全文获取类型
收费全文 | 669篇 |
免费 | 16篇 |
专业分类
电工技术 | 24篇 |
综合类 | 1篇 |
化学工业 | 113篇 |
金属工艺 | 14篇 |
机械仪表 | 18篇 |
建筑科学 | 11篇 |
能源动力 | 18篇 |
轻工业 | 58篇 |
水利工程 | 2篇 |
无线电 | 46篇 |
一般工业技术 | 110篇 |
冶金工业 | 210篇 |
原子能技术 | 4篇 |
自动化技术 | 56篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 9篇 |
2020年 | 4篇 |
2019年 | 11篇 |
2018年 | 13篇 |
2017年 | 8篇 |
2016年 | 10篇 |
2015年 | 2篇 |
2014年 | 12篇 |
2013年 | 33篇 |
2012年 | 15篇 |
2011年 | 34篇 |
2010年 | 18篇 |
2009年 | 19篇 |
2008年 | 21篇 |
2007年 | 16篇 |
2006年 | 20篇 |
2005年 | 17篇 |
2004年 | 24篇 |
2003年 | 18篇 |
2002年 | 13篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 14篇 |
1998年 | 73篇 |
1997年 | 65篇 |
1996年 | 32篇 |
1995年 | 12篇 |
1994年 | 14篇 |
1993年 | 22篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 12篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 9篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1975年 | 6篇 |
1973年 | 2篇 |
排序方式: 共有685条查询结果,搜索用时 0 毫秒
1.
Akira Watanabe Yoshimitsu Takeuchi Goji Saeki 《Journal of the American Ceramic Society》1985,68(11):308-C
The length of potassium titanate fibers produced by several conventional methods averages 50 μm, with a maximum of 100 μm. Extremely long fibers (most >1000 μm long) were obtained by calcination in N2 gas flowing at 5.2×10-4 m/s. 相似文献
2.
A simple method that used headgear and a functional appliance simultaneously was used for the correction of Class II, Division 1 cases with severe denture base discrepancy. The treatment restricted the forward growth of the maxilla and advanced the mandible. The functional appliance, referred to as the mandibular growth advancer (MGA), advances the mandible progressively with a splint, with the objective of remodeling the condyle and the glenoid fossa in the temporomandibular joint. Functional adaptation was achieved as the muscles that are attached to the mandible adjusted to new positions. In the two cases that illustrate this method, the ANB angle decreased and the Ar-B distance increased over a short period to four and six times the mean Japanese growth rate, respectively. After the correction of the denture-base discrepancy, a multibracket fixed appliance was used for dental alignment, and good skeletal, occlusal relationships and profiles were obtained. Treatment of severe denture-base discrepancy in this manner may reduce the skeletal abnormality, decrease the number of extraction cases, and shorten the subsequent multibracket treatment time. And it may reduce the iatrogenic side effects caused by prolonged mechanotherapy with a fixed appliance. 相似文献
3.
A new gram-positive, nonmotile coccus is described. Strains IFO 12422T (T = type strain) and IFO 15385 in the Institute for Fermentation, Osaka, culture collection, which were isolated from soil and water, respectively, have the following chemotaxonomic characteristics: menaquinone MK-9(H4); G + C content of DNA of 67 mol%; and LL-diaminopimelic acid, alanine, glycine, and glutamic acid in a molar ratio of ca. 1:2:1:1 (type A3 gamma). Mycolic acids are not present. The taxonomic characteristics of these organisms are different from those of previously described gram-positive, high-G + C-content cocci. The partial 16S rRNA sequence indicated that IFO 12422T represents a distinct line of descent among gram-positive bacteria with a high G + C content. The name Luteococcus japonicus gen. nov., sp. nov. is proposed. The type strain is strain IFO 12422. 相似文献
4.
Because of its high–temperature chemical stability, SiC ceramic is a promising material for high-temperature device applications such as thermoelectric energy converters. However, the electrical conductivity of SiC ceramic is too low for it to be used as a thermoelectric energy converter at the cold junction. Therefore, we propose a SiC-Si functionally gradient material (FGM) in order to improve the electrical conductivity of the SiC ceramic at the cold junction. An SiC rod was fired in a temperature gradient furnace. One end of the SiC rod was maintained at 2473 K and the other end was maintained at 1973 K for 30 min. After firing, the porous SiC edge fired at 1973 K was dipped into molten Si in order to infiltrate molten Si into the porous SiC. The microstructure of the FGM is classified into three regions: the SiC-Si composite material; the porous SiC ceramic; and the densified SiC ceramic. The electrical conductivity, the Seebeck coefficient and the thermal conductivity for each region of SiC-Si FGM was measured at 300 K; a figure of merit was calculated. The figure of merit of the SiC-Si FGM at the cold junction, at room temperature, was 108 times higher than that of a nongradient SiC ceramic. 相似文献
5.
S Hayashi T Sugiyama A Yachi K Yokota Y Hirai K Oguma N Fujii 《Canadian Metallurgical Quarterly》1997,32(5):593-597
STUDY OBJECTIVES: To determine the rates of alcohol-related morbidity and mortality in a cohort of intoxicated ED patients 5 years after presentation and to compare them with those of non-intoxicated ED patients. METHODS: The study group comprised 150 consecutive ED patients who presented with intoxication (blood alcohol level higher than 100 mg/dL) in June 1986 and 50 control patients matched for age, sex, ED arrival time, and date. The setting was an urban university hospital ED. Morbidity and mortality over a 5-year follow-up period were measured using hospital ED and admission records from all state Level I trauma centers and computerized statewide databases. RESULTS: The 5-year mortality rate among alcohol-intoxicated patients was 2.4 times that of the comparison group (95% confidence interval, .3 to 18.9). The 5-year death rate among intoxicated patients aged 40 to 69 years was especially high (19%). Thirty-seven percent of the intoxicated patients made at least one alcohol-related ED revisit during the follow-up period, compared with 6% of the comparison group (P < .001). Intoxicated patients were more likely to revisit EDs because of suicidal behavior or domestic violence (P = .001). Admission to an alcohol detoxification unit during the follow-up period occurred in 24% of the intoxicated patients, compared with 10% of the sober controls (P = .03). At least one arrest for drunk driving occurred in 47% of the intoxicated group; the rate was lower, but still substantial, in the comparison group (20%, P < .001). CONCLUSION: A single alcohol-related ED visit is an important predictor of continued problem drinking, alcohol-impaired driving and, possibly, premature death. 相似文献
6.
Eiichi Haginomori Kenji Yoshimura Shunichi Kobayashi Sadanori Kaneko Takeshi Yokota Masayuki Ishikawa 《Electrical Engineering in Japan》1994,114(4):50-61
To cope with the high rate of increase of power demand in the main industrialized districts in Japan, 550-kV transmission systems covering the districts have been reinforced, with most of the main power plants connected directly to these systems. Through 550-/300-kV substations, the majority of power to the districts is supplied by 300-kV systems. To limit the excess short-circuit capacity in the 300-kV systems, they tend to be reconstructed as so-called radial networks. In radial networks with high short-circuit capacity and relatively small number of transmission lines connected to the substation busbars, the rate of rise of TRV can be far higher than standard value. This paper analyzes the transient recovery voltages (TRV) in such extra-high-voltage radial networks in Japan, together with the relevant stresses to circuit-breakers during fault clearings. Future system conditions have also been introduced. As the typical rate of rise of the TRV values, more than twice that of today's standard ones are probable. 相似文献
7.
Di-, tri-, tetra-, penta- and hexasaccharides were formed during the hydrolysis of lactose by transgalactosylation reaction of Aspergillus oryzae β-galactosidase. In this study the isolation and characterization of the major constituents of tri-, tetra- and pentasaccharides are described. The structure elucidation of 3 tri-, 2 tetra- and 1 pentasaccharides was carried out by methylation analysis, mass spectrometry and 13C-nmr spectrometry. The trisaccharides are , and . Tetrasaccharides are and [or . Pentasaccharide is . 相似文献
8.
9.
NO
x
reduction with a combination of catalysts, Pd catalyst, NO
x
storage reduction (NSR) catalyst and Cu/ZSM-5 in turn, was investigated to elucidate for the high NO
x
reduction activity of this catalyst combination under oxidative atmosphere with periodic deep rich operation. The catalytic
activity was evaluated using the simulated exhaust gases with periodically fluctuation between oxidative and reductive atmospheres,
and it was found that the NO
x
reduction activity with this catalyst combination was apparently higher than that of the solely accumulation of these individual
activities, which was caused by the additional synergic effect by this combination. The Pd catalyst upstream of the NSR catalyst
improved NO
x
storage ability by NO2 formation under oxidative atmosphere. The stored NO
x
was reduced to NH3 on the NSR catalyst, and the generated NH3 was adsorbed on Cu/ZSM-5 downstream of the NSR catalyst under the reductive atmosphere, and subsequently reacted with NO
x
on the Cu/ZSM-5 under the oxidative atmosphere. 相似文献
10.
H. Yokota 《应用聚合物科学杂志》1985,30(1):263-277
The mechanism of cellulose alkalization in isopropyl alcohol (IPA)–water–sodium hydroxide system was studied from the viewpoint of the selective distribution of sodium hydroxide between cellulose and the medium, and of the lattice transition of cellulose. A mixture of IPA, water, and sodium hydroxide spontaneously separates into two layers, i.e., the upper layer solution (ULS) consists of IPA, water, and a small amount of sodium hydroxide and the lower one (LLS) consists of sodium hydroxide, water, and a very small quantity of IPA. The role of the ULS and the LLS was distinctive. The ULS has a function to distribute sodium hydroxide with water in cellulose uniformly according to the distribution equilibrium between ULS and cellulose, and the ULS recovers sodium hydroxide with water from the LLS as the distribution equilibrium shifts in the alkalization of cellulose. The concentration of sodium hydroxide in the LLS and that of IPA in the ULS exerts an influence on the lattice structure of alkali cellulose. During the transformation from cellulose I to alkali cellulose, decrystallization does not occur. Some portion of alkali cellulose reverted to cellulose I by regeneration. 相似文献