全文获取类型
收费全文 | 1797篇 |
免费 | 2篇 |
专业分类
电工技术 | 12篇 |
综合类 | 1篇 |
化学工业 | 14篇 |
金属工艺 | 1篇 |
建筑科学 | 2篇 |
轻工业 | 2篇 |
水利工程 | 2篇 |
一般工业技术 | 9篇 |
冶金工业 | 1755篇 |
自动化技术 | 1篇 |
出版年
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2017年 | 3篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 1篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2001年 | 4篇 |
1999年 | 46篇 |
1998年 | 596篇 |
1997年 | 316篇 |
1996年 | 204篇 |
1995年 | 126篇 |
1994年 | 75篇 |
1993年 | 100篇 |
1992年 | 12篇 |
1991年 | 17篇 |
1990年 | 22篇 |
1989年 | 19篇 |
1988年 | 10篇 |
1987年 | 15篇 |
1986年 | 8篇 |
1985年 | 20篇 |
1983年 | 1篇 |
1982年 | 12篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1978年 | 4篇 |
1977年 | 47篇 |
1976年 | 89篇 |
1955年 | 1篇 |
排序方式: 共有1799条查询结果,搜索用时 31 毫秒
21.
22.
MJ Kania SD Keeling SP McGorray TT Wheeler GJ King 《Canadian Metallurgical Quarterly》1996,66(6):423-432
This study examined risk factors associated with incisor injury in 3396 third and fourth grade school children in Alachua County, Florida. One of six orthodontists completed a standardized examination form for each child to assess severity of incisor injury, gender, age, race, skeletal relationships, morphologic malocclusion, incisor exposure, interlabial gap, TMJ sounds, chin trauma, and history of lower facial trauma. One in five (19.2%) exhibited some degree of incisor injury. This was limited to a single tooth in 73.1% of those with injury, while enamel injury predominated (89.4%). The majority of the injuries (75.4%) were localized in the maxillary arch, with central incisors the most frequently traumatized. Chi-square tests of association indicated that gender, race, school, orthodontist, history of lower facial trauma, chin trauma, profile, and maxillary and mandibular horizontal positions were associated with incisor injury (P < 0.05). Wilcoxon rank sum tests identified differences in age, overjet, time of screening, and interlabial gap between those with and without injury (P < 0.05). Results of logistic regression analyses indicated risk of incisor injury was greater for children who had a prognathic maxilla, a history of trauma, were older, were male, and had greater overjet and mandibular anterior spacing. 相似文献
23.
24.
25.
26.
27.
Inhibition of sickle beta-chain (betaS)-dependent polymerization by nonhuman alpha-chains. A superinhibitory mouse-horse chimeric alpha-chain 总被引:1,自引:0,他引:1
P Nacharaju RP Roy SP White RL Nagel AS Acharya 《Canadian Metallurgical Quarterly》1997,272(44):27869-27876
Horse alpha-chain inhibits sickle beta-chain-dependent polymerization; however, its inhibitory potential is not as high as that of mouse alpha-chain. Horse alpha-(1-30) and alpha-(31-141) segments make, respectively, minor and major contributions to the inhibitory potential of horse alpha-chain. The sum of the inhibitory potential of the two segments does not account for the inhibitory potential of the full-length horse alpha-chain. Although the polymerization inhibitory potential of horse alpha-chain is lower than mouse alpha-chain, the inhibitory potential of horse alpha-(31-141) is comparable to that of mouse alpha-(31-141). When mouse alpha-(1-30) is stitched to horse alpha-(31-141), the product is a chimeric alpha-chain with an inhibitory potential greater than mouse alpha-chain. In contrast, the stitching of horse alpha-(1-30) with mouse alpha-(31-141) had no additional inhibitory potential. Molecular modeling studies of HbS containing the mouse-horse chimeric alpha-chain indicate altered side-chain interactions at the alpha1beta1 interface when compared with HbS. In addition, the AB/GH corner perturbations facilitate a different stereochemistry for the interaction of the epsilon-amino group of Lys-16(alpha) with the beta-carboxyl group of Asp-116(alpha), resulting in a decrease in the accessibility of the side chain of Lys-16(alpha) to the solvent. Based on molecular modeling, we speculate that these perturbations by themselves, or in synergy with the altered conformational aspects of the alpha1beta1 interactions, represent the molecular basis of the superinhibitory potential of the mouse-horse chimeric alpha-chains. 相似文献
28.
29.
30.