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排序方式: 共有807条查询结果,搜索用时 15 毫秒
191.
192.
A simple treatment of increased gap due to fuel assembly bowing through correction of cross sections
Akio Yamamoto Tomohiro Endo Hiroaki Nagano Yasunori Ohoka Kento Yamamoto 《Journal of Nuclear Science and Technology》2019,56(6):471-478
Increased fuel assembly gap due to bowing in commercial light-water reactors (LWRs) has an impact on local pin-power distribution due to increased local moderation. In order to consider the effect of increased assembly gap without explicit consideration of increased gap width, a correction method of cross sections in the gap region is proposed. In this cross section correction method, the average chord length of gap region is preserved to capture the effect of increased gap width. The validity of the present method is confirmed by verification calculations in a single assembly and 5 × 5 assembly geometries using the GENESIS code, which is a transport code based on the method of characteristics. 相似文献
193.
The dynamic shear strength of rocks is required for the earthquake-resistant design of nuclear power plants in Japan.This research aims to propose a mathematical model for estimating the dynamic strength and to validate the model.Two different types of specimens were prepared for the model validation,and the monotonic and cyclic loading tests were conducted to obtain the mathematical model parameters.Subsequently,multistep cyclic loading tests were performed,followed by simulations using the mathematical model.The test results demonstrated that the dynamic shear strength exceeded the static shear strength,which agreed with previous researches.Furthermore,the dynamic shear strength calculated using the mathematical model was generally consistent with that obtained from the experimental data. 相似文献
194.
195.
Koji Takahashi Satoshi TsunoiTakumi Hara Tomohiro UenoAkira Mikami Hajime TakadaKotoji Ando Masaki Shiratori 《International Journal of Pressure Vessels and Piping》2010
Low-cycle fatigue tests were conducted using elbow specimens with local wall thinning. Local wall thinning was machined on the inside of the elbow in order to simulate metal loss from erosion corrosion. The local wall thinning was located in three different areas known as the extrados, crown and intrados. The elbow specimens were subjected to cyclic in-plane bending under displacement control without internal pressure. In addition, three-dimensional elastic-plastic analyses were also carried out using the finite element method. As a result, the crack penetration area and the crack growth direction were successfully predicted by the analyses. The fatigue lives estimated by the analyses were close to those obtained by the experiments. 相似文献
196.
Chunyu Zhu Haruya Hayashi Itoko Saita Tomohiro Akiyama 《International Journal of Hydrogen Energy》2009,34(17):7283
This paper describes the direct synthesis of magnesium hydride (MgH2) nanofibers by hydriding chemical vapor deposition (HCVD), in which the effect of hydrogen pressure on the production rate, the composition and the shape of products obtained were examined by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET). The XRD patterns showed that the main product in each case was MgH2; in particular, the products formed at 2, 3 and 4 MPa were highly pure. In contrast, at a hydrogen pressure of 1 MPa, unhydrided Mg was deposited along with MgH2. The SEM images also revealed orientation of the as-deposited products; higher pressures of 3 and 4 MPa caused the formation of straight and curved nanofibers, and lower ones of 1 and 2 MPa, highly curved nanofibers and nanorods with a few straight nanofibers. With pressurizing hydrogen, not only the BET specific surface areas of the products but also the production rate increased. The results also appealed that HCVD could control the shape/size of MgH2 nanofibers by changing the pressure via only a single operation. 相似文献
197.
Tomohiro Morohoshi Yusuke Yokoyama Mieko Ouchi Norihiro Kato Tsukasa Ikeda 《Journal of Bioscience and Bioengineering》2009,108(4):314-318
Edwardsiella tarda is a gram-negative bacterial pathogen of fish and animals. A number of gram-negative bacteria have quorum-sensing systems and produce N-acylhomoserine lactone (AHL) that they use as a quorum-sensing signaling molecule. We have already reported that E. tarda NUF251 produces AHLs and has the AHL-synthase gene, edwI. Inactivation of NUF251 edwI induces expression of an approximately 45 kDa extracellular protein, identified as a flagellin encoded by FliC. Mutation of edwI also changes the motility pattern of NUF251 from a radial expansion pattern to concentric rings. The addition of exogenous AHL was capable of restoring normal motility to NUF251 edwI mutants. These results demonstrate that quorum sensing negatively regulates motility and expression of the FliC protein. 相似文献
198.
Shipra Chauhan Toshiyuki Mori Tomohiro Kobayashi Shunya Yamamoto Shigeharu Ito Graeme Auchterlonie Roger Wepf Shigenori Ueda Fei Ye 《Journal of the American Ceramic Society》2021,104(5):1945-1952
To develop the state-of-the-art polymer membrane fuel cells. Both maximization of oxygen reduction reaction (ORR) activity on Pt cathode and minimization of Pt content in the cathode are required. For this challenge, the defect interface on oxide support was modified by proton beam irradiation method. Pt-CeOx nanowire/C (Pt/C = 0.02) was fabricated using the proton beam irradiation method. Since the radical density generated by proton beam irradiation is two orders of magnitude greater than that of electron beam irradiation, the CeOx nanowire surface was fully converted to a thin layer of Pt-O-Ce bonds under proton beam irradiation. The ORR activity observed for fabricated sample with above active surface layer was higher than that of conventional Pt/C (Pt/C = 0.2) and comparable to that of Pt-CeOx nanowire/C (Pt/C = 0.2) fabricated by conventional methods. From the combination of microanalysis characterization and surface atomistic simulation, we concluded that the Pt-O-Ce bond was formed on defect-rich regions of the CeOx nanowire and this leads to a maximized ORR activity on the fabricated sample. Based on all experimental data, it is concluded that the surface modification of CeOx nanowire support using proton beam irradiation is useful for a lowering the Pt content of the cathode with high ORR activity. 相似文献
199.
Akiyoshi Kamura Go Kurihara Tomohiro Mori Motoki Kazama Youngcheul Kwon Jongkwan Kim Jin-Tae Han 《Soils and Foundations》2021,61(3):658-674
This study presents a new approach to determine the damage degree of liquefaction caused by a large earthquake. We propose an artificial neural network (ANN) model based only on the seismic records of ground and define the degree of liquefaction “DDL” as a damage index. This ANN model predicts the degree of excess pore water pressure increase as the correct output label based on the seismic records obtained from the three-dimensional shaking table test. The proposed model achieved high accuracy, and the outcomes from training data indicated that the ANN model is suitable to function as a liquefaction assessment system. Further, to evaluate the applicability of the proposed ANN model in the real world, the datasets of waves from three actual seismic records were input to the ANN as validation data. The DDL judgment obtained was a good fit with the real phenomena observed. 相似文献
200.