Significance of nitrogen oxide and its metabolites in the development of embryos

A high content (about a millimole) of compounds, nitrogen oxide (NO) donors, is found in the amniotic fluid of chicken embryos and bovine placenta. Their high content is found also in the blood of newborn calves and chicks before hatching. The possible role of NO and its metabolites in embryogenesis is discussed.     

乌龙茶制造与品质形成的化学机理

乌龙茶制造与品质化学涉及制造原料理化性状、制造过程化学变化和成茶品质化学基础 3方面内容 .从原料、制造到成茶 ,贯穿其中的重要理论与技术原理是“控制”,即 :(1 )选择适当茶树品种和一定成熟度的新梢以限制原料中部分化学成分特别是多酚类物质的含量和比例 ;(2 )将多酚类物质制茶氧化控制在鲜叶局部和一定变化范围内进行 ;(3 )控制“做青”进程以促进内含物转移、转化 ;(4 )防止成茶色泽成分比例失调     

水气互作对滴灌加工番茄生长及品质的影响

为探明不同加气方式和灌水量互作对北疆滴灌加工番茄生长及产量品质的影响,以及适宜北疆加工番茄滴灌的最佳水气组合模式,设置3种加气方式[物理加气(O1)、不加气(O2)、化学加气(O3)]、4个灌水量水平[5400 m3/hm2(W1)、4950 m3/hm2(W2)、4500 m3/hm2(W3)、4050 m3/hm2...     

Wheat gluten protein and its impacts on wheat processing quality

Before the advent of the wheat genomic era, a wide range of studies were conducted to understand the chemistry and functions of the wheat storage proteins, which are the major determinants of wheat flour the suitability of wheat flour for various end products, such as bread, noodles and cakes. Wheat grain protein is divided into gluten and non-gluten fractions and the wheat processing quality mainly depends on the gluten fractions. Gluten provides the unique extensibility and elasticity of dough that are essential for various wheat end products. Disulfide bonds are formed between cysteine residues, which is the chemical bases for the physical properties of dough. Based on the SDS-extractability, grain protein is divided into SDS-unextractable polymeric protein (UPP) and SDS-extractable polymeric protein. The percentage of UPP is positively related to the formation of disulfide bonds in the dough matrix. In the wheat genomic era, new glutenins with long repetitive central domains that contain a high number of consensus hexapeptide and nonapeptide motifs as well as high content of cysteine and glutamine residues should be targeted.     

黑果腺肋花楸榨汁工艺研究与果汁品质评价

为制备具有强稳定性、高抗氧化与良好感官品质的黑果腺肋花楸汁,以出汁率、沉淀率和可溶性固形物含量为指标,优化料液比、果胶酶添加量,分析黑果腺肋花楸汁的总抗氧化性、抑制羟基自由基能力、清除DPPH能力;并从色度、总酚、花色苷含量、抗氧化性4个方面对不同贮藏方式的黑果腺肋花楸汁进行稳定性研究,用模糊数学法对黑果腺肋花楸汁进行感官评价。结果显示:料液比为1∶1、果胶酶添加量在0.4%时,黑果腺肋花楸汁的出汁率和可溶性固形物含量均较高;黑果腺肋花楸汁的总抗氧化能力为11.5 μmol·mL^-1,抑制羟基自由基能力为17 610.3 U·mL^-1。100 mL黑果腺肋花楸汁中相当于含有100.0 mg维生素C(V_C),总酚和花色苷含量分别为6.8、0.7 mg·mL^-1;在4 ℃避光贮藏120 d,果汁呈深紫红色,颜色变化不大,总酚和花色苷含量、抗氧化能力均未明显降低;感官评价介于优、良之间。通过工艺优化制备的黑果腺肋花楸汁具有较强抗氧化性和稳定性,且感官品质良好。     

氮磷钾肥施用量和运筹对稻米加工品质和外观品质质的影响

通过氮磷钾肥用量和追施磷钾肥试验,研究氮磷钾三元素对不同水稻品种稻米加工品质和外观品质的影响.结果表明,水稻品种与氮磷钾肥之间存在互作效应,氮磷钾三元素之间也存在一定的互作效应,增施氮肥能提高稻米加工和外观品质,增施磷钾肥整体也有利于加工和外观品质的提高,但不同品种的反应不同.     

土壤氮素矿化及其对烤烟品质的影响研究进展

在所有必需营养元素中,氮素是对烤烟产量和品质影响最大、最敏感的元素.在烟草生产中,维持烟株生长发育和形成优良品质的氮素来源,不仅仅是人为施入的肥料氮,土壤矿化氮在烤烟氮素营养中也占有重要地位.关于土壤矿化氮对蔬菜和粮食作物生产的贡献已有较多研究,但对烤烟产量和质量影响的研究尚不多见.针对此问题,笔者总结了现阶段土壤有机氮矿化及烤烟氮素营养的研究结果,详细阐述了土壤氮素矿化的影响因素和研究方法,分析了土壤矿化氮对烤烟氮素累积分配和烟叶烟碱含量的影响,并在文章最后对未来的研究方向作了展望.     

我国小麦优质生产与加工转化之思路

小麦是我国仅次于水稻的第二大粮食作物 ,总消费量占全国粮食总量的 1/ 4左右 ,年均收购量、销售量和库存量分别约为全国粮食作物总产量的 30 %、40 %及 35%。新中国成立以来 ,特别是近 2 0ａ来 ,随着生产条件的改善与麦作科技水平的不断提高 ,小麦生产得到持续快速的发展 ,不仅解决了数量短缺 ,而且还在一些产麦大省出现了小麦过剩或积压现象。然而 ,这种过剩是一种暂时过剩 ,是生产结构不适应消费结构的过剩。主要是因为普通品种与品质欠佳的品种供过于求 ,而优质小麦却是供不应求 ,并仍需进口。随着我国小麦制品工业 (特别是专用粉生产 )…     

Global air quality and pollution

The impact of global air pollution on climate and the environment is a new focus in atmospheric science. Intercontinental transport and hemispheric air pollution by ozone jeopardize agricultural and natural ecosystems worldwide and have a strong effect on climate. Aerosols, which are spread globally but have a strong regional imbalance, change global climate through their direct and indirect effects on radiative forcing. In the 1990s, nitrogen oxide emissions from Asia surpassed those from North America and Europe and should continue to exceed them for decades. International initiatives to mitigate global air pollution require participation from both developed and developing countries.     

N对叶菜型甘薯硝酸盐积累及品质的影响

研究5、10、20、40mmol·L-14个N浓度对叶菜型甘薯鲜嫩茎叶的硝酸盐含量、硝酸还原酶(NR)活性、可溶性蛋白及总糖含量的影响.结果表明:随着N含量的增加,植株体内硝酸盐含量呈线性增加,随处理时间延长,高N含量下硝酸盐积累持续增加,但在较低含量下硝酸盐积累在施N后6-8d达到极值后有所下降;NR活性随N含量增加显著提高;N含量与总糖含量呈负相关,N含量高不利于总糖积累;N含量提高,植株可溶性蛋白含量也有所提高,但效果不明显.     

高香型红茶初制加工工艺对茶叶品质的影响

本文中提到高香型红茶初制中萎凋、揉捻、发酵、干燥等加工工艺对茶叶品质的影响。研究表明：控制萎凋叶含水率60%时, 经揉捻后制茶率高, 茶叶品质好;黄观音等高香型型红茶品种,发酵室的环境温度为25～26℃,湿度90％以上,发酵时间以3～4h为宜,成茶品质好。     

Urban leakage of liquefied petroleum gas and its impact on Mexico city air quality

Alkane hydrocarbons (propane, isobutane, and n-butane) from liquefied petroleum gas (LPG) are present in major quantities throughout Mexico City air because of leakage of the unburned gas from numerous urban sources. These hydrocarbons, together with olefinic minor LPG components, furnish substantial amounts of hydroxyl radical reactivity, a major precursor to formation of the ozone component of urban smog. The combined processes of unburned leakage and incomplete combustion of LPG play a significant role in causing the excessive ozone characteristic of Mexico City. Reductions in ozone levels should be possible through changes in LPG composition and lowered rates of leakage.     

Agricultural products processing characteristics and quality evaluation

正Cereal,oil and fruit are the foundation of human survival which attracted much attention by their quality characteristics and products.Currently,there are about 410 000 wheat resources(Drikvand et al.2013),215 000 rice resources(Kaur et al.2014),35 000 peanut resources(Wang et al.2014),and 7 000 apple resources(Nie et al.2013).The pro     

滴灌水氮管理对玉米种植土壤无机氮含量和氧化亚氮排放的影响

【目的】获得玉米种植土壤氧化亚氮(N₂O)减排的滴灌施肥模式,揭示不同滴灌灌水量和施氮比例下土壤无机氮含量对土壤N₂O排放的影响。【方法】在移动防雨棚内开展2季玉米3种滴灌灌水量(W60、W80和W100分别为田间持水量的50%～60%、70%～80%和90%～100%)和2种滴灌施氮比例(等N量为180 kg·hm-2,其中,F55为50%氮肥作基肥土施、50%氮肥作滴灌施肥,F37为30%氮肥作基肥土施、70%氮肥作滴灌施肥)的田间试验,测定生育期内土壤N₂O通量和不同生育时期土壤无机氮含量,计算不同生育时期和全生育期土壤N₂O排放量,分析土壤N₂O通量与土壤无机氮含量之间的关系。【结果】2季玉米土壤的N₂O排放规律相似;相同施氮比例下,W100水分处理下土壤N₂O排放通量在多数玉米生育时期高于W60和W80,表明高水分处理下土壤N₂O排放通量高于中、低水分处理;相同水分处理下,除夏季玉米苗期外,土壤N     

上海环境空气质量变化研究

以上海市2000—2013年间的环境空气质量监测数据为依据,对SO_2、NO_2、PM_(10)和pH进行统计分析。结果表明:SO_2质量浓度从0.061 mg/m~3下降到0.024 mg/m~3;NO_2质量浓度从0.090 mg/m~3下降到0.048 mg/m~3;PM_(10)质量浓度从0.099 mg/m~3下降到0.071 mg/m~3;但是,降水pH在4.39—5.19,酸雨率呈上升趋势。近14年上海市空气质量优良率为89.7%,冬季较差,夏季较好。从空间分布来看,城市中心区域PM_(10)污染远高于非中心区域,其中杨浦区、普陀区、徐汇区、黄浦区的空气质量较差,金山区、崇明县的空气质量最好。相关数据分析表明,上海市空气污染源主要是工业燃煤、建筑施工扬尘和机动车尾气。     

氮肥水平对冬大麦产量、品质和氮肥利用效率的影响及其相关分析

以扬饲麦3号、港啤1号、扬农啤2号和Frankin等4个品种为试材,分析施氮水平对冬大麦产量、品质和氮肥利用效率的影响及其相关性。结果表明:随着施氮量的增加,各品种产量、单位面积有效穗数、每穗粒数、地上部含氮量及籽粒蛋白质含量增加,千粒重下降,各品种氮肥利用效率亦下降。不同氮肥处理水平下,大麦产量与千粒重呈极显著负相关,与籽粒蛋白质含量呈显著正相关,与氮肥偏生产力呈显著负相关。地上部氮积累量与氮肥生产效率、氮肥偏生产力和氮肥生理效率呈极显著负相关,千粒重与籽粒蛋白质含量呈显著负相关。氮肥生产效率与氮肥生理效率呈极显著正相关,氮肥农学效率与氮肥偏生产力呈显著正相关,氮肥偏生产力与氮肥生理效率呈显著正相关。     

Large-scale nitrogen oxide plumes in the tropopause region and implications for ozone

Continuous measurements of nitrogen oxide and ozone were performed from a commercial airliner during 1 year at cruising altitudes below and above the tropopause. The upper tropospheric nitrogen oxides distribution was found to be strongly influenced by large-scale plumes extending about 100 to 1300 kilometers along the flight track. The plumes were frequently observed downwind of thunderstorms and frontal systems, which most probably caused upward transport of polluted air from the continental boundary layer or nitrogen oxide production in lightning strokes, or both. Particularly in summer, average ozone concentrations in the plumes were enhanced compared to the tropospheric background levels.     

冷冻绿芦笋加工工艺及其质量控制

该文主要介绍冷冻绿芦笋的加工工艺,并对其重点工序的质量控制进行了阐述.采用此工艺加工的产品色泽鲜绿,口味鲜美,营养丰富.