非晶颗粒态玉米淀粉不同条件下酶降解活性研究

采用光学显微镜分析测试方法。对非晶颗粒态玉米淀粉不同条件下酶降解活性进行了观察和研究，结果发现，α-中温淀粉酶生物活性对非晶颗粒态淀粉作用能力高，使用较少量的酶作用于非晶颗粒淀粉。在颗粒表面上可以观察到明显变化．非晶颗粒态淀粉颗粒由于存在爆裂口。所以酶对非晶淀粉作用均从爆裂口开始，逐渐由爆裂口开始均匀扩张，颗粒模糊，最后颗粒消失，不同时间、酶量、温度对酶降解作用均产生一定影响．其中温度可明显加快酶降解速度，酶量的增加同样对酶降解产生显著影响．时间的延长也可以使非晶颗粒态淀粉逐渐降解，但变化较慢．     

Prediction of valid acidity in intact apples with Fourier transform near infrared spectroscopy

To develop nondestructive acidity prediction for intact Fuji apples, the potential of Fourier transform near infrared (FT-NIR) method with fiber optics in interactance mode was investigated. Interactance in the 800 nm to 2619 nm region was measured for intact apples, harvested from early to late maturity stages. Spectral data were analyzed by two multivariate calibration techniques including partial least squares (PLS) and principal component regression (PCR) methods. A total of 120 Fuji apples were tested and 80 of them were used to form a calibration data set. The influences of different data preprocessing and spectra treatments were also quantified. Calibration models based on smoothing spectra were slightly worse than that based on derivative spectra, and the best result was obtained when the segment length was 5 nm and the gap size was 10 points. Depending on data preprocessing and PLS method, the best prediction model yielded correlation coefficient of determination (r^2) of 0.759,low root mean square error of prediction (RMSEP) of 0.0677, low root mean square error of calibration (RMSEC) of 0.0562. The results indicated the feasibility of FT-NIR spectral analysis for predicting apple valid acidity in a nondestructive way.     

壳聚糖对玉米种子萌发和幼苗生长过程中生理活性的影响

以一定规格不同质量浓度的壳聚糖处理玉米种子，可明显提高萌发种子胚乳和幼苗中GA3、IAA含量，其对种子萌发和幼苗生长具有明显的生理调节功能。壳聚糖浓度对内源激素含量、α－淀粉酶活性、叶绿素含量及幼苗生长特性等影响浓度效应明显，其最佳作用范围为2－4g/L。     

三元混配合物[M(Hnta)(6-NO2-Bhim)2].xH2O(M=Zn,Ni,x=2.5,3.5)的合成与表征

合成了2种混配合物,通过元素分析、摩尔电导、红外光谱等测试分析,确定了配合物的组成分别为[Ni(Hnta)(6-NO2-Bhim)2].3.5H2O、[Zn(Hnta)(6-NO2-Bhim)2].2.5H2O,(Hnta=氨三乙酸阴离子;6-NO2-Bhim=6-硝基苯并咪唑),并对配合物在400～4000cm-1的主要红外光谱进行了归属.     

白芷与薏苡仁美白面膜制备

探索白芷与薏苡仁面膜的制备工艺及美白机理。通过单因素试验确定面膜成分的最优添加量,正交试验优化面膜配方,并采用酶法评价面膜样品对酪氨酸酶的抑制活性。结果显示,面膜样品对酪氨酸酶活性的抑制率为11.21%,证实白芷、薏苡仁面膜对皮肤黑色素有一定的抑制效果,具有一定美白作用。     

In vitro study of immunosuppressive effect of apoptotic cells

INTRODUCTION Apoptosis plays an important role in differen- tiation, development and pathophysiological proc- esses such as inflammation, neoplasia and autoim- mune diseases. For a long time, apoptotic cells per se and the clearance of apoptotic cells had been viewed as neutral in immune response. Recently many in- vestigations suggested that apoptotic cells actively regulate the immune response (Voll et al., 1997; Fadok et al., 1998; 2000; Byrne and Reen, 2002). Apoptotic cells release …     

关于"探索温度对淀粉酶活性的影响"的改进方案

1 问题的发现 人教版高中《生物》(试验修订版·必修)第一册实验七“探索影响淀粉酶活性的条件”是探讨不同的温度和pH值对酶活性的影响。在准备这一实验的过程中发现,完全按照教材上所提供的试剂浓度和数据,进行实验,不一定能得到预期的结果。问题出在哪里     

两种芦荟属（Aloe L．）植物花粉活性和柱头可授性的测定

文章采用TTC法和醋酸洋红染色法测定皂质芦荟[Aloe saponaric(Ait．)HaW．]和元江芦荟(Aloe yuanjiangensis Xiong，Zheng et Liu)的花粉活力。用TTC法测定的结果表明：皂质芦荟花粉的平均可育率为65．48％，元江芦荟花粉的平均可育率为52．28％醋酸洋红染色法测定的结果为：皂质芦荟花粉的平均可育率为64．02％，元江芦荟花粉的平均可育率为55．46％。用联苯胺-过氧化氢法测定柱头可授性的结果表明，二者的柱头均具较高的可授性。     

更正

综合2004年8月31日《新民晚报》和东方网2004年6月1日报道，美国波士顿大学的一个研究小组在美国专业杂志《PNAS》上发表了他们的这项研究结果。     

烷烃卤代反应选择性的讨论

根据过渡状态理论及Hammond假定的有关原理，找出烷烃卤代反应时，在控制步骤中不同卤素的过渡状态差异，得出烷烃卤代反应的选择性规律。