全文获取类型
收费全文 | 1750篇 |
免费 | 56篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 90篇 |
化学工业 | 457篇 |
金属工艺 | 43篇 |
机械仪表 | 44篇 |
建筑科学 | 27篇 |
能源动力 | 63篇 |
轻工业 | 167篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 143篇 |
一般工业技术 | 369篇 |
冶金工业 | 222篇 |
原子能技术 | 50篇 |
自动化技术 | 131篇 |
出版年
2023年 | 14篇 |
2022年 | 23篇 |
2021年 | 34篇 |
2020年 | 26篇 |
2019年 | 23篇 |
2018年 | 26篇 |
2017年 | 27篇 |
2016年 | 34篇 |
2015年 | 34篇 |
2014年 | 65篇 |
2013年 | 117篇 |
2012年 | 69篇 |
2011年 | 128篇 |
2010年 | 97篇 |
2009年 | 59篇 |
2008年 | 81篇 |
2007年 | 80篇 |
2006年 | 48篇 |
2005年 | 69篇 |
2004年 | 80篇 |
2003年 | 54篇 |
2002年 | 51篇 |
2001年 | 35篇 |
2000年 | 46篇 |
1999年 | 20篇 |
1998年 | 101篇 |
1997年 | 63篇 |
1996年 | 46篇 |
1995年 | 33篇 |
1994年 | 25篇 |
1993年 | 23篇 |
1992年 | 10篇 |
1991年 | 15篇 |
1990年 | 16篇 |
1989年 | 24篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 14篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1979年 | 9篇 |
1977年 | 7篇 |
1976年 | 11篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 2篇 |
排序方式: 共有1812条查询结果,搜索用时 15 毫秒
1.
Tsuneaki Matsudaira Masashi Wada Naoki Kawashima Miyuki Takeuchi Daisaku Yokoe Takeharu Kato Masasuke Takata Satoshi Kitaoka 《Journal of the European Ceramic Society》2021,41(5):3150-3160
Mass transfer in polycrystalline Yb2SiO5 wafers with precise composition control was evaluated and analyzed by oxygen permeation experiments at high temperatures using an oxygen tracer. Oxygen permeation proceeded due to mutual grain boundary diffusion of oxide ions and Yb ions without synergistic effects such as acceleration or suppression. The oxygen shielding properties of Yb2SiO5 were compared with those of the other line compounds such as Yb2Si2O7 and Al2O3 based on the determined mass transfer parameters. It was found that the more preferentially an oxide ion diffuses in the grain boundary compared to the interior of the grain, the greater the effect of suppressing the movement of the oxide ion by applying an oxygen potential gradient becomes. 相似文献
2.
Hideaki Kaneto Tomohiko Kimura Atsushi Obata Masashi Shimoda Kohei Kaku 《International journal of molecular sciences》2021,22(5)
While there are various kinds of drugs for type 2 diabetes mellitus at present, in this review article, we focus on metformin which is an insulin sensitizer and is often used as a first-choice drug worldwide. Metformin mainly activates adenosine monophosphate-activated protein kinase (AMPK) in the liver which leads to suppression of fatty acid synthesis and gluconeogenesis. Metformin activates AMPK in skeletal muscle as well, which increases translocation of glucose transporter 4 to the cell membrane and thereby increases glucose uptake. Further, metformin suppresses glucagon signaling in the liver by suppressing adenylate cyclase which leads to suppression of gluconeogenesis. In addition, metformin reduces autophagy failure observed in pancreatic β-cells under diabetic conditions. Furthermore, it is known that metformin alters the gut microbiome and facilitates the transport of glucose from the circulation into excrement. It is also known that metformin reduces food intake and lowers body weight by increasing circulating levels of the peptide hormone growth/differentiation factor 15 (GDF15). Furthermore, much attention has been drawn to the fact that the frequency of various cancers is lower in subjects taking metformin. Metformin suppresses the mechanistic target of rapamycin (mTOR) by activating AMPK in pre-neoplastic cells, which leads to suppression of cell growth and an increase in apoptosis in pre-neoplastic cells. It has been shown recently that metformin consumption potentially influences the mortality in patients with type 2 diabetes mellitus and coronavirus infectious disease (COVID-19). Taken together, metformin is an old drug, but multifaceted mechanisms of action of metformin have been unraveled one after another in its long history. 相似文献
3.
Machine Learning - We consider the problem of learning a binary classifier from only positive and unlabeled observations (called PU learning). Recent studies in PU learning have shown superior... 相似文献
4.
Atsushi Narumi Kosei Kawasaki Harumi Kaga Toshifumi Satoh Naoya Sugimoto Toyoji Kakuchi 《Polymer Bulletin》2003,49(6):405-410
Summary
The potato phosphorylase-catalyzed polymerization of α-D-glucose-1-phosphate (G-1-P) onto poly[styrene-block-(4-vinylbenzyl maltohexaoside)] (1) was performed at the molar ratios of [G-l-P]0 and [maltohexaose]0 of 35, 80, and 250. The product was found to be soluble in dimethyl sulfoxide, which was a good solvent for amylose, and
showed the complex-formation with iodine, indicating that the product was assignable to poly[styrene-block-(styrene-graft-amylose)] (2). The quantitative analysis of the liberated phosphoric acid gave the average degree of polymerization o f the glucose unit
(n) as 27, 5 1, and 180 for 2-I, 2-II, and 2-III, respectively.
Received: 29 November 2002/Accepted: 22 December 2002
Correspondence to Toyoji Kakuchi 相似文献
5.
We derive a linear correspondence between the variables of an encoder and those of a corresponding syndrome former. Using the derived correspondence, we show that the log-likelihood ratio of an information bit conditioned on a received sequence can be equally calculated using the syndrome trellis. It is shown that the proposed method also applies to recursive systematic convolutional codes which are typical constituent codes for turbo codes. Moreover, we show that soft-in syndrome decoding considering a priori probabilities of information bits is possible in the same way as for Viterbi decoding based on the code trellis. Hence, the proposed method can be applied to iterative decoding such as turbo decoding. We also show that the proposed method is effective for high-rate codes by making use of trellis modification. 相似文献
6.
M. Kawasaki T. Tsukamoto Y. Kimura T. Iwasaki H. Yamane 《Journal of Materials Science》2003,38(4):739-745
The damage imposed on SiO
x
deposited nylon 6 films as a result of abrasion with a cotton cloth and Gelboflex testing was examined by evaluating the rate at which copper plates, which were enveloped by the damaged films, were corroded by H2S. Abrasion with a cotton cloth caused some micro-cracking of the SiO
x
layer and the permeation rate of H2S approached that of the uncoated nylon 6 film. Damage to the SiO
x
layer by twisting and crushing progressed gradually with the number of Gelboflex test cycles and correspondingly the corrosion rate of the copper plates increased. Comparison of the corrosion rates of the copper plates kept in the pouches made of various commercial films with those obtained for the damaged SiO
x
deposited nylon 6 films showed a clear relationship between the H2 permeation rate of the films and the corrosion rate of the copper plates by H2S. 相似文献
7.
Improved visible-light responsive photocatalytic activity of N and Si co-doped titanias 总被引:1,自引:0,他引:1
Thermal reaction of titanium tetraisopropoxide and tetraethyl orthosilicate in 1,4-butanediol afforded nanocrystalline silica-modified
titanias having large surface area and superior thermal stability. In this study, the thus-obtained silica-modified titanias
were treated in an NH3 flow at high temperatures, and their physical and photocatalytic properties were investigated. Compared with NH3-treated TiO2 without silica modification, the NH3-treated silica-modified titanias showed a stronger absorption in the visible region (400–500 nm) and had a larger peak at
396 eV in the N 1s XPS spectrum. These results indicate that a larger amount of nitrogen was stably doped in the silica-modified
titania. The obtained products exhibited a high photocatalytic activity for degradation of Rhodamine B and decomposition of
acetaldehyde under visible light irradiation.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
8.
Hideo Sawada Hiroshi Kakehi Masashi Koizumi Yoshihiro Katoh Masashi Miura 《Journal of Materials Science》2007,42(17):7147-7153
Fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomer [RF-(DOBAA)
n
-RF] reacted with tetraethoxysilane (TEOS) and silica nanoparticles in the presence of low-molecular weight biocides such as
hibitane, hinokitiol, and hinokioil under alkaline conditions to afford RF-(DOBAA)
n
-RF/silica nanocomposites-encapsulated these biocides in excellent to moderate isolated yields. Fluoroalkyl end-capped N,N-dimethylacrylamide oligomer [RF-(DMAA)
n
-RF] and acrylic acid oligomer [RF-(ACA)
n
-RF]/silica nanocomposites-encapsulated hibitane were obtained under similar conditions. Dynamic light scattering measurements
showed that the size of these fluorinated nanocomposites-encapsulated biocides thus obtained is nanometer size-controlled.
Additionally, these fluorinated nanocomposites were shown to have a good dispersibility and stability in methanol and water.
Of particular interest, these fluorinated nanocomposites-encapsulated biocides were found to have a good antibacterial activity
against Staphylococcus aureus, and these nanocomposites were applied to the surface modification of traditional organic polymers such as poly(methyl methacrylate). 相似文献
9.
Masashi Morishita 《Journal of Low Temperature Physics》2007,148(5-6):761-765
Heat capacities of a submonolayer 3He solid film adsorbed on a graphite surface are measured in magnetic fields up to 400 Oe. The measured heat capacity shifts
to higher temperatures with an increasing magnetic field. The amplitudes of the shifts are twenty times larger than the magnitude
of the Zeeman energy, which is anomalously large. With regard to the origin of these large shifts, the reduction of frustrations
and the weakening of the competition between multiple spin exchange interactions are discussed. 相似文献
10.
Expansion and stress relaxation of expressed cake are discussed.
The expansion process of expressed cake after release of load is very similar to consolidation of solidndashliquid mixtures, although a liquid flow in the expansion process is opposite in direction to that in consolidalion. This process can be analyzed well by use of the Terzaghi Voigt combined model. It is shown that the rate of primary deformation in expansion is much smaller than that in consolidation under the same change in compressive pressure. It is also found that the ratio of secondary deformation to total deformation in expansion is much larger than that in consolidation.
Stress relaxation of expressed cake, which is observed when expression is stopped before attaining an equilibrium compression state of a material, can be explained by use of a consolidation and expansion theory. In the relaxation process, local expansion appears near the drainage surface while local consolndash idation appears near the center of the cake. The equilibrium cake stress is uniquely determined by the average consolidation ratio when the expression is interrupted. 相似文献
The expansion process of expressed cake after release of load is very similar to consolidation of solidndashliquid mixtures, although a liquid flow in the expansion process is opposite in direction to that in consolidalion. This process can be analyzed well by use of the Terzaghi Voigt combined model. It is shown that the rate of primary deformation in expansion is much smaller than that in consolidation under the same change in compressive pressure. It is also found that the ratio of secondary deformation to total deformation in expansion is much larger than that in consolidation.
Stress relaxation of expressed cake, which is observed when expression is stopped before attaining an equilibrium compression state of a material, can be explained by use of a consolidation and expansion theory. In the relaxation process, local expansion appears near the drainage surface while local consolndash idation appears near the center of the cake. The equilibrium cake stress is uniquely determined by the average consolidation ratio when the expression is interrupted. 相似文献