Totally found 10043316 items.

  • [期刊] 不同散叶装烟方式对烤烟主要化学成分的影响
    以K326为试验品种,探讨密集烤房散叶装烟方式在烘烤过程中烟叶主要化学成分的变化规律.结果表明,散叶插签叶尖朝上及朝下处理的淀粉质量分数随烘烤进程呈下降趋势,而总糖和还原糖质量分数呈升高趋势,蛋白质、总氮和烟碱逐渐分解,质量分数变化幅度较小.含碳及含氮物质变化主要集中在烘烤变黄前期(38℃以前),而钾、氯质量分数变化幅度较小,石油醚提取物质量分数在干筋期快速增加,两个处理在整个烘烤期间烟叶主要化学成分的质量分数差异无统计学意义.因此,散叶插签叶尖朝上和叶尖朝下装烟方式对烘烤过程中烟叶主要化学成分变化无显著影响.
  • [期刊] Association between prospective registration and overall reporting and methodological quality of systematic reviews: a meta-epidemiological study
    Abstract Objectives The aim of this study was to investigate the differences in main characteristics, reporting and methodological quality between爌rospectively registered and nonregistered systematic reviews. Study Design and Setting PubMed was searched to identify systematic reviews of randomized controlled trials published in 2015 in English. After title and abstract screening, potentially relevant reviews were divided into three groups: registered non-Cochrane reviews, Cochrane reviews, and nonregistered reviews. For each group, random number tables were generated in Microsoft Excel, and the first 50 eligible studies from each group were randomly selected. Data of interest from systematic reviews were extracted. Regression analyses were conducted to explore the association between total Revised Assessment of Multiple Systematic Review (R-AMSTAR) or Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) scores and the selected characteristics of systematic reviews. Results The conducting and reporting of literature search in registered reviews were superior to nonregistered reviews. Differences in 9 of the 11 R-AMSTAR items were statistically significant between registered and nonregistered reviews. The total R-AMSTAR score of registered reviews was higher than nonregistered reviews [mean difference (MD)??.82, 95% confidence interval (CI): 3.70, 5.94]. Sensitivity analysis by excluding the registration-related item presented similar result (MD??.34, 95% CI: 3.28, 5.40). Total PRISMA scores of registered reviews were significantly higher than nonregistered reviews (all reviews: MD??.47, 95% CI: 0.64-2.30; non-Cochrane reviews: MD??.49, 95% CI: 0.56-2.42). However, the difference in the total PRISMA score was no longer statistically significant after excluding the item related to registration (item 5). Regression analyses showed similar results. Conclusion Prospective registration may at least indirectly improve the overall methodological quality of systematic reviews, although its impact on the overall reporting quality was not significant.
  • [期刊] Effect of acoustically absorbing wall tubes on the near-limit detonation propagation behaviors in a methane-oxygen mixture
    Methane (CH4) is the main component of natural gas and produces less carbon dioxide for each unit of heat released and more heat per unit mass than other hydrocarbon fuels, and it is thus considered to be an environmental-friendly fuel. The explosion and detonation hazards associated with methane mixtures deserve special attention because of their potential safety hazards. Acoustically absorbing materials are effective in damping out the transverse wave of a detonation structure. A detonation could be attenuated or prohibited after passing over this material, but the failure mechanism of the detonation still needs further exploration. In this study, tubes made of an acoustically absorbing material (hole diameters of the wall are from 30 mu m to 300 mu m) are inserted in the smooth rigid wall tube to investigate the effect of the porous-walled material on the detonation propagation at the near-limit conditions. Porous-walled tubes with three different scales (L/D = 3.85, 7.69, and 15.38) are studied. Photodiodes and smoked foils are employed to simultaneously measure the local velocity of the combustion waves and record the cellular detonation structures, respectively. The results show that, for shorter porous-walled tubes, the prohibition effect of the absorbing material on the detonation propagation is only prominent at the critical and sub-critical conditions, but the material has a minor effect on the detonation propagation at the super-critical condition. In addition, the prohibition effect of the porous material on the detonation propagation becomes more evident with the increased length of the acoustically absorbing material. This outcome occurs because a transverse wave plays an important role in the propagation of a self-sustained detonation, as it is partially damped during the transmission of the detonation through the porous-walled tube; thus, extending the length of the porous-walled section results in increasing the losses of the incident and reflected shock waves due to a greater expansion and mass divergence into porous material. Therefore, the velocity of the combustion wave decreases faster in the downstream of the porous material with an increased length. On the other hand, the methane-oxygen mixture has a highly irregular cellular pattern and is characterized as an unstable mixture with a high degree of instability. The strong instability leads to an enhanced ability to generate new transverse waves in the far downstream, and therefore, at the super-critical condition (a relatively higher initial pressure), the instability partly compensates for the negative effect of the acoustically absorbing material on the detonation propagation.
  • [期刊] 船舶复杂建造工艺人机工程仿真评价方法
    船舶复杂建造工艺设计因缺乏人机工程角度的可行性验证手段,致使工艺设计更改和优化周期长,方案优劣依赖个人经验,在实际生产中时常出现工人操作可达性差、空间不足、盲装作业、疲劳作业和作业环境恶劣的现象。结合人机工程学在汽车和航空航天领域的应用,提出一种船舶复杂建造工艺人机工程仿真评价方法,制订相应的评价指标。以液化气船液罐吊装工艺为例,开展相应的人机工程仿真评价,提前暴露液罐吊装工艺潜在的问题,避免设计失误,降低研发制造成本,提高生产效率。
  • [专利] 原核苯丙氨酸解氨酶变异体的组合物以及利用其组合物的方法
    本发明提供由原核生物产生的苯丙氨酸解氨酶(PAL)变异体,其中这类原核PAL变异体与野生型PAL相比具有较大的苯丙氨酸转化活性和/或降低的免疫原性。本发明进一步提供原核PAL及其生物活性片段、突变体、变异体或者类似物的组合物,以及用于生产、纯化、配制这类组合物以及将其用于工业和治疗目的(例如治疗高苯丙氨酸血症(包含苯丙酮尿症)以及其他疾病(包含癌症))的方法。
  • [专利] 一种页岩气勘探用密封脂及其制备方法
    本发明公开了一种页岩气勘探用密封脂及其制备方法,其公开的一种页岩气勘探用密封脂,所述密封脂以重量份计,包含59~81.5份的基础油,10~30份的聚异丁烯增粘剂,5份提升粘度指数的乙烯丙烯共聚物,3~5份的聚合松香,0.5~1份的复合添加剂。本发明还公开了采用所述配方的页岩气勘探用密封脂的制备方法。
  • [期刊] Transphobia in the Workplace: A Qualitative Study of Employment Stigma
    Transgender individuals report frequent encounters with transphobia in the workplace, although relatively few studies have investigated this phenomenon. The present grounded theory analysis was conducted with 45 transgender and gender diverse participants to delineate their different experiences with bias and discrimination in the workplace. Qualitative data analysis revealed the following themes pertaining to work transphobia: lack of social support, workplace gender policing, personal safety threats, acquisition and advancement barriers, intersectional discrimination, intuited stigma, and lack of inclusive policy. Results suggest the diverse challenges faced by transgender individuals in the workplace and the need for further interventions, supports, and policy to counteract work-related transphobia.
  • [专利] 编码产黄青酶谷胱苷肽转移酶的基因及其应用
    本发明涉及来自产黄青霉的新的编码谷胱苷肽转移酶的基因(PcGSTA),该基因编码的多肽及含有该基因的表达载体。本发明同时提供了苯乙酸对本发明的新基因PcGSTA的表达的影响,进而提供了将本发明的新基因PcGSTA应用于产黄青霉菌改造以提高青霉素产量的途径。
  • [期刊] Wear properties and microstructural analyses of Fe-based coatings with various WC contents on H13 die steel by laser cladding
    Microhardness, wear properties and microstructure of Fe -based coatings with various WC contents on H13 hot working die steel by laser cladding were investigated. Special attention was paid to the effects of various WC contents on the microstructural characterization and wear properties of different coatings by means of optical microscopy (OM) and scanning electron microscopy (SEM). Results indicated that only a small part of the periphery of the WC in the WC -added coatings was melted, and the un-melted WC particles in the coatings acted as a hard reinforcement. Besides, the microhardness in the cladding layer increased with the increment of the mass fraction of WC particles, and presented a gradient distribution along in-depth direction of the coatings. Furthermore, the Fe -based clad coating with WC particles exhibited a higher wear resistance and a lower friction coefficient compared with the substrate and Fe -based clad coating. In addition, the influence mechanism of WC particles on microstructural evolution and wear resistance was also discussed.
  • [专利] 识别乙肝病毒(HBV)表面抗原S183-91表位的TCR及其用途
    本发明公开了一种分离抗原特异性T细胞以及从抗原特异性T细胞中克隆编码抗原特异性TCR基因的方法。本发明还提供了编码HBV表面抗原S183‑91特异性的TCR的核酸分子以及包含所述核酸分子的载体。本发明的TCR能够与HBV S183‑91抗原短肽复合物FLLTRILTI‑HLA*A0201结合,同时转导了本发明TCR的细胞能够被特异性激活并且对靶细胞具有很强的杀伤作用。
意见反馈
返回顶部