重金属砷对黄海、渤海主要几种经济贝类影响的研究进展

本文综述了重金属砷在海产品中的存在形态及其与食品安全的关系,讨论砷对几种经济贝类的生理生化影响。海水中砷含量的规定是≤0．03mg／L,对比目前国内标准中涉及到砷在贝类的限值发现,海洋贝类的无机砷限值在≤0．5mg／kg—lmg／kg,并且发现不同的标准规定值不一样。重金属对贝类的危害描述方法研究上,目前国内采用的研究...     

菲律宾蛤仔池塘养殖技术探析

菲律宾蛤仔是我国重要的海产贝类资源,菲律宾蛤仔等滩涂贝类的年产量近200万t,约占我国海水养殖总产量的20％,产量和价格呈逐年递增的趋势,在整个产业结构中的地位日益重要,已成为我国主要的海水养殖对象。由于过去菲律宾蛤仔一直依赖自然种苗进行养殖,随着养殖规模的扩大、强度的增加,苗种短缺问题日益严重,而养殖产业所用的野生型种质,潜在的病害问题严重。现就池塘养殖生产中一些需要注意的问题与大家共同探讨：     

New compounds obtained by evolution and oxidation of malvidin 3-O-glucoside in ethanolic medium

Two new colorless phenolic compounds were formed from malvidin 3- O-glucoside incubated in an ethanolic solution. Their structures were characterized by means of one- and two-dimensional NMR analysis and through electrospray ionization-mass spectrometry. As compared to the structure of the initial anthocyanin skeleton, the first new compound showed the presence of two fused five-membered rings replacing the pyran ring and of a carbonyl function on the 2-position. The first five-membered ring was shown to result from the formation of a new linkage between the B ring 6'-position and the C ring 4-position, while the second was a dihydro furan ring with an oxygenated ether linkage between the 8a-position and the 3-position. The second isolated compound was shown to have similar structure with an ethyl ether moiety in the 3-position instead of the glucose moiety. A mechanism explaining the formation of the isolated compounds involving the passage through the chalcone form of the anthocyanin and an oxidation process is proposed.     

南方养殖大菱鲆常见病害及防治技术

大菱鲆原产于欧洲沿海,分布于大西洋沿岸、北海、里海及地中海一带,属冷温性鱼类。由于它肉质细嫩鲜美,生长快可摄食人工饲料,易于集约化养殖等优点,而成为当前理想养殖品种之一。近几年,随着“北鱼南养”技术的突破,大菱鲆在南方地区逐渐掀起养殖热潮,近年来在福建沿海及广东沿海都有大面积养殖。笔者于2005年12月9日从山东省青岛市购进大菱     

兴建茶树良种繁育示范场的实践与体会

2000年由农业部投资,浙江开始在新昌县大市聚镇兴建国家级茶树良种繁育示范场.经过3年建设,示范场已初具规模,现有茶园面积1000亩,其中采穗园700亩、良种繁育苗圃200亩、种质资源圃20亩、设施茶园20亩、品种园60亩,年可提供无性系良种插穗40万kg ,无性系良种茶苗2000万株.     

Insecticide resistance in Bemisia tabaci (Homoptera: Aleyrodidae) populations from Crete

The resistance levels to alpha-cypermethrin, bifenthrin, pirimiphos-methyl, endosulfan and imidacloprid were determined in Bemisia tabaci (Gennadius) from Crete. Five B tabaci populations collected from greenhouse and outdoor crops were bioassayed and compared with a reference susceptible strain. Bemisia tabaci collected in a floriculture greenhouse exhibited the highest resistance against all insecticides: at LC50, resistance factors were 23-fold for bifenthrin, 80-fold for alpha-cypermethrin, 18-fold for pirimiphos-methyl, 58-fold for endosulfan and 730-fold for imidacloprid. A population collected on outdoor melons was more susceptible than the reference strain against all insecticides tested, suggesting the occurrence of local highly susceptible B tabaci populations in 'refugia'. In pairwise comparisons of resistance levels, correlation was observed between the LC50 values of the pyrethroid insecticides bifenthrin and alpha-cypermethrin.