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排序方式: 共有1007条查询结果,搜索用时 15 毫秒
931.
Modern explanatory inductive logic programming methods like Progol, Residue procedure, CF-induction, HAIL and Imparo use the principle of inverse entailment (IE). Those IE-based methods commonly compute a hypothesis in two steps: by first constructing an intermediate theory and next by generalizing its negation into the hypothesis with the inverse of the entailment relation. Inverse entailment ensures the completeness of generalization. On the other hand, it imposes many non-deterministic generalization operators that cause the search space to be very large. For this reason, most of those methods use the inverse relation of subsumption, instead of entailment. However, it is not clear how this logical reduction affects the completeness of generalization. In this paper, we investigate whether or not inverse subsumption can be embedded in a complete induction procedure; and if it can, how it is to be realized. Our main result is a new form of inverse subsumption that ensures the completeness of generalization. Consequently, inverse entailment can be reduced to inverse subsumption without losing the completeness for finding hypotheses in explanatory induction. 相似文献
932.
933.
This paper presents within the scope of the theory of static elasticity a derivation of soil spring constant in longitudinal direction of a buried pipeline in the seismic design. It is found that the spring constant depends on the shear modulus G of the soil deposits and the ratio λ of the radius of zero displacement over the radius of a buried pipeline structure. When λ increases, the soil spring constant decreases and the decreasing rate reduces remarkably when λ is greater than about 10. The ratio of soil spring constant over G is 2.7 when λ = 10. Furthermore, the dynamic effect of soil spring constants on buried pipeline structures is estimated analytically by the dynamic theory of elasticity. The soil spring constant that is derived, taking into account the boundary condition of ground surface, depends on the shear modulus G of the ground, nondimensional frequency ωb∕Vs (ω = circular frequency; b = radius of buried pipeline; Vs = ground shear-wave velocity) and nondimensional depth d∕b (d = depth of pipeline). 相似文献
934.
Masaaki Ohshima Katsuhisa Inagaki Hirofumi Shinohara 《Electrical Engineering in Japan》2008,165(1):74-81
In this paper, the authors present the system configuration and control scheme of a dispersed power source equipped with quick backup function, which acts as a dispersed power source when no fault exists in a commercial power network and functions as a backup power supply in case of a fault of the network. If a fault, such as a voltage interruption on the network, occurs, the dispersed power source disconnects critical loads from the network in an instant and continues supplying power to the critical loads. We also discuss the method of disconnecting a power network sufficiently quickly when some fault occurs on the network, adopting non‐gate‐turn‐off devices such as thyristors for the AC interconnecting switches. Since it takes only 2 ms to disconnect the loads from a faulted network, there are no negative effects on the loads. Simulations and experimental tests confirm the practicability of the proposed method. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(1): 74–81, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/ eej.20700 相似文献
935.
Hiroyuki Mochizuki Wataru Watanabe Yasuyuki Ozeki Kazuyoshi Itoh Katsumi Matsuda Satoshi Hirono 《Thin solid films》2009,518(2):714-2489
Bragg-type gratings were prepared by irradiation inside a series of optical polymers with femtosecond laser pulses and the preparation conditions of the grating were examined. Repeated scanning irradiation with femtosecond laser pulses formed gratings due to refractive index changes inside polymers. Among the polymers examined in the present study, polymethylpentene (PMP) showed the highest diffraction efficiency, which was an order of magnitude higher than those of other optical polymers. The density of PMP was the lowest among the polymers evaluated in the present study, and the large volume contraction based on its low density was responsible for the larger refractive index change of PMP. Furthermore, we fabricated large-area diffractive optical elements (DOEs) in PMP measuring 15 × 25 mm2 by widening the scanning area. 相似文献
936.
937.
Yuzuru Ueda Kosuke Kurokawa Takamitsu Itou Kiyoyuki Kitamura Katsumi Akanuma Masaharu Yokota Hiroyuki Sugihara Atsushi Morimoto 《Electrical Engineering in Japan》2008,164(1):21-33
An advanced method of analysis for grid‐connected PV systems is developed in this research. To investigate the issues which may arise in the clustered PV systems, a “Demonstration Project on Clustered PV Systems” was initiated in December 2002 in Oota, Japan, involving the installation of more than 500 residential PV systems in the demonstrative research area, and the development of battery‐integrated PV systems to avoid restrictions on output power due to the raising of the grid voltage. The annual performance of commercial PV systems without battery was analyzed and a performance ratio of 80% on average was found to have been achieved. Overvoltage of power distribution lines and snow are two major factors capable of causing very low performance ratio on a daily basis. The effects of batteries have also been analyzed, and the results indicate that there will be some reduction of energy losses due to the grid voltage, but the PCS efficiency will be at least 8% worse than that of commercial PV systems. It was also found that nonoptimized battery operation sometimes results in a fully charged situation at noontime and maximum reverse power flow may not be minimized in this situation. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 21–33, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20660 相似文献
938.
Katsumi Kushiya 《Solar Energy Materials & Solar Cells》2009,93(6-7):1037-1041
In a large-area approach up to 60 cm×120 cm size, monolithically integrated CIS-based thin-film PV modules have come to the efficiency level of 13%. The key near-term R&D issues to realize continuous improvement in CIS-based thin-film PV modules are related to their competitiveness against the crystalline-Si PV modules. In this contribution, the following three issues are discussed. The first and main issue is how important it is to understand the interfaces in the CIS-based thin-film circuit to improve the efficiency, because CIS-based thin-film circuits are fabricated in a stacked structure of four or five thin films. The second and third issues are how beneficial it is to develop the packaging and material recycle technologies in order to reduce the production cost. 相似文献
939.
Yuzuru Ueda Kosuke Kurokawa Kiyoyuki Kitamura Masaharu Yokota Katsumi Akanuma Hiroyuki Sugihara 《Solar Energy Materials & Solar Cells》2009,93(6-7):945-949
Performance and loss analysis of residential photovoltaic (PV) systems are conducted using the sophisticated verification (SV) method. Performance of the various system configurations is quantitatively analyzed and compared in this paper. The south-oriented systems have approximately 22% more reference yield than the systems that are not oriented south. Difference of the module manufacturers shows more than 10% differences of the performance ratio whereas array configuration shows less difference. Imbalance of the string voltages causes system peak power loss and MPP mismatch. This loss cannot be minimized by the DC/DC converter in most of the systems. 相似文献
940.
A zero‐bias‐current self‐sensing active magnetic bearing is proposed. One degree‐of‐freedom (DOF) of the rotor is controlled by a pair of electromagnets which are alternatively energized by the proposed circuit. The rotor position of the one DOF is measured by using both electromagnets: the nonenergized electromagnet also contributes to the position sensing. The proposed method gives good linearity in the position estimation. The controller of the magnetic levitation consists of a digital signal processor, DSP, which compensates the nonlinearity of the magnetic force and achieves good damping. In the experiment, the rotor can run at 45,000 min‐1. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(2): 69–76, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20616 相似文献