全文获取类型
收费全文 | 252篇 |
免费 | 9篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 23篇 |
化学工业 | 61篇 |
金属工艺 | 4篇 |
机械仪表 | 4篇 |
建筑科学 | 6篇 |
能源动力 | 14篇 |
轻工业 | 32篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 19篇 |
一般工业技术 | 33篇 |
冶金工业 | 26篇 |
自动化技术 | 37篇 |
出版年
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 10篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 12篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 9篇 |
2014年 | 15篇 |
2013年 | 14篇 |
2012年 | 20篇 |
2011年 | 23篇 |
2010年 | 12篇 |
2009年 | 19篇 |
2008年 | 9篇 |
2007年 | 7篇 |
2006年 | 11篇 |
2005年 | 5篇 |
2004年 | 7篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有262条查询结果,搜索用时 31 毫秒
101.
Ahti Jaatinen-Värri Pekka Röyttä Teemu Turunen-Saaresti Aki Grönman 《Journal of Mechanical Science and Technology》2013,27(4):1011-1020
Seven different vaneless diffuser designs for a centrifugal compressor, varying only in diffuser width, were studied experimentally. The studied diffuser widths versus impeller exit width were 1.0, 0.903, 0.854, and 0.806. Three of the narrowed diffusers had the width reduced from the hub and shroud divided evenly, and the three others had the width reduced only from the shroud. The total and static pressures, the total temperature and the flow angles at the diffuser inlet and outlet were measured at the design rotational speed with three different mass flows. The impeller and diffuser performance was studied along with the axial distributions of flow angles and velocities in the diffuser. The results revealed that the pinch improved the compressor stage and impeller performance but deteriorated the diffuser performance. The pinch clearly decreased the secondary flow region present near the shroud. The pinch implemented in the shroud is more beneficial than pinch divided between the hub and the shroud. In order to obtain the beneficial effects of pinch, the pinch should be sufficient. However, excessive pinch deteriorates the compressor performance. 相似文献
102.
Koji Yonehara Yasuyuki Miyoshi Aki Tsukajima Takeo Akatsuka Makoto Saito 《Advanced Synthesis \u0026amp; Catalysis》2011,353(7):1071-1075
The methodology in this article is a palladium(II)/copper(II)‐ or palladium(II)‐catalyzed intermolecular cyclization of acrylic acid with alkenes to produce α‐methylene‐γ‐butyrolactone derivatives using molecular oxygen as an environmentally benign oxidant. In this system, the carboxylato, especially trifluoroacetato, or trimethylacetato ligand, plays a quite important role to afford a high catalytic activity by suppressing the deposition of palladium(0) black. 相似文献
103.
Takashi Onishi Masao Mizuno Tetsuya Yoshikawa Jun Munemasa Takao Inoue Aki Miyagaki Hisashi Nakamoto 《Journal of Electronic Materials》2010,39(10):2255-2266
The behavior of void growth in ultra-large-scale integration Cu interconnections has been investigated by grain-boundary diffusion
simulation to confirm the effectiveness of the high-pressure reflow process for suppressing stress-induced voiding. Void growth
was simulated by combining stress analysis and atomic flux analysis. The former was calculated by the finite-element method
(FEM), and the latter was calculated by an unusual FEM in which grain boundaries were defined as elements. From the results
of void growth analysis, we found that voids tend to disappear during the isochronal annealing step and that the void shrinkage
rate can be increased by two to three times by applying pressure of 150 MPa compared with normal-pressure annealing. From
the simulation results, it can be conjectured that the high-pressure reflow process is effective for eliminating voids in
via holes of Cu interconnections. 相似文献
104.
Takashi Onishi Masao Mizuno Tetsuya Yoshikawa Jun Munemasa Takao Inoue Aki Miyagaki Hisashi Nakamoto Takayuki Onoda 《Journal of Electronic Materials》2010,39(3):318-325
The reflow phenomenon of Cu interconnections deposited over via holes was analyzed by viscoelastic deformation simulation
using a finite-element method to clarify the embedding mechanism of Cu interconnections into via holes in a novel dual-damascene
fabrication technology, which combined sputter deposition and high-pressure annealing. Cu is considered to be a viscoelastic
body, and the stress distribution and deformation behavior of Cu interconnections were calculated. As a result, the deformation
behavior of the Cu interconnections exhibited close agreement between the calculated and the observed values. From our series
of results, we inferred that Cu interconnections are embedded into via holes by the creep deformation mechanism defined in
this study during the high-pressure annealing process. 相似文献
105.
Hirohisa Aki Ichiro Sugimoto Tokuyoshi Sugai Masahisa Toda Masahiro Kobayashi Masayoshi Ishida 《International Journal of Hydrogen Energy》2018,43(32):14892-14904
As the popularity of fuel cell vehicles continues to rise in the global market, production and supply of low-carbon hydrogen are important to mitigate CO2 emissions. We propose a design for a hydrogen refueling station with a proton exchange membrane electrolyzer (PEM-EL)-based electrolysis system (EL-System) and photovoltaic generation (PV) to supply low-carbon hydrogen. Hydrogen is produced by the EL-System using electricity from PV and the power grid. The system was formulated as a mixed integer linear programming (MILP) model to allow analysis of optimal operational strategies. Case studies with different objective functions, CO2 emission targets, and capacity utilization of the EL-System were evaluated. Efficiency characteristics of the EL-System were obtained through measurements. The optimized operational strategies were evaluated with reference to three evaluation indices: CO2 emissions, capacity utilization, and operational cost of the system. The results were as follows: 1) Regardless of the objective function, the EL-System generally operated in highest efficiency state, and optimal operation depended on the efficiency characteristics of the EL-System; 2) mitigation of CO2 emissions and increase in capacity utilization of the EL-System required trade-offs; and 3) increased capacity utilization of the EL-System showed two opposing effects on hydrogen retail price. 相似文献
106.
Kawamoto S Aki T Yamashita M Tategaki A Fujimura T Tsuboi S Katsutani T Suzuki O Shigeta S Murooka Y Ono K 《Journal of Bioscience and Bioengineering》2002,94(4):285-298
Our research has focused on the molecular design of immunotherapeutic vaccines and the advancement of mite-allergy diagnosis. Here, we describe the research history of the major group 1 and group 2 allergens, immunoelectrophoretic analyses covering the complete spectrum of mite allergens, our results on allergens with distinctive characteristics (a conjunctival congestion-eliciting antigen [LM2], an immunotherapeutic antigen [HM2] with high efficacy and without definite adverse reactions, and a potent T-cell stimulatory antigen [HM1] with secretion of IFN-gamma), the full spectrum and immunochemical properties of the major and other important mite allergens (including our newly described allergens: a pan-allergen [tropomyosin, group 10], a potent T-cell stimulatory allergen [M-177, apolipophorin, group 14] and its peptide fragments Mag1 and Mag3, a moderate IgE-binding allergen [gelsolin/villin, group 16], an EF-hand Ca2+-binding allergen [group 17], and a less IgE-binding allergen [heat shock protein 70]), and prospects for the development of immunotherapeutic and diagnostic agents. 相似文献
107.
A voltage rise problem in distribution networks has been discussed as the foremost concern with respect to the spread of large numbers of photovoltaic systems. We focus on the latent ability of the present distribution network and photovoltaic systems to find a low‐cost solution to the problem and consider a solution to mitigate the voltage rise using the photovoltaic system's constant leading power factor operation. Previously, based on simulations using an aggregated model of a real distribution network, we proposed that a combination of a photovoltaic system's constant leading power factor operation and LDC makes it possible to maintain the line voltage and LTC tap position adequately. In this paper, additionally, we confirm some effects of the proposed method in an aggregated model of a distribution network and a trunk power system. One of them is that the proposed method reduces the frequency of restricting output power from photovoltaic systems and changing the LTC and SVR tap position, although photovoltaic systems rapidly fluctuate. Another is that the proposed method cannot make a significant impact on a trunk power system in a voltage class exceeding 6.6 kV. 相似文献
108.
Tsunehiro Aki Masaya Yamamoto Toshiaki Takahashi Kohki Tomita Rieko Toyoura Kazuhiro Iwashita Seiji Kawamoto Masashi Hosokawa Kazuo Miyashita Kazuhisa Ono 《Lipids》2014,49(2):133-141
The effects of a seaweed carotenoid, fucoxanthin, and its physiological metabolite, fucoxanthinol, on the biosynthesis of polyunsaturated fatty acids (PUFA) were investigated using cultured rat hepatoma BRL‐3A. The metabolism of α‐linolenic acid (18:3n‐3) was suppressed by the addition of these carotenoids, resulting in a decrease in the content of eicosapentaenoic acid (20:5n‐3), which suggested a down‐regulation of metabolic enzymes such as fatty acid desaturase and elongase. An increase in the content of docosahexaenoic acid (22:6n‐3), as observed in previous studies in vivo, might be a buffering action to maintain the membrane fluidity. The suppressive effect of fucoxanthinol on ?6 fatty acid desaturase was not at the level of gene expression but due to specific modifications of the protein via a ubiquitin–proteasome system. A proteomic analysis revealed several factors such as phosphatidylethanolamine‐binding protein that might be involved in the observed action of fucoxanthin. These findings will contribute to studies on the elucidation of the precise molecular mechanisms underlying the regulation of PUFA biosynthesis by fucoxanthin. 相似文献
109.
Drago Bokal Matt DeVosSandi Klav?ar Aki Mimoto Arne Ø. Mooers 《Computers & Mathematics with Applications》2011,62(10):3821-3828
We note here that quadratic entropy, a measure of biological diversity introduced by C.R. Rao, is a variant of the weighted Wiener index, a graph invariant intensively studied in mathematical chemistry. This fact allows us to deduce some efficient algorithms for computing the quadratic entropy in the case of given tip weights, which may be useful for community biodiversity measures. Furthermore, on ultrametric phylogenetic trees, the maximum of quadratic entropy is a measure of pairwise evolutionary distinctness in conservation biology, introduced by S. Pavoine. We present an algorithm that maximizes this quantity in linear time, offering a significant improvement over the currently used quadratic programming approaches. 相似文献
110.
Yasutaka Nagai Takashi Yamamoto Tsunehiro Tanaka Satohiro Yoshida Takamasa Nonaka Tokuhiko Okamoto Akihiko Suda Masahiro Sugiura 《Topics in Catalysis》2008,47(3-4):137-147
Three types of CeO2–ZrO2 (Ce:Zr = 1:1 molar ratio) compounds with different oxygen storage/release capacity (OSC) were characterized by means of the
Ce K-edge and Zr K-edge XAFS. In order to investigate the relationship between the OSC and local structure, the quantitative
EXAFS curve-fitting analysis was applied. By enhancing the homogeneity of the Ce and Zr atoms in the CeO2–ZrO2 solid solution, the OSC performance increased. Additionally, from the XRD analysis, the homogeneous CeO2–ZrO2 solid solution has an ordered cation arrangement, and exhibits the highest OSC. The crystal structure of this CeO2–ZrO2 solid solution is usually termed as “κ-CeZrO4 phase”. However, the OSC performance of κ-CeZrO4 degrades upon a high-temperature treatment under an oxidative atmosphere. The fresh κ-CeZrO4 was aged at 973, 1,273 and 1,473 K under an oxidative atmosphere, respectively. The OSC performance deteriorated as: the
fresh sample ≈973 > 1,273 > 1,473 K-aged samples. We also found that, if the temperature was beyond 1,273 K, the Ce/Zr ordered
arrangement would collapse and the local structure around Ce and Zr ions would also changed remarkably. These results indicated
that OSC was strongly dependent on its atomic structure. 相似文献