全文获取类型
收费全文 | 619篇 |
免费 | 19篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 42篇 |
综合类 | 1篇 |
化学工业 | 139篇 |
金属工艺 | 16篇 |
机械仪表 | 14篇 |
建筑科学 | 7篇 |
能源动力 | 22篇 |
轻工业 | 38篇 |
石油天然气 | 2篇 |
无线电 | 72篇 |
一般工业技术 | 113篇 |
冶金工业 | 104篇 |
原子能技术 | 22篇 |
自动化技术 | 50篇 |
出版年
2023年 | 5篇 |
2022年 | 11篇 |
2021年 | 17篇 |
2020年 | 10篇 |
2019年 | 6篇 |
2018年 | 18篇 |
2017年 | 9篇 |
2016年 | 17篇 |
2015年 | 9篇 |
2014年 | 17篇 |
2013年 | 37篇 |
2012年 | 21篇 |
2011年 | 30篇 |
2010年 | 24篇 |
2009年 | 23篇 |
2008年 | 33篇 |
2007年 | 20篇 |
2006年 | 14篇 |
2005年 | 23篇 |
2004年 | 20篇 |
2003年 | 21篇 |
2002年 | 16篇 |
2001年 | 9篇 |
2000年 | 12篇 |
1999年 | 17篇 |
1998年 | 50篇 |
1997年 | 30篇 |
1996年 | 23篇 |
1995年 | 9篇 |
1994年 | 9篇 |
1993年 | 13篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1973年 | 4篇 |
1967年 | 1篇 |
排序方式: 共有642条查询结果,搜索用时 15 毫秒
51.
K. Obayashi K. Kurihara Y. Okano H. Masaki D. B. Yarosh† 《International journal of cosmetic science》2005,27(3):191-191
The hair lipid composition collected from 44 Japanese females between 1 and 81 years of age was examined for eight lipids including hydrocarbons (HCs), squalene (SQ), wax esters (WEs), triglycerides (TGs), fatty acids (FAs), cholesterol (CH), ceramides (CERs), and 18-methyl eicosanoic acid (MEA). In this study, the 5-cm length from the proximal root end of hair fibers, which had never been exposed to any chemical treatment, was used after 5-min incubation with hexane following shampooing. Hair lipids were extracted with solvent and subsequent alkali-solvent and were then analyzed by a combination of chromatography. Although the average contents of the lipids showed great fluctuations among individuals, there were significant correlations between the levels of each lipid, which allowed for the classification of the hair lipids into four groups: group A: SQ, WEs, TGs, and FAs (designated as endogenous lipids based upon their sebum origin); group B: CH and CERs (designated as endogenous lipids); group C: HC (unknown origin); and group D: MEA (the other endogenous lipid). A principal component analysis for eight lipids revealed that the hair lipid composition was characterized by a predominant negative correlation between each lipid for groups A and B. This negative correlation suggests that the endogenous lipids in group B serve as a barrier against the penetration of predominantly sebum-derived exogenous lipids (group A). Endogenous lipids consisting of CH and CERs (group B) and MEA (group D) should be designated as intrinsic internal lipids of human hair. 相似文献
52.
Takatoshi Shindo Hideki Motoyama Toru Miki Mikihisa Saito Akiyori Matsueda Noriyasu Honma Tomohito Hida Kazuo Shinjo Kiyotaka Hayashi Hayato Awazu Katsuhisa Makabe Masato Fujikawa Satoshi Kurihara Masashi Sato 《IEEJ Transactions on Electrical and Electronic Engineering》2016,11(Z2):S28-S33
Nine electric power companies in Japan have been collecting lightning data with lightning location systems. Five years of the lightning data (2009–2013) are summarized and analyzed in this paper. The recent annual number of lightning flashes of which the current is more than 10 kA in Japan is around 1 million. The variations of lightning occurrence characteristics by areas, seasons, and so on, are clarified. Meteorological conditions that may affect lightning occurrence are also discussed. Furthermore, we show that there is a clear correlation between the number of lightning strikes and the outage rate of transmission lines. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
53.
Ooki Kurihara Takashi Tsuchida Genki Takahashi Gyeong-o Kang Hiroki Murakami 《Soils and Foundations》2018,58(5):1173-1186
Great amounts of soil and waste contaminated with radioactive cesium have been generated due to the decontamination work after the Fukushima Daiichi Nuclear Power Plant accident. The aim of this study is to develop a sealing geomaterial for use at the disposal facilities of the soil and waste constructed in the maritime environment. The geomaterial consists of marine clay, bentonite, and zeolite. The hydraulic conductivity and cesium-adsorption performance of the geomaterial were examined through laboratory tests with different proportions of bentonite and zeolite added to marine clay. It was concluded that the hydraulic conductivity could be reduced to the required level by increasing the amount of bentonite and that the cesium-adsorption capacity could be enhanced by increasing the amount of zeolite. 相似文献
54.
Tomoki Higa 《Polymer》2010,51(23):5576-5584
The crystal orientation of poly(?-caprolactone) (PCL) blocks in PCL-block-polyethylene (PE) copolymers has been investigated using two-dimensional small-angle X-ray scattering (2D-SAXS) and 2D wide-angle X-ray diffraction (2D-WAXD) as a function of crystallization temperature Tc and thickness of PCL layers dPCL. The PCL blocks were spatially confined in the solid lamellar morphology formed by the crystallization of PE blocks (PE lamellar morphology), an alternating structure of crystallized PE lamellae and amorphous PCL layers. This confinement is expected to be intermediate between hard confinement by glassy lamellar microdomains and soft confinement by rubbery ones, because the crystallized PE lamellae consist of hard PE crystals covered with amorphous (or soft) PE blocks. The 2D-SAXS results showed uniaxial orientation of the PE lamellar morphology after applying the rotational shear to the sample. Therefore, it was possible to investigate crystal orientation of PCL blocks within the oriented PE lamellar morphology. The 2D-WAXD results revealed that the c axis of PCL crystals (i.e., stem direction of PCL chains) was parallel to the lamellar surface normal irrespective of Tc when 16.5 nm ≥ dPCL ≥ 10.7 nm. However, it changed significantly with changing Tc when dPCL = 8.8 nm; the c axis was perpendicular to the lamellar surface normal at 45 °C ≥ Tc ≥ 25 °C while it was almost random at 20 °C ≥ Tc ≥ 0 °C. These results suggest that the PE lamellar morphology plays a similar role to glassy lamellar microdomains regarding spatial confinement against subsequent PCL crystallization. 相似文献
55.
Shinya Higashimoto Kohei Okada Tomoki Morisugi Masashi Azuma Hiroyoshi Ohue Tae-Ho Kim Masaya Matsuoka Masakazu Anpo 《Topics in Catalysis》2010,53(7-10):578-583
The photocatalytic oxidation of benzyl alcohol into benzaldehyde proceeded with high conversion and selectivity on a TiO2 photocatalyst by O2 under visible light irradiation. Surface complex formed by the interaction of benzyl alcohol with the Ti sites and/or surface OH groups of TiO2 play an important role in the absorption of visible light and unique selective photocatalytic reaction. 相似文献
56.
Kohei Urasaki Ken-ichiro Endo Tomoki Takahiro Ryuji Kikuchi Toshinori Kojima Shigeo Satokawa 《Topics in Catalysis》2010,53(7-10):707-711
Selective methanation of CO in the reformate gas (CO/CO2/H2/H2O = 0.175/17.9/70.9/11.1) proceeded over Ru catalysts supported on metal oxides and zeolites. CO was selectively methanated at wide temperature ranges (200–275 °C) over Ru/γ-Al2O3, Ru/TiO2 Ru/H-Y and Ru/H-beta catalysts. Higher Ru contents in Ru/γ-Al2O3 improved the selective CO methanation rate. 相似文献
57.
Atsushi Sano Masato Kurihara Kazuya Ogawa Tsuyoshi Iijima Satoshi Maruyama 《Journal of power sources》2009,192(2):703-707
The effect of alkali function group contained in electrode binder was investigated. Carboxy methyl cellulose (CMC) improved the initial irreversible capacity loss in graphite negative electrode. Lithium acetate also improved the initial cycle efficiency. On the other hand, ethyl cellulose (EC) and hydroxyl propyl methyl cellulose (HPMC), which do not have a carboxylic group, did not decrease the reductive electrolyte decomposition. After charge and discharge cycle, the surface film composition on the electrode with CMC was less than on the electrode without CMC. This suggests that a carboxylic group in the binder acted as a catalyst and promoted the solid electrolyte interphase (SEI) formation which prevents the excess electrolyte decomposition on the graphite electrode. 相似文献
58.
Shinya Yasumoto Andrew P. Jones Tomoki Nakaya Keiji Yano 《Computers, Environment and Urban Systems》2011,35(6):464-473
The development of virtual city models has provided novel possibilities for analyses that require consideration of building heights in urban areas. The study was undertaken to explore these possibilities by using the virtual Kyoto model to examine equity in access to views in the Japanese city. A sample of just over 5000 residences was selected by stratifying for population age and affluence. A series of viewsheds were computed to quantify the visibility of a range of environmental amenities (greenspaces, water bodies, historical buildings, mountains) and disamenities (factories and roads). Evidence of inequity in visual amenity was identified, whereby homes in areas with many old people were much less likely to have views of greenspaces and water bodies, although they were also less likely to see factories and roads and were more likely to view mountains. Homes in more affluent areas had better views of greenspaces, historical buildings, and mountains, and were less likely to see factories and water bodies. We discuss the potential of virtual city models for furthering analyses of the urban environment and raise some caveats regarding their use. 相似文献
59.
Alternating copolymers of carbon dioxide with glycidyl ethers for novel ion-conductive polymer electrolytes 总被引:1,自引:0,他引:1
To overcome the low ionic conduction of existing poly(ethylene oxide)-based polymer electrolytes, we consider polycarbonates obtained from the copolymerization of CO2 and epoxy monomers. We synthesized four types of polycarbonates possessing phenyl, n-butyl, t-butyl and methoxyethyl side groups using zinc glutarate, and measured the ionic conductivity of their electrolytes, including 10 mol% of LiTFSI. The electrolyte possessing methoxyethyl side groups had the highest conductivity, of the order of 10−6 S cm−1 at room temperature. The activation energy (Ea) for ionic conduction in the polycarbonate electrolytes was estimated from the VTF equation, and the Ea of the electrolyte possessing n-butyl side groups was almost the same with the polyether-based electrolytes. An interesting feature of our study is that the polycarbonate is a unique candidate for ion-conductive polymers because of its flexible and hydrophobic properties. 相似文献
60.
Thermosensitive 4VP‐NIPAAm‐4G copolymer beads containing pyridyl groups were first prepared by suspension copolymerization of 4‐vinylpyridine (4VP), N‐isopropylacrylamide(NIPAAm), and tetraethylene glycol dimethacrylate (4G; crosslinking reagent) in a saturated Na2SO4 aqueous solution in the presence of surfactant and MgCO3 as dispersants. Then the copolymer beads containing pyridinium groups were obtained by the quaternization of the copolymer beads with various alkyl iodides (CH3I, C4H9I, C8H17I) in N,N‐dimethylformamide. The 4VP‐NIPAAm‐4G (15 : 97 : 3) copolymer bead and the 4VP‐NIPAAm‐4G copolymer beads quaternized with butyl iodide exhibited high thermosensitivity in water, although the 4VP‐NIPAAm‐4G copolymer beads quaternized with methyl iodide or octyl iodide hardly exhibited thermosensitivity. All the quaternized copolymer beads exhibited antibacterial activity against Escherichia coli (E. coli), although the 4VP‐NIPAAm‐4G copolymer bead did not. In particular, the copolymer bead quaternized with butyl iodide exhibited the highest antibacterial activity against E. coli at 30°C. It was also found that the antibacterial activity of the quaternized 4VP‐NIPAAm‐4G copolymer beads was greatly affected by not only chain length of alkyl groups in alkyl iodides, with which the 4VP‐NIPAAm‐4G copolymer beads were quaternized, but also by temperature of the solutions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献