全文获取类型
收费全文 | 60篇 |
免费 | 1篇 |
专业分类
化学工业 | 16篇 |
金属工艺 | 2篇 |
矿业工程 | 1篇 |
轻工业 | 1篇 |
无线电 | 5篇 |
一般工业技术 | 7篇 |
冶金工业 | 21篇 |
原子能技术 | 8篇 |
出版年
2021年 | 1篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2013年 | 1篇 |
2012年 | 2篇 |
2011年 | 1篇 |
2010年 | 2篇 |
2008年 | 2篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2000年 | 5篇 |
1998年 | 10篇 |
1997年 | 7篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1982年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有61条查询结果,搜索用时 15 毫秒
1.
M Kawanishi T Matsuda A Nakayama H Takebe S Matsui T Yagi 《Canadian Metallurgical Quarterly》1998,417(2-3):65-73
Types of mutations induced by acrolein in the supF gene on the shuttle vector plasmid pMY189 replicated in normal human fibroblast cells were examined. Base sequence analysis of 92 plasmids with mutations in the supF gene revealed that the majority of the mutations were base substitutions (76%) and the others were deletions and insertions (24%). Single base substitutions were most frequently found (46%), while multiple base substitutions were 18% and tandem (two adjacent) base substitutions were 12% of the mutations. Of the base substitution mutations, G:C to T:A transversions were 44% and G:C to A:T transitions were 24%. The mutations were distributed not randomly but located at several hotspots. Acrolein produced DNA intra-strand cross-links between guanine residues, which might be responsible for rather high induction of the tandem base substitution mutations. 相似文献
2.
T Matsuda M Kawanishi T Yagi S Matsui H Takebe 《Canadian Metallurgical Quarterly》1998,26(7):1769-1774
Acetaldehyde is present in tobacco smoke and automotive exhaust gases, is produced by the oxidation of ethanol, and causes respiratory organ cancers in animals. We show both the types and spectra of acetaldehyde-induced mutations in supF genes in double- and single-stranded shuttle vector plasmids replicated in human cells. Of the 101 mutants obtained from the double-stranded plasmids, 63% had tandem base substitutions, of which the predominant type is GG to TT transversions. Of the 44 mutants obtained from the single-stranded plasmids, 39% had tandem mutations that are of a different type than the double-stranded ones. The GG to TT tandem substitutions could arise from intra-strand crosslinks. Our data indicate that acetaldehyde forms intra- as well as inter-strand crosslinks between adjacent two-guanine bases. Based upon the following observations: XP-A protein binds to acetaldehyde-treated DNA, DNA excision repair-deficient xeroderma pigmentosum (XP) cells were more sensitive to acetaldehyde than the repair-proficient normal cells, and a higher frequency of acetaldehyde-induced mutations of the shuttle vectors was found in XP cells than in normal cells, we propose that the DNA damage caused by acetaldehyde is removed by the nucleotide excision repair pathway. Since treatment with acetaldehyde yields very specific GG to TT tandem base substitutions in DNA, such changes can be used as a probe to identify acetaldehyde as the causal agent in human tumors. 相似文献
3.
We have studied the cathodoluminescence of AlxGa1-xAs/GaAs multilayers grown on ridge-type triangles by molecular beam epitaxy. The compositional variation of Al, as well as the distribution of impurity and/or defect, was revealed by variations in the cathodoluminescence spectra and images. The Al composition in an AlxGa1-xAs layer was highest in the (111)A facet and decreased in the order (100), (411)A, (111)-delta and (110) facets. On the other hand, the carbon concentration was highest in the (411)A facet and decreased in the order (111)A, (111)-delta, (100) and (110) facets. It should be noted that the (111)-delta facet has a significant effect on the redistribution of Al. Although our ridge-type triangles are rather large for the quantum structures, these data have elucidated the self-organization mechanism of the AlxGa1-xAs/GaAs system and have yielded information on the design of quantum structures. We conclude that cathodoluminescence observation is a powerful tool for studying the compositional variation or band structure of three-dimensional microscale or nanoscale construction. 相似文献
4.
Takebe M. Nakamura K. Paul N.C. Iiyama K. Takamiya S. 《Electron Devices, IEEE Transactions on》2004,51(3):311-316
Direct oxidation by an ultraviolet (UV) and ozone process and oxinitridation (plasma nitridation after oxidation) of GaAs surfaces were used to form nanometer-scale gate insulating layers for depletion-type recessed gate GaAs-MISFETs. The drain current-drain voltage characteristics of the oxide gate devices exhibit lower transconductance (max. 40 mS/mm), lower breakdown voltage and smaller gate capacitance than the oxinitrided gate devices. The presence of hysteresis in the oxide gate devices is also apparent. The maximum transconductance of the oxinitrided gate devices is 110 mS/mm and they have a sharper pinch-off, compared to the oxide gate devices. In addition, no hysteresis is observed in their current voltage curves. The current gain cutoff frequency of 1.4 /spl mu/m gate-length FETs for both types is 6 GHz. These results correspond well with results obtained from characterization of these insulating films. 相似文献
5.
T Kikuchi T Onuma M Shimura M Tsutsui A Boku J Matsui K Takebe 《Canadian Metallurgical Quarterly》1994,17(9):1059-1061
OBJECTIVE: To evaluate change both in lipoprotein(a) [Lp(a)] and lipid levels in other lipoproteins in non-insulin-dependent diabetes mellitus (NIDDM) after short-term improvement of glycemic control. RESEARCH DESIGN AND METHODS: We compared Lp(a) levels in 210 NIDDM patients with those in 46 control subjects and evaluated the relationship between glycemic control and Lp(a) levels in diabetic patients. In addition, changes in Lp(a) levels and lipid levels were assessed after the improvement of glycemic control in 54 poorly controlled NIDDM patients. RESULTS: In NIDDM, Lp(a) levels in all patients, 62 patients with HbA1c < 6.0%, and 75 patients with HbA1c between 6.0 and 8.0%, were significantly higher than those in control subjects (19.1 [1.7-106.6], 19.2 [6.0-106.6], and 20.3 [2.7-75.3] vs. 15.4 [2.0-61.7] mg/dl, median [range], P < 0.05). Lp(a) levels in 73 patients with HbA1c of > or = 8.0% (18.7 [1.7-58.8] mg/dl) were not significantly different from those in control subjects. After glycemic control, lipid levels in plasma and in other lipoproteins fell significantly, but Lp(a) did not change (from 18.3 [1.7-58.8] to 18.4 [6.6-95.3] mg/dl). Changes in lipid levels, including Lp(a), did not correlate with those in fasting plasma glucose or HbA1c. CONCLUSIONS: These results suggest that elevated Lp(a) levels do not reflect poor glycemic control and that Lp(a) levels are independent of lipid levels in other lipoproteins after improved glycemic control in NIDDM. 相似文献
6.
Glass fiber poling and applications 总被引:1,自引:0,他引:1
Recent developments in the application of poled optical fibers to second harmonic generation and electrooptic light modulation are reviewed 相似文献
7.
8.
The densities of molten nickel mattes Cu2S-Ni3S2 and FeS-Ni3S2 were measured in the temperature interval 970° to 1321°C over the complete composition range. Several density values were
also obtained for the ternary matte Cu2S-FeS-Ni3S2 in the same temperature range. The densities of the binary mattes Cu2S-Ni3S2, FeS-Ni3S2 and ternary matte Cu2S-FeS-Ni3S2 were measured as 4.94 to 5.83 g per cu cm, 3.55 to 6.23 g per cu cm, and 2.65 to 4.92 g per cu cm, respectively. Molar volumes
and excess molar volumes of the binary mattes were evaluated. 相似文献
9.
10.
Deformability enhancement in ultra-fine grained, Ar-contained W compacts by TiC additions up to 1.1%
S. Matsuo H. Kurishita H. Arakawa T. Takida M. Kato Y. Yamamoto K. Takebe M. Kawai N. Yoshida 《Materials Science and Engineering: A》2008,492(1-2):475-480
Nano-sized Ar bubbles give negative influence on the fracture resistance and occurrence of superplasticity in ultra-fine grained (UFG) W–TiC compacts. In order to enhance deformability in UFG, Ar-contained W–TiC compacts, effects of TiC addition on the high-temperature deformation behavior were examined. W–TiC compacts with TiC additions of 0, 0.25, 0.5, 0.8 and 1.1 wt% were fabricated by mechanical alloying in a purified Ar atmosphere and hot isostatic pressing. Tensile tests were conducted at 1673–1973 K (0.45–0.54 Tm, Tm: melting point of W) at initial strain rates from 5 × 10−5 to 5 × 10−3 s−1. It is found that as TiC addition increases, the elongation to fracture significantly increases, e.g., from 3 to 7% for W–0 and 0.25TiC/Ar to above 160% for W–1.1TiC/Ar when tested at 1873 and 1973 K at 5 × 10−4 s−1. The flow stress takes a peak at 0.25%TiC and decreases to a nearly constant level at 0.5–1.1%TiC. The ranges of the strain rate sensitivity of flow stress, m, and the activation energy for deformation, Q, with TiC additions are 0.17–0.30 and 310–600 kJ/mol, respectively. The observed effects of the TiC additions on the tensile properties are discussed. 相似文献