shigaki Masakatsu Nomura 《Electrical Engineering in Japan》2008,165(2):77-88
Recently, high‐voltage motor direct drive systems have been put to practical use, and various multilevel PWM strategies have also been proposed. This paper describes a multilevel PWM strategy [our group calls it the Carrier Phase Selection Method (CPS)] that has the lowest line voltage harmonic distortion in order to prevent the degradation of high‐voltage motor winding insulations. This method takes the adverse effect of dead time into consideration, and it controls the shift direction of a carrier phase. Therefore, a favorable output waveform without instantaneous voltage surges is achieved even if the line voltage level changes. Moreover, the switching transitions across all switching devices are well‐balanced, so the utilization of inverter unit cells is equalized. This is an important factor when designing the entire system. Based on simulation and experimental results, it is shown that this CPS method is particularly effective in high‐voltage motor direct drive systems. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(2): 77–88, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20474 相似文献
38.
Kazuya Tsujino 《Electrochimica acta》2007,53(1):28-34
Holes with diameters of tens of nanometers were bored in Si(1 0 0) in aqueous solutions containing hydrofluoric acid and hydrogen peroxide utilizing silver nanoparticles as catalysts. The holes grew deeply in the [1 0 0] direction when the concentration of hydrogen peroxide was about 0.18 M. In addition to these vertical holes, holes were generated horizontal to the surface in the 〈1 0 0〉 directions near the surface of the sample. We found that the silver particles making the deep holes in the [1 0 0] direction were more spherical than those making the horizontal holes near the surface. These results indicate that the shape of the silver particles is an important factor controlling the direction of the holes. When the hydrogen peroxide concentration was increased to 1.8 M, as well as the vertical and horizontal holes, a microporous layer was formed on the top surface region. On the other hand, when the hydrogen peroxide concentration was lowered to 0.0018 M, holes did not show any preference for growing direction and were crooked. Even in HF solutions that did not contain hydrogen peroxide, holes were generated at a very slow rate in random directions if the solutions contained oxygen. 相似文献
39.
40.
The aim of this paper is to investigate the influence of multi-valency of americium in its oxide for the lowering of the thermal conductivity and the uncertainty in measurement. In the present study, thermal conductivity of non-stoichiometric americium oxide was evaluated up to 2000 K by the non-equilibrium molecular dynamics calculations using the Born-Mayer-Huggins interatomic potential with the partially ionic model. The oxygen-to-americium ratio (O/Am) was varied from 1.6 to 1.9, which corresponded to the variation of the ratio of Am3+/Am4+. So, we prepared potential parameters for both Am3+ and Am4+. The calculated thermal conductivity of non-stoichiometric americium oxide decreased with an increase of temperature, and the degree of the temperature dependence became smaller with a decrease of the O/Am ratio. This was mainly caused by the phonon-scattering due to oxygen vacancies induced with Am3+ ions. Comparing two supercells in which (1) short-range ordered Am3+ clusters were contained and (2) Am3+ ions were randomly distributed, the thermal conductivity of the former seemed to be somewhat larger than that of the latter. 相似文献