共查询到20条相似文献，搜索用时 93 毫秒
1.
以已酸乙酯作内标,正已烷为溶剂,用毛细管气相色谱法测定了蜡制品中香茅油的含量。该方法操作简便,样品只须用正已烷溶解即可测定,其检出限为0.10g·kg-1,相对标准偏差为0.01%-4.25%,回收率为91.2%-98.1%。 相似文献
2.
使用气相色谱法,选择硝基苯作为内标物,得到了二甲苯溶剂中四种主要成分邻二甲苯、间二甲苯、对二甲苯和乙基苯的线性回归方程。对含该四组分的三组人工配制样品进行回收率测定实验,测得邻二甲苯、间二甲苯与对二甲苯总量以及乙基苯的回收率在91.8%-103.8%之间。利用上述气相色谱内标法对三种市售二甲苯溶剂进行了浓度测定。 相似文献
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样品用王水溶解后,在酸性介质中,以硫脲为基体改进剂,采用石墨炉原子吸收光谱法测定化探样品中镉的吸光度.测定结果的检出限为0.011μg/g,相对标准偏差为2.38%-13.6%(n=5),加标回收率为90%-103%. 相似文献
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该文利用毛细管气相色谱法测定了三种塑料食品包装材料中邻苯二甲酸二(2-乙基己基)酯(DEHP)的含量.该方法使用RTX-5为色谱柱,邻苯二甲酸二正辛酯(DNOP)为内标,FID为检测器,用内标标准曲线法定量.在优化的条件下,线性范围为0.035～0.560 mg/L,检出限为0.01 mg/L,相对标准偏差为0.14%～0.60%,加标回收率为99.8%～103.2%. 相似文献
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Ching-hung LIN Huang-chun LIEN Yen-shen LU Sung-hsin KUO Ann-lii CHENG King-jen CHANG Chiun-sheng HUANG 《Journal of Zhejiang University. Science. B》2010,11(1):1-9
Objective:To compare the prognostic prediction between dichotomized and fractionated evaluations of hormone receptor expressions. Methods: Patients with stages I-III breast cancers, who received adjuvant tamoxifen, were enrolled. The expression of estrogen receptor (ER) and progesterone receptor (PR) was evaluated by immu-nohistochemistry (IHC). A fractionated score (F score), the percentage of positive-staining nuclei (0=none, 1=1%-10%, 2=11%-30%, 3=31%-50%, 4=51%-70%, and 5=71%-100%), was assigned to each... 相似文献
6.
苏云金芽孢杆菌四个亚种对温度和pH值的耐受性 总被引：2，自引：0，他引：2
翟兴礼 《商丘师范学院学报》2009,25(6):103-105
以4个亚种的苏云金杆菌为材料,测定其对温度及pH值的耐受性.试验结果表明,经70℃水浴10min处理后,存活率为95%-100%,80℃水浴10 min处理后,存活率为45%-70%,90℃水浴10 min后,有27%-40%的存活率.说明这四株苏云金杆菌对高温有较强的耐受力.当将培养基的pH值调至3时,四株菌都无法生长.当培养基的pH值为4时有两菌无法生长,pH值为5时4个亚种都能生长,pH值为8、9时4个亚种都生长旺盛.说明其在酸性环境中生长性能较差,在弱酸性和微碱性环境中生长较好. 相似文献
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《顺德职业技术学院学报》2011,(4):95-F0003
压敏胶残留物水基清洗剂,ZL200710078159.5（冯才敏）。本发明涉及一种压敏残留物水基清洗剂,特点是：其包括苯甲醇、表面活性剂、丙三醇、有机助剂及水;其各含量的重量百分比为：苯甲醇为10%-25%,表面活性剂为1%-5%,丙三醇为1%-5%,有机助剂为0%-10%,水为余量。其具有挥发性低、渗透力强、高效安全、清洗速度快、挥发性低、对人体无毒无害等优点。 相似文献
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在云南低热槽区气候条件下,将烤烟品种红花大金元布局在1550-2100 m 5个海拔点、每个点又安排在4月15日-5月25日5个移栽期进行种植,考查海拔高度和移栽时期对烟叶质量的影响,结果表明：1）烟叶的主要化学成分及其协调性受海拔的影响较大,且在海拔1650-1950 m之间及移栽期4月25日-5月15日期间波动范围较明显.2）烟叶总糖和还原糖分别在17.0%-27.7%和13.6%-24.1%之间,随着海拔的增加而呈上升趋势;糖碱比和施木克值分别在5.5-12.5和2.1-4.1之间,随着海拔的增加呈＂N＂字形变化,这4个指标几乎不受移栽期的影响.3）烟叶烟碱和总氮分别在2.1%-3.5%和1.4%-2.2%之间,且随着海拔的增加呈下降趋势,而随着移栽期的推迟,仅中部烟叶的烟碱含量有一个明显的下降趋势.4）淀粉和氧化钾分别在5.3%-0.6%和2.1%-1.1%之间,且随着海拔的增加呈下降趋势,而随着移栽期的推迟则表现为上升趋势. 相似文献
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建立了阿奇霉素原料药中乙醇残留量的测定方法.采用气相色谱法,氢火焰离子化检测器(FID),以0.1 mol/L稀盐酸为溶剂,HP-FFAP弹性石英毛细管柱为色谱柱(30 m×0.25 mm,0.25μm),氮气为载气,分流比为60∶1,进样口温度为200℃,检测器温度250℃,柱温采用程序升温.乙醇在0.01%-2%的浓度范围内呈良好的线性关系(r=0.9994),RSD在0.78%-1.83%之间,最小检出限为5.0 ng. 相似文献
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This paper reports the procedure and results of a study analyzing Science-Technology-Society (STS) themes in state science curriculum frameworks in the United States. The criteria for the analysis consisted of 15 categories of standards derived from the K–12 content standards of the National Science Education Standards. Out of the 25 state science curriculum frameworks analyzed, 88% emphasized the standard Science and technology in society. Three standards (Environmental quality, Science as a human endeavor, and Nature of science and scientific knowledge) were represented in nearly 50% of the state science curriculum frameworks. The remaining 11 content standards were scarcely represented in the state science curriculum frameworks analyzed. The recommendations of this study include an examination of educational policy links to state science frameworks, and case studies of curriculum policy-to-practice transition in STS education. 相似文献
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许昌市现在执行《河南省居住建筑节能设计标准(寒冷地区)》、节能率为65%的标准.通过对许昌市热工区位、气温变化、能耗结构、经济水平等方面的分析,认为该标准目前并不适宜于许昌市,建议调整为《河南省居住建筑节能设计标准(夏热冬冷地区)》、节能率为50%的标准. 相似文献
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Brittany L. Hott Sarah Heiniger Jasmine Justus Kathleen M. Randolph Amal Al Shabibi Brooki Beasley Kerry Frank Wendy Mitchell Courtney Tennell Fanee Wester 《Learning disabilities research & practice》2023,38(3):224-238
Single-case research designs are useful for learning disability researchers interested in refining novel interventions (e.g., new mathematics intervention) before scaling, small n populations (e.g., students with comorbid learning and emotional and behavioral disabilities), and testing unique conditions (e.g., remote locales). Much attention has been devoted to developing research quality standards, which is essential for replication and implementation fidelity; however, little is known about the reporting quality of single-case design studies. To gain insight into the quality of learning disability single-case research design study reporting, we analyzed 72 articles published between 2010 and 2021 in six learning disability-focused journals using the Single-Case Reporting Guideline In BEhavioral interventions (SCRIBE) standards. Findings suggest that reporting quality has remained stagnant, and none of the studies reviewed met all of the reporting standards. Alignment with standards ranged from 33% to 77%. Implications for researchers and practitioners are discussed. 相似文献
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Science education in the United States will increasingly be driven by testing and accountability requirements, such as those mandated by the No Child Left Behind Act, which rely heavily on learning outcomes, or "standards," that are currently developed on a state-by-state basis. Those standards, in turn, drive curriculum and instruction. Given the importance of standards to teaching and learning, we investigated the quality of life sciences/biology standards with respect to genetics for all 50 states and the District of Columbia, using core concepts developed by the American Society of Human Genetics as normative benchmarks. Our results indicate that the states' genetics standards, in general, are poor, with more than 85% of the states receiving overall scores of Inadequate. In particular, the standards in virtually every state have failed to keep pace with changes in the discipline as it has become genomic in scope, omitting concepts related to genetic complexity, the importance of environment to phenotypic variation, differential gene expression, and the differences between inherited and somatic genetic disease. Clearer, more comprehensive genetics standards are likely to benefit genetics instruction and learning, help prepare future genetics researchers, and contribute to the genetic literacy of the U.S. citizenry. 相似文献
15.
李泉 《暨南大学华文学院学报》2012,(1):51-59
本文回顾和讨论了国际汉语教师的标准问题,结合汉语国际化的现状及外语教学的性质和特点,提出应明确面向海外培养的国际汉语教师的规格,并主张以“合格”为汉语教师培养的基本规格。文中讨论和例示了合格的国际汉语教师必须具备的基本知识、基本能力和基本素养（“三基”）,并强调在国际汉语教师特别是汉语国际教育专业硕士培养过程中,“三基”类课程应不低于总课程量的60％,其中属于基本知识的汉语（语音、词汇、语法）及汉字本体知识的课程亦不应低于“三基”类课程的60％．以此保证我们培养的人才首先是合格的汉语教师,保证他们未来汉语教学的质量。 相似文献
16.
为了研究中国湖南省大型商业办公建筑室内空气品质环境现状及其改善对策,选取湖南省长沙市某大型商业办公建筑为研究对象,对此建筑在2008年7月的室内空气品质状况进行了调研.采用问卷调查和现场测试的方法收集数据,并基于这些数据对12个房间的室内空气品质进行客观和主观评价.结果表明,这些房间室内空气品质的主要参数基本满足客观评价的标准,但大部分房间的CO2平均浓度未能达到清洁标准规定值1255mg/m^3.这些房间室内空气品质的平均接受率为71%,低于ASHRAE55—1992标准规定值（80%）.适当地提高空气流速、增加新风量可以很好地改善室内空气品质的主、客观评价. 相似文献
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The proliferation of bioinformatics in modern biology marks a modern revolution in science that promises to influence science education at all levels. This study analyzed secondary school science standards of 49 U.S. states (Iowa has no science framework) and the District of Columbia for content related to bioinformatics. The bioinformatics content of each state's biology standards was analyzed and categorized into nine areas: Human Genome Project/genomics, forensics, evolution, classification, nucleotide variations, medicine, computer use, agriculture/food technology, and science technology and society/socioscientific issues. Findings indicated a generally low representation of bioinformatics-related content, which varied substantially across the different areas, with Human Genome Project/genomics and computer use being the lowest (8%), and evolution being the highest (64%) among states' science frameworks. This essay concludes with recommendations for reworking/rewording existing standards to facilitate the goal of promoting science literacy among secondary school students. 相似文献
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The purpose of this study was to evaluate the perceived benefit of the core curriculum standards of the Council for Accreditation of Counseling and Related Educational Programs (CACREP; 2001). A total of 641 individuals, whose names were obtained from a 6% proportional randomized sample of members from the American Mental Health Counselors Association, American School Counselor Association, and Association for Counselor Education and Supervision, responded to this study. Results suggest various perceptions both within and between groups regarding the 8 CACREP core curriculum standards. 相似文献
19.
This paper provides a detailed analysis of the inclusion of aspects of nature of science (NOS) in the Next Generation Science Standards (NGSS). In this new standards document, NOS elements in eight categories are discussed in Appendix H along with illustrative statements (called exemplars). Many, but not all, of these exemplars are linked to the standards by their association with either the “practices of science” or “crosscutting concepts,” but curiously not with the recommendations for science content. The study investigated all aspects of NOS in NGSS including the accuracy and inclusion of the supporting exemplar statements and the relationship of NOS in NGSS to other aspects of NOS to support teaching and learning science. We found that while 92 % of these exemplars are acceptable, only 78 % of those written actually appear with the standards. “Science as a way of knowing” is a recommended NOS category in NGSS but is not included with the standards. Also, several other NOS elements fail to be included at all grade levels thus limiting their impact. Finally, NGSS fails to include or insufficiently emphasize several frequently recommended NOS elements such as creativity and subjectivity. The paper concludes with a list of concerns and solutions to the challenges of NOS in NGSS. 相似文献
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按照《中国药典》（2010版）中关于水分、总灰分和浸出物测定方法,对三台县川产道地药材一麦冬的相关含量进行了测定与分析．结果表明：三台县川产道地药材一麦冬的水分含量范围为（9．77±0．27）％～（12．41±0．41）％,平均值为10．69％,总灰分含量范围为（2．43±0．06）O～（3．05±0．08）O,平均值为2．84％,浸出物含量范围为（70．91±0．97）％～（76．12±1．30）％,平均值是73．80％,均满足《中国药典》（2010版）麦冬的用药标准,而且水分含量不超过14．0％,总灰分含量不高于4．00,水溶性浸出物不低于70％． 相似文献