全文获取类型
收费全文 | 544篇 |
免费 | 8篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 20篇 |
综合类 | 3篇 |
化学工业 | 110篇 |
金属工艺 | 18篇 |
机械仪表 | 11篇 |
建筑科学 | 11篇 |
能源动力 | 14篇 |
轻工业 | 26篇 |
无线电 | 48篇 |
一般工业技术 | 119篇 |
冶金工业 | 120篇 |
原子能技术 | 14篇 |
自动化技术 | 39篇 |
出版年
2023年 | 3篇 |
2022年 | 1篇 |
2021年 | 18篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 11篇 |
2017年 | 4篇 |
2016年 | 10篇 |
2015年 | 4篇 |
2014年 | 10篇 |
2013年 | 26篇 |
2012年 | 21篇 |
2011年 | 25篇 |
2010年 | 28篇 |
2009年 | 25篇 |
2008年 | 26篇 |
2007年 | 20篇 |
2006年 | 17篇 |
2005年 | 17篇 |
2004年 | 7篇 |
2003年 | 8篇 |
2002年 | 14篇 |
2001年 | 14篇 |
2000年 | 10篇 |
1999年 | 15篇 |
1998年 | 53篇 |
1997年 | 30篇 |
1996年 | 28篇 |
1995年 | 17篇 |
1994年 | 7篇 |
1993年 | 14篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 8篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有553条查询结果,搜索用时 15 毫秒
61.
Using a two-dimensional frictional force microscope, we studied the two-dimensional nature of the atomic scale friction between a Si3N4 sharp tip and a cleaved graphite surface, which is composed of only C atoms and is a good conductor. As a result, we observed the two-dimensionally quantized friction with the lattice periodicity of the graphite surface, similarly to mica, MoS2 and NaF surfaces. Thus quantized friction occurs at material surfaces which are composed of not only some elements but also of a single element, and the quantized friction does not depend on the conductivity of the surface. 相似文献
62.
H Kido A Nakano N Okishima H Wakabayashi F Kishi Y Nakaya M Yoshizumi T Tamaki 《Canadian Metallurgical Quarterly》1998,379(7):885-891
We report the novel role of human chymase in the production of bioactive 31-amino acid length endothelins (ETs), which may play a role in allergies and vascular diseases. In the bronchi of asthmatic patients, the vascular tissue in atherosclerosis, and the heart muscle in cardiac hypertrophy, both ET-like immunoreactivity and the accumulation of mast cells significantly increase. Chymase from human mast cells selectively cleaves big ET-1, -2 and -3 at their Tyr31-Gly32 bonds, and produces novel bioactive 31-amino acid length ETs, ETs(1-31), without any further degradation products. However, chymases from other species, human cathepsin G, and porcine alpha-chymotrypsin, degrade big ETs. ETs(1-31) at concentrations between 10(-9) M and 10(-7) M exhibited various contractile potencies in rat tracheae and porcine coronary arteries in a dose-dependent manner. Furthermore, ET-1(1-31) at concentrations between 10(-14) M and 10(-10) M caused a significant increase in the intracellular free Ca2+ concentration. The contractile activity of ETs(1-31) may not be the consequence of conversion to the corresponding ETs(1-21) by phosphoramidon-sensitive ET converting enzyme(s) or other chymotrypsin-type proteases and metallo-endopeptidases, because the contractile activity was not significantly inhibited on treatment with inhibitors of these proteases prior to the addition of ET-1(1-31). 相似文献
63.
This paper describes the modal analysis of optical fibers with symmetrically distributed multiple cores. Each core has an identical, axially symmetrical, and nonuniform refractive index profile. Group theoretical approach is applied to treat the symmetry of the waveguide structure. The point-matching method combined with the staircase-approximation method is used to take into account complex boundary conditions and complex refractive index distributions. The numerical computation based on this approach has been found to be very effective 相似文献
64.
65.
T Shimazu T Yoshioka Y Nakata K Ishikawa Y Mizushima F Morimoto M Kishi M Takaoka H Tanaka A Iwai A Hiraide 《Canadian Metallurgical Quarterly》1997,42(4):641-646
BACKGROUND: Crush syndrome is a form of traumatic rhabdomyolysis characterized by systemic involvement, in which acute renal failure is potentially life-threatening. METHODS: Clinical and laboratory data of 14 crush-syndrome patients transferred to a tertiary emergency department after the Hanshin-Awaji earthquake were analyzed. The patients were buried under collapsed houses for the average of 6.7 +/- 5.7 (SD) hours (range, 1 to 24 hours). They were referred to us 6 to 250 hours after the earthquake. RESULTS: Of those who arrived at our institution within 40 hours, 25% (two of eight) developed renal failure, whereas all six patients who arrived after 40 hours developed renal failure. Peak serum creatine kinase ranged from 6,677 to 134,200 U/L (51,674 +/- 41,776). Renal failure was highly associated with massive muscle damage (serum creatine kinase above 25,000 U/L) and insufficient initial fluid resuscitation (below 10,000 mL/2 days). CONCLUSIONS: Prompt and adequate, if not massive, fluid resuscitation is the key to preventing renal failure after such injury. 相似文献
66.
67.
K Mizuseki M Kishi M Matsui S Nakanishi Y Sasai 《Canadian Metallurgical Quarterly》1998,125(4):579-587
Broad-scale differences in soil microbial community composition were analyzed in two contrasting soils using DNA reassociation and % G + C profiles for analysis on the community-level, and filter- and whole cell hybridization techniques for a coarse-level characterization of larger phylogenetic groups of bacteria. Reassociation analysis of DNA from bacterial fractions extracted from the organic soil Seim and the mineral soil Hau revealed similar complexity of the communities with 5700 and 4900 different bacterial genomes (g soil [dry wt])-1, respectively. Thermal denaturation studies showed wide % G + C distributions in DNA from bacteria of both soils. Differences in the median % G + C with 55 to 61% for the bacterial community in soil Seim and 61 to 66% for that in soil Hau indicated a higher proportion of bacteria with a high DNA G + C content in soil Hau. In situ hybridization with fluorescent (Cy3-labeled) probes targeting larger phylogenetic groups showed minor differences between both soils, and between direct detection of bacteria in dispersed soil slurries and in bacterial fractions extracted from soils through about 90% of the total bacteria were lost during extraction. In dispersed slurries of both soils, only probes ALF1b, SRB385, and PLA46 hybridized to cells accounting for more than 1% of the DAPI-stained cells, while numbers obtained after hybridization with probes ARCH915, BET42a, GAM42a, HGC69a, and CF319a were below the detection limit set at < 1%. These results were confirmed by in situ hybridization with horseradish peroxidase (HRP)-labeled probes and subsequent Cy3-tyramide signal amplification. In contrast, dot blot hybridization with probe HGC69a indicated significant amounts of Gram-positive bacteria with a high DNA G + C content in both soils. These could subsequently be visualized in non-dispersed soil slurries by in situ hybridization with HRP-labeled probe HGC69a and Cy3-tyramide signal amplification. Filamentous Gram-positive bacteria with a high DNA G + C content, likely actinomycetes, which are present in soil Hau in significant numbers are obviously destroyed by procedures used for soil dispersion. 相似文献
68.
69.
Iichiro Inoue Tetsuya Miyashita Tatsuo Uchida Yuichiro Yamada Yutaka Ishii 《Journal of the Society for Information Display》2003,11(3):571-576
Abstract— Quick, stable transition from splay‐to‐bend alignment in optically compensated bend (OCB) mode is crucial for practical use. This has been achieved by surface treating part of a pixel with a chiral dopant to induce a twist alignment while controlling the twist direction. The effectiveness of this new method was confirmed in a prototype TFT‐LCD panel. 相似文献
70.