家蚕品种间游离氨基酸和酯酶同工酶的研究

家蚕血液中游离氨基酸总含量在品种间差异很大，最大开差可达２倍。蚕体合成丝素原料的丝氨酸、脯氨酸、苏氨酸、甘氨酸等４种氨基酸以及组氨酸、赖氨酸、胱氨酸在血液中含量较高。肠液中氨基酸总含量显著低于血液中，两者最大差值达２０倍，无相关性。品种间酯酶同工酶酶带的相似系数为０．６７～１．００，说明在某些品种问有较高的相似性，而在另一些品种间又有明显的差异性。     

Antioxidative activity of extracts from Luffa cylindrica

AIM: To isolate the active compounds of Luffa cylindrica and investigate their antioxidative activity. METHODS: Antioxidants from Luffa cylindrica were isolated using solvent extraction and Sephadex column chromatography. Active compounds of the extracts were identified with the antioxidative activity assays. RESULTS: With solvent extracting procedure, four extracts (Ⅱ, Ⅲ, Ⅳ and Ⅴ) were obtained. Among these extracts, extract Ⅲ had significant antioxidative activity, which exerted a potent scavenging effect for both DPPH· and OH· assays. For further purification, extract Ⅲ was subject to Sephadex column and five fractions ( A, B, C, D and E ) were isolated. Fraction D and E showed good efficiency on scavenging DPPH· and OH·, and exhibited flavanoid characteristics. CONCLUSION: Luffa cylindrica efficiently scavenges free radical species, and flavanoid exerts this action.     

The effect of increased atmospheric carbon dioxide concentration on emissions of nitrous oxide, carbon dioxide and methane from a wheat field in a semi-arid environment in northern China

There are no reports on the effects of elevated carbon dioxide [CO₂] on the fluxes of N₂O, CO₂ and CH₄ from semi-arid wheat cropping systems. These three soil gas fluxes were measured using closed chambers under ambient (420 ± 18 μmol mol⁻¹) and elevated (565 ± 37 μmol mol⁻¹) at the Free-Air Carbon dioxide Enrichment experimental facility in northern China. Measurements were made over five weeks on a wheat crop (Triticum aestivum L. cv. Zhongmai 175). Elevated [CO₂] increased N₂O and CO₂ emission from soil by 60% and 15%, respectively, but had no significant effect on CH₄ flux. There was no significant interaction between [CO₂] and N application rate on these gas fluxes, probably because soil N was not limiting. At least 22% increase in C storage is required to offset the observed increase in greenhouse gas emissions under elevated [CO₂].     

4105柴油机曲轴自由模态分析与试验研究

基于虚拟样机技术建立4105柴油机曲轴三维模型,并对曲轴自由模态进行了计算分析,得出2 000 Hz内共有9阶模态,其中最低阶模态为曲轴振动的危险区域,在柴油机工作转速范围内会引起共振。采用多点激励单点响应法对4105柴油机曲轴进行了模态试验,获得了0～2 000 Hz频率范围内的曲轴模态参数。模态试验结果和有限元计算结果对比分析表明,有限元计算结果较好地反映了曲轴的固有振动特性。     

热激对温敏核不育系“安农S-1”花药生理变化的影响

试验研究热激对温敏核不育系“安农S-1”花药生理变化的影响结果表明,温敏核不育系“安农S-1”在花粉母细胞形成至减数分裂期经热激(38℃)处理后,其花药中游离氨基酸总量、天冬氨酸和丙氨酸含量均显著高于低温(23℃)处理;而游离脯氨酸和可溶性蛋白质含量则显著低于低温处理。对照经热激(38℃)处理后,其花药中游离氨基酸和可溶性蛋白质含量与低温处理基本一致,这些生理变化可能影响花粉母细胞正常的形成和减数分裂,以致花粉不能正常发育并最终导致花粉败育。     

糙米发芽工艺参数研究

[目的]优化糙米发芽工艺参数.[方法]以黑龙江省糙米为原料制备发芽糙米,通过单因素试验确定最佳的糙米浸泡温度、浸泡时间、发芽温度、发芽时间,紫外分光光度法快速测定确定糙米及发芽糙米中的γ-氨基丁酸和游离氨基酸的含量为指标,进行正交试验.[结果]试验表明,浸泡温度为30℃,浸泡时间为10 h,发芽温度为35 ℃,发芽时间为34 h,此条件下γ-氨基丁酸的积累量达最高.浸泡温度为35℃,浸泡时间为12 h,发芽温度为25 ℃,发芽时间为34 h,此条件游离氨基酸积累量达最高.[结论]研究可为进一步了解黑龙江省七台河糙米产品提供依据.     

我国《反垄断法》立法中几个基本问题

目前，我国反垄断方面还没有形成完整的法律体系，制定一部与已有的《反不正当竞争法》相互协调，对市场竞争起到保护和促进作用的《反垄断法》已是当务之急。在此立法中，要明确反垄断法的立法宗旨、反垄断法规范制约的垄断行为、反垄断法的列外、反垄断执法机构的设置与职责，以及垄断行为应承担的法律责任等几个主要问题。     

植物组织中自由水和束缚水含量测定方法的改进

在对测定植物组织自由水和束缚水的常规方法——阿贝折射仪法的误差来源进行分析的基础上,对其测定方法进行了改进,将测定糖液的浓度改为直接测定叶片的质量,通过测试不同蔬菜的组织材料,确定了改进后的测定方法——称重法。称重法操作简便,误差小。     

仔猪红细胞内游离原卟啉微量测定法及正常值探讨

利用荧光分析法建立了猪红细胞内游离原卟啉（ＦＥＰ）微量测定法。经回收率和重复性测定，证明该法准确度高，完全符合实验要求。可以用于仔猪缺铁性贫血的诊断，并可以作为研究仔猪铁代谢的一个主要参数。应用本法首次测定了３～３０日龄仔猪在补铁与未补铁情况下ＦＥＰ值和ＦＥＰ／Ｈｂ比值。补铁组ＦＥＰ值为１８５．２４±１３．１２～２５８．６３±２１．０９μｇ／ｄｌＲＢＣ；ＦＥＰ／Ｈｂ比值为７．００±０．５４～９．４３±０．７３μｇ／ｇＨｂ，未补铁组ＦＥＰ值为１９４．６９±９．２３～２４７．８８±１５．１４μｇ／ｄｌＲＢＣ；ＦＥＰ／Ｈｂ比值在６．９６±０．３３～１０．１９±０．７３μｇ／ｇＨｂ。关键词     

Effect of mild hypothermia on energy metabolism and hydroxyl radical production after cerebral ischemia/reperfusion in gerbils

AIM: To study the effect of mild hypothermia on energy metabolism and hydroxyl radical production as well as delayed neuronal death (DND) in hippocampus during cerebral ischemia/reperfusion in gerbils.METHODS: Forebrain ischemia was induced by occluding bilateral common carotid arteries with aneurysm clamps for 10 min in gerbils. The DND in hippocampal CA1 sector was assessed by histological examination, and hydroxyl radical, ATP (adenosine triphosphate), ADP (adenosine diphosphate),AMP (adenosine monophosphate) levels were determined by high performance liquid chromatography with electrochemical or ultraviolet detection. RESULTS: The number of survival neuronal in hippocampal CA1 sector in mild hypothermia + I/R group was more than that in I/R group after ischemia/reperfusion 96 h. The content of 2,3-DHBA (2,3- dihydroxybenzoic acid) in hippocampus in I/R group was much higher than those in sham operation and mild hypothermia + I/R group after reperfusion 6 h (P＜0.01), but there were no significant differences in 2,3-DHBA outputs among 3 groups 48 h and 96 h after reperfusion. There were no obvious differences in ATP, ADP, AMP level in hippocampus among 3 groups 6 h after reperfusion. However, the content of ATP,ADP,AMP in mild hypothermia + I/R group was much higher than those in I/R group 48 and 96 h after reperfusion (P＜0.01).CONCLUSION: Mild hypothermia can reduced DND by improving the cerebral energy metabolism during forebrain ischemia/reperfusion in gerbils.