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51.
52.
中国小麦产业发展与科技进步 总被引:26,自引:2,他引:24
文章总结分析了新中国成立以来中国小麦生产发展和品种选育与栽培技术研究的历史进程。小麦生产发展分为4个阶段,即1949—1957年恢复性增长、1958—1978年稳定增长、1979—1999年单产快速增长和2000—2016年产量质量同步提升。简要介绍了1949年前的育种起步历史,1950年以后小麦育种取得了巨大进展,经历了抗病稳产早熟、矮化抗倒高产和高产优质高效3个阶段,矮秆基因和1B/1R易位系利用与株型改良起到关键作用,育成了碧蚂1号、泰山4号、扬麦158、豫麦21、济麦22等突破性品种,主产麦区经历了8~9次品种更新换代。黄淮麦区的矮秆高产育种和长江中下游麦区的抗赤霉病育种在国际上产生重要影响。概括了种质资源、远缘杂交、矮败小麦、品质改良、兼抗型成株抗性育种、基因组学等领域的新进展。小麦栽培研究经历了4个阶段,20世纪50年代以合理密植为核心,20世纪六七十年代重点研究不同麦区小麦生长发育规律与高产栽培历程,20世纪80年代提出了各主要麦区栽培技术模式包括精播高产、节水高产等技术,20世纪90年代以优质和信息技术应用为主。未来产业发展面临提升质量、降低成本和保护环境三大挑战,气候变化、病害加重、缺乏优质高效抗病品种制约生产发展,建议加强优质抗病高效品种选育与新技术应用研究,实现栽培研究与植保、土肥、农机等有机结合,以全面提高小麦产业的竞争力。 相似文献
53.
用响应面法优化红甘蓝色素提取工艺参数 总被引:14,自引:0,他引:14
选取红甘蓝色素提取时间、提取温度和料液比3个因素进行中心组合设计,利用响应面法对其提取工艺参数进行优化研究。利用Design Expert软件对红甘蓝色素提取产量的二次多项数学模型解逆矩阵分析表明:在提取温度为43.6℃,提取时间37.9 m in,料液比1∶21.3时,红甘蓝色素提取产量最高,最大提取产量预测值为8.957 mg.g-1,与实测值相符。利用优化工艺参数提取红甘蓝色素时,具有最大的提取产量。 相似文献
54.
55.
茶多酚中儿茶素类的HPLC分析方法学考察 总被引:25,自引:0,他引:25
本文建立了一种非梯度洗脱的儿茶素HPLC定性定量分析方法 ,同时对茶多酚中的四种主要儿茶素(EC ,EGCG ,ECG ,EGC)考察了其方法学。得到最佳色谱条件为 :ODS (5 μm ,4 6× 2 5 0mm)柱 ,以重蒸水∶乙睛∶乙酸乙酯 =86∶12∶2 (v v v)为流动相 (浓硫酸调pH值至 3 0~ 4 0 ) ,流速为 1 0ml min ,UV检测波长 2 80nm。探讨了分离测定条件并验证其精密度及方法的稳定性 相似文献
56.
J.M. Sargeant A. Thompson J. Valcour R. Elgie J. Saint-Onge P. Marcynuk K. Snedeker 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2010,24(1):44-50
Background: To address concerns about the quality of reporting of randomized controlled trials, and the potential for biased treatment effects in poorly reported trials, medical journals have adopted a common set of reporting guidelines, the Consolidated Standards of Reporting Trials (CONSORT) statement, to improve the reporting of randomized controlled trials.
Hypothesis: The reporting of clinical trials involving dogs and cats might not be ideal, and this might be associated with biased treatment effects.
Animals: Dogs and cats used in 100 randomly selected reports of clinical trials.
Methods: Data related to methodological quality and completeness of reporting were extracted from each trial. Associations between reporting of trial features and the proportion of positive treatment effects within trials were evaluated by generalized linear models.
Results: There were substantive deficiencies in reporting of key trial features. An increased proportion of positive treatment effects within a trial was associated with not reporting: the method used to generate the random allocation sequence ( P < .001), the use of double blinding ( P < .001), the inclusion criteria for study subjects ( P = .003), baseline differences between treatment groups ( P = .006), the measurement used for all outcomes ( P = .002), and possible study limitations ( P = .03).
Conclusions and Clinical Importance: Many clinical trials involving dogs and cats in the literature do not report details related to methodological quality and aspects necessary to evaluate external validity. There is some evidence that these deficiencies are associated with treatment effects. There is a need to improve reporting of clinical trials, and guidelines, such as the CONSORT statement, can provide a valuable tool for meeting this need. 相似文献
Hypothesis: The reporting of clinical trials involving dogs and cats might not be ideal, and this might be associated with biased treatment effects.
Animals: Dogs and cats used in 100 randomly selected reports of clinical trials.
Methods: Data related to methodological quality and completeness of reporting were extracted from each trial. Associations between reporting of trial features and the proportion of positive treatment effects within trials were evaluated by generalized linear models.
Results: There were substantive deficiencies in reporting of key trial features. An increased proportion of positive treatment effects within a trial was associated with not reporting: the method used to generate the random allocation sequence ( P < .001), the use of double blinding ( P < .001), the inclusion criteria for study subjects ( P = .003), baseline differences between treatment groups ( P = .006), the measurement used for all outcomes ( P = .002), and possible study limitations ( P = .03).
Conclusions and Clinical Importance: Many clinical trials involving dogs and cats in the literature do not report details related to methodological quality and aspects necessary to evaluate external validity. There is some evidence that these deficiencies are associated with treatment effects. There is a need to improve reporting of clinical trials, and guidelines, such as the CONSORT statement, can provide a valuable tool for meeting this need. 相似文献
57.
响应曲面法优化雪莲果果粉喷雾干燥工艺研究 总被引:1,自引:0,他引:1
[目的]对雪莲果果粉喷雾干燥工艺进行优化。[方法]选取料液固形物含量(A)、进料流量(B)、进风温度(C)3个影响雪莲果果粉喷雾干燥感官品质的主要因素进行3因素3水平响应面试验设计;建立雪莲果果粉喷雾干燥感官评定标准;通过DesignExpert软件对试验数据进行方差分析和回归分析,进而预测出最优的雪莲果果粉啧雾干燥工艺,对回归模型的精度及优化工艺的可行性进行验证,并对雪莲果果粉的理化指标和微生物指标进行检测。[结果]利用DesignExpert软件进行二次多元回归拟合,得到雪莲果果粉喷雾干燥产品感官评分预测值(Y)对编码自变量A、B和C的二次多项回归方程为:Y=85.40+2.75A-1.13B-3.13C-0.75AB-1.75AC-8.50BC-4.20A^2-4.45B^2-10.95C^2。利用DesignExpert得到优化的喷雾干燥工艺为:料液固形物含量37.27%,进料流量18.93ml/min,进风温度156.14℃。3次重复试验的最大相对误差为3.34%,证明应用响应曲面法得到的回归模型的精度较高,优化的雪莲果果粉喷雾干燥工艺是可行的.[结论]该研究为雪莲果的深加工提供了参考依据。 相似文献
58.
Great Britain's wintering coastal wader populations have been estimated for the period 1994/1995-1998/1999 from data provided from two sources: the Wetland Bird Survey (WeBS) and the Non-estuarine Coastal Waterfowl Survey (UK-NEWS). New methodology for estimating the number of wintering waders is applied. It imputes (fills in) the value of missing counts before estimating the population size of each species as being the mean of the largest annual count made between November and March over the relevant 5-year period. This methodology has led to an 11% larger estimate of the number of waders present on Great Britain's coasts than the traditional approach based on averaging just January counts over a 5-year period, and it suggests that Great Britain's coastline supports ca. 2.1 million waders. Updated values are presented from which site evaluations based on 1% of the national population can be derived. Great Britain is of considerable international importance for waders. It holds >25 and >50% of the flyway populations of nine and four species of wader, respectively, but for the first time since the start of monitoring in the early 1970s, the historical increase in the number of predominantly coastal waders wintering in Great Britain is coming to an end. Seven of the 14 species that have shown population changes of >5% since the last set of 1987/1988-1991/1992 population estimates have declined in numbers. The possible causes of the fluctuations in wader populations, such as climate change and changing nutrient inputs to coastal waters are discussed. There is an urgent need to identify the causative factors leading to these declines, and to use the new population estimates to identify new sites that should be afforded legal protection, an action that should help Great Britain maintain its internationally important wader populations. The decrease in the updated population estimate of Eurasian oystercatcher, for example, has made it possible to determine that 19 rather than 17 sites in Great Britain are worthy of statutory protection on the basis of holding 1% or more of its national population. 相似文献
59.
W. Foissner 《Biology and Fertility of Soils》1997,25(4):317-339
This paper provides, for the first time, comprehensive data on alpha diversity of soil ciliates from evergreen tropical and
temperate rain forests. Thirty-three samples were collected in Australia, Tasmania, Amazonia and Costa Rica and analysed with
the non-flooded Petri dish method, which reactivates the ciliates’ resting cysts from air-dried samples. The 175 taxa found
contained 34 new species, 4 of which are described in this paper, viz. Platyophrya paoletti n. sp., Lamtostyla abdita n. sp., L. granulifera n. sp., and Apoamphisiella tihanyiensis (Gellért and Tamás 1958) n. gen., n. comb. Although this is a considerable number, it is much lower than one would expect.
The data would be even more perplexing if the four rich samples (up to 90 species/sample) from the Manaus floodplain were
excluded. We then would be confronted with about 90 taxa in 29 samples, of which 13 contained fewer than ten species. A hypothesis
is put forward that the non-flooded Petri dish method is inappropriate for studying soil ciliate diversity in evergreen rain
forests because most species have a reduced capacity to produce dry-resistant (protective) resting cysts due to the permanent
wetness of their habitats. This view is supported by a comparative analysis of a fresh (containing 40 species) and air-dried/rewetted
(2 species only) sample from a cloud rain forest near Merida (Venezuela), and the observation that the capacity of soil ciliates
to produce resting cysts often dramatically decreases after prolonged laboratory cultivation in liquid media. Direct microscopy
of fresh samples seems to be an appropriate alternative because specimens can be easily collected due to their considerable
abundance (≥1000 individuals/g wet mass of litter).
Received: 8 April 1997 相似文献
60.
为了提高灵芝(Ganoderma lucidum)AM21菌株菌丝产灵芝三萜的能力,采用响应面法对其液体发酵培养基配方进行优化.首先采用Plackett- Burman设计法对影响菌丝体三萜含量的9个相关因素进行筛选,确定主要影响因子为豆粕粉和山药,然后用最陡爬坡试验逼近2个主要因素的最大响应区域,并通过中心组合设计和响应面分析,确定主要影响因子的最佳浓度.优化后的培养基组成为1.84%豆粕粉,1%玉米粉,1%葡萄糖,0.92%山药,0.5%酵母粉,0.1%麸皮,0.1% KH2 PO4,0.1% MgSO4·7H2O,0.01% VB1.使用该培养基生产的灵芝菌丝体中三萜含量较使用基础发酵培养基生产的高29.13%. 相似文献