正交设计优选细果角茴香中总黄酮的提取工艺条件

[目的]研究细果角茴香中总黄酮的最佳提取工艺,并测定其含量.[方法]以总黄酮含量为考察指标,以甲醇浓度、料液比和提取时间为考察因素,通过正交试验确定提取总黄酮的最佳条件.[结果]吸收曲线测定结果显示,总黄酮在510 nm处有最大吸收.正交试验结果可知,最佳的提取条件为A1B2C2,即甲醇浓度为50％,料液比为1∶15（g/ml）,超声提取2次,每次提取时间为20 min;在此条件下,总黄酮的含量最高为48.63 mg/g.[结论]该方法操作简捷,结果准确可靠,提取效率高.     

Physiological Determinants of Crop Growth and Yield in Maize,Sunflower and Soybean

SUMMARY

This review focuses on the mechanisms determining yield in maize, sunflower and soybean, the three major summer crops of the Argentinean Pampas. Emphasis is given to the capture of light by the crop canopy and the processes determining grain set and grain filling. A strong correlation between grain yield and the physiological status of crops or plants at crop-specific critical periods is confirmed. This basic physiological information is used (i) to evaluate and understand the effect of agricultural management practices on crop yield and (ii) as the source of concepts and quantitative relationships for crop simulation models. Finally, we discuss the relevance of the described physiological processes for crop breeding.     

烟台黑猪胴体品质及肉质营养研究

烟台黑猪肉质鲜美,营养丰富。本试验对烟台黑猪进行了屠宰测定、肉质测定和营养成分测定,测定发现烟台黑猪屠宰测定指标与杜长大猪差异不显著,烟台黑猪大部分肉质测定指标显著高于杜长大猪,氨基酸含量烟台黑猪显著高于杜长大猪,饱和脂肪酸烟台黑猪显著低于杜长大猪,不饱和脂肪酸烟台黑猪显著高于杜长大猪。结果表明,烟台黑猪比杜长大猪肌肉色泽、多汁性、嫩度和风味明显要好,肌肉鲜味更浓,营养价值更高,更具有营养和保健作用。     

人组织蛋白酶K在毕赤酵母中的表达、纯化及活性测定

在动物和人的骨代谢疾病中,组织蛋白酶K是木瓜蛋白酶家族中的一种半胱氨酸蛋白酶,是负责骨吸收过程中溶骨的主要关键酶,是新药物的分子作用靶点。通过毕赤酵母表达系统表达出重组组织蛋白酶K,进一步用离子交换和分子筛系统进行纯化得到高纯度有活性的重组组织蛋白酶K。运用FluStar荧光酶标仪测定390 nm(激发光)和460 nm(发射光)波长下荧光强度的变化并计算出组织蛋白酶K的酶活力为119.6 U,为进一步筛选骨质疏松等骨代谢疾病的新药提供参考。     

农田灌溉水中挥发酚的流动分析-分光光度分析法的建立

主要通过使用流动分析仪对农田灌溉水中的挥发酚进行测定,有效地提高了检测的精密度与准确度。相比传统分光光度计检测法,此法更方便和快捷,大大降低了样品的使用量,节省了人力物力,较好地满足了批量样品测定的要求,值得大力推广和应用。     

加速溶剂提取-固相萃取净化-高效液相色谱法测定土壤中12种三嗪类除草剂的残留量

建立了加速溶剂（ASE）提取-固相萃取（SPE）净化-高效液相色谱（HPLC）同时检测土壤中12种三嗪类除草剂残留量的方法。土壤样品经过乙腈提取,氨基（NH2）固相萃取柱净化,高效液相色谱法-二极管阵列检测器（DAD）测定,外标法定量。12种三嗪类除草剂在0.02~2.00 mg·L-1范围内线性关系良好,相关系数在0.998 4~0.999 9之间,方法检出限在0.004~0.005 mg·kg-1之间。在0.02、0.04和0.10 mg·kg-1 3个浓度水平,平均添加回收率在75.2%~112.7     

噻呋酰胺在马铃薯和土壤中检测方法及残留动态研究

建立了马铃薯果实、植株和土壤样品中噻呋酰胺的分析方法,并测定了噻呋酰胺在马铃薯田中的残留消解动态及最终残留量。样品采用丙酮提取,二氯甲烷萃取,气相色谱-电子捕获检测器(GC-ECD)检测。当样品中添加的质量分数为0.001～0.05 mg·kg^-1时,平均添加回收率为85.76%～93.53%,相对标准偏差(RSD)为1.44%～7.33%,噻呋酰胺的最低检出质量浓度(LOQ)为0.001 mg·kg^-1。2009-2010年在天津和南京两地的田间残留试验结果表明:噻呋酰胺在马铃薯植株和土壤中消解较快,半衰期分别为6.08～6.30 d和4.92～7.07 d,施药后21 d的消解率均在91%以上;240 g·L^-1噻呋酰胺悬浮剂按推荐剂量480 g·hm^-2和1.5倍推荐剂量720 g·hm^-2兑水喷雾1次,在马铃薯收获期时噻呋酰胺在马铃薯果实和土壤中的最终残留量分别为质量浓度0.076 2～0.649 6 mg·kg^-1和0.020 7～0.305 0 mg·kg^-1。根据大田试验结果,建议噻呋酰胺在马铃薯中的最大残留限量标准为1.0 mg·kg^-1。     

Determination of Bicarbonate in Substrate Extracts Using Back‐Titration and the Gran Plot Approach

Abstract

The back‐titration procedure, associated with the Gran Plot method to detect the process end point, was compared with other volumetric procedures for the potentiometric acid‐base titration determination of bicarbonate and was explored as a tool for the determination of the bicarbonate content in substrates used as growing media. This procedure was compared with the second derivative approach as well as with continuous titration with standard HCl on the extract solution (“direct measurement”), until reaching pH 4.0. By using known standard samples, it was noted that the results obtained with the second derivative method were both lower and inconsistent, because of the high dilution of both the sample solution and the titrant. On the other hand, the continuous direct titration (until pH 4.0) presents positive errors due to the presence of dissolved CO₂ in the titrated solution. Although comparable in precision, the best performance and accuracy were observed for the back‐titration with the Gran Plot approach. These aspects, associated with its low cost and inherent operational simplicity, permit us to suggest the Gran Plot method as a reliable option for routine determination of bicarbonate in substrate extracts and related materials.     

Evaluation of Techniques for Determination of Molybdenum in Sugarcane Leaves

Abstract

In crops of the sugarcane, the concentrations of molybdenum (Mo) in the leaves are generally lower than 0.3 mg Mo kg^?1. These low concentrations have resulted in limitations in the methods and instruments that can be used for these analyses. The objective of this study was to evaluate three different techniques to determine the concentration of Mo in sugarcane leaves sampled in the principal sugarcane‐producing areas in Brazil. Two spectrometric techniques were evaluated by using ICP‐EAS (Inductively Coupled Plasma‐Emission Automated System) and DCP‐MEAS (Direct Coupled Plasma–Multiple Emission Automated System) and a colorimetric technique of the reaction between potassium iodide and hydrogen peroxide (KI‐H₂O₂). The techniques ICP‐EAS and KI‐H₂O₂ produced results of satisfactory accuracy and precision, whereas the DCP‐MEAS consistently overestimated the Mo concentrations in cane leaves. The KI‐H₂O₂ technique showed sensitivity 5 times greater than the ICP‐EAS, with minimum detection limits of 0.1 and 0.5 mg Mo kg^?1, respectively.