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指出了影响气门弹簧钢丝疲劳性能的主要因素是冶金因素,介绍了国外先进的气门弹簧钢丝生产的冶炼、轧制和拉拔新工艺,提出了提高国产气门弹簧钢丝质量应采取的措施。 相似文献
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玉米须脂溶性化学成分的研究 总被引:2,自引:0,他引:2
从吉林省吉林地区产玉米的花柱和柱头中,分别经石油醚和乙醇提取、柱层析粗分、制备性薄层板细分、混合溶剂重结晶得到两个化合物,通过高效薄层、红外光谱和核磁共振等分别确定为亚油酸(Ⅰ)和β-谷甾醇(Ⅱ),其中亚油酸(Ⅰ)是在玉米须中首次分离的化合物. 相似文献
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Media as Educator,Media as Disruptor: Conceptualizing the Role of Social Context in Media Effects
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We document how social contexts serve to refract media effects. We theorized the relationship between media use and individual‐level knowledge (and attitude) would be stronger when community‐level knowledge (and attitude) was low than when it was high. Data come from a national survey (N = 12,608 women and 1,237 men) conducted in Nepal. Knowledge and stigma toward people living with HIV were the 2 dependent variables. Hypotheses were tested 12 times: across the use of 3 media (newspaper, radio, television) × 2 study outcomes (knowledge and attitudes) × 2 genders. Predicted interactions were supported in 9 of the 12 tests. Findings point to the need to take into account the role of community factors in theorizing about media effects. 相似文献
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Sakaki T Zähringer U Warnecke DC Fahl A Knogge W Heinz E 《Yeast (Chichester, England)》2001,18(8):679-695
The occurrence of glycolipids such as sterol glycosides, acylated sterol glycosides, cerebrosides and glycosyldiacylglycerols was examined in the three yeast species Candida albicans, Pichia pastoris and Pichia anomala, as well as in the six fungal species Sordaria macrospora, Pyrenophora teres, Ustilago maydis, Acremonium chrysogenum, Penicillium olsonii and Rhynchosporium secalis. Cerebroside was found in all organisms tested, whereas acylated sterol glycosides and glycosyldiacylglycerols were not found in any organism. Sterol glycosides were detected in P. pastoris strain GS115, U. maydis, S. macrospora and R. secalis. This glycolipid occurred in both yeast and filamentous forms of U. maydis but in neither form of C. albicans. This suggests that sterol glycoside is not correlated with the separately grown dimorphic forms of these organisms. Cerebrosides and sterol glycosides from P. pastoris and R. secalis were purified and characterized by mass spectrometry and nuclear magnetic resonance spectroscopy. The cerebrosides are beta-glucosyl ceramides consisting of a saturated alpha-hydroxy or non-hydroxy fatty acid and a Delta4,8-diunsaturated, C9-methyl-branched sphingobase. Sterol glycoside from P. pastoris was identified as ergosterol-beta-D-glucopyranoside, whereas the sterol glucosides from R. secalis contain two derivatives of ergosterol. The biosynthesis of sterol glucoside in P. pastoris CBS7435 and GS115 depended on the culture conditions. The amount of sterol glucoside in cells grown in complete medium was much lower than in cells from minimal medium and a strong increase in the content of sterol glucoside was observed when cells were subjected to stress conditions such as heat shock or increased ethanol concentrations. From these data we suggest that, in addition to Saccharomyces cerevisiae, new yeast and fungal model organisms should be used to study the physiological functions of glycolipids in eukaryotic cells. This suggestion is based on the ubiquitous and frequent occurrence of cerebrosides and sterol glycosides, both of which are rarely detected in S. cerevisiae. We suggest P. pastoris and two plant pathogenic fungi to be selected for this approach. 相似文献
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以黑木耳(Auricularia auricula)为菌种发酵玉米须制备多糖,通过单因素试验和响应面试验优化其发酵工艺条件,并考察玉米须多糖体外抗氧化活性。结果表明,玉米须最佳发酵工艺为:接种量8%、发酵温度26℃、发酵时间7 d。此优化条件下多糖的含量为13.12 mg/L。玉米须多糖的红外光谱分析结果表明,其具有糖类物质的特征吸收峰,对羟基自由基(·OH)和1,1-二苯基-2-三硝基苯肼自由基(DPPH·)最大清除率分别为34.5%和43.3%,实验表明其具有一定的抗氧化活性。 相似文献
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Lori A. Chambers James Watson Sean B. Rourke Ruthann Tucker Jay Koornstra 《住房,理论和社会》2014,31(3):310-333
The literature has identified housing as a fundamental unmet need for people living with HIV; yet there has been little qualitative evidence exploring housing and HIV, particularly from a Canadian context. This paper focuses on our qualitative analyses of the housing experiences of 48 HIV-positive people living in Ontario. Findings from our interviews illustrate healthy housing as a dynamic interconnection between health, housing and other social factors that are influential to the health and well-being of people with HIV. Four salient themes have emerged from our qualitative findings: the interplay between healthy housing and economic security; the relationship between HIV, health and housing precariousness; the interconnection between housing, HIV, safety, stigma, social isolation and social exclusion; and the meaning of healthy housing for people living with HIV. These findings re-emphasize the importance of housing policies that consider housing as more than just a roof over one’s head, but also as something that supports the physical, mental, emotional and social well-being of people living with HIV. 相似文献
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